Scopus
EXPORT DATE:28 Mar 2021

Jiang, W., Wang, C., Meng, Y.
Fully distributed time-varying formation tracking control of linear multi-agent systems with input delay and disturbances
(2020) 146, art. no. 104814, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096665475&doi=10.1016%2fj.sysconle.2020.104814&partnerID=40&md5=193041e5eb55bd664812f94b362d75c9
AFFILIATIONS: Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Espoo, Finland; 
School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China; 
School of Physics and Astronomy, Sun Yat-Sen University, Zhuhai, Guangdong, 519082, China
ABSTRACT: This paper investigates the time-varying formation tracking (TVFT) control problem considering a constant input delay and unknown external disturbances for the general linear multi-agent system (MAS) under a directed communication graph containing a spanning tree. To achieve that, a new time-varying shape format is firstly proposed. Then, a disturbance observer (DO) is introduced to compensate the unknown disturbance effect. After that, the Artstein's model reduction technique is adopted and modified to design a state predictor in order to transform the MAS with a delayed input into a delay-free system. Fourthly, an adaptive observer (AO), which is used to estimate the designed state predictor, is proposed by using the neighbors’ information such as the inputs, time-varying shapes, DOs, AOs and relative state measurements. The convergence of closed-loop system is guaranteed by the designed algebraic Riccati equation. The whole controller requires no eigenvalue information of the Laplacian matrix of communication graph, thus is fully distributed. Finally, the effectiveness of proposed fully distributed controller (FDC) is verified by numerical examples and factors influencing FDC performances are analyzed. © 2020

Toyoda, M., Tanaka, M.
Local R-linear convergence of ADMM-based algorithm for ℓ1-norm minimization with linear and box constraints
(2020) 146, art. no. 104824, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096198548&doi=10.1016%2fj.sysconle.2020.104824&partnerID=40&md5=047d0331a30800521946e89952d3f87a
AFFILIATIONS: Department of Mechanical Systems Engineering, Tokyo Metropolitan University, Tokyo, Japan; 
Department of Statistical Inference and Mathematics, The Institute of Statistical Mathematics, Tokyo, Japan; 
RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
ABSTRACT: This paper presents an efficient algorithm based on the alternating direction method of multipliers (ADMM) for an ℓ1-norm minimization problem with linear equality and box constraints. In the ADMM iterations, sub-problems, called proximal minimizations, are solved to obtain the next updating points by exploiting closed formulae. Furthermore, the local R-linear convergence is established by analysis, focusing on the dynamical structure of the ADMM iterations. Numerical examples illustrate obtained theoretical results and the effectiveness of the algorithm. © 2020 The Authors

Kant, N., Mukherjee, R.
Orbital Stabilization of Underactuated Systems using Virtual Holonomic Constraints and Impulse Controlled Poincaré Maps
(2020) 146, art. no. 104813, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095967788&doi=10.1016%2fj.sysconle.2020.104813&partnerID=40&md5=8bddf77fc512cc83a0704bfc56a2685a
AFFILIATIONS: Department of Mechanical Engineering, Michigan State University, East Lansing, United States
ABSTRACT: The problem of orbital stabilization of underactuated mechanical systems with one passive degree-of-freedom (DOF) is revisited. Virtual holonomic constraints are enforced using a continuous controller; this results in a dense set of closed orbits on a constraint manifold. A desired orbit is selected on the manifold and a Poincaré section is constructed at a fixed point on the orbit. The corresponding Poincaré map is linearized about the fixed point; this results in a discrete linear time-invariant system. To stabilize the desired orbit, impulsive inputs are applied when the system trajectory crosses the Poincaré section; these inputs can be designed using standard techniques such as LQR. The Impulse Controlled Poincaré Map (ICPM) based control design has lower complexity and computational cost than control designs proposed earlier. The generality of the ICPM approach is demonstrated using the 2-DOF cart–pendulum and the 3-DOF tiptoebot. © 2020 Elsevier B.V.

Zwart, H., Morris, K.A., Iftime, O.V.
Optimal linear–quadratic control of asymptotically stabilizable systems using approximations
(2020) 146, art. no. 104802, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095915183&doi=10.1016%2fj.sysconle.2020.104802&partnerID=40&md5=2d33b1e9c6bfac75a27cee96e9338d43
AFFILIATIONS: Department of Applied Mathematics, University of Twente, Netherlands; 
Department of Mechanical Engineering, Eindhoven University of Technology, Netherlands; 
Department of Applied Mathematics, University of Waterloo, Canada; 
Department of Econometrics, Economics and Finance, University of Groningen, Nettelbosje 2, Groningen, 9747 AE, Netherlands
ABSTRACT: In this paper we study approximations to the infinite-horizon quadratic optimal control problem for linear systems that may be only asymptotically stabilizable. For linear systems, this issue only arises with infinite-dimensional systems. We provide sufficient conditions which guarantee when approximations to the optimal feedback result in the cost converging to the optimal cost. One technique for approximate solution of the optimal control problem is to use Newton–Kleinman iterations for the associated Riccati equation. Some new results in this direction are provided. Several important classes of systems, lightly damped second-order systems and a platoon-type system, are shown to be optimizable. Also, finding an initial stabilizing control for the Newton–Kleinman iteration can be non-trivial. The initial iterate for these classes is described. © 2020 Elsevier B.V.

Wang, K., Wang, Z., Yao, W.
Boundary feedback stabilization of quasilinear hyperbolic systems with partially dissipative structure
(2020) 146, art. no. 104815, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095754322&doi=10.1016%2fj.sysconle.2020.104815&partnerID=40&md5=02b46a731d543668ecfd683b9220e033
AFFILIATIONS: Department of Mathematics, Donghua University, Shanghai, 201620, China; 
School of Mathematical Sciences and Shanghai Key Laboratory for Contemporary Applied Mathematics, Fudan University, Shanghai, 200433, China; 
School of Mathematical Sciences, Fudan University, Shanghai, 200433, China
ABSTRACT: In this paper, we study the boundary feedback stabilization of a quasilinear hyperbolic system with partially dissipative structure. Thanks to this structure, we construct a suitable Lyapunov function which leads to the exponential stability to the equilibrium of the H2 solution. As an application, we also obtain the feedback stabilization for the Saint-Venant-Exner model under physical boundary conditions. © 2020 Elsevier B.V.

Michiels, W., Zhou, B.
On the fixed-time stabilization of input delay systems using act-and-wait control
(2020) 146, art. no. 104807, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095696660&doi=10.1016%2fj.sysconle.2020.104807&partnerID=40&md5=7ab3a975a217ada1be1fc051956718e3
AFFILIATIONS: Department of Computer Science, KU Leuven, Heverlee, B-3001, Belgium; 
Center for Control Theory and Guidance Technology, Harbin Institute of Technology, Harbin, China
ABSTRACT: We address the state feedback stabilization of linear systems with input delay using the so-called act-and-wait control strategy. The latter approach induces an analysis of the closed-loop stability based on a finite-dimensional monodromy operator, and rendering this matrix nilpotent results in fixed-time stability. We show that any controllable planar system can be stabilized in a fixed time, and the constructive proof reveals that always two isolated solutions for the corresponding controller gain co-exist. Next, for the fixed-time stabilization of general linear systems, we present both a novel numerical approach for the computation of the controller gain, and an analytic approach relying on incorporating a predictor and an appropriately defined feedback transformation in the control scheme. Several illustrations complete the presentation. © 2020 Elsevier B.V.

Zhang, S., Li, X., Xiong, J.
A stochastic maximum principle for partially observed stochastic control systems with delay
(2020) 146, art. no. 104812, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095458279&doi=10.1016%2fj.sysconle.2020.104812&partnerID=40&md5=bf77fc2e6d2ef279a132a3981aab60cd
AFFILIATIONS: School of Mathematics, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China; 
Department of Applied Mathematics, The Hong Kong Polytechnic University, Hong Kong; 
Department of Mathematics, Southern University of Science and Technology, Shenzhen, China
ABSTRACT: This paper deals with partially-observed optimal control problems for the state governed by stochastic differential equation with delay. We develop a stochastic maximum principle for this kind of optimal control problems using a variational method and a filtering technique. Also, we establish a sufficient condition without assumption of the concavity. Two examples that shed light on the theoretical results are established in the paper. In particular, in the example of an optimal investment problem with delay, its numerical simulation shows the effect of delay via a discretization technique for forward–backward stochastic differential equations (FBSDEs) with delay and anticipate terms. © 2020 Elsevier B.V.

Ortega, R., Yi, B., Romero, J.G.
Robustification of nonlinear control systems vis-à-vis actuator dynamics: An immersion and invariance approach
(2020) 146, art. no. 104811, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094210109&doi=10.1016%2fj.sysconle.2020.104811&partnerID=40&md5=7e2acdbfa74f00ab5679f24f0b742bc4
AFFILIATIONS: Departamento Académico de Sistemas Digitales, ITAM, Progreso Tizapán 1, Ciudad de México04100, Mexico; 
Department of Control Systems and Robotics, ITMO University, Kronverkskiy av. 49, Saint Petersburg, 197101, Russian Federation; 
Australian Centre for Field Robotics, The University of Sydney, Sydney, NSW  2006, Australia
ABSTRACT: In this brief note we pose, and solve, the problem of robustification of controller designs where the actuator dynamics was neglected. This situation is very common in applications where, to validate the assumption that the actuator dynamics can be neglected, a high-gain inner-loop that enforces a time-scale separation between the actuator and the plant dynamics is implemented. Of course, the injection of the high-gain has well-known deleterious effects. Moreover, a stability, and robustness, analysis of such a control configuration is usually unavailable. Our first main contribution is to provide an alternative to such a scheme, with provable robust stability properties. The second contribution is to, applying this result, propose a robustification procedure to the industry standard field-oriented control of current-fed induction motors, which is usually implemented neglecting the actuator dynamics, with no rigorous proof of stability available to date. Finally, we propose the first solution of smooth, time-invariant regulation of the dynamic model of a class of nonholonomic systems, that includes the widely popular unicycle example. Simulation examples prove the superior performance of the proposed controller compared with the existing switching and/or time-varying alternatives reported in the literature. © 2020 Elsevier B.V.

Bekiaris-Liberis, N.
Hybrid boundary stabilization of linear first-order hyperbolic PDEs despite almost quantized measurements and control input
(2020) 146, art. no. 104809, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85094163747&doi=10.1016%2fj.sysconle.2020.104809&partnerID=40&md5=0b4f701b0e142be2d68c7874300137df
AFFILIATIONS: Department of Electrical and Computer Engineering, Technical University of Crete, Chania, 73100, Greece
ABSTRACT: We develop a hybrid boundary feedback law for a class of scalar, linear, first-order hyperbolic PDEs, for which the state measurements or the control input are subject to quantization. The quantizers considered are Lipschitz functions, which can approximate arbitrarily closely typical piecewise constant, taking finitely many values, quantizers. The control design procedure relies on the combination of two ingredients—A nominal backstepping controller, for stabilization of the PDE system in the absence of quantization, and a switching strategy, which updates the parameters of the quantizer, for compensation of the quantization effect. Global asymptotic stability of the closed-loop system is established through utilization of Lyapunov-like arguments and derivation of solutions’ estimates, providing explicit estimates for the supremum norm of the PDE state, capitalizing on the relation of the resulting, nonlinear PDE system (in closed loop) to a certain, integral delay equation. A numerical example is also provided to illustrate, in simulation, the effectiveness of the developed design. © 2020 Elsevier B.V.

Zheng, J., Zhu, G.
ISS-like estimates for nonlinear parabolic PDEs with variable coefficients on higher dimensional domains
(2020) 146, art. no. 104808, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85093669360&doi=10.1016%2fj.sysconle.2020.104808&partnerID=40&md5=ff06bff64087d6ae3161a26493815520
AFFILIATIONS: School of Mathematics, Southwest Jiaotong University, Chengdu, Sichuan, 611756, China; 
Department of Electrical Engineering, Polytechnique Montréal, P.O. Box 6079, Station Centre-Ville, Montreal, QCH3T 1J4, Canada
ABSTRACT: This paper presents a maximum principle-based approach in the establishment of ISS-like estimates for a class of nonlinear parabolic partial differential equations (PDEs) with variable coefficients and different types of nonlinear boundary conditions on higher dimensional domains. Comparing with the existing literature, the ISS-like estimates established in this paper are independent of the nonlinear terms of the PDEs. Technical development on ISS analysis of the considered systems is detailed, and an example of establishing ISS-like estimates for a nonlinear parabolic equation with, respectively, a nonlinear Robin boundary condition and a nonlinear Dirichlet boundary condition is provided to illustrate the application of the developed method. © 2020 Elsevier B.V.

Arevalo-Castiblanco, M.F., Tellez-Castro, D., Sofrony, J., Mojica-Nava, E.
Adaptive synchronization of heterogeneous multi-agent systems: A free observer approach
(2020) 146, art. no. 104804, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092692435&doi=10.1016%2fj.sysconle.2020.104804&partnerID=40&md5=c0ab905ee41665de32ba333e6565f0d0
AFFILIATIONS: Department of Electrical and Electronic Engineering, Universidad Nacional de Colombia, Colombia; 
Department of Mechanical and Mechatronic Engineering, Universidad Nacional de Colombia, Colombia
ABSTRACT: Adaptive synchronization protocols for heterogeneous multi-agent network are investigated. The interaction between each of the agents is carried out through a directed graph. We highlight the lack of communication between agents and the presence of uncertainties in each system among the conventional problems that can arise in cooperative networks. Two methodologies are presented to deal with the uncertainties: A strategy based on robust optimal control and a strategy based on neural networks. Likewise, an input estimation methodology is designed to face the disconnection that any agent may present on the network. These control laws can guarantee synchronization between agents even when there are disturbances or no communication from any agent. Stability and boundary analyzes are performed. Cooperative cruise control simulation results are shown to validate the performance of the proposed control methods. © 2020 Elsevier B.V.

Morris, K.A.
Optimal output estimation for infinite-dimensional systems with disturbances
(2020) 146, art. no. 104803, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092430211&doi=10.1016%2fj.sysconle.2020.104803&partnerID=40&md5=667dc39cffc71ec3bb0b7290c9daaf58
AFFILIATIONS: Department of Applied Mathematics, University of Waterloo, WaterlooON  N2L 3G1, Canada
ABSTRACT: Often only some aspect of the state needs to be estimated, not the whole state. This problem is referred to as output estimation Also, there may be disturbances other than Gaussian noise. In such situations a Kalman filter may not be the most appropriate estimator. Two alternative approaches are to reduce the H2 or H∞ output estimation error. A derivation of both types of estimators for output estimation of linear infinite-dimensional systems is provided. A practical framework for constructing finite-dimensional estimators that provide performance arbitrarily close to optimal is developed. © 2020

Tuong, T.D., Nguyen, N.N., Yin, G.
Longtime behavior of a class of stochastic tumor-immune systems
(2020) 146, art. no. 104806, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092428271&doi=10.1016%2fj.sysconle.2020.104806&partnerID=40&md5=5d5e83caf5a07efd00d4c3865caa0336
AFFILIATIONS: Faculty of Basic Sciences, Ho Chi Minh University of Transport, 2 Vo Oanh, Ho Chi Minh, Viet Nam; 
Department of Mathematics, University of Connecticut, Storrs, CT  06269, United States
ABSTRACT: This paper focuses on a class of stochastic systems describing tumor-immune dynamics. The underlying systems are given by stochastic differential equations. Our study concentrates on longtime behavior. A sharp threshold-type condition is obtained, which characterizes the dynamic systems, and pinpoints sufficient and nearly necessary conditions for persistence and extinction. Examples and numerical results are provided to illustrate our findings. © 2020 Elsevier B.V.

Heintz, C., Hoagg, J.B.
Formation control for agents modeled with extended unicycle dynamics that includes orientation kinematics on SO(m) and speed constraints
(2020) 146, art. no. 104784, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092406480&doi=10.1016%2fj.sysconle.2020.104784&partnerID=40&md5=c8a9e3b7c211d22badc380d4cadc5b92
AFFILIATIONS: Department of Mechanical Engineering, The University of Kentucky, Lexington, KY  40506-0503, United States
ABSTRACT: We present a formation control algorithm for agents with extended unicycle dynamics that include orientation kinematics on SO(m), first-order uncertain speed dynamics, and hard constraints on speed. The desired interagent positions are expressed in a leader-fixed coordinate frame. Thus, the desired interagent positions vary in time as the leader-fixed frame rotates. We assume that each agent has relative-position feedback of its neighbor agents, where the neighbor sets are such that the interagent communication (i.e., feedback) structure is a quasi-strongly connected directed graph. We assume that at least one agent (which is a center vertex of the graph) has access to a measurement its position relative to the leader. The main analytic results show that for almost all initial conditions, each agent converges to its desired relative position with the leader and the other agents, and each agent's speed satisfies the speed constraints for all time. We also present an adaptive extension of the formation control algorithm that addresses uncertain speed dynamics, which are parameterized as an unknown linear combination of known basis functions. Finally, we present numerical simulations to demonstrate both the non-adaptive and adaptive formation control methods. © 2020 Elsevier B.V.

Kwon, S.-H., Ahn, H.-S.
Generalized weak rigidity: Theory, and local and global convergence of formations
(2020) 146, art. no. 104800, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092333366&doi=10.1016%2fj.sysconle.2020.104800&partnerID=40&md5=d7b71fcd24d5d3fe92d7f675f5edd582
AFFILIATIONS: School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea
ABSTRACT: This paper proposes a generalized weak rigidity theory, and aims to apply the theory to formation control problems with a gradient descent flow law. The generalized weak rigidity theory is utilized in order to characterize desired rigid formations by a general set of pure inter-agent distances and subtended angles, where the rigid formation shape with distances and subtended angles is determined up to translations and rotations (if the formation shape is composed of only subtended angles, then it is determined up to translations, rotations and, additionally, scaling factors). As the first result of its applications, this paper provides analysis of local exponential stability for a formation control system with pure distance/angle or only angle constraints in 2- and 3-dimensional spaces. Then, as the second result, it is shown that if there are three agents in 2-dimensional space then almost global exponential stability is ensured for a formation control system with pure distance/angle or only angle constraints. © 2020 Elsevier B.V.

Zakwan, M., Ahmed, S.
Dwell-time based stability analysis and L2 control of LPV systems with piecewise constant parameters and delay
(2020) 145, art. no. 104805, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092257878&doi=10.1016%2fj.sysconle.2020.104805&partnerID=40&md5=60c7523bd0feef55cbd71f1511d9bcdc
AFFILIATIONS: Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, 1015, Switzerland; 
Department of Mechanical and Process Engineering, University of Kaiserslautern, Kaiserslautern, 67663, Germany
ABSTRACT: Dwell-time based stability conditions for a class of LPV systems with piecewise constant parameters under time-varying delay are derived using clock-dependent Lyapunov–Krasovskii functional. Sufficient synthesis conditions for clock-dependent gain-scheduled state-feedback controllers ensuring L2-performance are also provided. Several numerical and practical examples, to illustrate the efficacy of the results, are given. © 2020 Elsevier B.V.

Loxton, R., Lin, Q., Padula, F., Ntogramatzidis, L.
Minimizing control volatility for nonlinear systems with smooth piecewise-quadratic input signals
(2020) 145, art. no. 104797, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092110579&doi=10.1016%2fj.sysconle.2020.104797&partnerID=40&md5=988bd8fa931d3db6c38799c97a3a3d99
AFFILIATIONS: School of Electrical Engineering, Computing, and Mathematical Sciences, Curtin University, Perth, Australia
ABSTRACT: We consider a class of nonlinear optimal control problems in which the aim is to minimize control variation subject to an upper bound on the system cost. This idea of sacrificing some cost in exchange for less control volatility—thereby making the control signal easier and safer to implement—is explored in only a handful of papers in the literature, and then mainly for piecewise-constant (discontinuous) controls. Here we consider the case of smooth continuously differentiable controls, which are more suitable in some applications, including robotics and motion control. In general, the control signal's total variation—the objective to be minimized in the optimal control problem—cannot be expressed in closed form. Thus, we introduce a smooth piecewise-quadratic discretization scheme and derive an analytical expression, which turns out to be rational and non-smooth, for computing the total variation of the approximate piecewise-quadratic control. This leads to a non-smooth dynamic optimization problem in which the decision variables are the knot points and shape parameters for the approximate control. We then prove that this non-smooth problem can be transformed into an equivalent smooth problem, which is readily solvable using gradient-based numerical optimization techniques. The paper includes a numerical example to verify the proposed approach. © 2020 Elsevier B.V.

Meng, T., Lin, Z.
Leader-following almost output consensus for linear multi-agent systems with disturbance-affected unstable zero dynamics
(2020) 145, art. no. 104787, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092057708&doi=10.1016%2fj.sysconle.2020.104787&partnerID=40&md5=5a217b7e298f1dcd56c7889c9ed9b8d5
AFFILIATIONS: Charles L. Brown Department of Electrical and Computer Engineering, University of Virginia, P.O. Box 400743, Charlottesville, VA  22904-4743, United States
ABSTRACT: In this paper, we formulate and investigate the leader-following almost output consensus problem for linear multi-agent systems with disturbance affected unstable zero dynamics. Conditions on the communication topology, agent dynamics and the way the disturbances affect the zero dynamics are established under which low-and-high gain based consensus protocols are designed. These protocols are shown to achieve leader-following almost output consensus, that is, output consensus of the system can be achieved to an arbitrary level of accuracy with the states remain bounded in the absence of the disturbances, and when the system is operating in output consensus within the desired accuracy, the L2-gain from the disturbances to the difference between each follower agent's output with and without the disturbances from the same initial condition can be made arbitrarily small. A numerical example is shown to verify the theoretical results. © 2020 Elsevier B.V.

Monge, A., Zuazua, E.
Sparse source identification of linear diffusion–advection equations by adjoint methods
(2020) 145, art. no. 104801, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092043848&doi=10.1016%2fj.sysconle.2020.104801&partnerID=40&md5=4a5216d49ed36c1e516f88d659ced4ae
AFFILIATIONS: Chair in Applied Analysis, Alexander von Humboldt–Professorship, Department of Mathematics, Friedrich-Alexander-Universität, Erlangen-NürnbergErlangen, 91058, Germany; 
Chair of Computational Mathematics, Fundación Deusto, Bilbao, Basque Country  48007, Spain; 
Departamento de Matemáticas, Universidad Autónoma de Madrid, Madrid, 28049, Spain
ABSTRACT: We present an algorithm for the time-inversion of diffusion–advection equations, based on the adjoint methodology. Given a final state distribution our main aim is to recover sparse initial conditions, constituted by a finite combination of Kronecker deltas, identifying their location and mass. We discuss the strengths of the adjoint machinery and the difficulties that are to be faced, in particular when the diffusivity coefficient or the time horizon is large. © 2020 Elsevier B.V.

Liu, R., Mei, L., Lu, J.
K-memory-embedded insertion mechanism for opacity enforcement
(2020) 145, art. no. 104785, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091984407&doi=10.1016%2fj.sysconle.2020.104785&partnerID=40&md5=1577403a897af0394737a7fe723869d9
AFFILIATIONS: School of Cyber Science and Engineering, Southeast University, Nanjing, 210096, China; 
Department of Systems Science, School of Mathematics, Southeast University, Nanjing, 210096, China; 
School of Information Science and Engineering, Chengdu University, Chengdu, 610106, China
ABSTRACT: Opacity is a privacy property which aims to determine whether the “secret” of a system can be deduced by an outside intruder. In this paper, we investigate the enforcement of opacity using insertion functions which insert additional events if necessary to modify the output of the system. Inspired by the existing insertion mechanisms, we propose a mechanism named k-memory-embedded insertion mechanism for the enforcement of opacity. In our k-memory-embedded insertion mechanism, the insertion functions are determined based on the knowledge of system's exact states and the stored next sequence of events with length k. Especially, we define the property of ik-E-enforceability that a k-memory-embedded insertion function needs to satisfy for opacity enforcement, and further construct a verifier to determine whether a given opacity notion of the system is ik-E-enforceable or not. Our mechanism improves the embedded insertion mechanism by applying to a broader class of systems. Also, we improve the k-memory insertion mechanism by requiring a smaller number of consecutive events which need to be stored. © 2020 Elsevier B.V.

Bisoffi, A., De Persis, C., Tesi, P.
Data-based stabilization of unknown bilinear systems with guaranteed basin of attraction
(2020) 145, art. no. 104788, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091746592&doi=10.1016%2fj.sysconle.2020.104788&partnerID=40&md5=a057a2b0109bc3152c39f99fb80ff883
AFFILIATIONS: ENTEG and the J.C. Willems Center for Systems and Control, University of Groningen, 9747 AG Groningen, Netherlands; 
DINFO, University of Florence, Florence, 50139, Italy
ABSTRACT: Motivated by the goal of having a building block in the design of direct data-driven controllers for nonlinear systems, we show how, for an unknown discrete-time bilinear system, the data collected in an offline open-loop experiment enable us to design a feedback controller and provide a guaranteed underapproximation of its basin of attraction. Both can be obtained by solving a linear matrix inequality for a fixed scalar parameter, and possibly iterating on different values of that parameter. The results of this data-based approach are compared with the ideal case when the model is known perfectly. © 2020 The Authors

Wijnbergen, P., Besselink, B.
Existence of decentralized controllers for vehicle platoons: On the role of spacing policies and available measurements
(2020) 145, art. no. 104796, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091679134&doi=10.1016%2fj.sysconle.2020.104796&partnerID=40&md5=35674a703fe969944dae7245809117a7
AFFILIATIONS: Bernoulli Institute for Mathematics, Computer Science and Artificial Intelligence, University of Groningen, Groningen, Netherlands
ABSTRACT: This paper considers the decentralized control of vehicle platoons and gives necessary and sufficient conditions for the existence of such controllers. Specifically, we consider a predecessor–follower control structure in which a vehicle is responsible for tracking of a desired spacing policy with respect to its predecessor, regardless of the control action of the latter. By building on geometric control theory, this perspective enables to state necessary and sufficient conditions for the existence of decentralized controllers that guarantee tracking and asymptotic stabilization of a general (linear) spacing policy. For a given spacing policy, these conditions fully characterize the measurements that are required to achieve the desired control objectives. Furthermore, in this geometric framework with the predecessor–follower structure, string stability properties are shown to be the result of the spacing policy rather than the details of control design. As an example, we fully characterize all state and output feedback controllers that achieve the control goals for the constant headway spacing policy. The results are illustrated through simulations. © 2020 The Authors

Logemann, H.
Some spectral properties of operator-valued positive-real functions
(2020) 145, art. no. 104786, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091628105&doi=10.1016%2fj.sysconle.2020.104786&partnerID=40&md5=3a5529755152e10344069b419ba023a6
AFFILIATIONS: Department of Mathematical Sciences, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom
ABSTRACT: We consider operator-valued positive-real functions H and show that the intersections of the point, continuous and residual spectra of H(s) with the imaginary axis do not depend on s. In particular, if H is positive real and H(z) is invertible for some z in the open right-half plane, then H(s) is invertible for all s in the open right-half plane. Furthermore, we prove that the eigenspace of H(s) corresponding to an imaginary eigenvalue does not depend on s. It is also shown that the intersection of the numerical range of H(s) with the imaginary axis is independent of s. Finally, we prove that, under suitable assumptions, application of a “sufficiently positive-real” static output feedback to a positive-real transfer function leads to a strictly positive-real closed-loop system. © 2020 Elsevier B.V.

De Lara, M., Gajardo, P., Vicencio, D.
Comparison theorem for viability kernels via conic preorders
(2020) 145, art. no. 104799, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091567999&doi=10.1016%2fj.sysconle.2020.104799&partnerID=40&md5=56db8b285b1a0b2338c6cc28801f049f
AFFILIATIONS: CERMICS, Ecole des Ponts, Marne-la-Vallée, France; 
Departamento de Matemática, Universidad Técnica Federico Santa María, Avenida España, Valparaíso, 1680, Chile
ABSTRACT: In natural resource management, decision-makers often aim at maintaining the state of the system within a desirable set for all times. For instance, fisheries management procedures include keeping the spawning stock biomass over a critical threshold. Another example is given by the peak control of an epidemic outbreak that encompasses maintaining the number of infected individuals below medical treatment capacities. In mathematical terms, one controls a dynamical system. Then, keeping the state of the system within a desirable set for all times is possible when the initial state belongs to the so-called viability kernel. We introduce the notion of conic quasimonotonicity reducibility. With this property, we provide a comparison theorem by inclusion between two viability kernels, corresponding to two control systems in the infinite horizon case. We also derive conditions for equality. We illustrate the method with a model for the biocontrol of a vector-transmitted epidemic. © 2020

Li, H., Dou, W.
On reducible state variables of logical control networks
(2020) 145, art. no. 104798, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091343254&doi=10.1016%2fj.sysconle.2020.104798&partnerID=40&md5=8a1cb351170046acedadea79966fbfd2
AFFILIATIONS: School of Mathematics and Statistics, Shandong Normal University, Jinan, 250014, China
ABSTRACT: Reducible state variables are important for the study of reduced-order observer and control design of logical control networks (LCNs). This paper studies the number of reducible state variables of LCNs. Based on the upper bound of reducible state variables, several sufficient/necessary conditions are presented for the number of reducible state variables. In addition, using the regular subspace theory, the coordinate transformation as well as the swap matrix are constructed, and some new criteria are proposed to calculate reducible state variables. © 2020 Elsevier B.V.

Wen, L., Tao, G., Song, G.
Higher-order tracking properties of nonlinear adaptive control systems
(2020) 145, art. no. 104781, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091069951&doi=10.1016%2fj.sysconle.2020.104781&partnerID=40&md5=b03316796c46016a79affe4c9950f592
AFFILIATIONS: College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; 
Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA  22903, United States
ABSTRACT: While the asymptotic output tracking property has been proven for many nonlinear adaptive control systems, their higher-order output tracking property has not been reported. In this paper, the higher-order derivative convergence of the output tracking error e(t) is studied for nonlinear adaptive control systems using the feedback linearization design. It is proven that not only each error component ej(t) from e(t)=[e1(t),e2(t),…,em(t)]T converges to zero asymptotically but also its up to kth-order time-derivative ej(k)(t) converges to zero, for k=1,2,…,ρj, where ρj, j=1,2,…,m, are the control relative degrees of the nonlinear system with m inputs. © 2020 Elsevier B.V.

Holta, H., Aamo, O.M.
Adaptive set-point regulation of linear n+1 hyperbolic systems with uncertain affine boundary condition using collocated sensing and control
(2020) 145, art. no. 104777, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090880103&doi=10.1016%2fj.sysconle.2020.104777&partnerID=40&md5=db17e4db5cf4704c48cbdfd280cf2973
AFFILIATIONS: Department of Engineering Cybernetics. Norwegian University of Science and Technology, Trondheim, N-7491, Norway
ABSTRACT: We solve an adaptive control problem for n+1 hyperbolic systems using collocated sensing and control, extending recent results for adaptive control of 2×2 systems and systems with non-collocated sensing and control. The boundary condition has an affine form with both unknown reflective and additive parameters and can be used to model well–reservoir interactions in oil and gas drilling where properties of the reservoir are unknown. Boundedness of the system states in the L2-norm, and convergence to a steady state profile satisfying a control objective relevant to the drilling application, are proved. The state estimation error is shown to converge to zero in the L2-norm and one of the boundary parameter estimates (modelling the reservoir pressure in the drilling application) is shown to converge to the true parameter value. The design is illustrated in a simulation example. © 2020 The Author(s)

Wu, X.-H., Feng, H., Guo, B.-Z.
Output feedback stabilization for 1-D wave equation with variable coefficients and non-collocated observation
(2020) 145, art. no. 104780, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090716583&doi=10.1016%2fj.sysconle.2020.104780&partnerID=40&md5=e0396ca887437f7ac470659f4f835aee
AFFILIATIONS: School of Mathematical Sciences, Shanxi University, Taiyuan, Shanxi, 030006, China; 
School of Mathematics and Physics, North China Electric Power University, Beijing, 102206, China
ABSTRACT: In this paper, we consider exponential stabilization for a 1-D wave equation with variable coefficients and Neumann boundary actuation. A novel transformation is constructed to convert the wave equation into an equation of the same type with constant coefficient and low order term. By using the backstepping approach, we design a state observer via non-collocated boundary displacement and velocity measurement. An observer based output feedback is then designed using the backstepping gain to stabilize the system exponentially. The well-posedness and the exponential stability of the closed-loop system are proved. As an illustration, some numerical simulations are presented. © 2020 Elsevier B.V.

Benvenuti, L.
An upper bound on the dimension of minimal positive realizations for discrete time systems
(2020) 145, art. no. 104779, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090574138&doi=10.1016%2fj.sysconle.2020.104779&partnerID=40&md5=89434e610707ab9bbf6732f84614ef96
AFFILIATIONS: Dipartimento di Ingegneria informatica, automatica e gestionale “A. Ruberti”, Sapienza Università di Roma, via Ariosto 25, Roma, 00185, Italy
ABSTRACT: In some applications one is interested in having a state–space realization with nonnegative matrices (positive realization) of a given transfer function and it is known that such a realization may have a dimension strictly larger than the order of the transfer function itself. Moreover, in most cases, it is desirable to have a realization with minimal dimension. Unfortunately, it is not known, to date, how to determine in general the minimum dimension of a positive realization and only lower and upper bounds to it are available. This letter provides an upper bound on the dimension of a minimal positive realization for transfer functions with simple poles. This is a considerable improvement on an earlier upper bound in which only transfer functions with real poles were considered. © 2020 Elsevier B.V.

Wang, B., Feng, J.-E.
Detectability of Boolean networks with disturbance inputs
(2020) 145, art. no. 104783, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090558303&doi=10.1016%2fj.sysconle.2020.104783&partnerID=40&md5=41f18b830e0418eb110df4da9fb4e1e0
AFFILIATIONS: School of Mathematics, Shandong University, Jinan, Shandong  250100, China
ABSTRACT: This paper concerns the detectability problem of Boolean networks with disturbance inputs using the semi-tensor product approach. Detectability like observability describes the ability of the system state to be indirectly measured, which is an important issue to be considered in designing the controller. Four kinds of detectability, weak, weak periodical, strong and strong periodical ones, are defined. A systematic matrix method is developed and formed via three tools respectively called detection operator, detection matrix and detectable set. The former is used to generate the state estimate at each time. The other two are derived from the dynamics of the system and produce several necessary and sufficient conditions for checking detectability. Two examples are provided to demonstrate the effectiveness of the main results. Furthermore, how the proposed methods can be applied and extended to other kinds of disturbance is briefly discussed. © 2020 Elsevier B.V.

Yamashita, Y., Adachi, N., Nonaka, R., Kobayashi, K.
Design of global smooth implicit control Lyapunov function for multiple-integrator system with input constraint
(2020) 145, art. no. 104776, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090401459&doi=10.1016%2fj.sysconle.2020.104776&partnerID=40&md5=c5859fbd918a8f7568ba0b968cb9c13e
AFFILIATIONS: Faculty of Information Science and Technology, Hokkaido University, N14W9, Kita-ku, Sapporo, 060-0814, Japan; 
Uematsu Electric Co., Ltd., 230-50, Kyowa-cho, Akabira, 079-1101, Japan; 
Graduate School of Information Science and Technology, Hokkaido University, N14W9, Kita-ku, Sapporo, 060-0814, Japan
ABSTRACT: In this study, we propose a new method to design a smooth implicit control Lyapunov function and a smooth control law for a multi-integrator system with an input constraint. The proposed controller is almost linear near the origin, and it tends to a homogeneous controller of the previous implicit Lyapunov function methods as the state goes to infinity. The proposed method can be used for the backstepping method with a restricted virtual input, which is a nonlinear function of the state, and the desired virtual input is designed as a bounded function. Furthermore, we apply our method to the control of a magnetic levitation system, and a simulation result presents the advantage of the proposed method. © 2020 The Authors

Sklyar, G.M., Woźniak, J., Firkowski, M.
Exact observability conditions for Hilbert space dynamical systems connected with Riesz basis of divided differences
(2020) 145, art. no. 104782, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090401091&doi=10.1016%2fj.sysconle.2020.104782&partnerID=40&md5=8532830bb866ac9c32ebd37895672834
AFFILIATIONS: Institute of Mathematics, University of Szczecin, Wielkopolska 15, 70-451, Szczecin, Poland; 
School of Mathematics, West Pomeranian University of Technology Szczecin, Piastów 48Szczecin, 70-311, Poland
ABSTRACT: In the paper we consider the problem of exact observability of a general class of distributed parameter systems in Hilbert spaces. We show that under some conditions on asymptotic behavior of the spectrum of the differential operator the system is not exact observable in default topologies, and find a stronger topology for state observation for which the system becomes exactly observable. We illustrate this result with a vibrating clamped-free Timoshenko beam model. © 2020 Elsevier B.V.

Malzer, T., Rams, H., Schöberl, M.
On structural invariants in the energy-based in-domain control of infinite-dimensional port-Hamiltonian systems
(2020) 145, art. no. 104778, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090291419&doi=10.1016%2fj.sysconle.2020.104778&partnerID=40&md5=2b9c1a312576a0645f242e5f76ec65be
AFFILIATIONS: Institute of Automatic Control and Control Systems Technology, Johannes Kepler University Linz, Austria; 
B&R Industrial Automation GmbH, B&R Straße 1, Eggelsberg, 5142, Austria
ABSTRACT: This contribution deals with energy-based in-domain control of systems governed by partial differential equations with spatial domain up to dimension two. We exploit a port-Hamiltonian system description based on an underlying jet-bundle formalism, where we restrict ourselves to systems with 2nd-order Hamiltonian. A certain power-conserving interconnection enables the application of a dynamic control law based on structural invariants. Furthermore, we use various examples such as beams and plates with in-domain actuation to demonstrate the capability of our approach. © 2020 Elsevier B.V.

Lopez-Ramirez, F., Efimov, D., Polyakov, A., Perruquetti, W.
Finite-time and fixed-time input-to-state stability: Explicit and implicit approaches
(2020) 144, art. no. 104775, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090183113&doi=10.1016%2fj.sysconle.2020.104775&partnerID=40&md5=3966fa6fad42d9d856bae9fda314331e
AFFILIATIONS: Inria, Univ. Lille, CNRS, UMR 9189 - CRIStAL, Lille, F-59000, France; 
ITMO University, 49 Kronverkskiy av., 197101 Saint Petersburg, Russian Federation; 
École Centrale de Lille, CNRS, UMR 9189 - CRIStAL, Cité Scientifique, 59651 Villeneuve d'Ascq Cedex, France
ABSTRACT: The present article gathers the analysis of non-asymptotic convergence rates (finite-time and fixed-time) with the property of input-to-state stability. Theoretical tools to determine this joint property are presented for the case where an explicit ISS Lyapunov function is known, and when it remains in implicit form (e.g. as a solution of an algebraic equation). For the case of finite-time input-to-state stability, necessary and sufficient conditions are given whereas for the fixed-time case only a sufficient condition is obtained. Academic examples and numerical simulations support the obtained results. © 2020 Elsevier B.V.

Farivarnejad, H., Berman, S.
Design and analysis of a potential-based controller for safe robot navigation in unknown GPS-denied environments with strictly convex obstacles
(2020) 144, art. no. 104772, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090155390&doi=10.1016%2fj.sysconle.2020.104772&partnerID=40&md5=d6fcc8645393a35120f1acb7165eed9c
AFFILIATIONS: School for Engineering of Matter, Transport and Energy, Arizona State University (ASU), Tempe, AZ  85287, United States
ABSTRACT: In this paper, we propose an obstacle avoidance controller for a disk-shaped holonomic robot with double-integrator dynamics and local sensing. The control objective is for the robot to converge to a target velocity while avoiding collisions with strictly convex obstacles in an unbounded environment. We assume that the robot has no information about the location and geometry of the obstacles, has no localization capabilities, and can only measure its own velocity and its relative position vector to the closest point on any obstacles in its sensing range. We first propose a potential-based controller for the case with a single obstacle, and we prove that the robot safely navigates past the obstacle and attains the desired velocity. For the case with multiple obstacles, we propose a switching control scheme in which the robot applies the single-obstacle controller for the closest obstacle at each instant. We investigate the correctness of this switching control law and demonstrate the absence of local stable equilibrium points that would trap the robot. We validate our analytical results through simulations of a robot that uses the proposed controllers to successfully navigate through an environment with strictly convex obstacles of various shapes and sizes. © 2020 Elsevier B.V.

Zhang, J., Sun, J.
Optimal cooperative multiple-attackers scheduling against remote state estimation of cyber-physical systems
(2020) 144, art. no. 104771, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090049658&doi=10.1016%2fj.sysconle.2020.104771&partnerID=40&md5=788ad0442caf865e6eed3d9c244cb6ac
AFFILIATIONS: School of Mathematical Sciences, Tongji University200092, China; 
Institute for Intelligent Systems, Faculty of Engineering and the Built Environment, University of Johannesburg, South Africa
ABSTRACT: In this paper, we consider multiple-attackers schedule problem against remote state estimation in cyber-physical systems (CPSs). Compared with the existing results in which only one type of attacker is considered, we aim to address the case that Denial-of-Service (DoS) attacker and linear deception attacker exist in CPSs simultaneously. With limited resource, the two attackers have to, cooperatively, decide whether to launch or not and which type of attack to inject at each time and further determine optimal schedule over a finite time horizon to degrade the performance of system at the largest. First of all, the evolutions of remotely estimated state and error covariance under an attack schedule are derived. Next, we regard average error and terminal error as performance indexes of systems, respectively, and analyze their intrinsic properties to find out the corresponding optimal attack scheduling schemes. Finally, an example is given to show the effectiveness of our theoretical results. © 2020 Elsevier B.V.

Ji, H., Xi, F.
Stationary distribution of stochastic population dynamics in state-dependent random environments
(2020) 144, art. no. 104774, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090024737&doi=10.1016%2fj.sysconle.2020.104774&partnerID=40&md5=53468705186163b098911a71f3c57928
AFFILIATIONS: School of Mathematics and Statistics, Beijing Institute of Technology, Beijing, 100081, China; 
School of Mathematics and Computer Science, Shanxi Normal University, Linfen, Shanxi Province, 041000, China
ABSTRACT: This work studies the stationary distribution of stochastic Lotka–Volterra population dynamics in state-dependent random environments. We first use the stochastic comparison approach to handle the difficulty caused by the state-dependent regime-switching. Then the ergodic property and positive recurrence are investigated by the theory of M-matrix under small perturbation. The mean of the stationary distribution is also estimated. At last, the main results are illustrated by a numerical example. © 2020 Elsevier B.V.

Roy, S., Kosmatopoulos, E.B., Baldi, S.
On vanishing gains in robust adaptation of switched systems: A new leakage-based result for a class of Euler–Lagrange dynamics
(2020) 144, art. no. 104773, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089835344&doi=10.1016%2fj.sysconle.2020.104773&partnerID=40&md5=7f6422e01c7c1c282a771791878d554a
AFFILIATIONS: Robotics Research Center, International Institute of Information Technology Hyderabad, Hyderabad, India; 
Delft Center for Systems and Control (DCSC), Technische Universiteit Delft (TU Delft), Delft, Netherlands; 
School of Mathematics, Southeast University, Nanjing, China; 
Department of Electrical and Computer Engineering, Democritus University of Thrace, Xanthi, Greece; 
Information Technologies Institute, Centre of Research & Technology - Hellas (ITI-CERTH), Thessaloniki, Greece
ABSTRACT: In the presence of unmodelled dynamics and uncertainties with no a priori constant bounds, conventional robust adaptation strategies for switched systems cannot allow the control gains of inactive subsystems to remain constant during inactive intervals: vanishing gains are typically required in order to prove bounded stability. As a consequence, these strategies, known in literature as leakage-based adaptive methods, might introduce poor transients at each switching instant. Leakage-based adaptive control becomes even more problematic in the switched nonlinear case, where non-conservative state-dependent upper bounds for uncertainties and unmodelled dynamics are required. This work shows that, for a class of switched Euler–Lagrange systems, such difficulties can be mitigated: a novel leakage-based stable mechanism is introduced which allows the gains of inactive subsystems to remain constant. At the same time, unmodelled dynamics and uncertainties with no a priori bounds can be handled by a quadratic state-dependent upper bound structure that reduces conservativeness as compared to state-of-the-art structures. The proposed design is validated analytically and its performance is studied in simulation with a pick-and-place robotic manipulator example. © 2020 Elsevier B.V.

Augner, B., Laasri, H.
Exponential stability for infinite-dimensional non-autonomous port-Hamiltonian Systems
(2020) 144, art. no. 104757, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089819819&doi=10.1016%2fj.sysconle.2020.104757&partnerID=40&md5=2349f608e33904ed1141bda65bfa0d1d
AFFILIATIONS: Technische Universität Darmstadt, Fachbereich Mathematik, Mathematische Modellierung und Analysis, Schlossgartenstraße 7, Darmstadt, 64289, Germany; 
Arbeitsgruppe Funktionalanalysis, Fakultät für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, Gaußstraße 20, Wuppertal, 42119, Germany
ABSTRACT: We study the non-autonomous version of an infinite-dimensional linear port-Hamiltonian system on an interval [a,b]. Employing abstract results on evolution families, we show C1-well-posedness of the corresponding Cauchy problem, and thereby existence and uniqueness of classical solutions for sufficiently regular initial data. Further, we demonstrate that a dissipation condition in the style of the dissipation condition sufficient for uniform exponential stability in the autonomous case also leads to a uniform exponential decay rate of the energy in this non-autonomous setting. © 2020 Elsevier B.V.

Frankowska, H., Osmolovskii, N.P.
Distance estimates to feasible controls for systems with final point constraints and second order necessary optimality conditions
(2020) 144, art. no. 104770, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089813429&doi=10.1016%2fj.sysconle.2020.104770&partnerID=40&md5=891fcfae7ae9452e60e8c63f6a5354c4
AFFILIATIONS: CNRS, Institut de Mathématiques de Jussieu - Paris Rive Gauche, Sorbonne Université, Case 247, 4 Place Jussieu, Paris, 75252, France; 
Systems Research Institute, Polish Academy of Sciences, ul. Newelska 6, Warszawa, 01-447, Poland
ABSTRACT: We prove an inverse mapping theorem on a metric space of controls that allows to “control” final points of trajectories of a nonlinear system. More precisely, our result provides local distance estimates of arbitrary controls from feasible ones. As an application we derive second-order necessary optimality conditions for L1-local minima for the Mayer optimal control problem with a general control constraint U⊂Rm, state constraints described by inequalities and final point constraints, possibly having empty interior. Thanks to this inverse mapping theorem we first get a second-order variational inequality as a necessary optimality condition. Then the separation theorem leads in a straightforward way to second-order necessary conditions. © 2020 Elsevier B.V.

Tang, Y., Qu, G., Li, N.
Semi-global exponential stability of augmented primal–dual gradient dynamics for constrained convex optimization
(2020) 144, art. no. 104754, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089740317&doi=10.1016%2fj.sysconle.2020.104754&partnerID=40&md5=32f4e9ba7e0a36cfb365d5b3473664b6
AFFILIATIONS: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA  02138, United States; 
Department of Computing and Mathematical Sciences, California Institute of Technology, Pasadena, CA  91125, United States
ABSTRACT: Primal–dual gradient dynamics that find saddle points of a Lagrangian have been widely employed for handling constrained optimization problems. Building on existing methods, we extend the augmented primal–dual gradient dynamics (Aug-PDGD) to incorporate general convex and nonlinear inequality constraints, and we establish its semi-global exponential stability when the objective function is strongly convex. We also provide an example of a strongly convex quadratic program of which the Aug-PDGD fails to achieve global exponential stability. Numerical simulation also suggests that the exponential convergence rate could depend on the initial distance to the KKT point. © 2020 Elsevier B.V.

Karafyllis, I., Ahmed-Ali, T., Giri, F.
A note on sampled-data observers
(2020) 144, art. no. 104760, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089596257&doi=10.1016%2fj.sysconle.2020.104760&partnerID=40&md5=65e5d695ce374134b97e97d9c793a708
AFFILIATIONS: Department of Mathematics, National Technical University of Athens, Zografou Campus, Athens, 15780, Greece; 
Normandie UNIV, UNICAEN, ENSICAEN, LAC, Caen, 14000, France
ABSTRACT: We present a new design methodology of sampled-data observers that unifies and generalizes many existing design methodologies. The approach is based on continuous-time observers that feature two characteristics: (i) exhibit exponential convergence in the noiseless case with respect to a given Observer Lyapunov Function, and (ii) satisfy an Input-to-Output Stability property with respect to output measurement noise. The design approach applies to a wide class of systems and yields sampled-data observers that inherit these two performance characteristics of the underlying continuous-time observer. The main component of the proposed sampled-data observer is a novel output predictor that encompasses both inter-sample predictors and Zero-Order-Hold predictors. © 2020 Elsevier B.V.

Kasis, A., Monshizadeh, N., Lestas, I.
A distributed scheme for secondary frequency control with stability guarantees and optimal power allocation
(2020) 144, art. no. 104755, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089540941&doi=10.1016%2fj.sysconle.2020.104755&partnerID=40&md5=93697af149370775fdd31f5aa9d62077
AFFILIATIONS: Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, United Kingdom; 
Engineering and Technology Institute, University of Groningen, Nijenborgh 4, Groningen, 9747AG, Netherlands
ABSTRACT: We consider the problem of distributed secondary frequency regulation in power networks such that stability and an optimal power allocation are guaranteed. This is a problem that has been widely studied in the literature, where two main control schemes have been proposed, usually referred to as ’Primal-Dual’ and ’distributed averaging proportional–integral (DAPI)’ respectively. However, each has its limitations, with the former incorporating additional information flow requirements which may limit its applicability, and with the existing literature on the latter relying on static models for generation and demand, which is restrictive. We propose a novel control scheme that aims to overcome these issues by making use of generation measurements in the control policy. In particular, our controller relies on practical measurements and allows distributed stability and optimality guarantees to be deduced for a broad range of linear generation dynamics, that can be of higher order. We show how the controller parameters can be selected in a computationally efficient way by solving appropriate linear matrix inequalities (LMIs). Furthermore, we demonstrate how the proposed analysis applies to various examples of turbine governor dynamics by using realistic numerical data. The practicality of our analysis is demonstrated with numerical simulations on the Northeast Power Coordinating Council (NPCC) 140-bus system that verify that our proposed controller achieves convergence to the nominal frequency, an economically optimal power allocation, and improved performance compared to existing schemes used in the literature. © 2020 Elsevier B.V.

Xu, H., Wang, J., Wang, B., Song, Y., Brahmia, I.
Comments on “Output synchronization of nonlinear heterogeneous multi-agent systems with switching networks”: [Systems & Control Letters 125 (2019) 45-50]
(2020) 144, art. no. 104756, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089531138&doi=10.1016%2fj.sysconle.2020.104756&partnerID=40&md5=4d82efadf99d5827765e9228d30af09f
AFFILIATIONS: Department of Automation, Shanghai Jiao Tong University, Key Laboratory of System Control and Information Processing, Ministry of Education of China, Shanghai, 200240, China; 
Autonomous Systems and Intelligent Control International Joint Research Center, Xi'an Technological’ University, Xi'an, Shaanxi, 710021, China; 
School of Aerospace Science and Technology, Xidian University, Xi'an710071, China; 
Department of Control Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China
ABSTRACT: In this note, an effort is put forward to make two revisions with respect to mistakes in the derivations of Khan et al. (2019). The main result of Khan et al. (2019) claimed that the Laplacian matrix L is a symmetric matrix. However, the paper only assumed that the jointly connected graph contains a spanning tree. Clearly, L is a symmetric matrix if and only if the joint graph is strongly connected. Hence, the basic Assumption needs to be revised. Also, some equations need to be modified without treating L as a symmetric matrix. This revision will affect the stability conditions of switching topologies, which leading thereby to redesign the parameters λ and μ appeared in Theorem 4.1 (Khan et al., 2019). In addition, there is a mistake when the authors designing real reference systems. The output matrix C=[Cv,0] should be C=[NCv,0], otherwise the follower systems will track a wrong trajectory pattern. © 2020 Elsevier B.V.

Neuman, E., Schied, A., Weng, C., Xue, X.
A central bank strategy for defending a currency peg
(2020) 144, art. no. 104761, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089479974&doi=10.1016%2fj.sysconle.2020.104761&partnerID=40&md5=814aaf7e856826c60f6205133a54fde3
AFFILIATIONS: Department of Mathematics, Imperial College London, London, SW7 2AZ, United Kingdom; 
Department of Statistics and Actuarial Science, University of WaterlooON  N2L 3G1, Canada; 
School of Management, Shandong University, Jinan, 250100, China
ABSTRACT: We consider a central bank strategy for maintaining a two-sided currency target zone, in which an exchange rate of two currencies is forced to stay between two thresholds. To keep the exchange rate from breaking the prescribed barriers, the central bank is generating permanent price impact and thereby accumulating inventory in the foreign currency. Historical examples of failed target zones illustrate that this inventory can become problematic, in particular when there is an adverse macroeconomic trend in the market. We model this situation through a continuous-time market impact model of Almgren–Chriss-type with drift, in which the exchange rate is a diffusion process controlled by the price impact of the central bank's intervention strategy. The objective of the central bank is to enforce the target zone through a strategy that minimizes the accumulated inventory. We formulate this objective as a stochastic control problem with random time horizon. It is solved by reduction to a singular boundary value problem that was solved by Lasry and Lions (1989). Finally, we provide numerical simulations of optimally controlled exchange rate processes and the corresponding evolution of the central bank inventory. © 2020 Elsevier B.V.

Ma, W., Luo, X., Zhu, Q.
Practical exponential stability of stochastic age-dependent capital system with Lévy noise
(2020) 144, art. no. 104759, . Cited 10 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089201532&doi=10.1016%2fj.sysconle.2020.104759&partnerID=40&md5=9e8ff88437c5b96a3be0483dfd92beca
AFFILIATIONS: School of Information Engineering, Ningxia University, Yinchuan, Ningxia, 750021, China; 
School of Computer and Information Science, Southwest University, Chongqing, 400715, China; 
MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, Hunan, 410081, China; 
School of Information Science and Engineering, Chengdu University, Chengdu, 610106, China
ABSTRACT: It is well known that stability is one of most important topics in economy and control. In this paper, we focus on the practical stability problem for a class of stochastic age-dependent (vintage) capital system with Lévy noise. Compared with the classical Lyapunov stability theory, practical stability can depict not only qualitative behavior but also quantitative properties, such as specific trajectory bounds and specific transient behavior. With the help of the stochastic analysis theory and Itô’s formula, we establish some novel criteria for the mean square and almost sure practical exponential stability of the addressed system. The obtained results improve some previous works given in the literature. Moreover, an example is provided to illustrate the theoretical results. © 2020 Elsevier B.V.

Schrangl, P., Giarré, L.
On optimal design of experiments for static polynomial approximation of nonlinear systems
(2020) 143, art. no. 104758, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089138047&doi=10.1016%2fj.sysconle.2020.104758&partnerID=40&md5=03f28e7c7237aceea3a9e58d3fe6f199
AFFILIATIONS: Dipartimento di Ingegneria “Enzo Ferrari”, Università di Modena e Reggio Emilia, Via Vivarelli 10, Modena, 41125, Italy; 
Johannes Kepler University (JKU), Altenberger Strasse 69, Linz, 4040, Austria
ABSTRACT: Models are of great importance for many purposes, including control design. However, most real systems are complex, frequently nonlinear and first principle models tend to be too complicated, or even unknown, for control-oriented modeling. Therefore, data-based models are often used; however, since most likely the true system is not an element of any assumed model class, the available model is an approximation of the real system. To identify nonlinear systems, universal approximations are often used, e.g., polynomial nonlinear models whose number of parameters rapidly increases with model complexity. Because of the high number of parameters to be identified and the presence of nonlinearity, the accurate choice of an appropriate excitation becomes essential and not trivial. The aim of the present paper is to analyze classical design of experiment (DOE) and present its limits in terms of prediction error, for the static polynomial setup under investigation. First, when the system belongs to the assumed model class, we suggest the use of a more suitable optimization criterion that we prove to be a generalization of the well-known V-optimality. Second, we show that if we design the excitation input based on a higher degree model than the one to be identified, it gives rise to a more efficient approximation. © 2020 Elsevier B.V.

Lucia, S., Subramanian, S., Limon, D., Engell, S.
Stability properties of multi-stage nonlinear model predictive control
(2020) 143, art. no. 104743, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088541100&doi=10.1016%2fj.sysconle.2020.104743&partnerID=40&md5=83e1a024dec13b5d6c00709c2ae68bc4
AFFILIATIONS: Internet of Things for Smart Buildings, Technische Universität Berlin and Einstein Center Digital Future, Einsteinufer 17, Berlin, 10587, Germany; 
Process Dynamics and Operations Group, Technische Universität Dortmund, Emil-Figgestr. 70, Dortmund, 44227, Germany; 
Escuela Superior de Ingenieros, Departamento de Ingeniería de Sistemas y Automática, Avda. de los descubrimientos s/n, Sevilla, 41092, Spain
ABSTRACT: This paper discusses the stability properties of a robust nonlinear model predictive control (NMPC) scheme that is based on a multi-stage optimization formulation. The use of a scenario tree to represent the uncertainty makes it possible to formulate a closed-loop robust approach with recourse which improves the open-loop approach in terms of performance and domain of attraction. We show that a straightforward formulation of a multi-stage NMPC scheme does not guarantee Input-to-State stability (ISS) in a deterministic setting, in contrast to the results that one gets using stochastic stability concepts. Since for many applications deterministic stability guarantees are desired, we provide an alternative formulation to achieve deterministic ISS and recursive feasibility guarantees for the case of discrete values of the uncertainty. The design and the performance of the proposed schemes are illustrated by simulations for a highly nonlinear example. © 2020 Elsevier B.V.

Tomei, P., Marino, R.
Adaptive nonlinear control with constrained parallel parameter estimates
(2020) 143, art. no. 104739, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088521235&doi=10.1016%2fj.sysconle.2020.104739&partnerID=40&md5=77870effb9093214131b4d56c99f56fd
AFFILIATIONS: Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, Rome, 00133, Italy
ABSTRACT: The state feedback regulation of nonlinear systems of order n in parametric strict-feedback form is considered. A simple, easy to tune, adaptive control with projected parameter estimates is proposed. The uncertain parameter vector is estimated by n parallel vector estimates whose differences are constrained to tend asymptotically to zero. When the uncertain parameter vector is identifiable, the closed loop system is globally asymptotically and locally exponentially stable. Three comparative examples illustrate the advantages of the proposed simple adaptive control over the tuning functions or extended matching approaches. © 2020 Elsevier B.V.

Anahtarcı, B., Karıksız, C.D., Saldi, N.
Value iteration algorithm for mean-field games
(2020) 143, art. no. 104744, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088382162&doi=10.1016%2fj.sysconle.2020.104744&partnerID=40&md5=7c0e1b372ab812c7c2ecf810985939ca
AFFILIATIONS: Özyeğin University, Çekmeköy, İstanbul, Turkey
ABSTRACT: In the literature, existence of mean-field equilibria has been established for discrete-time mean field games under both the discounted cost and the average cost optimality criteria. In this paper, we provide a value iteration algorithm to compute stationary mean-field equilibrium for both the discounted cost and the average cost criteria, whose existence proved previously. We establish that the value iteration algorithm converges to the fixed point of a mean-field equilibrium operator. Then, using this fixed point, we construct a stationary mean-field equilibrium. In our value iteration algorithm, we use Q-functions instead of value functions. © 2020 Elsevier B.V.

Shen, G., Xu, W., Zhu, D.
The stability with general decay rate of neutral stochastic functional hybrid differential equations with Lévy noise
(2020) 143, art. no. 104742, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088025564&doi=10.1016%2fj.sysconle.2020.104742&partnerID=40&md5=4bd2164b5cae9f14f11b0f618f417e2e
AFFILIATIONS: Department of Mathematics, Anhui Normal University, Wuhu, 241000, China
ABSTRACT: This paper is concerned with the existence and uniqueness, the almost sure stability with general decay rate (including almost sure exponential stability, almost sure polynomial stability and almost sure logarithmic stability) for the global solution of nonlinear neutral stochastic functional hybrid differential equations with Lévy noise. The key technique used is the method of Lyapunov function, nonnegative semi-martingale convergence theorem and the theory of M-matrix. We use auxiliary functions to dominate the corresponding Lyapunov function and the diffusion operator. Our conditions on the diffusion operator are weaker than those in the related existing works. Finally, one example is given to show the effectiveness of the obtained theory. © 2020 Elsevier B.V.

Benner, P., Goyal, P., Van Dooren, P.
Identification of port-Hamiltonian systems from frequency response data
(2020) 143, art. no. 104741, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088009396&doi=10.1016%2fj.sysconle.2020.104741&partnerID=40&md5=c09032c3d2f9d4153fe58818783aa6a1
AFFILIATIONS: Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, Magdeburg, 39106, Germany; 
Université catholique de Louvain, Louvain-La-Neuve, Belgium
ABSTRACT: In this paper, we study the identification problem of strictly passive systems from frequency response data. We present a simple construction approach based on the Mayo–Antoulas generalized realization theory that automatically yields a port-Hamiltonian realization for every strictly passive system with simple spectral zeros. Furthermore, we discuss the construction of a frequency-limited port-Hamiltonian realization. We illustrate the proposed method by means of several examples. © 2020 Elsevier B.V.

Li, H., Xu, J., Zhang, H.
Linear quadratic regulation for discrete-time systems with input delay and colored multiplicative noise
(2020) 143, art. no. 104740, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087888163&doi=10.1016%2fj.sysconle.2020.104740&partnerID=40&md5=1011be27ed79d310f4ab898c3cd681b9
AFFILIATIONS: School of Control Science and Engineering, Shandong University, JinanShandong, 250061, China
ABSTRACT: This paper is concerned with the linear quadratic regulation (LQR) problem for discrete-time systems involving input delay and colored multiplicative noise. Due to the correlation of the adjoining state, this problem will be more complicated than the case of white noise. In this paper, the necessary and sufficient condition for the solvability of optimal control problem is presented by solving the forward and backward stochastic difference equations (FBSDEs). Moreover, the optimal LQR controller is given in terms of the coupled difference equations developed in this paper. © 2020 Elsevier B.V.

Firoozi, D., Jaimungal, S., Caines, P.E.
Convex analysis for LQG systems with applications to major–minor LQG mean–field game systems
(2020) 142, art. no. 104734, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087337890&doi=10.1016%2fj.sysconle.2020.104734&partnerID=40&md5=ccd3a56d3d809a80d03e5997e180b866
AFFILIATIONS: Department of Decision Sciences, HEC Montréal, Montreal, QC, Canada; 
Department of Statistical Sciences, University of Toronto, Toronto, ON, Canada; 
Centre for Intelligent Machines (CIM) and the Department of Electrical and Computer Engineering (ECE), McGill UniversityMontrealQC, Canada
ABSTRACT: We develop a convex analysis approach for solving LQG optimal control problems and apply it to major–minor (MM) LQG mean–field game (MFG) systems. The approach retrieves the best response strategies for the major agent and all minor agents that attain an ϵ-Nash equilibrium. An important and distinctive advantage to this approach is that unlike the classical approach in the literature, we are able to avoid imposing assumptions on the evolution of the mean–field. In particular, this provides a tool for dealing with complex and non–standard systems. © 2020 Elsevier B.V.

Polcz, P., Péni, T., Kulcsár, B., Szederkényi, G.
Induced L2-gain computation for rational LPV systems using Finsler's lemma and minimal generators
(2020) 142, art. no. 104738, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087273048&doi=10.1016%2fj.sysconle.2020.104738&partnerID=40&md5=0d39e19f8aeaa46046fac7a0a3e0ffbe
AFFILIATIONS: Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Práter 50/a, Budapest, H-1083, Hungary; 
Systems and Control Laboratory, Institute for Computer Science and Control (MTA SZTAKI), Hungarian Academy of Sciences, Kende u. 13-17, Budapest, H-1111, Hungary; 
Automatic Control group, Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, SE-412 96, Sweden
ABSTRACT: This paper proposes a novel method to compute an upper bound on the induced L2-gain for a linear parameter varying (LPV) system with rational parameter dependence. The proposed method relies on a standard dissipation inequality condition. The storage function is a quadratic function of the state and a rational function of the parameters. The specific parameter dependence is restricted to involve (fixed) rational functions and an affine term with free decision variables. Finsler's lemma and affine annihilators are used to formulate sufficient linear matrix inequality (LMI) conditions for the dissipativity relation. The dimension and conservatism of the resulting LMI problem are reduced by the joint application of minimal generators and maximal annihilators. An LPV model of a pendulum–cart system is used to demonstrate the proposed method and compare it to existing techniques in the literature. © 2020 Elsevier B.V.

Dettmann, C.P., Jungers, R.M., Mason, P.
Lower bounds and dense discontinuity phenomena for the stabilizability radius of linear switched systems
(2020) 142, art. no. 104737, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086990107&doi=10.1016%2fj.sysconle.2020.104737&partnerID=40&md5=013ebf9757471ceac38f340b61ec5ef5
AFFILIATIONS: School of Mathematics, University of Bristol, Fry Building, Woodland RoadBristol BS81UG, United Kingdom; 
ICTEAM Institute, Université catholique de Louvain, 4 avenue Georges Lemaitre, B-1348 Louvain-la-Neuve, Belgium; 
Université Paris-Saclay, CNRS, CentraleSupélec, Laboratoire des signaux et systèmes91190, Gif-sur-Yvette, France
ABSTRACT: We investigate the stabilizability of discrete-time linear switched systems, when the sole control action of the controller is the switching signal, and when the controller has access to the state of the system in real time. Despite their apparent simplicity, determining if such systems are stabilizable appears to be a very challenging problem, and basic examples have been known for long, for which the stabilizability question is open. We provide new results allowing us to bound the so-called stabilizability radius, which characterizes the stabilizability property of discrete-time linear switched systems. These results allow us to compute significantly improved explicit lower bounds on the stabilizability radius for the above-mentioned examples. As a by-product, we exhibit a discontinuity property for this problem, which brings theoretical understanding of its complexity. © 2020 Elsevier B.V.

Lance, G., Trélat, E., Zuazua, E.
Shape turnpike for linear parabolic PDE models
(2020) 142, art. no. 104733, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086738020&doi=10.1016%2fj.sysconle.2020.104733&partnerID=40&md5=6657c7171b6b69e8f35ddf9bf14188d9
AFFILIATIONS: Sorbonne Université, CNRS, Université de Paris, Inria, Laboratoire Jacques-Louis Lions (LJLL), Paris, F-75005, France; 
Chair in Applied Analysis, Alexander von Humboldt-Professorship, Department of Mathematics Friedrich-Alexander-Universität, Erlangen-Nürnberg, Erlangen, 91058, Germany; 
Chair of Computational Mathematics, Fundación Deusto Av. de las Universidades 24, 48007 Bilbao, Basque Country, Spain; 
Departamento de Matemáticas, Universidad Autónoma de Madrid, Madrid, 28049, Spain
ABSTRACT: We introduce and study the turnpike property for time-varying shapes, within the viewpoint of optimal control. We focus here on second-order linear parabolic equations where the shape acts as a source term and we seek the optimal time-varying shape that minimizes a quadratic criterion. We first establish existence of optimal solutions under some appropriate sufficient conditions. We then provide necessary conditions for optimality in terms of adjoint equations and, using the concept of strict dissipativity, we prove that state and adjoint satisfy the measure-turnpike property, meaning that the extremal time-varying solution remains essentially close to the optimal solution of an associated static problem. We show that the optimal shape enjoys the exponential turnpike property in terms of Hausdorff distance for a Mayer quadratic cost. We illustrate the turnpike phenomenon in optimal shape design with several numerical simulations. © 2020

Yin, H., Packard, A., Arcak, M., Seiler, P.
Reachability analysis using dissipation inequalities for uncertain nonlinear systems
(2020) 142, art. no. 104736, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086734480&doi=10.1016%2fj.sysconle.2020.104736&partnerID=40&md5=a31c3ef5d5f2812e6214d95cf2d2911c
AFFILIATIONS: Department of Mechanical Engineering, University of California, Berkeley, United States; 
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, United States; 
Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, United States
ABSTRACT: We propose a method to outer bound forward reachable sets on finite horizons for uncertain nonlinear systems with polynomial dynamics. This method makes use of time-dependent polynomial storage functions that satisfy appropriate dissipation inequalities that account for time-varying uncertain parameters, L2 disturbances, and perturbations Δ characterized by integral quadratic constraints (IQCs) with both hard and soft factorizations. The use of IQCs in forward reachability analysis allows for various types of uncertainty, including unmodeled dynamics. The generalized S-procedure and Sum-of-Squares techniques are used to derive algorithms with the goal of finding the tightest outer bound with a desired shape. Both pedagogical and practically motivated examples are presented, including a 7-state F-18 aircraft model. © 2020 Elsevier B.V.

Wang, Y., Zhou, X.
Exact controllability of stochastic differential equations with memory
(2020) 142, art. no. 104732, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086589155&doi=10.1016%2fj.sysconle.2020.104732&partnerID=40&md5=e4cae8f427fc054e4315c6bf14f7ddfb
AFFILIATIONS: School of Mathematics and Statistics, Southwest University, Chongqing, 400715, China; 
School of Mathematics and Statistics, Lingnan Normal University, Zhanjiang, 524048, China
ABSTRACT: In this work, we mainly study the exact controllability of stochastic differential equations with memory. For time invariant systems, by applying forward backward stochastic differential equations, some rank criteria ensuring systems’ exact controllability are provided. For time variant systems, equivalent conditions guaranteeing systems’ exact controllability are given. For deterministic systems, as a special case of stochastic ones, more easily checkable rank criteria (for time invariant systems) and alternative conditions (for time variant systems) are proposed. © 2020

Kurula, M.
Optimal approximation of discrete-time multirate systems on Hilbert spaces
(2020) 142, art. no. 104735, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086579568&doi=10.1016%2fj.sysconle.2020.104735&partnerID=40&md5=1e4ca43bd72dc5a93893d56142be9f23
AFFILIATIONS: Å bo Akademi Mathematics, Domkyrkotorget 1, Å bo, 20500, Finland
ABSTRACT: We study discrete-time (m,n)-multirate systems on separable Hilbert spaces, solving the problem of approximating such a system by one which has a shorter multirate period (m∕q,n∕q), optimally in the Hilbert–Schmidt norm. We work in the state–space setting, providing two state–space representations of the optimal approximant which are expressed in terms of a state–space representation of the original system. © 2020 Elsevier B.V.

Lin, P., Li, G., Huang, K.
Position-constrained containment for second-order discrete-time multi-agent systems
(2020) 142, art. no. 104708, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086404664&doi=10.1016%2fj.sysconle.2020.104708&partnerID=40&md5=5cf6f36c43a8bf281816e1f1d6b27b41
AFFILIATIONS: School of Automation, Central South University, Changsha, 410083, China
ABSTRACT: In this paper, we study a containment control problem for second-order multi-agent systems in the presence of convex position constraints and switching graphs. A distributed algorithm with a nonlinear projection operator is proposed to guarantee that each agent eventually converges into the convex hull spanned by some given multiple static points, while the position of each agent is kept lying in a given closed set. It is proved that all agents ultimately converge into the convex hull while each agent remains in its constraint set as long as there exists a directed path from the static points to the agents in the union of the graphs in each bounded time interval. Finally, a numerical example is given to illustrate the obtained theoretical results. © 2020 Elsevier B.V.

Basak, G.K., Dasgupta, A.
Weak convergence of dynamical systems in two timescales
(2020) 142, art. no. 104718, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086073184&doi=10.1016%2fj.sysconle.2020.104718&partnerID=40&md5=9229cf8c4cad98177ebe2a2d462650a7
AFFILIATIONS: Stat-Math Unit, Indian Statistical Institute, 203 B. T. Road, Kolkata, 700108, India
ABSTRACT: Dynamical systems driven by two or multi-timescales arise in systems science, natural and social sciences quite naturally. Work done by Vivek S. Borkar (1997) on stochastic approximation driven by two timescales and later by others pave the pathway for wide applications of such systems. In this article we provide weak convergence of such systems for the linear case. © 2020 Elsevier B.V.

Halanay, A., Safta, C.A.
A critical case for stability of equilibria of delay differential equations and the study of a model for an electrohydraulic servomechanism
(2020) 142, art. no. 104722, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086068339&doi=10.1016%2fj.sysconle.2020.104722&partnerID=40&md5=716ccd7adf83e245a051b11102f153f4
AFFILIATIONS: Department of Mathematics and Informatics, University Politehnica of Bucharest, 313 Splaiul Independentei, Bucharest, RO-060042, Romania; 
Department of Hydraulics and Hydraulic Machinery, University Politehnica of Bucharest, 313 Splaiul Independentei, Bucharest, RO-060042, Romania
ABSTRACT: A general theorem is proved on the stability of an equilibrium point of a nonlinear delay differential equation, in the critical case when zero is a simple root of the characteristic equation for linearized equation. It extends the classical theorem of Malkin from the case of ordinary differential equations. An application to the case of a electrohydraulic governor with delay in control is given. © 2020 Elsevier B.V.

Bayili, G., Aissa, A.B., Nicaise, S.
Same decay rate of second order evolution equations with or without delay
(2020) 141, art. no. 104700, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085642263&doi=10.1016%2fj.sysconle.2020.104700&partnerID=40&md5=93ba5e0a816fac6e31bdb7b3a7c5be0c
AFFILIATIONS: Université Joseph KI-ZERBO, Unité de Recherche et de Formation en Sciences Exactes et Appliquées, Département de Mathématiques, Ouagadougou, Burkina Faso; 
UR Analysis and Control of PDE's, UR 13ES64, Department of Mathematics, Faculty of Sciences of Monastir, University of Monastir, Monastir, 5019, Tunisia; 
Université Polytechnique Hauts-de-France, EA 4015 - LAMAV - Laboratoire de Mathématiques et leurs Applications de Valenciennes, FR CNRS 2956, Valenciennes, F-59313, France
ABSTRACT: We consider abstract second order evolution equations with unbounded feedback with delay. If the delay term is small enough, we rigorously prove the fact that the system with delay has the same decay rate than the one without delay. Some old and new results easily follow. © 2020 Elsevier B.V.

Kárný, M.
Axiomatisation of fully probabilistic design revisited
(2020) 141, art. no. 104719, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085607647&doi=10.1016%2fj.sysconle.2020.104719&partnerID=40&md5=35ab6d3d94a2026def51a48ff0051907
AFFILIATIONS: The Czech Academy of Sciences, Institute of Information Theory and Automation, Pod Vodárenskou věží 4, Prague, 182 08, Czech Republic
ABSTRACT: Fully probabilistic design (FPD) of control strategies models both the closed control loop and control objectives by joint probabilities of involved variables. It selects the optimal strategy as the minimiser of Kullback–Leibler (KL) divergence of the closed-loop model to its ideal counterpart expressing the control objectives. Since its proposal (Kárný, 1996) and general algorithmisation (Kárný and Guy, 2006), FPD has been axiomatised (Kárný and Kroupa, 2012) and successfully applied both theoretically (Kárný and Guy, 2012) and practically (Quinn et al., 2003; Kárný et al., 2006)[1]. This paper refines the FPD axiomatisation and bridges FPD to standard stochastic control theory, which it encompasses, in a better way. This enhances applicability of both as well as of its popular, independently proposed, special case known as KL control (Guan et al., 2014). © 2020

Li, J., Li, X.
Online sparse identification for regression models
(2020) 141, art. no. 104710, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085601275&doi=10.1016%2fj.sysconle.2020.104710&partnerID=40&md5=c14f127c8e5748b0a37d9e28e010637e
AFFILIATIONS: School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, 430074, China
ABSTRACT: In this paper, we propose an online alternating minimization (OAM) algorithm to estimate the sparse coefficients of stochastic regression models from time-series data. We apply the alternating minimization (AM) directly to the penalty function of the variant of the least absolute shrinkage and selection operator (Lasso), which leads to convex subproblems, and thereby can be solved efficiently. Moreover, under certain mild assumptions, we derive a convergence analysis framework and establish the strong consistency for the OAM estimator. Numerical experiments demonstrate the effectiveness of the proposed algorithm. © 2020 Elsevier B.V.

Ben Amara, J., Boughamda, W.
Exponential stability of two strings under joint damping with variable coefficients
(2020) 141, art. no. 104709, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085270681&doi=10.1016%2fj.sysconle.2020.104709&partnerID=40&md5=b664853362e058df9a6974b05e266a49
AFFILIATIONS: University of Tunis El Manar, Faculty of Sciences of Tunis, Tunisia
ABSTRACT: We study the stabilization of two vibrating strings with variable physical coefficients joined by a feedback control at a common endpoint and subject to non-symmetrical boundary conditions. We prove that this system is exponentially stable under sufficient conditions on the physical coefficients. For this result, we show that the system has a sequence of the generalized eigenvectors which forms a Riesz basis with parentheses for the state Hilbert space, and as a consequence the spectrum-determined growth condition holds. © 2020

Dzhafarov, V., Esen, Ö., Büyükköroğlu, T.
On polytopes in Hurwitz region
(2020) 141, art. no. 104706, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085192183&doi=10.1016%2fj.sysconle.2020.104706&partnerID=40&md5=6de4a10fb13d7a96e31602ab4ccabcb4
AFFILIATIONS: Department of Mathematics, Faculty of Science, Eskişehir Technical University, Eskişehir, 26470, Turkey; 
School for the Handicapped, Anadolu University, Eskişehir, 26470, Turkey
ABSTRACT: We consider the stability region of monic polynomials in the coefficient space. Starting from specially chosen stable points we define polytopes, whose edges are either stable or belong to the stability boundary. Therefore by the Edge Theorem the interiors are stable. Stable polytopes, in the reverse directions which are directed to infinity have been studied in the work (Dzhafarov et al., 2019). Some applications of the obtained results to the synthesis of fixed-order stabilizing controllers are given. © 2020 Elsevier B.V.

Silm, H., Efimov, D., Michiels, W., Ushirobira, R., Richard, J.-P.
A simple finite-time distributed observer design for linear time-invariant systems
(2020) 141, art. no. 104707, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085164935&doi=10.1016%2fj.sysconle.2020.104707&partnerID=40&md5=0069e028a45a83dd1e9c1208c531d7ee
AFFILIATIONS: Univ. Lille, CNRS, Inria, Centrale Lille, UMR 9189 - CRIStAL, Lille, 59000, France; 
Inria, Univ. Lille, CNRS, UMR 9189 - CRIStAL, Lille, 59000, France; 
Department of Computer Science, KU Leuven, Heverlee, 3001, Belgium; 
ITMO University, Saint Petersburg, 197101, Russian Federation
ABSTRACT: A design of a distributed observer is proposed for continuous-time systems with nonlinear observer nodes such that the estimation errors converge in a finite time to zero. By taking advantage of individual observability decompositions, the designs for the locally observable and the unobservable substate are made independent from each other. For the observable substate of each node, standard centralized finite-time observer techniques are applied. To estimate distributively the unobservable substate, the observer nodes employ consensus coupling in a linear term and an additional term embedded in a fractional power. The approach is derived using homogeneity arguments and it leads to a simple design with an LMI that is guaranteed to be feasible under general conditions. © 2020 Elsevier B.V.

Xiang, C., Petersen, I.R., Dong, D.
Static and dynamic coherent robust control for a class of uncertain quantum systems
(2020) 141, art. no. 104702, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084954328&doi=10.1016%2fj.sysconle.2020.104702&partnerID=40&md5=783268d1ad427863641016ccc1e50cdf
AFFILIATIONS: School of Automation, Hangzhou Dianzi University, Hangzhou, Zhejiang, 310018, China; 
Research School of Engineering, Australian National University, Canberra, ACT 2601, Australia; 
School of Engineering and Information Technology, University of New South Wales, Canberra, ACT 2600, Australia
ABSTRACT: This paper concerns a class of uncertain linear quantum systems subject to quadratic perturbations in the system Hamiltonian. In order to obtain improved control performance, we propose two methods to design coherent robust controllers for the system. One is to formulate a static quantum controller by adding a controller Hamiltonian to the given system, and the other is to build a dynamic quantum controller which is directly coupled to the given system. © 2020 Elsevier B.V.

Santana, D.D., Martins, M.A.F., Odloak, D.
An efficient cooperative-distributed model predictive controller with stability and feasibility guarantees for constrained linear systems
(2020) 141, art. no. 104701, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084937109&doi=10.1016%2fj.sysconle.2020.104701&partnerID=40&md5=0d8ae1b32f3ad210fed2fb6ceb872955
AFFILIATIONS: Departamento de Engenharia Química, Escola Politécnica, Universidade Federal da Bahia, Rua Aristides Novis, 2, Federação, Salvador, BA  40210-630, Brazil; 
Departamento de Engenharia Química, Escola Politécnica, Universidade de São Paulo, Av. Prof. Luciano Gualberto, trv 3 380, São Paulo, SP  61548, Brazil
ABSTRACT: This paper proposes a quadratic programming based cooperative-distributed model predictive control strategy, with stability and feasibility guarantees. Its feasibility is achieved by considering slacked terminal constraints of the optimization problem without the assessment of an invariant terminal set. The stability proof uses Lyapunov arguments and is carried out by properly setting the move suppression matrix elements for each agent. A case study involving a process system composed of two CSTR in series with a flash vessel illustrates the effectiveness of the proposed method, especially in a scenario that limits the information exchanged as well as imposes a short time interval for communication among the agents. © 2020 Elsevier B.V.

Paunonen, L., Seifert, D.
Asymptotics and approximation of large systems of ordinary differential equations
(2020) 140, art. no. 104703, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084954223&doi=10.1016%2fj.sysconle.2020.104703&partnerID=40&md5=c055cf0aa589d18053765e75dbc1a34b
AFFILIATIONS: Mathematics and Statistics, Tampere University, PO. Box 692, Tampere, 33101, Finland; 
School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon TyneNE1 7RU, United Kingdom
ABSTRACT: In this paper we continue our earlier investigations into the asymptotic behaviour of infinite systems of coupled differential equations. Under the mild assumption that the so-called characteristic function of our system is completely monotonic we obtain a drastically simplified condition which ensures boundedness of the associates semigroup. If the characteristic function satisfies certain additional conditions we deduce sharp rates of convergence to equilibrium. We moreover address the important and delicate issue of the role of the infinite system in understanding the asymptotic behaviour of large but finite systems, and we provide a precise way of obtaining size-independent rates of convergence for families of finite-dimensional systems. Finally, we illustrate our abstract results in the setting of the well-known platoon problem. © 2020 Elsevier B.V.

Wang, F., Lai, G.
Fixed-time control design for nonlinear uncertain systems via adaptive method
(2020) 140, art. no. 104704, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084953283&doi=10.1016%2fj.sysconle.2020.104704&partnerID=40&md5=9450388b3e9663839f35f6171cd27422
AFFILIATIONS: College of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao, 266590, China; 
Faculty of Automation, Guangdong University of Technology, Guangzhou, Guangdong, 510006, China
ABSTRACT: This article addresses a fixed-time tracking problem of uncertain nonlinear system. Firstly, a sufficient condition for practical fixed-time stability is given. Secondly, on the basis of the sufficient condition, a novel adaptive control strategy is proposed. The designed parameter adaptive law is expressed as a nonlinear differential equation, which is different from the existing adaptive design method. Under the proposed adaptive control scheme, the system performance can be guaranteed in a fixed time, and the upper bound of the settling time is merely affected by the control design parameters, which is independent on the initial states of system. Then, based on the new established inequalities, the fixed-time stability of the closed-loop system is proved. Finally, an example is provided to illustrate the effectiveness of the main result. © 2020

Co, T.
On the control of a class of non-strongly stabilizable SISO plants
(2020) 140, art. no. 104705, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084941902&doi=10.1016%2fj.sysconle.2020.104705&partnerID=40&md5=8563f681f7a74b35ff0a1c49dda0d0a4
AFFILIATIONS: Department of Chem. Eng., Michigan Technological University, Houghton, MI, United States
ABSTRACT: In this paper, under the limited class of strictly proper, unstable non-strongly stabilizable plants with one real finite positive zero, we have proposed some general designs of a stable compensator which will modify the output of the original plant into one that satisfies the parity interlacing property. Once the parity interlacing properties have been achieved, standard stabilizations can be implemented. We include simulation examples in which an outer PID loop was added to control the stabilized plant to satisfy the tracking of setpoints. © 2020 Elsevier B.V.

Pham, V.T., Messai, N., Hoa Nguyen, D., Manamanni, N.
Robust formation control under state constraints of multi-agent systems in clustered networks
(2020) 140, art. no. 104689, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084833590&doi=10.1016%2fj.sysconle.2020.104689&partnerID=40&md5=7c7bcb8aba831623d86c9eeab50ca6ff
AFFILIATIONS: University of Reims Champagne Ardenne, CReSTIC EA 3804, Reims, 51097, France; 
WPI-I2CNER and IMI, Kyushu University, Fukuoka, 819-0395, Japan
ABSTRACT: This paper studies the formation control problem in clustered network systems composing of linear agents that are subjected to state constraints. In each cluster, there exists an agent called a leader who can communicate with other leaders outside of its cluster at some specific discrete instants. Moreover, the continuous-time communication structure in each cluster is represented by a fixed and undirected graph. A robust formation control protocol is proposed to deal with the hybrid communication described above and the constraints on states of agents. It is next shown that the hybrid robust formation control design for clustered multi-agent networks can be indirectly solved through the robust stabilization design of an equivalent system obtained by matrix theory and algebraic graph theory. Then, a robust controller is designed for the initial clustered network system in terms of linear matrix inequalities. Finally, a formation design for unmanned aerial vehicles is carried out and simulated to illustrate the effectiveness of the proposed hybrid formation control design method. © 2020 Elsevier B.V.

Kang, W., Fridman, E.
Constrained control of 1-D parabolic PDEs using sampled in space sensing and actuation
(2020) 140, art. no. 104698, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084794553&doi=10.1016%2fj.sysconle.2020.104698&partnerID=40&md5=0731fd9240341677ae4f06355109cdef
AFFILIATIONS: School of Automation and Electrical Engineering, University of Science and Technology Beijing, China; 
Department of Electrical Engineering-Systems, Tel Aviv University, Israel
ABSTRACT: We consider distributed control of a class of 1-D parabolic PDEs under distributed in-domain point actuation and measurements in the presence of control constraints. This class includes unstable diffusion-reaction equations as well as stable Burgers’ equations, where we aim to locally improve the convergence. We suggest an observer-based control law that employs the averaged values of the observer state. This allows to regionally stabilize the system. We derive linear matrix inequalities (LMIs) conditions that provide an estimate on the set of initial conditions starting from which the state trajectories of the system are exponentially converging to zero. A numerical example validates the efficiency of the method. © 2020 Elsevier B.V.

Wang, B., Zhu, Q.
Stability analysis of discrete-time semi-Markov jump linear systems with partly unknown semi-Markov kernel
(2020) 140, art. no. 104688, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084788586&doi=10.1016%2fj.sysconle.2020.104688&partnerID=40&md5=292859ff419a62d8098e609284d9b72e
AFFILIATIONS: School of Mathematics and Statistics, Xuzhou University of Technology, Xuzhou, Jiangsu  221000, China; 
MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, Hunan  410081, China
ABSTRACT: This paper is concerned with the problems of stability analysis and stabilization synthesis for a class of discrete-time semi-Markov jump linear systems. The novel sufficient stability conditions for such systems are obtained, in which the sojourn times are allowed to be unbounded, and thus these conditions are applicable to discrete-time Markov jump linear systems. Moreover, by truncating the sojourn times of switching process to be bounded, the numerically testable existence conditions of stabilizing controller for the resulting closed-loop systems with partly unknown semi-Markov kernel are obtained. An example is given to illustrate the effectiveness of our results. © 2020 Elsevier B.V.

Zhu, Q., Huang, T.
Stability analysis for a class of stochastic delay nonlinear systems driven by G-Brownian motion
(2020) 140, art. no. 104699, . Cited 15 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084579945&doi=10.1016%2fj.sysconle.2020.104699&partnerID=40&md5=a45857604742b6a812f8e05d1acd2856
AFFILIATIONS: MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, Hunan, 410081, China; 
Science Program, Texas A & M University at Qatar, Doha, 23874, Qatar
ABSTRACT: This paper is devoted to study the pth moment exponential stability problem for a class of stochastic delay nonlinear systems (SDNSs) driven by G-Brownian motion. The delays considered in this paper are time-varying delays τi(t)∈[0,τ] (1≤i≤3) and they are not required to be differentiable. Different from the traditional methods, we use a new approach: stochastic delay feedback controls. We firstly compare the SDNS with the corresponding stochastic nonlinear system (SNS) instead of studying the stability of the SDNS directly. Then, we impose the condition on the SNS to ensure the pth moment exponential stability of the SNS. Furthermore, we show that there is a positive constant τ∗ such that the SDNS is also pth moment exponentially stable provided τ<τ∗. In particular, we give an implicit lower bound for τ∗ which can be computed numerically. © 2020 Elsevier B.V.

Wang, G., Wang, T.
Time inconsistent asset–liability management with partial information
(2020) 140, art. no. 104687, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083691324&doi=10.1016%2fj.sysconle.2020.104687&partnerID=40&md5=43c57986880098ed9ea317933a94695d
AFFILIATIONS: School of Control Science and Engineering, Shandong University, Jinan, 250061, China; 
School of Mathematics, Sichuan University, Chengdu, 610065, China
ABSTRACT: In this paper, we study a time inconsistent asset–liability management problem of an insurance firm, where the liability is controllable, the surplus is partially observable. We introduce the open-loop equilibrium premium operator (OLEPO), by which the open-loop equilibrium premium strategy (OLEPS) can be represented. We give the characterization and explicit forms of OLEPO, and also obtain the existence and uniqueness of OLEPS, which is a feedback form of surplus filtering estimate. © 2020 Elsevier B.V.

Wu, F., Lian, J.
Stabilization of constrained switched systems via multiple Lyapunov R-functions
(2020) 139, art. no. 104686, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083329821&doi=10.1016%2fj.sysconle.2020.104686&partnerID=40&md5=9acc8b30c709fe178b077a00fad9f0b8
AFFILIATIONS: Key Laboratory of Intelligent Control and Optimization for Industrial Equipment, Ministry of Education, China; 
School of Control Science and Engineering, Dalian University of Technology, Dalian, 116024, China
ABSTRACT: This paper investigates the stabilization problem of switched linear systems subject to state constraints, input saturation and external disturbance. Within the set-theoretic framework of R-function, the multiple Lyapunov R-functions (MLRFs) are presented, and merge both the multiple polyhedral and the multiple quadratic Lyapunov functions. The advantages of the MLRFs are that the external level sets are designed in accordance to the state constraints and inner level sets arbitrary can be made as close as possible to the smooth one. Based on the MLRFs method, stabilization conditions for the constrained switched system under a gradient-based switching law are derived. The union of the invariant truncated ellipsoidal sets is provided as an alternative approximation to the domain of attraction of the constrained switched system. Each truncated ellipsoidal set is the intersection of a polyhedral set and an ellipsoidal set, which come from the polyhedral Lyapunov function and the quadratic Lyapunov function, respectively. The sub-optimality bounds are investigated by a policy iteration. Two examples are simulated to show the benefits of the proposed strategy. © 2020 Elsevier B.V.

Reddy, A.S., Apte, A., Vadlamani, S.
Asymptotic properties of linear filter for deterministic processes
(2020) 139, art. no. 104676, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083296706&doi=10.1016%2fj.sysconle.2020.104676&partnerID=40&md5=bab21ade132e66f62e9b3a0c5572dcf5
AFFILIATIONS: International Centre for Theoretical Sciences - Tata Institute of Fundamental Research, Bangalore, India; 
TIFR Centre for Applied Mathematics, Bangalore, India
ABSTRACT: It is known that Kalman–Bucy filter is stable with respect to initial conditions under the assumptions of uniform complete controllability and uniform complete observability. In this paper, we prove the stability of Kalman-Bucy filter for the case of noise free dynamical system, i.e., for deterministic processes. The earlier stability results cannot be applied for this case, as the system is not controllable. We further show that the optimal linear filter for a general class of non-Gaussian initial conditions is asymptotically proximal to Kalman–Bucy filter. It is also shown that the filter corresponding to non-zero system noise in the limit of small system noise approaches the filter corresponding to zero system noise in the case of Gaussian initial conditions. © 2020 Elsevier B.V.

Berger, T., Puche, M., Schwenninger, F.L.
Funnel control in the presence of infinite-dimensional internal dynamics
(2020) 139, art. no. 104678, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083081111&doi=10.1016%2fj.sysconle.2020.104678&partnerID=40&md5=8423573e3e4fbfbafa90ce0f770908bd
AFFILIATIONS: Institut für Mathematik, Universität Paderborn, Warburger Str. 100, Paderborn, 33098, Germany; 
Fachbereich Mathematik, Universität Hamburg, Bundesstraße 55, Hamburg, 20146, Germany; 
Department of Applied Mathematics, University of Twente, P.O. Box 217, Enschede, 7500 AE, Netherlands
ABSTRACT: We consider output trajectory tracking for a class of uncertain nonlinear systems whose internal dynamics may be modelled by infinite-dimensional systems which are bounded-input, bounded-output stable. We describe under which conditions these systems belong to an abstract class for which funnel control is known to be feasible. As an illustrative example, we show that for a system whose internal dynamics are modelled by a transport equation, which is not exponentially stable, we obtain prescribed performance of the tracking error. © 2020 Elsevier B.V.

Ding, Y., Ren, W.
Sampled-data containment control for double-integrator agents with dynamic leaders with nonzero inputs
(2020) 139, art. no. 104673, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083002565&doi=10.1016%2fj.sysconle.2020.104673&partnerID=40&md5=f31145446d4a8765b117dc72497c9a3c
AFFILIATIONS: Department of Electrical and Computer Engineering, University of California, Riverside, CA  92521, United States
ABSTRACT: The objective of containment control in multi-agent systems is to design control algorithms for the followers to converge to the convex hull spanned by the leaders. Sampled-data based containment control algorithms are suitable for the cases where the power supply and sensing capacity are limited, due to their low-cost and energy-saving features resulting from discrete sensing and interactions. In addition, sampled-data control has advantages in performance, price and generality. On the other hand, when the agents have double-integrator dynamics and the leaders are dynamic with nonzero inputs, the existing algorithms are not directly applicable in a sampled-data setting. To this end, this paper proposes a sampled-data based containment control algorithm for a group of double-integrator agents with dynamic leaders with nonzero inputs under directed communication networks. By applying the proposed control algorithm, the followers converge to the convex hull spanned by the dynamic leaders with bounded position and velocity containment control errors, and the ultimate bound of the overall containment error is proportional to the sampling period. A numerical simulation is presented to illustrate the proposed algorithm. © 2020 Elsevier B.V.

Zhao, C., Lin, W.
Memoryless linear feedback control for a class of upper-triangular systems with large delays in the state and input
(2020) 139, art. no. 104679, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083000546&doi=10.1016%2fj.sysconle.2020.104679&partnerID=40&md5=e67035a94484bdb3af70bc31c7ae23cf
AFFILIATIONS: Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu Province, 212013, China; 
Department of Electrical, Computer, and Systems Engineering, Case Western Reserve University, Cleveland, OH  44106, United States
ABSTRACT: This paper studies the problem of global asymptotic stabilization for a class of upper-triangular systems with large delays in the state and input. Using the idea of feedback domination, we develop a Lyapunov-Krasovskii method for the design of time-invariant, memoryless linear state and output feedback controllers, achieving global asymptotic stabilization of the closed-loop systems under a linear growth condition. The resulting controllers are different from predictor-based or delay-dependent controllers in the sense that they are delay-free and easier to be implemented due to the nature of “memoryless” feedback. Two examples are presented to demonstrate the effectiveness of the proposed delay-free state and output feedback control strategies. © 2020 Elsevier B.V.

Aubin-Frankowski, P.-C.
Lipschitz regularity of the minimum time function of differential inclusions with state constraints
(2020) 139, art. no. 104677, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082875218&doi=10.1016%2fj.sysconle.2020.104677&partnerID=40&md5=84eccd7c6d1bd55a0afd4562b45779f7
AFFILIATIONS: École des Ponts ParisTech and CAS, MINES ParisTech, PSL Research University, France
ABSTRACT: For control systems, the local regularity of the minimum time function τmin in the absence of state constraints has been extensively studied and related both to inward-pointing conditions and to small-time controllability in the neighborhood of a closed target C. In the presence of state constraints, assessing this regularity is crucial to ensure the existence of solutions when perturbing the initial condition. In this paper, we prove, without imposing the inclusion C⊂IntK, that, for differential inclusions with closed state constraints K and under general assumptions, τmin is locally Lipschitz continuous on its domain which is open in K. We discuss as well extensions to nonautonomous systems and to point targets. © 2020 Elsevier B.V.

Bonnet, C., Partington, J.R.
L2 and BIBO stability of systems with variable delays
(2020) 139, art. no. 104671, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082859281&doi=10.1016%2fj.sysconle.2020.104671&partnerID=40&md5=db6db9c952f098f7fd423c4458eb7c75
AFFILIATIONS: Université Paris Saclay, Inria, CNRS, CentraleSupelec, Laboratoire des signaux et systèmes, 3 rue Joliot Curie, Gif-sur-Yvette, 91190, France; 
School of Mathematics, University of Leeds, Leeds, LS2 9JT, United Kingdom
ABSTRACT: This paper considers L2 and BIBO stability and stabilization issues for systems with time-varying delays which can be of retarded or neutral type. An important role is played by a nominal system with fixed delays which are close to the time-varying ones. Under stability or stabilizability conditions of this nominal system, sufficient conditions are given in order to ensure similar properties for the system with time-varying delays. © 2020 Elsevier B.V.

Cacace, F., Conte, F., Germani, A., Palombo, G.
Optimal linear and quadratic estimators for tracking from distance measurements
(2020) 139, art. no. 104674, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082848940&doi=10.1016%2fj.sysconle.2020.104674&partnerID=40&md5=e41821a80c2886b21f714b5052aac7e7
AFFILIATIONS: Università Campus Bio-Medico di Roma, Roma, Italy; 
DITEN, Università degli Studi di Genova, Genova, Italy; 
DISIM, Università degli Studi dell'Aquila, L'Aquila, Italy; 
IASI-CNR, Roma, Italy
ABSTRACT: We consider the tracking problem of a point moving in a three-dimensional space using only measurements of distance from a set of reference points. The approach followed in this paper is to derive a linear map with multiplicative noise through a quadratic transformation of the distance measurements. A suitable rewriting by means of an output injection term makes the multiplicative noise of the linear map amenable to be processed by recursive estimators. These estimators are guaranteed to be internally stable and the variance of the estimation error is estimated. We compare the performance of the resulting algorithm for the linear and quadratic case with standard alternatives. © 2020 Elsevier B.V.

Su, P., Tucsnak, M., Weiss, G.
Stabilizability properties of a linearized water waves system
(2020) 139, art. no. 104672, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082468025&doi=10.1016%2fj.sysconle.2020.104672&partnerID=40&md5=cbf53f72d895416fdaf50533ca505aa2
AFFILIATIONS: Institut de Mathématiques de Bordeaux, Université de Bordeaux, 351, Cours de la Libération - F 33 405, TALENCE, France; 
School of Electrical Engineering, Tel Aviv University, Ramat Aviv 69978, Israel
ABSTRACT: We consider the strong stabilization of small amplitude gravity water waves in a two dimensional rectangular domain. The control acts on one lateral boundary, by imposing the horizontal acceleration of the water along that boundary, as a multiple of a scalar input function u, times a given function h of the height along the active boundary. The state z of the system consists of two functions: the water level ζ along the top boundary, and its time derivative ζ̇. We prove that for suitable functions h, there exists a bounded feedback functional F such that the feedback u=Fz renders the closed-loop system strongly stable. Moreover, for initial states in the domain of the semigroup generator, the norm of the solution decays like (1+t)−1/6. Our approach uses a detailed analysis of the partial Dirichlet to Neumann and Neumann to Neumann operators associated to certain edges of the rectangular domain, as well as recent abstract non-uniform stabilization results by Chill et al. (2019). © 2020 Elsevier B.V.

Stanković, S.S., Beko, M., Stanković, M.S.
Nonlinear robustified stochastic consensus seeking
(2020) 139, art. no. 104667, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082173626&doi=10.1016%2fj.sysconle.2020.104667&partnerID=40&md5=f1e94e4a1022865e607f6177baf1e99c
AFFILIATIONS: School of Electrical Engineering, University of Belgrade, Serbia; 
Vlatacom Institute, Belgrade, Serbia; 
COPELABS, Universidade Lusófona de Humanidades e Tecnologias, Campo Grande 376, Lisboa, 1749-024, Portugal; 
UNINOVA, Monte de Caparica, Caparica, 2829-516, Portugal; 
Innovation Center, School of Electrical Engineering, University of Belgrade, Serbia; 
School of Technical Sciences, Singidunum University, Belgrade, Serbia
ABSTRACT: In this paper we propose a novel stochastic consensus seeking algorithm based on the introduction of a nonlinear transformation aimed at robustification with respect to noise influence. The introduced nonlinear transformation is selected according to the methodology of stochastic approximation and robust statistics. The proposed algorithm represents a general nonlinear stochastic consensus seeking scheme, not yet treated in the literature. It provides a significant improvement over the linear algorithms from the point of view of robustness to noise, ensuring better convergence rate and lower sensitivity of the limit state value at consensus. One of the main contributions of the paper is the proof that the algorithm converges almost surely to consensus under general conditions. A detailed analysis of the limit state value at consensus is provided together with an insight into achievable convergence rate. Illustrative simulation results are also provided, demonstrating great advantages of the proposed algorithm compared to the existing consensus schemes. © 2020 Elsevier B.V.

Dontchev, A.L., Kolmanovsky, I.V., Krastanov, M.I., Veliov, V.M., Vuong, P.T.
Approximating optimal finite horizon feedback by model predictive control
(2020) 139, art. no. 104666, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081716550&doi=10.1016%2fj.sysconle.2020.104666&partnerID=40&md5=c294f86a9cbef5693ab8a54e46664ab0
AFFILIATIONS: American Mathematical Society, United States; 
University of Michigan, United States; 
Department of Aerospace Engineering, University of Michigan, United States; 
Faculty of Mathematics and Informatics, University of Sofia, Bulgaria; 
Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Sofia, Bulgaria; 
Institute of Statistics and Mathematical Methods in Economics, Vienna University of Technology, Austria
ABSTRACT: We consider a finite-horizon continuous-time optimal control problem with nonlinear dynamics, an integral cost, control constraints and a time-varying parameter which represents perturbations or uncertainty. After discretizing the problem we employ a Model Predictive Control (MPC) approach by first solving the problem over the entire remaining time horizon and then applying the first element of the optimal discrete-time control sequence, as a constant in time function, to the continuous-time system over the sampling interval. Then the state at the end of the sampling interval is measured (estimated) with certain error, and the process is repeated at each step over the remaining horizon. As a result, we obtain a piecewise constant function of time representing MPC-generated control signal. Hence MPC turns out to be an approximation to the optimal feedback control for the continuous-time system. In our main result we derive an estimate of the difference between the MPC-generated state and control trajectories and the optimal feedback generated state and control trajectories, both obtained for the same value of the perturbation parameter, in terms of the step-size of the discretization and the measurement error. Numerical results illustrating our estimate are reported. © 2020 Elsevier B.V.

Espitia, N.
Observer-based event-triggered boundary control of a linear 2 × 2 hyperbolic systems
(2020) 138, art. no. 104668, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082136178&doi=10.1016%2fj.sysconle.2020.104668&partnerID=40&md5=63f04f7d79d4030ef62edfb13e7db382
AFFILIATIONS: Univ. Lille, CNRS, Centrale Lille, UMR 9189 - CRIStAL - Centre de Recherche en Informatique Signal et Automatique de Lille, Lille, F-59000, France
ABSTRACT: This paper deals with an observer-based event-triggered boundary control for a coupled 2 × 2 linear hyperbolic system. The approach builds on an output feedback controller depending on estimated states along with a dynamic triggering condition which establishes the time instants at which the control value needs to be sampled/updated. This work combines some recent results on boundary stabilization via the backstepping approach with some event-triggered control strategies for this kind of PDE system. In this paper, it is shown that under the proposed event-triggered boundary control, there exists a minimal dwell-time (independent on initial conditions) between two triggering times and furthermore the well-posedness and global exponential stability are guaranteed. A simulation example is presented to validate the theoretical results with further discussions on the advantages of the proposed scheme. © 2020 Elsevier B.V.

Shi, Q.
Fractional smoothness of derivative of self-intersection local times with respect to bi-fractional Brownian motion
(2020) 138, art. no. 104627, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082100699&doi=10.1016%2fj.sysconle.2020.104627&partnerID=40&md5=a9ab1686973fc22db1af5640a26b0e28
AFFILIATIONS: School of Mathematics and Information Science, Jiangxi Normal University, Nanchang, Jiangxi, 330022, China
ABSTRACT: Let BHi,Ki={Bt Hi,Ki,t≥0},i=1,2 be two independent bifractional Brownian motions with respective indices Hi∈(0,1) and Ki∈(0,1]. In this paper, we study the fractional smoothness of derivative of the local time and the self-intersection local time for a bifractional Brownian motion, and the collision local time for two independent bifractional Brownian motion. © 2020 Elsevier B.V.

Wakaiki, M., Yamamoto, Y.
Stability analysis of perturbed infinite-dimensional sampled-data systems
(2020) 138, art. no. 104652, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081997364&doi=10.1016%2fj.sysconle.2020.104652&partnerID=40&md5=3e1ad7396e030a11a9549fe5f8bd4c1a
AFFILIATIONS: Department of Applied Mathematics, Graduate School of System Informatics, Kobe University, Kobe, 657-8501, Japan; 
Graduate School of Informatics, Kyoto University, Kyoto, 606-8510, Japan
ABSTRACT: This paper addresses the stability analysis of infinite-dimensional sampled-data systems under unbounded perturbations. We present two classes of unbounded perturbations preserving the exponential stability of sampled-data systems. To this end, we investigate the continuity of strongly continuous semigroups with respect to their generators, considering the uniform operator topology. © 2020

Beaver, L., Malikopoulos, A.A.
An energy-optimal framework for assignment and trajectory generation in teams of autonomous agents
(2020) 138, art. no. 104670, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081666852&doi=10.1016%2fj.sysconle.2020.104670&partnerID=40&md5=6a776742d940894b0191be24133bb9ee
AFFILIATIONS: Department of Mechanical Engineering, University of Delaware, Newark, DE  19716, United States
ABSTRACT: In this paper, we present an approach for solving the problem of moving N homogeneous agents into M≥N goal locations along energy-minimizing trajectories. We propose a decentralized framework that only requires knowledge of the goal locations and partial observations of the global state by each agent. The framework includes guarantees on safety through dynamic constraints, and a method to impose a dynamic, global priority ordering on the agents. A solution to the goal assignment and trajectory generation problems is derived in the form of a binary program and a nonlinear system of equations. Then, we present the conditions for optimality and characterize the conditions under which our algorithm is guaranteed to converge to a unique assignment of agents to goals. We also solve the fully constrained decentralized trajectory generation problem considering the state, control, and safety constraints. Finally, we validate the efficacy of our approach through a numerical simulation in MATLAB. © 2020 Elsevier B.V.

Jacob, B., Möller, S., Wyss, C.
Stability radius for infinite-dimensional interconnected systems
(2020) 138, art. no. 104662, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081651228&doi=10.1016%2fj.sysconle.2020.104662&partnerID=40&md5=a75130ea80ab8f6b078e1909a551581c
AFFILIATIONS: School of Mathematics and Natural Sciences, University of Wuppertal, Wuppertal, Germany
ABSTRACT: The stability radius for finitely many interconnected linear exponentially stable well-posed systems with respect to static perturbations is studied. If the output space of each system is finite-dimensional, then a lower bound for the stability radius in terms of the norm of the corresponding transfer functions is given. Moreover, for regular linear systems with zero feedthrough operator and finite-dimensional output spaces a formula for the stability radius is developed. Dedicated to the memory of Ruth F. Curtain © 2020 Elsevier B.V.

Fan, X., Wang, Z.
Event-triggered integral sliding mode control for linear systems with disturbance
(2020) 138, art. no. 104669, . Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081160586&doi=10.1016%2fj.sysconle.2020.104669&partnerID=40&md5=a8c41d4ade20b7bd9f250f10ddf6f105
AFFILIATIONS: College of Information Science and Engineering, Northeastern University, Shenyang, 110819, China
ABSTRACT: An event-triggered integral sliding mode controller design problem for linear systems with disturbance is investigated in this paper. A time-varying triggering threshold is employed in the event-triggered condition to guarantee that the trajectory of system will enter a bounded region. Two types of integral sliding mode switching functions are established. One is the continuous-state-dependent sliding mode switching function, which is used to analyze the reachability of sliding mode surface. The other is the triggered-state-dependent sliding mode switching function, which is applied to design the event-triggered integral sliding mode controller. Moreover, a sufficient condition of ultimate boundedness for sliding motion is established and a positive lower bound of the internal execution time is ensured. Finally, two examples are presented to illustrate the effectiveness of obtained theoretical results. © 2020 Elsevier B.V.

Zhang, J., Zhang, L., Raïssi, T.
A linear framework on the distributed model predictive control of positive systems
(2020) 138, art. no. 104665, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081134738&doi=10.1016%2fj.sysconle.2020.104665&partnerID=40&md5=57c611aff0b0be9303754bffe1bde121
AFFILIATIONS: School of Automation, Hangzhou Dianzi University, Hangzhou, 310018, China; 
Key Laboratory of System Control and Information Processing, Ministry of Education of China, Shanghai, 200240, China; 
College of Automation Science and Technology, South China University of Technology, Guangzhou, 510640, China; 
Cedric-Lab, Conservatoire National des Arts et Metiers, Paris, 75141, France
ABSTRACT: This paper investigates the distributed model predictive control (DMPC) for positive systems with interval and polytopic uncertainties, respectively. Different from the traditional quadratic DMPC, a new linear DMPC framework is established for positive systems. First, a linear cooperative cost function (performance index function) is introduced for the DMPC of positive systems. Accordingly, some linear constraint conditions are imposed on the systems. Then, a linear co-positive Lyapunov function is constructed. Using the linear Lyapunov function, the DMPC controllers are designed for interval positive systems and polytopic positive systems, respectively. The controller of each subsystem contains not only the state information of the subsystem but also the state information of other correlated subsystems. Linear programming based optimization algorithm is addressed to compute the controller parameters. To guarantee the feasibility and stability of the systems, a cone invariant set is proposed. Finally, two case studies are provided to illustrate the effectiveness of the theoretical findings. © 2020 Elsevier B.V.

Wang, F., Wang, J.-M.
Stability of an interconnected system of Euler–Bernoulli beam and wave equation through boundary coupling
(2020) 138, art. no. 104664, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081122315&doi=10.1016%2fj.sysconle.2020.104664&partnerID=40&md5=27f7e096b9adbe458e5a24a642a12b50
AFFILIATIONS: School of Mathematics and Statistics, Beijing Institute of Technology, Beijing, 100081, China
ABSTRACT: In this paper, we study the stabilization of a coupled system of Euler–Bernoulli beam through boundary coupling with a wave equation, where the dissipative damping is designed only at the wave equation. By using the Riesz basis approach, we prove the whole system is exponentially stable, which says that the damped wave equation can stabilize the Euler–Bernoulli beam only through boundary coupling. The theoretical results are validated via a numerical simulation. © 2020 Elsevier B.V.

Lhachemi, H., Shorten, R., Prieur, C.
Exponential input-to-state stabilization of a class of diagonal boundary control systems with delay boundary control
(2020) 138, art. no. 104651, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081120322&doi=10.1016%2fj.sysconle.2020.104651&partnerID=40&md5=bee5a4f92644d501f552624ea5fe2e3a
AFFILIATIONS: School of Electrical and Electronic Engineering, University College Dublin, Dublin 4D04 V1W8, Ireland; 
Dyson School of Design Engineering, Imperial College London, London, United Kingdom; 
CNRS, Grenoble-INP, GIPSA-Lab, université Grenoble Alpes, Grenoble, 38000, France
ABSTRACT: This paper deals with the exponential input-to-state stabilization with respect to boundary disturbances of a class of diagonal infinite-dimensional systems via delay boundary control. The considered input delays are uncertain and time-varying. The proposed control strategy consists of a constant-delay predictor feedback controller designed on a truncated finite-dimensional model capturing the unstable modes of the original infinite-dimensional system. We show that the resulting closed-loop system is exponentially input-to-state stable with fading memory of both additive boundary input perturbations and disturbances in the computation of the predictor feedback. © 2020 Elsevier B.V.

Ratajczak, J., Tchoń, K.
Normal forms and singularities of non-holonomic robotic systems: A study of free-floating space robots
(2020) 138, art. no. 104661, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081007402&doi=10.1016%2fj.sysconle.2020.104661&partnerID=40&md5=2987eed20bb9b19eadb66026c98b41e8
AFFILIATIONS: Chair of Cybernetics and Robotics, Electronics Faculty, Wrocław University of Science and Technology, ul. Janiszewskiego 11/17, Wrocław, 50–372, Poland
ABSTRACT: This paper promotes an idea of describing singularities of non-holonomic robotic systems by normal forms under feedback of associated control systems. In order to increase the explanatory power of the presentation this idea has been applied to the dynamics of a planar free-floating space robot composed of a base (a spacecraft) and a k-DOF (Degrees Of Freedom) on board manipulator. A general Lagrangian dynamics model of the robot is provided. Relying on the preservation of the linear and angular momenta, the affine Pfaffian constraints of motion are obtained. These constraints are expressed in specific coordinates resulting in a pre-normal form of the dynamics model of the robot, represented as a control-affine system, and an associated differential form. The pre-normal form is further transformed by feedback to a normal form, using some tools of the theory of differential forms. Normal forms of the space robot dynamics for k=2 up to k=8 DOF on board are computed that describe the ultimate structure of the dynamics model as well as characterize configuration singularities of the space robot. © 2020 Elsevier B.V.

Kadam, S., Banavar, R.N.
Variational dynamic interpolation for kinematic systems on trivial principal bundles
(2020) 138, art. no. 104648, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081003116&doi=10.1016%2fj.sysconle.2020.104648&partnerID=40&md5=4a4a67769d4eef0ea521e6941400ba6d
AFFILIATIONS: Systems and Control Engineering Department, Indian Institute of Technology Bombay, Mumbai, 400072, India
ABSTRACT: This article presents the dynamic interpolation problem for locomotion systems evolving on a trivial principal bundle Q. Given an ordered set of points in Q, we wish to generate a trajectory which passes through these points by synthesizing suitable controls. The global product structure of the trivial bundle is used to obtain an induced Riemannian product metric on Q. The squared L2-norm of the covariant acceleration is considered as the cost function, and its first order variations are taken for generating the trajectories. The nonholonomic constraint is enforced through the local form of the principal connection and the group symmetry is employed for reduction. The explicit form of the Riemannian connection for the trivial bundle is employed to arrive at the extremal of the cost function. The result is applied to generate a trajectory for the generalized Purcell's swimmer - a low Reynolds number microswimming mechanism. © 2020 Elsevier B.V.

Sahoo, P.R., Ghosh, S.
On computing critical delay for fixed mode radius: Centralized and decentralized control
(2020) 138, art. no. 104647, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080974530&doi=10.1016%2fj.sysconle.2020.104647&partnerID=40&md5=89524827040c988b05f3eabcf5e3c7da
AFFILIATIONS: Department of Electrical & Electronics Engineering, Madanapalle Institute of Technology & Science, Madanapalle, 517325, India; 
Department of Electrical Engineering, Indian Institute of Technology (BHU), Varanasi, 221005, India
ABSTRACT: Fixed mode radius is a perturbation measure used to represent how ‘close’ a system is from having at least one fixed mode. In this paper, a catalog of measures for critically delayed fixed mode radius that correspond to critical delays having minimum radius is introduced for systems with input and output delays. Computable formulas are derived using perturbation measures for both centralized and decentralized control systems. Numerical examples are presented to demonstrate the critical delay feature. © 2020 Elsevier B.V.

Emami, A., Araújo, R., Asvadi, A.
Distributed simultaneous estimation of states and unknown inputs
(2020) 138, art. no. 104660, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080126694&doi=10.1016%2fj.sysconle.2020.104660&partnerID=40&md5=334f2ff83f2398840f89bd689a98c453
AFFILIATIONS: Institute of Systems and Robotics (ISR-UC), and Department of Electrical and Computer Engineering (DEEC-UC), University of Coimbra, Pólo II, Coimbra, PT-3030-290, Portugal
ABSTRACT: In this paper, the problem of distributed estimation in linear discrete-time large-scale stochastic systems is explored. The objective is to estimate the states as well as the unknown inputs of the system under partial observation of the system states by utilizing a number of estimators. The main assumption is that the estimator at each node of the system can exchange its estimated state with the neighboring estimators through communication links. With this consideration, a recursive distributed filter is introduced and its unbiasedness and minimum variance are examined. Furthermore, the necessary and sufficient conditions for the stability and convergence of the proposed distributed filter are investigated. Finally the performance on a numerical example is presented. © 2020 Elsevier B.V.

Li, R.
Distributed algorithm design for optimal resource allocation problems via incremental passivity theory
(2020) 138, art. no. 104650, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080079275&doi=10.1016%2fj.sysconle.2020.104650&partnerID=40&md5=a7abc566bdd7a1b44e9358648e5500f0
AFFILIATIONS: College of Information Science and Engineering, Northeastern University, Shenyang, 110819, China
ABSTRACT: The paper is concerned with distributed optimal resource allocation problems on multi-agent systems that each agent has single-integrator dynamics. For the single-integrator multi-agent system, a local feasible set constraint is introduced and a distributed algorithm with projection operator is proposed. Compared with the algorithms in the existing literature on the single-integrator multi-agent systems, the proposed algorithm has simpler structure that reduces computation burden but without sacrificing the optimality. Incremental passivity theory is utilized to analyze the convergence of the algorithms. The simulation results illustrate the effectiveness of the proposed algorithms. © 2020 Elsevier B.V.

Kim, J., Kim, H.
Synchronization of Lur'e-type nonlinear systems in linear dynamical networks having fast convergence rate and large DC gain
(2020) 138, art. no. 104641, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079881846&doi=10.1016%2fj.sysconle.2020.104641&partnerID=40&md5=ef0436a199285f1aceea7dcb2da75328
AFFILIATIONS: Agency for Defense Development, Daejeon, 34186, South Korea; 
School of Mechatronics Engineering, Korea University of Technology and Education, Cheonan, 31253, South Korea
ABSTRACT: This paper studies the problem of synchronization in a dynamical network, where we identify the nodes of the undirected graph as identical Lur'e-type nonlinear systems and the edges as heterogeneous and asymptotically stable linear systems, i.e., both of the nodes and edges are dynamical systems. It is shown that sufficiently fast convergence rate of each edge guarantees the dynamic edges degenerate into their associated static maps, equivalent to assigning the constant weights to the edges (as in the usual synchronization problems). Thus, in effect, the dynamical network becomes the static one characterized by the Laplacian matrix of the graph with the weights being the gains of the static maps. Then, the large DC gains of the edges, i.e., the large weights, are shown to yield the synchronization of the state variables of the Lur'e-type systems in the static network. The synchronization in the dynamical network is at last guaranteed by the combination of these two results. The results in this paper are applicable to the synchronization of the terminal voltages of the Lur'e-type circuits that are interconnected with each other via the lines having their associated line admittances. © 2020 Elsevier B.V.

Noroozi, N., Geiselhart, R., Grüne, L., Wirth, F.R.
Control of discrete-time nonlinear systems via finite-step control Lyapunov functions
(2020) 138, art. no. 104631, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079835892&doi=10.1016%2fj.sysconle.2020.104631&partnerID=40&md5=2eb53d3a873f5c44890333c934f5ffb4
AFFILIATIONS: Otto-von-Guericke University of Magdeburg, Laboratory for Systems Theory and Automatic Control, Magdeburg, 39106, Germany; 
University of Ulm, Institute of Measurement, Control and Microtechnology, Albert-Einstein-Allee 41, Ulm, 89081, Germany; 
University of Bayreuth, Mathematical Institute, Universitätsstraße 30, Bayreuth, 95440, Germany; 
University of Passau, Faculty of Computer Science and Mathematics, Innstraße 33, Passau, 94032, Germany
ABSTRACT: In this work, we establish different control design approaches for discrete-time systems, which build upon the notion of finite-step control Lyapunov functions (fs-CLFs). The design approaches are formulated as optimization problems and solved in a model predictive control (MPC) fashion. In particular, we establish contractive multi-step MPC with and without reoptimization and compare it to classic MPC. The idea behind these approaches is to use the fs-CLF as running cost. These new design approaches are particularly relevant in situations where information exchange between plant and controller cannot be ensured at all time instants. An example shows the different behavior of the proposed controller design approaches. © 2020 Elsevier B.V.

Katriel, G.
Optimality of constant arrival rate for a linear system with a bottleneck entrance
(2020) 138, art. no. 104649, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079684273&doi=10.1016%2fj.sysconle.2020.104649&partnerID=40&md5=38c7f7ff02f3ab30bacf95730afac928
AFFILIATIONS: Department of Mathematics, ORT Braude College, Karmiel, Israel
ABSTRACT: Sadeghi et al. considered a bottleneck system with periodic arrival rate, and proved that a constant-rate arrival maximizes the time-averaged output rate among all periodic arrival rates. Here we provide a short and elementary proof of this result, without use of optimal control theory. The new approach developed here allows us to prove an extension of the result to the case of a general non-periodic arrival rate. © 2020 Elsevier B.V.

Liu, X., Xie, Y., Li, F., Gui, W.
Cooperative output regulation of singular multi-agent systems under adaptive distributed protocol and general entirety method
(2020) 138, art. no. 104628, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079612790&doi=10.1016%2fj.sysconle.2020.104628&partnerID=40&md5=5205c0ac460418b202d53d4eaade360f
AFFILIATIONS: School of Automation, Central South University, Changsha, 410083, China
ABSTRACT: This paper investigates the cooperative output regulation problem of heterogeneous linear multi-agent systems under singular dynamics and adaptive distributed protocol. Considering the followers do not know the matrix information of the leader, two novel adaptive distributed protocols are developed based on the state and measurement output. Then, as the technology basis of the cooperative output regulation strategy of the singular multi-agent systems considered in this paper, some stability analysis results of linear time-varying singular systems are proved. Next, sufficient conditions are established to solve the cooperative output regulation problem of heterogeneous singular multi-agent systems with the adaptive distributed protocols designed in this paper. The general entirety method is proposed, which avoids the design of standard reduction transformation matrices, the calculation of model reduction and the impulse-free hypothesis in the standard reduction method. Finally, numerical results are provided to demonstrate the feasibility and effectiveness of the proposed techniques. © 2020 Elsevier B.V.

Stefanovski, J., Juričić, Ð.
Fault-tolerant control in presence of disturbances based on fault estimation
(2020) 138, art. no. 104646, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079588888&doi=10.1016%2fj.sysconle.2020.104646&partnerID=40&md5=e8c509fd7cbeecbb3baec656b3e7f135
AFFILIATIONS: Control & Informatics Div., JP “Streževo”, Bitola, North Macedonia; 
Department of Systems and Control, Jožef Stefan Institute, Jamova cesta 39, Ljubljana, SI-1000, Slovenia
ABSTRACT: A new formulation of the fault-tolerant control (FTC) problem in presence of disturbances is given, based on fault estimation (FE). Two solutions/controllers to this problem are given. The first one is a new controller that includes a fault estimator, a nominal controller and a fault accommodation block. This controller requires the strict conditions that the nominal controller is stable, and that the transfer matrix of the fault accommodation block is also stable. The second controller does not require these strict conditions, and is obtained by unifying the three blocks of the first controller, in a single controller whose realization is minimal. Therefore, it does not include a fault estimator. A dedicated fault estimator can be added out of the control loop, in order to monitor the performance of the FTC, as defined in the new problem formulation. With respect to the literature, the two controllers can be applied to a larger class of systems, because of the weaker assumptions. An example is presented, which illustrates with comparison, that the controller of the paper has better properties in respect to existing controllers. © 2020 Elsevier B.V.

Opmeer, M.R.
Decay of singular values for infinite-dimensional systems with Gevrey regularity
(2020) 137, art. no. 104644, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079352434&doi=10.1016%2fj.sysconle.2020.104644&partnerID=40&md5=b415a162e1787301ef1f2b860c87558e
AFFILIATIONS: Department of Mathematical Sciences, University of Bath, Bath, BA2 7AY, United Kingdom
ABSTRACT: We consider the decay rate of the singular values of the input map, the output map and the Hankel operator for a class of infinite-dimensional systems. This class is characterized by the control operator (or the observation operator) having a smoothing effect. We capture this in the definition of a Gevrey operator (which generalizes the known concept of a Gevrey vector). In applications to PDEs, this abstract assumption on the control operator is typically satisfied when the input is multiplied by a function which is a compactly supported Gevrey function in the spatial variable. Using the theory of polynomial approximation (in particular: truncated Chebyshev expansions), we obtain that the singular values decay exponentially in a root of the approximation dimension. The power of the root depends on the order of the Gevrey operator and on whether the underlying semigroup is nilpotent, exponentially stable or polynomially stable. © 2020 Elsevier B.V.

Ngoc, P.H.A., Tran, T.B., Tinh, C.T., Huy, N.D.
Scalar criteria for exponential stability of functional differential equations
(2020) 137, art. no. 104642, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079351663&doi=10.1016%2fj.sysconle.2020.104642&partnerID=40&md5=fc01c09e4a2aec49915c32b72b90e2f9
AFFILIATIONS: Department of Mathematics, International University, Viet Nam; 
Vietnam National University, Ho Chi Minh city, Thu Duc District, Saigon, Viet Nam; 
Faculty of Information Systems, University of Information Technology, Viet Nam; 
Department of Mathematics, University of Information Technology, Viet Nam; 
Division of Applied Mathematics, Faculty of Applied Sciences, University of Technology, Viet Nam
ABSTRACT: Using a novel approach, we present some scalar criteria for the exponential stability of general functional differential equations. Both delay-independent and delay-dependent stability criteria are provided. A discussion of the obtained results is given. © 2020 Elsevier B.V.

Cârjă, O., Lazu, A.I.
Minimum time and minimum energy for linear control systems
(2020) 137, art. no. 104629, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079350034&doi=10.1016%2fj.sysconle.2020.104629&partnerID=40&md5=d1dc2284df3cc53c000cdad974de7356
AFFILIATIONS: Department of Mathematics, “Al. I. Cuza” University, Iaşi 700506 and “Octav Mayer” Mathematics Institute, Romanian Academy, Iaşi 700505, Romania; 
Department of Mathematics, “Gh. Asachi” Technical University, Iaşi 700506, Romania
ABSTRACT: In this paper we give estimates concerning regularity properties of the minimum time function and the minimum norm controls involving the controllability function given by the observability inequalities. We further study the continuity of the minimum time function in two variables (the initial point and the radius of the ball that limits the control). We prove a maximum principle for both time and norm optimal control problems. © 2020 Elsevier B.V.

Shen, M., Fei, C., Fei, W., Mao, X.
Stabilisation by delay feedback control for highly nonlinear neutral stochastic differential equations
(2020) 137, art. no. 104645, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079342687&doi=10.1016%2fj.sysconle.2020.104645&partnerID=40&md5=753dea9d612142098eab0e073ec6bade
AFFILIATIONS: Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment, Ministry of Education, and School of Mathematics and Physics, Anhui Polytechnic University, Wuhu, 241000, China; 
School of Science, Nanjing University of Science and Technology, Nanjing, Jiangsu, 210094, China; 
Glorious Sun School of Business and Management, Donghua University, Shanghai, 200051, China; 
Department of Mathematics and Statistics, University of Strathclyde, Glasgow, G1 1XH, United Kingdom
ABSTRACT: Given an unstable hybrid neutral stochastic differential equation (NSDE), can we design a delay feedback control to make the controlled hybrid NSDE become stable? It has been proved that this is possible under the linear growth condition. However, there is no answer to the question if the drift and diffusion coefficients of the given unstable NSDE satisfy highly nonlinear growth condition. The aim of this paper is to design delay feedback controls in order to stabilise a class of highly nonlinear hybrid NSDEs whose coefficients satisfy the polynomial growth condition. © 2020 Elsevier B.V.

Pakshin, P., Emelianova, J., Rogers, E., Gałkowski, K.
Repetitive process based stochastic iterative learning control design for linear dynamics
(2020) 137, art. no. 104625, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079190764&doi=10.1016%2fj.sysconle.2020.104625&partnerID=40&md5=98441e1f519347619cf22f0324a95c99
AFFILIATIONS: Arzamas Polytechnic Institute of R.E. Alekseev Nizhny Novgorod State Technical University, 19, Kalinina Street, Arzamas, 607227, Russian Federation; 
Lobachevsky State University of Nizhny Novgorod, Prospekt Gagarina, 23, Nizhny Novgorod, 603950, Russian Federation; 
School of Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ, United Kingdom; 
Institute of Control and Computation Engineering, University of Zielona Góra, ul. Podgórna 50, Zielona Góra, 65-246, Poland
ABSTRACT: A new set of iterative learning control laws for systems described by stochastic discrete linear dynamics is developed using the passivity based stability theory for discrete nonlinear repetitive processes. This setting allows the application of a nonlinear control law to discrete linear systems. The advantages of such a control law in tuning the performance of the design is demonstrated by a case study that also compares the performance of one member of this class of new laws against an existing design. © 2020 Elsevier B.V.

Sato, M.
One-shot design of performance scaling matrices and observer-based gain-scheduled controllers depending on inexact scheduling parameters
(2020) 137, art. no. 104632, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079148403&doi=10.1016%2fj.sysconle.2020.104632&partnerID=40&md5=9dd84d4dd757c92561c289d18e11876e
AFFILIATIONS: Aeronautical Technology Directorate, Japan Aerospace Exploration Agency, Osawa 6-13-1, Mitaka, Tokyo, 181-0015, Japan
ABSTRACT: This paper addresses the design problem of continuous-/discrete-time observer-based Gain-Scheduled Output Feedback (GSOF) controllers for Linear Parameter-Varying (LPV) systems, in which some of the state-space matrices are multi-affine with respect to parameters, with the simultaneous design of scaling matrices for multiple uncertainty blocks under the supposition that inexact scheduling parameters are available. In the design of GSOF controllers for practical systems in induced L2∕l2-norm control framework, the following features are to be incorporated; i) structured and easily-understandable controllers are preferable to enhance the practicality, ii) the scaling matrices related to multiple uncertainty blocks which represent various design specifications are also to be designed to reduce conservatism, and iii) one-shot design is preferable to prevent numerical problems in iterative algorithm. However, in general, neither the design problems of the structured controllers nor the simultaneous design of controllers and the performance scaling matrices are formulated in terms of Linear Matrix Inequalities (LMIs). Under the supposition that the uncertainties in the provided scheduling parameters are bounded (this supposition holds true for proportional uncertainties and for absolute uncertainties as well as for the mixed ones of them), we derive a new tractable one-shot multi-affine condition for our problem via dilated/extended LMI technique under some mild assumptions for LPV systems. A numerical example well illustrates the effectiveness of our method. © 2020 Elsevier B.V.

Liu, X., Xie, C.
Control law in analytic expression of a system coupled by reaction–diffusion equation
(2020) 137, art. no. 104643, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079138981&doi=10.1016%2fj.sysconle.2020.104643&partnerID=40&md5=bb19ae9241816a4253a4071577ad1318
AFFILIATIONS: School of Mathematics and System Science, Southwest University, China
ABSTRACT: Control design of a coupled ODE–PDE boundary control system is considered in this paper. The PDE is one dimensional reaction–diffusion equation, with constant parameters, actuated at one of the boundaries and coupled to a linear and time-invariant ODE at the opposite boundary. By introducing a two-step backstepping design procedure, analytic solutions of the kernel and vector-valued functions in the backstepping transformations are obtained. Therefore, a boundary control law in analytic expression is constructed for this coupled ODE–PDE control system. © 2020 Elsevier B.V.

Chen, X., Zhang, X., Liu, Q.
Prescribed-time decentralized regulation of uncertain nonlinear multi-agent systems via output feedback
(2020) 137, art. no. 104640, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079086656&doi=10.1016%2fj.sysconle.2020.104640&partnerID=40&md5=751a2cb9fdb2a2452ecd7ad7dedae8c1
AFFILIATIONS: School of Control Science and Engineering, Shandong University, Jinan, 250061, China; 
School of Mathematics and Quantitative Economics, Shandong University of Finance and Economics, Jinan, 250014, China
ABSTRACT: This paper addresses the global prescribed-time decentralized regulation problem for a family of uncertain nonlinear multi-agent systems. The dynamics of each agent is supposed to be in the strict feedback form, where the uncertain nonlinearities admit Lipschitz growth conditions with an unknown positive constant gain multiplying by a time-varying continuous function gain. It is firstly defined error systems, which are composed of the leader and their followers, and shown that the prescribed-time decentralized regulation problem of the original systems is equivalent to the prescribed-time regulation problem of error systems. Then, by introducing a novel state transformation involving a time-scaling function, the prescribed-time regulation problem is then converted into designing appropriate gain parameters. Finally, based on the Lyapunov stability theorem, the prescribed-time regulation of the closed-loop systems is proved and the prescribed-time decentralized regulation of the original systems is thus guaranteed. An example is presented to show the feasibility of the proposed prescribed-time decentralized protocols. © 2020 Elsevier B.V.

Turner, M.C., Sofrony, J., Prempain, E.
Anti-windup for model-reference adaptive control schemes with rate-limits
(2020) 137, art. no. 104630, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079059035&doi=10.1016%2fj.sysconle.2020.104630&partnerID=40&md5=cc0d87edff75c51c16930447e8825fb6
AFFILIATIONS: School of Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ, United Kingdom; 
Department of Mechatronics, Nacional University of Colombia, Bogota, Colombia; 
Department of Engineering, University of Leicester, Leicester, LE1 7RH, United Kingdom
ABSTRACT: This paper proposes an anti-windup like scheme for an LTI plant with rate-limits. The plant is controlled using a model-reference adaptive controller, making the anti-windup design problem highly nonlinear. It is assumed that the rate-limit is modelled as a first order feedback loop for which the state is unavailable, but that the bandwidth of this loop is known. The anti-windup scheme uses a “hedging” term and a “positive μ” term. The structure of the problem makes the rate-limit case considerably more difficult than the magnitude limit case. Nevertheless it is proved that convergence of the system state to the ideal model can be accomplished under conditions similar to those found in anti-windup compensation for purely linear systems. © 2020 Elsevier B.V.

Picarelli, A., Reisinger, C.
Probabilistic error analysis for some approximation schemes to optimal control problems
(2020) 137, art. no. 104619, . Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079045595&doi=10.1016%2fj.sysconle.2019.104619&partnerID=40&md5=aaca84b98daf475fe772410dbe8ec885
AFFILIATIONS: Economics Department, University of Verona, Via Cantarane 24, Verona, 37129, Italy; 
Mathematical Institute, University of Oxford, Andrew Wiles Building, Oxford, OX2 6GG, United Kingdom
ABSTRACT: We introduce a class of numerical schemes for optimal stochastic control problems based on a novel Markov chain approximation, which uses, in turn, a piecewise constant policy approximation, Euler–Maruyama time stepping, and a Gauß-Hermite approximation of the Gaußian increments. We provide lower error bounds of order arbitrarily close to 1/2 in time and 1/3 in space for Lipschitz viscosity solutions, coupling probabilistic arguments with regularization techniques as introduced by Krylov. The corresponding order of the upper bounds is 1/4 in time and 1/5 in space. For sufficiently regular solutions, the order is 1 in both time and space for both bounds. Finally, we propose techniques for further improving the accuracy of the individual components of the approximation. © 2020

Liu, L., Wu, Z.
Intermittent stochastic stabilization based on discrete-time observation with time delay
(2020) 137, art. no. 104626, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078699075&doi=10.1016%2fj.sysconle.2020.104626&partnerID=40&md5=849b5c1bc71150600f10c64094da1fd5
AFFILIATIONS: Department of Mathematics, Hohai University, Nanjing, 210098, China; 
School of Mathematics and Informational Science, Yantai University, Yantai, 264005, China
ABSTRACT: This paper is concerned with the stochastic stabilization via hybrid control strategies. First, a sufficient criterion on stochastic stabilization based on discrete-time observation with time delay is derived. Next, with the aid of an established dynamical property for the non-autonomous system, a sufficient criterion is derived to ensure the intermittent stochastic stabilization based on discrete-time observation with time delay. Finally, simulation on a numerical example is performed to illustrate the theoretical results. © 2020 Elsevier B.V.

Chung, Y.-F., Kia, S.S.
Distributed leader following of an active leader for linear heterogeneous multi-agent systems
(2020) 137, art. no. 104621, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078164429&doi=10.1016%2fj.sysconle.2020.104621&partnerID=40&md5=7520beb5bbf6bc2e30cdd58f78c60ada
AFFILIATIONS: Department of Mechanical and Aerospace Engineering, University of California, Irvine, 4200 Engineering Gateway, Irvine, CA  92697, United States
ABSTRACT: This paper considers a leader-following problem for a group of heterogeneous linear time invariant (LTI) followers that are interacting over a directed acyclic graph. Only a subset of the followers has access to the state of the leader in specific sampling times. The dynamics of the leader that generates its sampled states is unknown to the followers. For interaction topologies in which the leader is a global sink in the graph, we propose a distributed algorithm that allows the followers to arrive at the sampled state of the leader by the time the next sample arrives. Our algorithm is a practical solution for a leader-following problem when there is no information available about the state of the leader except its instantaneous value at the sampling times. Our algorithm also allows the followers to track the sampled state of the leader with a locally chosen offset that can be time-varying. When the followers are mobile agents whose state or part of their state is their position vector, the offset mechanism can be used to enable the followers to form a transnational invariant formation about the sampled state of the leader. We prove that the control input of the followers to take them from one sampled state to the next one is minimum energy. We also show in case of the homogeneous followers, after the first sampling epoch the states and inputs of all the followers are synchronized with each other. Numerical examples demonstrate our results. © 2020 Elsevier B.V.

Shi, M., De Persis, C., Tesi, P.
On the benefits of saturating information in consensus networks with noise
(2020) 137, art. no. 104623, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078161821&doi=10.1016%2fj.sysconle.2020.104623&partnerID=40&md5=d0fafa28153d149035e9db7e24ef9060
AFFILIATIONS: ENTEG, University of Groningen, Groningen, 9747 AG, Netherlands; 
DINFO, University of Florence, Firenze, 50139, Italy
ABSTRACT: In a consensus network subject to non-zero mean noise, the system state may be driven away even when the disagreement exhibits a bounded response. This is unfavourable in applications since the nodes may not work properly and even be faulty outside their operating region. In this paper, we propose a new control algorithm to mitigate this issue by assigning each node a favourite interval that characterizes the nodes desired convergence region. The algorithm is implemented in a self-triggered fashion. If the nodes do not share a global clock, the network operates in a fully asynchronous mode. By this algorithm, we show that the state evolution is confined around the favourite interval and the node disagreement is bounded by a simple linear function of the noise magnitude, without requiring any priori information on the noise. We also show that if the nodes share some global information, then the algorithm can be adjusted to make the nodes evolve into the favourite interval, improve on the disagreement bound and achieve asymptotic consensus in the noiseless case. © 2020 Elsevier B.V.

Wang, B., Zhu, Q.
The novel sufficient conditions of almost sure exponential stability for semi-Markov jump linear systems
(2020) 137, art. no. 104622, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078101462&doi=10.1016%2fj.sysconle.2020.104622&partnerID=40&md5=87fae1742422dd0d6da6d93fe650ff64
AFFILIATIONS: School of Mathematics and Physics, Xuzhou Institute of Technology, Xuzhou, Jiangsu  221000, China; 
MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, Hunan  410081, China; 
Key Laboratory of Applied Statistics and Data Science, Hunan Normal University, College of Hunan Province, Changsha, 410081, China
ABSTRACT: This paper discusses the almost sure exponential stability problem for semi-Markov jump linear systems. By comprehensively utilizing the coupled Lyapunov matrices and the ergodic property of semi-Markov switching process, the novel sufficient stability conditions for the considered systems are obtained, which are expressed in terms of linear matrix inequalities and the probability structure of semi-Markov switching process. Finally, an example is given to illustrate the effectiveness of our results. © 2020 Elsevier B.V.

Tian, R., Yu, Z., Zhang, R.
A closed-loop saddle point for zero-sum linear-quadratic stochastic differential games with mean-field type
(2020) 136, art. no. 104624, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078570980&doi=10.1016%2fj.sysconle.2020.104624&partnerID=40&md5=4f43c625f4a8893141c5c2b11e4c3436
AFFILIATIONS: Shandong University-Zhongtai Securities Institute for Financial Studies, Jinan, Shandong, 250100, China; 
School of Mathematics, Shandong University, Jinan, Shandong, 250100, China
ABSTRACT: This paper is concerned with a linear-quadratic zero-sum differential game with mean-field type. The notions of explicit and implicit strategy laws are proposed. Based on them, a closed-loop formulation for saddle points in the mixed-strategy-law form is established. In order to construct the saddle point, the classical entire completion-of-square argument is developed to a four-step-completion-of-square argument, and a pair of optimality conditions is proposed. © 2020 Elsevier B.V.

Redmann, M.
An LT 2-error bound for time-limited balanced truncation
(2020) 136, art. no. 104620, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078120145&doi=10.1016%2fj.sysconle.2019.104620&partnerID=40&md5=66db590fe86ea637c7a0cc638842af3d
AFFILIATIONS: Martin Luther University Halle-Wittenberg, Institute of Mathematics, Theodor-Lieser-Str. 5, Halle (Saale), 06120, Germany
ABSTRACT: Model order reduction (MOR) is often applied to spatially-discretized partial differential equations to reduce their order and hence decrease computational complexity. A reduced system can be obtained, e.g., by time-limited balanced truncation, a method that aims to construct an accurate reduced order model on a given finite time interval [0,T]. This particular balancing related MOR technique is studied in this paper. An LT 2-error bound based on the truncated time-limited singular values is proved and is the main result of this paper. The derived error bound converges (as T→∞) to the well-known H∞-error bound of unrestricted balanced truncation, a scheme that is used to construct a good reduced system on the entire time line. The techniques within the proofs of this paper can also be applied to unrestricted balanced truncation so that a relatively short time domain proof of the H∞-error bound is found here. © 2020 Elsevier B.V.

Terushkin, M., Fridman, E.
Network-based control of a semilinear damped beam equation under point and pointlike measurements
(2020) 136, art. no. 104617, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077944737&doi=10.1016%2fj.sysconle.2019.104617&partnerID=40&md5=69e95e78cd4511e813d116d9e25ed4ab
AFFILIATIONS: Department of Electrical Engineering and Systems, Tel Aviv university, Tel aviv, 69978, Israel
ABSTRACT: We consider distributed static output-feedback stabilization of a damped semilinear beam equation. Distributed in space measurements are either point or pointlike, where a pointlike measurement is the state value averaged on a small subdomain. Network-based implementation of the control law which enters the PDE through shape functions is studied, where variable sampling intervals and transmission delays are taken into account. Our main objective is to derive and compare the results under both types of measurements in terms of the upper bound on the delays and sampling intervals that preserve the stability for the same (as small as possible) number of sensors/actuators. For locally Lipschitz nonlinearities, regional stabilization is achieved. Numerical results show that the pointlike measurements lead to larger delays and samplings, provided the subdomains, where these measurements are averaged, are not too small. © 2019 Elsevier B.V.

Gilmore, M.E., Guiver, C., Logemann, H.
Semi-global incremental input-to-state stability of discrete-time Lur'e systems
(2020) 136, art. no. 104593, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077739576&doi=10.1016%2fj.sysconle.2019.104593&partnerID=40&md5=5c129f3484c70ff3402db82c6d3d9733
AFFILIATIONS: Department of Mathematical Sciences, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom
ABSTRACT: We present sufficient conditions for semi-global incremental input-to-state stability of a class of forced discrete-time Lur'e systems. The results derived are reminiscent of well-known absolute stability criteria such as the small gain theorem and the circle criterion. We derive a natural sufficient condition which guarantees that asymptotically (almost) periodic inputs generate asymptotically (almost) periodic state trajectories. As a corollary, we obtain sufficient conditions for the converging-input converging-state property to hold. © 2019 Elsevier B.V.

Wang, Z., Liu, F., Zhao, C., Ma, Z., Wei, W.
Distributed optimal load frequency control considering nonsmooth cost functions
(2020) 136, art. no. 104607, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077733221&doi=10.1016%2fj.sysconle.2019.104607&partnerID=40&md5=4f3192a67ef7bdd45fb9ad2e849427a5
AFFILIATIONS: State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China; 
Department of Information Engineering, The Chinese University of Hong Kong, Hong Kong
ABSTRACT: This work addresses the distributed frequency control problem in power systems considering controllable load with a nonsmooth cost. The nonsmoothness exists widely in power systems, such as tiered price, greatly challenging the design of distributed optimal controllers. In this paper, we first formulate an optimization problem that minimizes the nonsmooth regulation cost, where both capacity limits of controllable load and tie-line flow are considered. Then, a distributed controller is derived based on the primal–dual gradient method, where the Clark generalized gradient is utilized to address the nonsmoothness. We also prove the optimality of the equilibrium of the closed-loop system as well as its stability. Simulations carried out on the IEEE 68-bus system verifies the effectiveness of the proposed method. © 2019 Elsevier B.V.

Chen, Y., Zuo, Z., Wang, Y.
Bipartite consensus for a network of wave equations with time-varying disturbances
(2020) 136, art. no. 104604, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077688178&doi=10.1016%2fj.sysconle.2019.104604&partnerID=40&md5=b0c7f123d2b2351aedc266de3e1c41dc
AFFILIATIONS: Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin, 300072, China
ABSTRACT: This paper studies the consensus problem for a network of wave equations subject to antagonistic interactions and exogenous disturbances. To this end, a distributed boundary algorithm is proposed with the aid of infinite-dimensional observers. We first deal with the well-posedness of the underlying system. Then we show that the bipartite consensus problem can be solved. In addition, it is also illustrated that the negative effect induced by the boundary disturbances can be eliminated by virtue of the proposed algorithm. Finally, a numerical example is presented to support the derived results. © 2019 Elsevier B.V.

Liu, H., Hu, P.
Boundary sampled-data feedback stabilization for parabolic equations
(2020) 136, art. no. 104618, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077494024&doi=10.1016%2fj.sysconle.2019.104618&partnerID=40&md5=23708237fb2840783f341fbe8b99d2e8
AFFILIATIONS: School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074, China
ABSTRACT: The aim of this work is to design an explicit finite dimensional boundary feedback controller of sampled-data form for locally exponentially stabilizing the equilibrium solutions to semilinear parabolic equations. The feedback controller is expressed in terms of the eigenfunctions corresponding to unstable eigenvalues of the linearized equation. This stabilizing procedure is applicable for any sampling rate, and when the sampling period tends to zero, the feedback converges to certain feedback designed for stabilizing the parabolic equations with continuous-time boundary feedback control. © 2019 Elsevier B.V.

Roy, S., Xue, M.
Controllability-Gramian submatrices for a network consensus model
(2020) 136, art. no. 104575, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077389560&doi=10.1016%2fj.sysconle.2019.104575&partnerID=40&md5=7f7f8d9591562ff692e8e5ed4f83d71f
AFFILIATIONS: School of Electrical Engineering and Computer Science at Washington State University, United States
ABSTRACT: Principal submatrices of the controllability Gramian and their inverses are examined, for a network-consensus model with inputs at a subset of network nodes. Several properties of the Gramian submatrices and their inverses – including dominant eigenvalues and eigenvectors, diagonal entries, and sign patterns – are characterized by exploiting the special doubly-nonnegative structure of the matrices. In addition, majorizations for these properties are obtained in terms of cutsets in the network's graph, based on the diffusive form of the model. The asymptotic (long time horizon) structure of the controllability Gramian is also analyzed. The results on the Gramian are used to study metrics for target control of the network-consensus model. © 2020 Elsevier B.V.

Komatsu, H., Nakajima, H.
The Deficiency Zero Theorem and global asymptotic stability for a class of chemical reaction networks with arbitrary time delays
(2020) 136, art. no. 104601, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077123698&doi=10.1016%2fj.sysconle.2019.104601&partnerID=40&md5=43d41fdec1924f5fd2c6afee6dab41f2
AFFILIATIONS: Institute for Frontier Life and Medical Sciences, Kyoto University, 53 Shogoin Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan; 
Graduate School of Systems Engineering, Kindai University, 1 Takaya Umenobe, Higashi-Hiroshima, Hiroshima, 739-2116, Japan
ABSTRACT: The Deficiency Zero Theorem (DZT) is extended to be applied to chemical reaction networks (CRNs) with time delays, the time evolution of concentrations of species in which networks is described by delay differential equations (DDEs). The extended DZT provides a sufficient condition for a positive equilibrium point of DDEs to exist and be locally asymptotically stable. Furthermore, it is proven that the absence of boundary equilibria is a sufficient condition for the positive equilibrium point to be globally asymptotically stable. These results are natural analogues of theorems proven for CRNs without time delays. © 2019 Elsevier B.V.

Hu, W., Zhu, Q.
Stability analysis of impulsive stochastic delayed differential systems with unbounded delays
(2020) 136, art. no. 104606, . Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077119943&doi=10.1016%2fj.sysconle.2019.104606&partnerID=40&md5=63c2fc603b881ce3afa4af0183c3b05d
AFFILIATIONS: School of Mathematics and Physics, Jiangsu University of Technology, Changzhou, Jiangsu, 213001, China; 
MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, Hunan, 410081, China
ABSTRACT: In this paper, the stability analysis for impulsive stochastic delayed differential equations with unbounded delays is considered by applying stochastic analysis techniques and average dwell time approach. A novel Razumikhin-type criterion of the pth moment exponential stability is derived for the related systems. The feature of the criterion shows that time-derivatives of the Lyapunov functions are allowed to be indefinite, even unbounded, which can loosen the constraints of the existing results. As a corollary, the criterion of the pth moment exponential stability for stochastic delayed differential equations with unbounded delays without impulsive effects is also obtained. Finally, some examples are given to illustrate the usefulness and significance of the theoretical results. © 2019 Elsevier B.V.

Chen, J., Huang, B., Zhu, Q., Liu, Y., Li, L.
Global convergence of the EM algorithm for ARX models with uncertain communication channels
(2020) 136, art. no. 104614, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077057737&doi=10.1016%2fj.sysconle.2019.104614&partnerID=40&md5=b451897127c2e40a51ef958e3a86354a
AFFILIATIONS: Key Laboratory of Advanced Process Control for Light Industry (Ministry of Education), Jiangnan University, Wuxi, 214122, China; 
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, T6G 2G6, Canada; 
Department of Engineering Design and Mathematics, University of the West of England, Bristol, BS16 1QY, United Kingdom
ABSTRACT: An expectation maximization (EM) algorithm is presented for ARX modeling with uncertain communication channels. The considered model consists of two parts: a dynamic model which is expressed by an ARX model, and an output model, both subject to white Gaussian noises. Since the true outputs of the ARX model are assumed to be unknown, a modified Kalman filter is derived to estimate the output, and then the parameters are estimated by the EM algorithm using the estimated outputs. The Kullback–Leibler divergence and the submartingale are used to prove that the parameter estimates can converge to the true values with the EM algorithm. Furthermore, a simulation example is presented to verify the theoretical results. © 2019

Tran, D., Yucelen, T.
Finite-time control of perturbed dynamical systems based on a generalized time transformation approach
(2020) 136, art. no. 104605, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076988466&doi=10.1016%2fj.sysconle.2019.104605&partnerID=40&md5=5d16995913444bdd49ee90a6e555b28e
AFFILIATIONS: Department of Mechanical Engineering, University of South Florida, Tampa, FL  33620, United States
ABSTRACT: We study finite-time control of perturbed dynamical systems based on the time transformation approach. For addressing time-critical applications, where the execution of a control algorithm over a prescribed time interval [0,τ) is necessary with τ being a user-defined convergence time, we introduce a new class of scalar, time-varying gain functions entitled as “generalized finite-time gain functions” that have the capability to convert an original baseline control algorithm into a time-varying one. Based on these generalized finite-time gain functions, in particular, the corresponding “generalized time transformation functions” are obtained and used to transform a resulting algorithm over the prescribed time interval [0,τ) to an equivalent algorithm over the stretched infinite-time interval [0,∞) for stability analysis, where the connection between the generalized finite-time gain functions and their corresponding generalized time transformation functions are investigated in detail. A procedure for designing finite-time control algorithms is further proposed and illustrated by numerical examples showing that the method is applicable to, but not limited to, a class of nonlinear systems as well as multiagent systems. In addition, we show all the conditions on the proposed generalized finite-time gain functions that guarantee the boundedness and convergence of the state and control signals. An application of our theoretical findings to the distributed control of networked multiagent systems problem over a prescribed time interval is also presented. © 2019 Elsevier B.V.

Sarafrazi, M.A., Kotta, Ü., Bartosiewicz, Z.
Finite determination of accessibility and singular points of nonlinear systems: An algebraic approach
(2020) 136, art. no. 104600, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076712671&doi=10.1016%2fj.sysconle.2019.104600&partnerID=40&md5=1df6051cccba3c41185be0849269a8dd
AFFILIATIONS: Rezvan complex, Motahari Sq., Motahari Blvd., Shiraz, 71868-98544, Iran; 
Department of Software Science, Tallinn University of Technology, Tallinn, 12618, Estonia; 
Bialystok University of Technology, Faculty of Computer Science, Wiejska 45A, Białystok, 15-351, Poland
ABSTRACT: Exploiting tools from algebraic geometry, the problem of determination of accessibility/strong accessibility is investigated for polynomial systems and also for analytic systems that are immersible into polynomial systems. The results are constructive, and algorithms are given to find the maximum depth of Lie brackets necessary for deciding accessibility/strong accessibility of the system at any point, called here accessibility/strong accessibility index of the system, and known as the degree of non-holonomy in the literature. Alternatively, upper bounds on the accessibility/strong accessibility index are obtained, which can be computed easier. In each approach, the entire set of accessibility/strong accessibility singular points are obtained, as a limiting algebraic set of a strictly increasing chain of ideals, that stabilizes in finite time. Several examples demonstrate the applicability of the results using computer algebra tools. © 2019 Elsevier B.V.

Borri, A., Carravetta, F., Palumbo, P.
Cubification of σπ-SDE and exact moment equations
(2020) 136, art. no. 104602, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076710564&doi=10.1016%2fj.sysconle.2019.104602&partnerID=40&md5=d15a5323d80f19df7706cf928cb45122
AFFILIATIONS: Istituto di Analisi dei Sistemi ed Informatica, Consiglio Nazionale delle Ricerche, Via dei Taurini, 19, Roma, 00185, Italy
ABSTRACT: For an Itô-like Stochastic Differential Equation (SDE) system, with drift and diffusion that are formal polynomials of the independent variables, we show that all moments satisfy an infinite, countable, set of linear ordinary differential equations. This result is achieved by means of the exact cubification of the SDE, which consists in a set of deterministic transformations of the state variables, giving place to a new SDE with further finitely many state variables. Exact cubification can be considered as an extension to the ‘stochastic case’ of the exact quadratization of deterministic nonlinear systems, available in the literature. An example is finally shown, taken from systems biology, in which, for a basic chemical reaction network the exact moment equation is written down, and an approximate solution is calculated through a moment closure method. © 2019

Wang, W., Chen, W.
Stochastic Nicholson-type delay system with regime switching
(2020) 136, art. no. 104603, . Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076675066&doi=10.1016%2fj.sysconle.2019.104603&partnerID=40&md5=132adf10ec1f7dc921f539a4cb757f57
AFFILIATIONS: School of Mathematics, Physics and Statistics, Shanghai University of Engineering Science, Shanghai, 201620, China; 
School of Statistics and Mathematics, Shanghai Lixin University of Accounting and Finance, Shanghai, 201209, China
ABSTRACT: Focusing on Nicholson-type delay system under perturbations of white and color environmental noises, we introduce the stochastic system with regime switching. By constructing a classic Lyapunov function, we show that the system has a unique global positive solution. Then we estimate its ultimate boundedness, moment and Lyapunov exponent. Finally, an example with its numerical simulations is presented to check theoretical results. © 2019 Elsevier B.V.

Kong, F.H., Manchester, I.R.
Contraction analysis of nonlinear noncausal iterative learning control
(2020) 136, art. no. 104599, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076564878&doi=10.1016%2fj.sysconle.2019.104599&partnerID=40&md5=22e00859874e2155af1b90ecc9cd2644
AFFILIATIONS: Australian Centre for Field Robotics and Sydney Institute for Robotics and Intelligent Systems, School of Aerospace, Mechanical and Mechatronic Systems, The Universty of Sydney, Australia
ABSTRACT: Iterative learning control (ILC) is a method for learning input signals for repetitive control tasks. In this paper, we provide a new method based on convex optimization for certifying convergence and estimating convergence rate in ILC schemes involving a nonlinear plant and a noncausal update law, which are common in practice. Using sum-of-squares (SOS) optimization, we compute the convergence rate of an example nonlinear, noncausal ILC system and verify its accuracy in experiment. © 2019 Elsevier B.V.

Niu, B., Liu, M., Li, A.
Global adaptive stabilization of stochastic high-order switched nonlinear non-lower triangular systems
(2020) 136, art. no. 104596, . Cited 11 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076523547&doi=10.1016%2fj.sysconle.2019.104596&partnerID=40&md5=3e89701b101755b241fb116ae58dbf8b
AFFILIATIONS: School of Information Science and Engineering, Shandong Normal University, Jinan, 250014, China; 
Research Center of Satellite Technology, Harbin Institute of Technology, Harbin Heilongjiang, 150080, China
ABSTRACT: This paper aims to deal with the global adaptive stabilization problem for a class of uncertain stochastic high-order switched nonlinear systems. The most distinctive feature of the studied system is that all drift terms of each subsystem are non-lower triangular nonlinear functions. To achieve the control objective, the retrogressed form of the studied system is first considered and a common state-feedback controller of all subsystems is first systematically constructed in the framework of the common Lyapunov function (CLF) method combined with the adding a power integrator technique, which assures the global stability in probability of the corresponding closed-loop retrogressed system under arbitrary switching. Then a sufficient condition is deliberately proposed by designing a state-dependent switching law in combination with the common state-feedback controller to ensure that the system states can be regulated to the origin almost surely and the globally stability in probability of the whole closed-loop system. Finally, two simulation examples are given to illustrate the effectiveness of the presented control schemes. © 2019 Elsevier B.V.

Kundu, A.
A new condition for stability of switched linear systems under restricted minimum dwell time switching
(2020) 135, art. no. 104597, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076724417&doi=10.1016%2fj.sysconle.2019.104597&partnerID=40&md5=807bbafb95c97abde6e4eefc9d4220fa
AFFILIATIONS: Department of Electrical Engineering, Indian Institute of Science, Bangalore, India
ABSTRACT: We propose matrix commutator based stability characterization for discrete-time switched linear systems under restricted switching. Given an admissible minimum dwell time, we identify sufficient conditions on subsystems such that a switched system is stable under all switching signals that obey the given restriction. The primary tool for our analysis is commutation relations between the subsystem matrices. Our stability conditions are robust with respect to small perturbations in the elements of these matrices. In case of arbitrary switching (i.e., given minimum dwell time =1), we recover the prior result (Agrachev et al., 2012, Proposition 1) as a special case of our result. © 2019 Elsevier B.V.

Liu, T., Fernández-Kim, V., de Queiroz, M.
Switching formation shape control with distance + area/angle feedback
(2020) 135, art. no. 104598, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076265967&doi=10.1016%2fj.sysconle.2019.104598&partnerID=40&md5=b8ea0582762f159323e85e5988abe784
AFFILIATIONS: Department of Mechanical and Industrial Engineering, Louisiana State University, Baton RougeLA  70803, United States
ABSTRACT: A well known problem with distance-based formation control is the existence of multiple equilibrium points not associated with the desired formation. This problem can be mitigated by introducing an additional controlled variable. In this paper, we consider distance + area (or angle) schemes for 2D formations of single-integrator agents. By using directed graphs and triangulation of the n-agent formation, we introduce switching control laws that ensure the asymptotic stability of the desired formation for almost all initial agent positions. The state-dependent switching strategy is designed to force the formation to escape the subspaces of the incorrect equilibria. The switching strategy also allows us to remove restrictions on the shape of the desired formation that were present in previous results. © 2019 Elsevier B.V.

Karafyllis, I., Krstic, M.
Stability results for the continuity equation
(2020) 135, art. no. 104594, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076253478&doi=10.1016%2fj.sysconle.2019.104594&partnerID=40&md5=88b0943ce9e5e639ac152570b8360f2d
AFFILIATIONS: Department of Mathematics, National Technical University of Athens, Zografou Campus, Athens, 15780, Greece; 
Department of Mechanical and Aerospace Eng., University of California, San Diego, La Jolla, CA  92093-0411, United States
ABSTRACT: We provide a thorough study of stability of the 1-D continuity equation, which models many physical conservation laws. In our system-theoretic perspective, the velocity is considered to be an input. An additional input appears in the boundary condition (boundary disturbance). Stability estimates are provided in all Lp state norms with p>1, including the case p=+∞. However, in our Input-to-State Stability estimates, the gain and overshoot coefficients depend on the velocity. Moreover, the logarithmic norm of the state appears instead of the usual norm. The obtained results can be used in the stability analysis of larger models that contain the continuity equation. In particular, it is shown that the obtained results can be used in a straightforward way for the stability analysis of non-local, nonlinear manufacturing models under feedback control. © 2019 Elsevier B.V.

Lian, J., Li, C.
Event-triggered control for a class of switched uncertain nonlinear systems
(2020) 135, art. no. 104592, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076091826&doi=10.1016%2fj.sysconle.2019.104592&partnerID=40&md5=923f115d1930ada023fa15142bce9d48
AFFILIATIONS: School of Control Science and Engineering, Dalian University of Technology, Dalian, 116024, China
ABSTRACT: This paper investigates the event-triggered tracking control for switched nonlinear systems with parametric uncertainties. Due to the interplay between system switching and event-triggered sampling, two problems arise in the control scheme design. One is the mismatch between subsystems and the corresponding controllers as the switch occurs inside the sampling interval. This problem is rather challenging because the existing methods need to know/assume the maximum mismatch period a priori and use some calculation techniques that are only applicable for linear systems. The other is to avoid the Zeno behavior in the event-triggered control since the switch may trigger additional events while such a switch can be sufficiently close to the last triggering instant. To solve the above problems, we co-design a novel switching event-triggered mechanism and a mode-dependent adaptive control law. With this control scheme, the mismatch behavior is addressed without strict assumptions in the literature, and the absence of Zeno is guaranteed by providing a positive minimum inter-trigger time. The tracking error can be regulated to an adjustable neighborhood of the origin. The obtained results are validated by the tracking control of a single-link robotic manipulator. © 2019 Elsevier B.V.

Camacho-Solorio, L., Vazquez, R., Krstic, M.
Boundary observers for coupled diffusion–reaction systems with prescribed convergence rate
(2020) 135, art. no. 104586, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076048912&doi=10.1016%2fj.sysconle.2019.104586&partnerID=40&md5=991218e3be039aa7b7ec9df73a2ad5a7
AFFILIATIONS: Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA  92093-0411, United States; 
Department of Aerospace Engineering, Universidad de Sevilla, Camino de los Descubrimiento s.n., Sevilla, 41092, Spain
ABSTRACT: Following recent results on the boundary stabilization of coupled first-order hyperbolic equations by means of integral transformations, here a new result is presented for the problem of state estimation of coupled linear reaction–diffusion PDEs with Neumann boundary conditions from boundary measurements. For this purpose, an observer is constructed with a prescribed convergence rate. The stability of the estimation error system is derived by mapping the estimation error system to a stable target system using a pair of integral transformations. Our method is applicable as well to the dual problem of boundary stabilization of coupled linear reaction–diffusion PDEs. A numerical scheme, based on power series approximations of the kernels is formulated, taking into account the fact that the kernels are only piecewise differentiable. © 2019 Elsevier B.V.

Zhou, B., Tian, Y., Lam, J.
On construction of Lyapunov functions for scalar linear time-varying systems
(2020) 135, art. no. 104591, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075987424&doi=10.1016%2fj.sysconle.2019.104591&partnerID=40&md5=3cbfed608eb435118e09e164f24abe58
AFFILIATIONS: Center for Control Theory and Guidance Technology, Harbin Institute of Technology, Harbin, 150001, China; 
Deep Space Exploration Research Center, School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China; 
Department of Mechanical Engineering, University of Hong Kong, Hong Kong
ABSTRACT: It is known that the construction of Lyapunov functions for scalar linear time-varying systems is related with solutions to the scalar Lyapunov differential equation, whose solution involves both improper integrals and double integrals, and thus are not easy to compute in general. This paper establishes a systematic method for constructing Lyapunov functions for scalar linear time-varying systems. The constructed Lyapunov functions involve an integral of the system parameter with a weighting function over a finite interval. Explicit conditions are imposed on the weighting function and the integral interval such that the Lyapunov function is both positive definite and uniformly bounded, and its time-derivative is negative definite. As a result, constructive solutions to the associated scalar Lyapunov differential equations are also obtained. The established method includes some existing ones as special cases. Examples demonstrate the effectiveness of the proposed methods. © 2019 Elsevier B.V.

Benvenuti, L.
A lower bound on the dimension of minimal positive realizations for discrete time systems
(2020) 135, art. no. 104595, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075976348&doi=10.1016%2fj.sysconle.2019.104595&partnerID=40&md5=f67fd0d0b397e83721ab4eb8233a8f75
AFFILIATIONS: Dipartimento di Ingegneria informatica, automatica e gestionale “A. Ruberti”, Sapienza Università di Roma, via Ariosto 25, Roma, 00185, Italy
ABSTRACT: In some applications, one is interested in having a state–space realization with nonnegative matrices (positive realization) of a given transfer function and it is known that such a realization may have a dimension strictly larger than the order of the transfer function itself. The aim of this letter is to provide a lower bound on the minimum dimension of a positive realization taking into account some spectral properties of nonnegative matrices. © 2019 Elsevier B.V.

Burlion, L., Malisoff, M., Mazenc, F.
Stabilization for a chain of saturating integrators arising in the visual landing of aircraft with sampling
(2020) 135, art. no. 104574, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075888925&doi=10.1016%2fj.sysconle.2019.104574&partnerID=40&md5=b9fbf06745a30570b401f590d24b721c
AFFILIATIONS: Department of Mechanical and Aerospace Engineering, 98 Brett Road, Rutgers University, Piscataway, NJ  08854, United States; 
Department of Mathematics, Louisiana State University, Baton Rouge, LA  70803-4918, United States; 
Inria EPI DISCO, L2S-CNRS-CentraleSupélec, 3 rue Joliot Curie, 91192, Gif-sur-Yvette, France
ABSTRACT: We provide a new output feedback control design for a chain of saturating integrators with imprecise output measurements where the outputs can also contain delays and sampling. Using a backstepping approach that leads to pointwise delays in the control and a dynamic extension, we prove input-to-state stability using a new dynamic extension approach. We utilize our main result to solve a problem in the visual landing of aircraft in the glide phase in the presence of delayed and sampled image processing. © 2019 Elsevier B.V.

Ma, A., Liu, K., Zhang, Q., Xia, Y.
Distributed MPC for linear discrete-time systems with disturbances and coupled states
(2020) 135, art. no. 104578, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075800060&doi=10.1016%2fj.sysconle.2019.104578&partnerID=40&md5=8f685922e8948e9d4c7ae0f5422dcd63
AFFILIATIONS: School of Automation, Beijing Institute of Technology, Beijing, 100081, China
ABSTRACT: This paper presents a robust non-iterative distributed model predictive control algorithm for spatially interconnected systems. The system consists of multiple linear discrete-time subsystems, which are weakly coupled in their states. Each subsystem is subject to state and input constraints as well as disturbances. The predictive model of each subsystem updates its state, depending on its own state and the neighboring states. The disturbance and the model error are handled via robustness constraints. The recursive feasibility of the optimization problems and the stability of the closed-loop systems are established. Finally, the effectiveness and advantages of the proposed algorithm are verified via simulations. © 2019 Elsevier B.V.

Nuño, E., Sarras, I., Loría, A., Maghenem, M., Cruz-Zavala, E., Panteley, E.
Strict Lyapunov–Krasovskiĭ Functionals for undirected networks of Euler–Lagrange systems with time-varying delays
(2020) 135, art. no. 104579, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075789520&doi=10.1016%2fj.sysconle.2019.104579&partnerID=40&md5=3850305e84275a522f0ccd815e30cd0a
AFFILIATIONS: Department of Computer Science, CUCEI, University of Guadalajara, Guadalajara, Mexico; 
DTIS, ONERA, Université Paris-Saclay, Palaiseau, F-91123, France; 
Laboratoire des Signaux et Systèmes, CNRS, Gif-sur-Yvette, France; 
Department of Computer Engineering, University of California Santa CruzCA, United States; 
ITMO University, Kronverkskiy av. 49, Saint Petersburg, 197101, Russian Federation
ABSTRACT: For an undirected network of nonidentical interconnected Euler–Lagrange systems whose communication is affected by varying time-delays that may not be differentiable, we consider the problem of establishing leaderless and leader–follower consensus via the simplest Proportional plus damping decentralized controller. The main contribution of this work is to prove that the agents’ positions and velocities converge uniformly, globally, and asymptotically to a common non-specified position in the leaderless case, and to a given reference in the leader–follower case. The main results are established via Lyapunov's direct method; a Strict Lyapunov–Krasovskiĭ Functional is constructed, to the best of our knowledge, for the first time in the literature. It is shown that the resulting closed-loop system is Input-to-State Stable with regards to external additive inputs (perturbations). In turn, the separation principle applies to a certainty-equivalence controller, implemented with any globally convergent velocity estimator, such as the Immersion and Invariance observer. © 2019 Elsevier B.V.

Ji, S., Kong, C., Sun, C.
A filtering problem with uncertainty in observation
(2020) 135, art. no. 104589, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075584744&doi=10.1016%2fj.sysconle.2019.104589&partnerID=40&md5=51c5b53d7cd3b6dbd90cd107b32c2637
AFFILIATIONS: Zhongtai Securities Institute for Financial Studies, Shandong University, Jinan, Shandong, 250100, China; 
School of Mathematical Sciences, University of Jinan, Jinan, Shandong, 250022, China
ABSTRACT: This paper is concerned with a generalized Kalman-Bucy filtering model and corresponding robust problem under model uncertainty. We find that this robust problem is equivalent to considering an estimate problem under some sublinear operator. Therefore, we turn to obtaining the minimum mean square estimator under a sublinear operator. By Girsanov theorem and minimax theorem, we obtain the optimal estimator xˆt of the signal process xt for given time t∈(0,T]. © 2019 Elsevier B.V.

Sasane, A.
Algebraic characterization of approximate controllability of behaviours of spatially invariant systems
(2020) 135, art. no. 104590, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075530081&doi=10.1016%2fj.sysconle.2019.104590&partnerID=40&md5=6efc877aefb4e5a0972fa6471199d01b
AFFILIATIONS: Department of Mathematics, London School of Economics, Houghton Street, London, WC2A 2AE, United Kingdom
ABSTRACT: An algebraic characterization of the property of approximate controllability is given, for behaviours of spatially invariant dynamical systems, consisting of distributional solutions w, that are periodic in the spatial variables, to a system of partial differential equations M [Formula presented], …, [Formula presented], [Formula presented] w=0, corresponding to a polynomial matrix M∈(ℂ[ξ1,…,ξd,τ])m×n. This settles an issue left open in Sasane (2004). © 2019 Elsevier B.V.

Li, X., Wang, J.
Fault-tolerant tracking control for a class of nonlinear multi-agent systems
(2020) 135, art. no. 104576, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074894315&doi=10.1016%2fj.sysconle.2019.104576&partnerID=40&md5=732ff4dc213f4699a6b7dd9c3112c28a
AFFILIATIONS: State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, 100871, China
ABSTRACT: This paper investigates the fault-tolerant tracking control problem for a class of leader–follower nonlinear multi-agent systems with actuator faults and directed communication topology. Time-varyingloss of actuator effectiveness faults and actuator bias faults are taken into consideration. By selecting a novel Lyapunov function skillfully, a fully distributed adaptive fault-tolerant tracking consensus protocol is proposed for each follower to track with the state of the leader. A simulation example is presented to illustrate the effectiveness of the proposed fault-tolerant tracking consensus protocol. © 2019 Elsevier B.V.

Koga, S., Krstic, M.
Single-boundary control of the two-phase Stefan system
(2020) 135, art. no. 104573, . Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074892746&doi=10.1016%2fj.sysconle.2019.104573&partnerID=40&md5=6692a2e62cbc2671df146997514542cd
AFFILIATIONS: Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA  92093-0411, United States
ABSTRACT: This paper presents the control design of the two-phase Stefan problem. The two-phase Stefan problem is a representative model of liquid–solid phase transition by describing the time evolutions of the temperature profile, which is divided by subdomains of liquid and solid phases as the liquid–solid moving interface position. The mathematical formulation is given by two diffusion partial differential equations (PDEs) defined on a time-varying spatial domain described by an ordinary differential equation (ODE) driven by the Neumann boundary values of both PDE states, resulting in a nonlinear coupled PDE–ODE–PDE system. We design a state feedback control law by means of energy-shaping to stabilize the interface position to a desired setpoint by using single boundary heat input. We prove that the closed-loop system under the control law ensures some conditions for model validity, and the global exponential stability estimate is shown in the spatial L2 norm. Furthermore, the robustness of the closed-loop stability with respect to the uncertainties of the physical parameters is shown. Numerical simulation is provided to illustrate the desired performance of the proposed control law in comparison to the control design for the one-phase Stefan problem. © 2019 Elsevier B.V.

Wang, M., Zhang, C., Zhang, L.
Observability on lattice points for heat equations and applications
(2019) 134, art. no. 104564, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074449648&doi=10.1016%2fj.sysconle.2019.104564&partnerID=40&md5=c922083ce76eacceb8084a82646789e6
AFFILIATIONS: School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074, China; 
School of Mathematics and Statistics, Wuhan University; Computational Science Hubei Key Laboratory, Wuhan University, Wuhan, 430072, China; 
Department of Mathematics, Wuhan University of Technology, Wuhan, 430070, China
ABSTRACT: Observability inequalities on lattice points are established for non-negative solutions of the heat equation with potentials in the whole space. As applications, some controllability results of heat equations are derived by the above-mentioned observability inequalities. © 2019 Elsevier B.V.

Hughes, T.H., Morelli, A., Smith, M.C.
On a concept of genericity for RLC networks
(2019) 134, art. no. 104562, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074365748&doi=10.1016%2fj.sysconle.2019.104562&partnerID=40&md5=9a164c43f8dde349222367f34b218084
AFFILIATIONS: College of Engineering, Mathematics and Physical Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9EZ, United Kingdom; 
Department of Engineering, University of CambridgeCB2 1PZ, United Kingdom
ABSTRACT: A recent definition of genericity for resistor–inductor–capacitor (RLC) networks is that the realisability set of the network has dimension one more than the number of elements in the network. We prove that such networks are minimal in the sense that it is not possible to realise a set of dimension n with fewer than n−1 elements. We provide an easily testable necessary and sufficient condition for genericity in terms of the derivative of the mapping from element values to impedance parameters, which is illustrated by several examples. We show that the number of resistors in a generic RLC network cannot exceed k+1 where k is the order of the impedance. With an example, we show that an impedance function of lower order than the number of reactive elements in the network need not imply that the network is non-generic. We prove that a network with a non-generic subnetwork is itself non-generic. Finally we show that any positive-real impedance can be realised by a generic network. In particular we show that sub-networks that are used in the important Bott–Duffin synthesis method are in fact generic. © 2019 Elsevier B.V.

Sklyar, K.V.
On mappability of control systems to linear systems with analytic matrices
(2019) 134, art. no. 104572, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074211487&doi=10.1016%2fj.sysconle.2019.104572&partnerID=40&md5=ec1865d140730739804b8c7dc8c40cdb
AFFILIATIONS: Institute of Mathematics, University of Szczecin, Wielkopolska str. 15, Szczecin, 70-451, Poland
ABSTRACT: The paper deals with the problem of analytic linearizability for nonlinear non-autonomous control systems, i.e., the problem of mapping of a nonlinear non-autonomous control system to a linear system with analytic matrices by a transformation of coordinates. We introduce a concept of a driftless form of a non-autonomous system, which allows simplifying our analysis. We give linearizability conditions and find invariants for nonlinear systems that are mappable to a preassigned linear system. © 2019 The Author

Yao, L., Zhang, W.
Adaptive tracking control for a class of stochastic switched systems with stochastic input-to-state stable inverse dynamics and input saturation
(2019) 134, art. no. 104555, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074177666&doi=10.1016%2fj.sysconle.2019.104555&partnerID=40&md5=69de2ffdf277ad5a1b3d4079ca58c9bc
AFFILIATIONS: College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao, Shandong  266590, China; 
School of Mathematics and Information Science, Yantai University, Yantai, Shandong  264005, China
ABSTRACT: This paper focuses on the adaptive tracking control for a class of stochastic switched systems. Firstly, a new exponentially practical stability criterion in the moment sense is established for stochastic switched systems, which improves the previous stability criteria in existing literature. Secondly, an adaptive tracking controller based on the stochastic backstepping method is constructed for a class of stochastic systems with stochastic input-to-state stable (SISS) inverse dynamics and input saturation under arbitrary switching strategy. The corresponding closed-loop system is fourth moment exponentially practically stable and the tracking error can be regulated small enough by the obtained stability results. Finally, simulation examples verify the feasibility and effectiveness of the obtained results. © 2019 Elsevier B.V.

Weiss, G., Dörfler, F., Levron, Y.
A stability theorem for networks containing synchronous generators
(2019) 134, art. no. 104561, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074162256&doi=10.1016%2fj.sysconle.2019.104561&partnerID=40&md5=915cdfc8d7b64b133459ffe2e44af2d6
AFFILIATIONS: School of Electrical Engineering, Tel Aviv University, Ramat Aviv, 69978, Israel; 
Department of Information Technology and Electrical Engineering, ETH Zürich, Physikstrasse 3, Zürich, 8092, Switzerland; 
Viterbi Faculty of Electrical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel
ABSTRACT: We revisit a by now well known stability result for power networks containing several synchronous generators, due to F. Dörfler and F. Bullo, SIAM Journal on Control and Optimization, 2012. The approximate (or reduced) model that we work with is called the network reduced power system (NRPS) model. The mentioned result from 2012 is that under certain conditions, the state trajectory of the NRPS model is close to the trajectory of the corresponding Kuramoto model (that is obtained by setting the inertias of the generators to zero), if both start from the same initial angles. The Kuramoto model is locally exponentially stable, so that this gives us useful indications on the behavior of the power network. We show that the mentioned result can be generalized and strengthened in several aspects. For instance, we show that the Kuramoto model has a unique asymptotically stable equilibrium point and we give an explicit characterization of its domain of attraction. We also characterize the region in the state space of the NRPS model where the asymptotic approximation by the state trajectories of the Kuramoto model is valid. We also significantly enlarge the class of NRPS models for which the result applies, and we prove the local exponential stability of the NRPS model for small enough inertia constants. We briefly indicate how this result can be useful for analyzing the stability of microgrids containing virtual synchronous machines. © 2019 Elsevier B.V.

Crespo, L.G., Colbert, B.K., Kenny, S.P., Giesy, D.P.
On the quantification of aleatory and epistemic uncertainty using Sliced-Normal distributions
(2019) 134, art. no. 104560, . Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074157818&doi=10.1016%2fj.sysconle.2019.104560&partnerID=40&md5=0dee3cdd8513abddf5a7ee7bac37f352
AFFILIATIONS: Dynamic Systems & Controls Branch, NASA Langley Research Center, Hampton, VA, United States
ABSTRACT: This paper proposes a means to characterize multivariate data. This characterization, given in terms of both probability distributions and data-enclosing sets, is instrumental in assessing and improving the robustness properties of system designs. To this end, we propose the Sliced-Normal (SN) class of distributions. The versatility of SNs enables characterizing complex parameter dependencies with minimal modeling effort. A polynomial mapping which injects the physical space into a higher dimensional (so-called) feature space is first defined. Optimization-based strategies for the estimation of SNs from data in both physical and feature space are proposed. The non-convex formulations in physical space yield SNs having the best performance. However, the formulations in feature space either admit an analytical solution or yield a convex program thereby facilitating their application to high-dimensional datasets. The semi-algebraic form of the superlevel sets of a SN, form which a tight data-enclosing set can be readily identified, makes them amenable to rigorous worst-case based approaches to robustness analysis and robust design. Furthermore, we propose a chance-constrained optimization framework for identifying and eliminating the effects of outliers in the prescription of such a set. In addition, the distribution-free and non-asymptotic Scenario Theory framework is used to rigorously bound the probability of unseen data falling outside the identified data-enclosing set. © 2019

Zhao, D., Yan, S., Matsushita, S., Xu, L.
Common eigenvector approach to exact order reduction for Roesser state-space models of multidimensional systems
(2019) 134, art. no. 104559, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074143152&doi=10.1016%2fj.sysconle.2019.104559&partnerID=40&md5=7547d55c1e28c8704432f52f363c7c2e
AFFILIATIONS: School of Information Science and Engineering, Lanzhou University, Lanzhou, China; 
Department of Intelligent Mechatronics, Akita Prefectural University, Akita, Japan
ABSTRACT: The well-known Popov–Belevitch–Hautus (PBH) tests play an important role in the Kalman decomposition of 1-D systems and reveal the relationship among the eigenvalues, the eigenvectors and the reducibility of a given 1-D state-space model. This paper is to try to generalize the PBH tests to the n-D case for the exact reducibility of n-D Roesser models by exploiting the so-called common eigenvectors. Specifically, the notion of constrained common eigenvectors is introduced, for the first time, which provides insight into the relationship between reducibility and multiple eigenvalues. Based on this result, new reducibility conditions and the corresponding reduction procedure are developed for n-D Roesser models. It will be shown that this common eigenvector approach is applicable to a larger class of Roesser models for which the existing approaches may not be applied to do further order reduction. A Gröbner basis approach is proposed to compute such a constrained common eigenvector, which also leads to an equivalent reducibility condition. Moreover, a generalization to the state delay case is also given so that the eigenvalues of both the system matrix and the state-delay system matrix can be treated simultaneously. © 2019 Elsevier B.V.

Drăgan, V., Ivanov, I.G., Popa, I.-L.
Stochastic linear quadratic differential games in a state feedback setting with sampled measurements
(2019) 134, art. no. 104563, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073918745&doi=10.1016%2fj.sysconle.2019.104563&partnerID=40&md5=3cb8b03db10958f1e60b60030bf5f2a2
AFFILIATIONS: Institute of Mathematics ”Simion Stoilow” of the Romanian Academy, PO Box 1-764, RO-014700, Bucharest, Romania; 
Academy of the Romanian Scientists, Romania; 
Faculty of Economics and Business Administration, Sofia University, Sofia, 1113, Bulgaria; 
College Dobrich, Shumen University, Shumen, Bulgaria; 
Department of Exact Science and Engineering, University ”1st December 1918” of Alba Iulia, Alba Iulia, 510009, Romania
ABSTRACT: The problem of sampled-data Nash equilibrium strategy in a state feedback setting for a stochastic linear quadratic differential game is addressed. It is assumed that the admissible strategies are constant on the interval between two measurements. The original problem is converted into an equivalent one for a linear stochastic system with finite jumps. This new formulation of the problem allows us to derive necessary and sufficient conditions for the existence of a sampled-data Nash equilibrium strategy in a state feedback form. These conditions are expressed in terms of solvability of a system of interconnected matrix linear differential equations with finite jumps and subject to some algebraic constraints. We provide explicit formulae of the gain matrices of the Nash equilibrium strategy in the class of piece-wise constant strategies in a state feedback form. The gain matrices of the feedback Nash equilibrium strategy are computed based on the solution of the considered system of matrix linear differential equations with finite jumps. For the implementation of these strategies only measurements at discrete-time instances of the states of the dynamical system are required. Finally, we show that under some additional assumptions regarding the sign of the weights matrices in the performance criteria of the two players, there exists a unique piecewise Nash equilibrium strategy in a state feedback form if the maximal length of the sampling period is sufficiently small. © 2019 Elsevier B.V.

Qiu, S.-B., Liu, X.-G., Wang, F.-X., Chen, Q.
Stability and passivity analysis of discrete-time linear systems with time-varying delay
(2019) 134, art. no. 104543, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072670177&doi=10.1016%2fj.sysconle.2019.104543&partnerID=40&md5=35218591d3d37f9946b9556719a38eae
AFFILIATIONS: School of Mathematics and Statistics, Hunan University of Finance and Economics, Changsha, Hunan, 410205, China; 
School of Mathematics and Statistics, Central South University, Changsha, Hunan, 410083, China
ABSTRACT: This paper focuses on the stability and passivity analysis for a class of discrete-time linear systems. A novel general free-matrix-based summation inequality is proposed, and two improved stability criteria in terms of linear matrix inequalities (LMIs) are derived by employing the new summation inequality. Furthermore, when an external disturbance appears, a sufficient condition is established to ensure the considered linear system to be passive. Three numerical examples are provided to demonstrate the improvement of the proposed method. © 2019 Elsevier B.V.

Zhang, L., Li, X.
Mean field game for linear–quadratic stochastic recursive systems
(2019) 134, art. no. 104544, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072603906&doi=10.1016%2fj.sysconle.2019.104544&partnerID=40&md5=c678f0ec7a368873ba48cbc036b9a180
AFFILIATIONS: School of Science, Beijing University of Posts and Telecommunications, Beijing, 100876, China; 
Department of Applied Mathematics, The Hong Kong Polytechnic University, Hong Kong
ABSTRACT: This paper focuses on linear–quadratic (LQ for short) mean-field games described by forward–backward stochastic differential equations (FBSDEs for short), in which the individual control region is postulated to be convex. The decentralized strategies and consistency condition are represented by a kind of coupled mean-field FBSDEs with projection operators. The well-posedness of consistency condition system is obtained using the monotonicity condition method. The ϵ-Nash equilibrium property is discussed as well. © 2019 Elsevier B.V.

Ma, R., Shao, X., Liu, J., Wu, L.
Event-triggered sliding mode control of Markovian jump systems against input saturation
(2019) 134, art. no. 104525, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072600755&doi=10.1016%2fj.sysconle.2019.104525&partnerID=40&md5=93f8c17d42854063c77902cb9e9be239
AFFILIATIONS: School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: In this work, we pay attention to investigating event-triggered sliding mode control (SMC) strategy with input saturation for a class of Markovian jump systems (MJSs). The state vectors of MJSs are to be sufficiently sampled by a performed event trigger mechanism in a periodic computation way. However, there are some inevitable delays, on the channel from sensor to controller, occurring on the sampling process. For the demand of updates of control input, it is necessary to keep receiving and sending delayed state signals, thus we employ a zero-order-hold (ZOH) in the proposed framework to make the event-triggered SMC strategy come true. Then, by designing an integral-type sliding surface function, combining with the prior knowledge of event trigger scheme, the sliding mode dynamics is derived and the criterion of stochastic stability with H∞ attenuation performance are established. After that, an event-triggered SMC law, which aims at impelling the system trajectories to arrive on the sliding surface, is designed. Furthermore, we take input saturation into account, and specially, in this situation, we propose an adaptive control law of the integral-type sliding surface for the first time. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed results. © 2019 Elsevier B.V.

Li, J., Wang, Z., Zhang, W., Raïssi, T., Shen, Y.
Interval observer design for continuous-time linear parameter-varying systems
(2019) 134, art. no. 104541, . Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072595934&doi=10.1016%2fj.sysconle.2019.104541&partnerID=40&md5=d166a7b584d28f54115cffeb1dfaf3d2
AFFILIATIONS: School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China; 
Conservatoire National des Arts et Metiers (CNAM), Cedric-lab 292, Rue Saint-Martin, Paris Cedex 03, 75141, France
ABSTRACT: This paper studies interval observer design for linear parameter-varying systems subject to uncertainties in parameters, input and output. Based on a general assumption that these uncertainties are unknown but bounded by known intervals, a novel interval observer is presented to estimate the bounds of state. To attenuate the effect of uncertainties and obtain tight state intervals, a novel L∞ norm based design method is proposed. Numerical simulations are conducted to demonstrate the performance of the proposed method. © 2019 Elsevier B.V.

Gashi, B.
Optimal stochastic regulators with state-dependent weights
(2019) 134, art. no. 104522, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072583741&doi=10.1016%2fj.sysconle.2019.104522&partnerID=40&md5=7e7f498e4c1ad1947ae08161f6d9e51e
AFFILIATIONS: Department of Mathematical Sciences, The University of Liverpool, Peach Street, Liverpool, L69 7ZL, United Kingdom
ABSTRACT: We introduce two optimal regulators for linear stochastic systems. The first is of a linear state-feedback form, and it generalises the linear–quadratic regulator by introducing state-dependent weights in the cost functional. The second is a certain risk-sensitive version of the first, and it is of a nonlinear state-feedback form. Both regulators are applied to the optimal investment problem. © 2019 Elsevier B.V.

Qi, Y., Liu, Y., Fu, J., Zeng, P.
Event-triggered L∞ control for network-based switched linear systems with transmission delay
(2019) 134, art. no. 104533, . Cited 9 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072567018&doi=10.1016%2fj.sysconle.2019.104533&partnerID=40&md5=4f2ecb87eefc0b31f0f817b436690b09
AFFILIATIONS: School of Automation, Shenyang Aerospace University, Shenyang, 110136, China; 
State Key Laboratory of Synthetical Automation for Process Industries, Northeastern University, Shenyang, 110819, China
ABSTRACT: This paper investigates the event-triggered L∞ control for network-based switched linear systems with transmission delay. Necessary samplings of the feedback signal are determined by the improved periodic sampling based event-triggering schemes with extra design parameters, which can further reduce redundant signal transmissions and updates. Moreover, under the state feedback control, a time-delay closed-loop switched system is developed. Particularly, in the developing process an active packet loss technique is given to fully deal with the relationship between the network transmission delay and sampling period. Then by utilizing the piecewise Lyapunov functional method and average dwell time technique, sufficient conditions in terms of linear matrix inequalities (LMIs) are constructed to render the time-delay closed-loop switched system globally uniformly ultimately bounded (GUUB) and having an L∞ performance. In addition, since the event-triggered instants and switching instants both exist in the system and may stagger with each other, their coupling effect on the stability analysis is clarified. Subsequently, the conditions for finding the parameters of state feedback gains and improved event-triggering schemes are presented. An example is provided to show the effectiveness of the proposed method. © 2019 Elsevier B.V.

Li, F., Liu, Y.
Global output-feedback stabilization with prescribed convergence rate for nonlinear systems with structural uncertainties
(2019) 134, art. no. 104521, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072555891&doi=10.1016%2fj.sysconle.2019.104521&partnerID=40&md5=8bf81910a5a091f50779eb86581797a1
AFFILIATIONS: School of Control Science and Engineering, Shandong University, Jinan, 250061, China
ABSTRACT: This paper considers the global output-feedback stabilization for a class of uncertain strict-feedback nonlinear systems. Besides the unavailability of system state, the nonlinear systems allow unknown control directions and non-parametric uncertainties, which are both arguably the most severe structural uncertainties. Even so, a refined stabilization objective with prescribed convergence rate is pursued in this paper. To solve the control problem, a new output-feedback scheme is established by introducing delicate time-varying gains and utilizing a filtered transformation, where the time-varying gains are pivotal for counteracting the structural uncertainties and guaranteeing the prescribed performance. By forcing certain system signals to evolve within a pre-specified funnel, the designed output-feedback controller can guarantee the system state to converge to zero with prescribed rate. Moreover, unlike the common backstepping design for strict-feedback systems, the established scheme can effectively prevent the computation complexity for controller construction from extremely increasing with system dimension. © 2019 Elsevier B.V.

Zhan, J., Hu, Y., Li, X.
Adaptive event-triggered distributed model predictive control for multi-agent systems
(2019) 134, art. no. 104531, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072302744&doi=10.1016%2fj.sysconle.2019.104531&partnerID=40&md5=59acb463881dfae25a6f7a2f22fffd3c
AFFILIATIONS: Beijing Key Laboratory of Transportation Engineering, College of Metropolitan Transportation, Beijing University of Technology, Beijing, 100124, China; 
Adaptive Networks and Control Lab, Department of Electronic Engineering, Fudan University, Shanghai, 200433, China; 
Research Center of Smart Networks and Systems, School of Information Science and Engineering, Fudan University, Shanghai, 200433, China
ABSTRACT: Event-triggered control is an effective control approach with control update instants determined by pre-defined event-triggering conditions, and the triggering conditions are usually required to be tested continuously. In this paper, we present an adaptive event-triggered distributed model predictive control algorithm for nonlinear continuous-time multi-agent systems. All the agents are able to adaptively determine when to check the triggering conditions, which means the triggering conditions are tested intermittently with intervals determined adaptively. We prove the feasibility of the proposed algorithm, and also prove that the multi-agent system under the algorithm will converge to an invariant set in finite time by utilizing variable prediction horizon approach instead of the Lyapunov function method, such that the event-triggering conditions are less conservative. Finally, we provide numerical examples to verify the effectiveness and superiority of the proposed algorithm, revealing that the proposed algorithm can efficiently reduce the communication and computation cost as well as the sensing load. © 2019 Elsevier B.V.

Mei, Z.-D., Guo, B.-Z.
Stabilization for infinite-dimensional linear systems with bounded control and time delayed observation
(2019) 134, art. no. 104532, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072298671&doi=10.1016%2fj.sysconle.2019.104532&partnerID=40&md5=b825c045a94c3e1b4f0b3a9ccfdd2896
AFFILIATIONS: School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, 710049, China; 
School of Mathematics and Physics, North China Electric Power University, Beijing, 102206, China; 
School of Mathematics and Big Data, Foshan University, Foshan, China
ABSTRACT: For a practical control system, there is most often a time delay between the controller to be implemented and the information via the observation of the system. The time delay suffered from observation presents a mathematical challenge in output feedback stabilization for linear infinite-dimensional systems because the time delay may destroy the stability. This drives us to re-design stabilizing controller in the presence of time delay. In this paper, based on our previous work, we develop a stabilizing controller for systems with bounded linear control operators by observer based output feedback in the time interval where the observation is available and the predictor where the observation is not available. The result is applied to the stabilization of the several partial differential equation control systems with time delay in observations. © 2019 Elsevier B.V.

Praly, L.
Observers to the aid of “strictification” of Lyapunov functions
(2019) 134, art. no. 104510, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072259922&doi=10.1016%2fj.sysconle.2019.104510&partnerID=40&md5=28c52643225073ae96b24addd1d67e40
AFFILIATIONS: CAS, MINES ParisTech, PSL Research University, 35 rue St Honoré, Fontainebleau, 77300, France
ABSTRACT: We present a procedure for modifying a weak Lyapunov function V into a strict one. For this we augment the given function with an auxiliary function Va obtained as a Lyapunov function associated with the error dynamics given by an observer designed for the system with the derivative of V as an output function. © 2019 Elsevier B.V.

Kara, A.D., Saldi, N., Yüksel, S.
Weak Feller property of non-linear filters
(2019) 134, art. no. 104512, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072248784&doi=10.1016%2fj.sysconle.2019.104512&partnerID=40&md5=2b6ae250789f8d01f8a9138065eb408f
AFFILIATIONS: Department of Mathematics and Statistics, Queen's University, Kingston, ON, Canada; 
Department of Natural and Mathematical Sciences, Ozyegin University, Cekmekoy, Istanbul, Turkey
ABSTRACT: Weak Feller property of controlled and control-free Markov chains leads to many desirable properties. In control-free setups this leads to the existence of invariant probability measures for compact spaces and applicability of numerical approximation methods. For controlled setups, this leads to existence and approximation results for optimal control policies. We know from stochastic control theory that partially observed systems can be converted to fully observed systems by replacing the original state space with a probability measure-valued state space, with the corresponding kernel acting on probability measures known as the non-linear filter process. Establishing sufficient conditions for the weak Feller property for such processes is a significant problem, studied under various assumptions and setups in the literature. In this paper, we prove the weak Feller property of the non-linear filter process (i) first under weak continuity of the transition probability of controlled Markov chain and total variation continuity of its observation channel, and then, (ii) under total variation continuity of the transition probability of controlled Markov chain. The former result (i) has first appeared in Feinberg et al. (2016). Here, we present a concise and easy to follow alternative proof for this existing result. The latter result (ii) establishes weak Feller property of non-linear filter process under conditions which have not been previously reported in the literature. © 2019 Elsevier B.V.

Liu, J., Guo, B.-Z.
A novel semi-discrete scheme preserving uniformly exponential stability for an Euler–Bernoulli beam
(2019) 134, art. no. 104518, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072200933&doi=10.1016%2fj.sysconle.2019.104518&partnerID=40&md5=c47e5738eccbcf8bd229e735952cdd6e
AFFILIATIONS: School of Mathematical Sciences, Shanxi University, Taiyuan, 030006, China; 
School of Mathematics and Physics, North China Electric Power University, Beijing, 102206, China; 
Key Laboratory of System and Control, Academy of Mathematics and Systems Science Academia Sinica, Beijing, 100190, China; 
School of Computer Science and Applied Mathematics, University of the Witwatersrand, Johannesburg, 2050, South Africa
ABSTRACT: In this paper, a novel space semi-discretized numerical scheme which is based on finite volume method is proposed for approximation of uniformly exponential decay of Euler–Bernoulli beam system, which turns out to be an alternative of finite-difference scheme from order reduction point of view. The new scheme is constructed on equidistant grid points without using any numerical viscosity terms. The uniformly exponential decay is proved by the Lyapunov function method and the energy multiplier technique. With construction of a new gradient recovery function, the numerical solution is proved to be convergent to the (weak) solution of the original continuous system. Compared with the existing literature, the proposed approach has potentially achieved the following objectives: a) It removes the introduction of the numerical viscosity term to achieve uniform convergence; b) It can deal with any type of boundary conditions without help of the spectral analysis which is limited only for some special boundary conditions; c) the convergence proof is simplified significantly with the similar techniques in dealing with the continuous counterpart. © 2019 Elsevier B.V.

Tuna, S.E.
Synchronization of linear systems via relative actuation
(2019) 134, art. no. 104527, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072194607&doi=10.1016%2fj.sysconle.2019.104527&partnerID=40&md5=571acddbc2939af2a27013c1fb9b21a8
AFFILIATIONS: Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, 06800, Turkey
ABSTRACT: Synchronization in networks of discrete-time linear time-invariant systems is considered under relative actuation. Neither input nor output matrices are assumed to be commensurable. A distributed algorithm that ensures synchronization via dynamic relative output feedback is presented. © 2019 Elsevier B.V.

Castillo, A., García, P., Fridman, E., Albertos, P.
Extended state observer-based control for systems with locally Lipschitz uncertainties: LMI-based stability conditions
(2019) 134, art. no. 104526, . Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072176399&doi=10.1016%2fj.sysconle.2019.104526&partnerID=40&md5=f08589c5402bea212878bafe02b06606
AFFILIATIONS: Instituto de Automática e Informática Industrial, Universitat Politècnica de València, Valencia, 46020, Spain; 
Department of Electrical Engineering and Systems, Tel Aviv University, Tel Aviv, 69978, Israel
ABSTRACT: This paper deals with the closed-loop stability of an extended state observer-based control for systems with locally Lipschitz uncertainties. Novel stability conditions are developed, in terms of Linear Matrix Inequalities (LMI), in order to prove its local/global input-to-state or exponential stability, respectively. The stability conditions of this paper do not require neither the uncertainty to satisfy the so-called matched condition, nor the system to be expressed in the canonical integral chain form. LMI-based optimization methodologies are also developed in order to optimize the presented results. © 2019 Elsevier B.V.

Karafyllis, I., Ahmed-Ali, T., Giri, F.
Sampled-data observers for 1-D parabolic PDEs with non-local outputs
(2019) 133, art. no. 104553, . Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073993011&doi=10.1016%2fj.sysconle.2019.104553&partnerID=40&md5=404ea9a8b332f504701cb4297cea033a
AFFILIATIONS: Department of Mathematics, National Technical University of Athens, Zografou Campus, Athens, 15780, Greece; 
Normandie UNIV, UNICAEN, ENSICAEN, LAC, Caen, 14000, France
ABSTRACT: The present work provides a systematic approach for the design of sampled-data observers to a wide class of 1-D, parabolic PDEs with non-local outputs. The studied class of parabolic PDEs allows the presence of globally Lipschitz nonlinear and non-local terms in the PDE. Two different sampled-data observers are presented: one with an inter-sample predictor for the unavailable continuous measurement signal and one without an inter-sample predictor. Explicit conditions on the upper diameter of the (uncertain) sampling schedule for both designs are derived for exponential convergence of the observer error to zero in the absence of measurement noise and modeling errors. Moreover, explicit estimates of the convergence rate can be deduced based on the knowledge of the upper diameter of the sampling schedule. When measurement noise and/or modeling errors are present, Input-to-Output Stability (IOS) estimates of the observer error hold for both designs with respect to noise and modeling errors. The main results are illustrated by two examples which show how the proposed methodology can be extended to other cases (e.g., boundary point measurements). © 2019 Elsevier B.V.

Wan, N., Li, D., Hovakimyan, N.
Sensitivity analysis of linear continuous-time feedback systems subject to control and measurement noise: An information-theoretic approach
(2019) 133, art. no. 104548, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073758903&doi=10.1016%2fj.sysconle.2019.104548&partnerID=40&md5=1a79ab04d22ba3f9d4eb0474d7a1fce4
AFFILIATIONS: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL  61801, United States; 
JD.com Silicon Valley Research Center, Santa ClaraCA  95054, United States
ABSTRACT: Sensitivity of linear continuous-time SISO feedback systems, subject to control and measurement noise, is analyzed by deriving the lower bounds of Bode-like integrals via an information-theoretic approach. Bode integrals of four different sensitivity-like functions are employed to gauge the performance limitations of feedback systems. When the signals of the control system are stationary Gaussian, these four different Bode-like integrals can be represented as the differences between mutual information rates. These mutual information rates and hence the corresponding Bode-like integrals are proven to be bounded below by the unstable poles and zeros of the plant model, if the signals of the control system are wide-sense stationary. © 2019 Elsevier B.V.

Ahmed, S., Malisoff, M., Mazenc, F.
Finite time estimation for time-varying systems with delay in the measurements
(2019) 133, art. no. 104551, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073752186&doi=10.1016%2fj.sysconle.2019.104551&partnerID=40&md5=e8ada03203cbbc4567d374c89ae083a7
AFFILIATIONS: Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey; 
Department of Mathematics, Louisiana State University, Baton Rouge, LA  70803-4918, United States; 
EPI DISCO Inria-Saclay, Laboratoire des Signaux et Systèmes, CNRS, CentraleSupélec, Université Paris-Sud, 3 rue Joliot CurieGif-sur-Yvette  91192, France
ABSTRACT: We build finite time observers for time-varying nonlinear systems with delays in the outputs, using a dynamic extension that computes fundamental matrices. Our observers achieve finite time convergence when no disturbances are present. When disturbances are present, we provide approximate values for the solutions, which lead to an upper bound on the approximation error after a suitable finite time. We illustrate our work in a class of systems arising in the study of vibrating membranes, where time-varying coefficients can be used to represent intermittent measurements. © 2019 Elsevier B.V.

Sanjeevini, S., Bernstein, D.S.
Minimal-delay FIR delayed left inverses for systems with zero nonzero zeros
(2019) 133, art. no. 104552, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073675991&doi=10.1016%2fj.sysconle.2019.104552&partnerID=40&md5=665c98817baf5125891c1c47179d62c8
AFFILIATIONS: Department of Aerospace Engineering, University of Michigan, Ann Arbor, United States
ABSTRACT: This paper considers finite-time input reconstruction for discrete-time linear time-invariant systems in the case where the initial condition is unknown. There are three main results. First, a specific construction of finite-impulse-response (FIR) delayed left inverse with the minimal delay for systems with zero nonzero zeros is presented. Next, it is shown that, in the presence of an arbitrary unknown initial condition, finite-time input reconstruction is possible using a delayed left inverse H if and only if H is FIR. Finally, it is shown that a transfer function with full column normal rank has an FIR delayed left inverse with the minimal delay if and only if the system has zero nonzero zeros. © 2019 Elsevier B.V.

Luo, S., Deng, F., Zhang, B., Hu, Z.
Almost sure stability of hybrid stochastic systems under asynchronous Markovian switching
(2019) 133, art. no. 104556, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073573617&doi=10.1016%2fj.sysconle.2019.104556&partnerID=40&md5=a64afc6cec0738c545e0330300b72f7b
AFFILIATIONS: School of Automation Science and Engineering, South China University of Technology, Guangzhou, 510640, China; 
School of Automation, Guangdong University of Technology, Guangzhou, 510006, China; 
School of Electrical and Information Engineering, Shantou University, Shantou, 515063, China
ABSTRACT: This paper presents two novel Lyapunov methodologies for almost sure stability of hybrid stochastic systems under asynchronous Markovian switching. One is established by a concave composite Lyapunov function with exponential martingale inequality. The other is derived by the strong law of large numbers, which can explore the coupling between the drift part and diffusion part of the systems, thus fully capturing the stabilizing effect of the stochastic noise. Both of these stability conditions give a quantitative relationship between the size of the detected delay of switching signal, the stationary distribution and the generator of Markov chain. As applications, easy-to-check stability and stabilization criteria are further provided for one-sided growth nonlinear systems and linear systems. Numerical examples illustrate the proposed theoretical results. © 2019 Elsevier B.V.

Basu, H., Yoon, S.Y.
Distributed state estimation by a network of observers under communication and measurement delays
(2019) 133, art. no. 104554, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073570242&doi=10.1016%2fj.sysconle.2019.104554&partnerID=40&md5=26af5104da994dfc05d9a348f4bb5980
AFFILIATIONS: Department of Electrical and Computer Engineering, University of New Hampshire, Durham, NH  03824, United States
ABSTRACT: In this paper we study the distributed state estimation of autonomous dynamic systems, under arbitrarily large communication and measurement delays. In the distributed estimation problem, we consider a network of observer agents that cannot independently determine all the states of the observed plant from their own collected measurements, but they must collaborate with neighboring agents to agree on the correct state estimation. Our current work considers the presence of arbitrarily large time delays in the communication and measurements of the observer agents, and we propose a framework for distributed observers following the low gain methodology. Sufficient conditions for the stability of the corresponding observation error dynamics are derived, including an upper bound for the low gain parameter of the observer equations. In the presence of bounded noisy measurements from the plant, we derive the upper-bound on the local estimation errors. The results of the distributed state estimation is then applied to propose a solution to the leader–follower synchronization problem for multi-agent systems under leader-agent and inter-agent communication delays. An illustrative example is also presented to verify the effectiveness of the theoretical analysis. © 2019 Elsevier B.V.

Xiong, Y., Gao, Y., Yang, L., Wu, L.
An integral sliding mode approach to distributed control of coupled networks with measurement Quantization
(2019) 133, art. no. 104557, . Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073550483&doi=10.1016%2fj.sysconle.2019.104557&partnerID=40&md5=cfbdc3e69016439327558eff3c337bfa
AFFILIATIONS: School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China; 
College of Automation, Harbin Engineering University, Harbin, 150001, China
ABSTRACT: This paper is concerned with the distributed sliding mode control problem of complex networks under quantization mechanism. The complex networked control system is considered with inner coupling, uncertainties and quantized measurements among the agents. The quantizer, which is adopted as a logarithmic one, is designed to be on the sensor unit to implement the digital communication. In order to avoid the discontinuity of the sliding mode control law, namely, the sliding surface, an adaptive filter is utilized. Based on the filtered signal, an integral sliding-mode manifold is designed for each agent. A series of dynamic sliding mode control laws are synthesized to achieve the exponential reaching onto the sliding surface within a finite time for the whole networked system. The resulting sliding motion is analyzed using the Lyapunov functional approach, and a finite-gain L2 stability criterion is established. Finally, the effectiveness of the designed distributed sliding mode control scheme is illustrated with some simulation results. © 2019 Elsevier B.V.

Barabanov, N., Ortega, R., Pyrkin, A.
On contraction of time-varying port-Hamiltonian systems
(2019) 133, art. no. 104545, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073549840&doi=10.1016%2fj.sysconle.2019.104545&partnerID=40&md5=88b96b5e31f452f71e6f8b80f5a5ea52
AFFILIATIONS: Department of Mathematics, North Dakota State University, FargoND  58105, United States; 
Department of Control Systems and Informatics, ITMO University, Saint Petersburg197101, Russian Federation; 
Laboratoire des Signaux et Systèmes, CNRS-SUPELEC, Gif-sur-Yvette, 91192, France
ABSTRACT: In this paper we identify classes of port-Hamiltonian systems which are contracting. Our motivation in this study is two-fold, on one hand, it is well-known that many physical systems are described by port-Hamiltonian models. On the other hand, contraction is a fundamental property that has been efficiently exploited for the design of observers, as well as tracking, adaptive and multi-agent controllers for nonlinear systems. The conditions for contraction are given in terms of feasibility of linear matrix inequalities, hence their verification is computationally efficient. © 2019 Elsevier B.V.

Qi, J., Krstic, M., Wang, S.
Stabilization of reaction–diffusions PDE with delayed distributed actuation
(2019) 133, art. no. 104558, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073459719&doi=10.1016%2fj.sysconle.2019.104558&partnerID=40&md5=6d354aed37c02566a2ddaa3c0824050d
AFFILIATIONS: College of Information Science and Technology, Engineering Research Center of Digitized Textile and Fashion Technology Ministry of Education, Donghua University, Shanghai, 201620, China; 
Department of Mechanical Aerospace Engineering, University of California, San Diego, CA  92093-0411, United States
ABSTRACT: This paper pursuits control design for an unstable reaction–diffusion equation with arbitrarily large input delay affecting the in-domain actuator. We introduce a transport PDE which results in an extended spatial domain where the reaction–diffusion PDE and the transport PDE are in cascade. Based on the conception of predictor-feedback, an backstepping integral transformation is introduced to transform the original coupled system to a stable target system. A predictor control which compensates the delay via distributed in-domain actuation is designed. The kernel function weighting the state feedback and the historical control employs a Dirac delta function as its initial condition. Due to singularity of the kernel function, the norm equivalence between the original and the target system is proved before we finally reach the exponential stability in H1 norm for the coupled system with the delay compensated feedback. A numerical simulation illustrates the effectiveness of the control. © 2019 Elsevier B.V.

Zhang, J., Sun, J.
A game theoretic approach to multi-channel transmission scheduling for multiple linear systems under DoS attacks
(2019) 133, art. no. 104546, . Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073004257&doi=10.1016%2fj.sysconle.2019.104546&partnerID=40&md5=b010c6325fc263b0b771ff61e6311ca3
AFFILIATIONS: School of Mathematical Sciences, Tongji University, Shanghai, 200092, China; 
Institute for Intelligent Systems, Faculty of Engineering and the Built Environment, University of Johannesburg, South Africa
ABSTRACT: Recent years have illustrated the soaring importance of security issues of cyber-physical systems (CPSs). In this paper, we consider the remote state estimation of a CPS while subject to denial-of-service (DoS) attacks. A number of sensors monitor different linear dynamical systems and transmit the measurements to a remote estimator through a multi-channel network that may suffer corruption due to an intelligent attacker. Both sensors and the attacker have energy constraints. At each time-step, sensors select which channel to transmit over while the attacker chooses which channel to congest. Both sides select strategies based on the current state. In order to model the infinite horizon decision problem, we construct a two player zero-sum game and propose a Nash Q-learning algorithm to solve for the optimal strategies of both players. Finally, simulations are provided to illustrate our results. © 2019 Elsevier B.V.

Liu, L.
QCs characterization of robust stability with simultaneous uncertainties in plant and controller
(2019) 133, art. no. 104550, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072966860&doi=10.1016%2fj.sysconle.2019.104550&partnerID=40&md5=1bd2ad7304d32f06da54d18349fd86e9
AFFILIATIONS: School of Mathematical Sciences, Dalian University of Technology, Dalian, 116024, China
ABSTRACT: Within the frame work of nest algebra, the robust stability of feedback interconnections of time-varying discrete-time systems with combined uncertainties in the plant and controller is derived via quadratic constraint (QC) approach, where the plant and controller are taken from two path connected uncertainty sets with respect to the topology induced by the gap metric. Some sufficient conditions for the existence of complementary QCs for the components of stable uncertain feedback systems are derived. The path-connectedness is established for some uncertainty sets with particular properties. The fundamental robust stability result represents a generalization of the input–output operator robust stability theorem of uncertainties appearing in the plant alone, to include the case of simultaneous uncertainties appearing in the controller. © 2019

Letrouit, C.
From internal to pointwise control for the 1D heat equation and minimal control time
(2019) 133, art. no. 104549, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072963835&doi=10.1016%2fj.sysconle.2019.104549&partnerID=40&md5=11d40005922f72fce444bf74548aaf36
AFFILIATIONS: Sorbonne Université, CNRS, Université de Paris, Inria, Laboratoire Jacques-Louis Lions (LJLL), Paris, F-75005, France; 
DMA, École normale supérieure, CNRS, PSL Research University, Paris, 75005, France
ABSTRACT: Our goal is to study controllability and observability properties of the 1D heat equation with internal control (or observation) set ωε=(x0−ε,x0+ε), in the limit ε→0, where x0∈(0,1). It is known that depending on arithmetic properties of x0, there may exist a minimal time T0 of pointwise control at x0 of the heat equation. Besides, for any ε fixed, the heat equation is controllable with control set ωε in any time T>0. We relate these two phenomena. We show that the observability constant on ωε does not converge to 0 as ε→0 at the same speed when T>T0 (in which case it is comparable to ε1∕2) or T<T0 (in which case it converges faster to 0). We also describe the behavior of optimal L2 null-controls on ωε in the limit ε→0. © 2019

Babazadeh, M.
Robust controllability assessment and optimal actuator placement in dynamic networks
(2019) 133, art. no. 104547, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072941244&doi=10.1016%2fj.sysconle.2019.104547&partnerID=40&md5=6bdaf3f67ffe8bee019e3485e7fd829f
AFFILIATIONS: Department of Electrical Engineering, Sharif University of Technology, Iran
ABSTRACT: This paper presents a new framework for the optimal placement of actuators in uncertain dynamic networks. The objective is to select a subset of nodes from a set of potential actuator placements, such that the controllability of the network with norm-bounded perturbation is preserved over the entire uncertain region. Evaluation of robust controllability is known to be computationally intractable. The recent results of Babazadeh and Nobakhti (2016) are utilized to establish equivalent conditions for robust controllability of uncertain networks. It is shown that for a large class of dynamic systems, including undirected networks, the exact distance to uncontrollability is evaluated by solving a convex program. Properties of positive-definite polynomial matrices and duality theory facilitate formation of a non-convex optimization problem with linear matrix inequalities whose solution is the exact distance to uncontrollability for a general uncertain network. The underlying optimization averts the difficulty of gridding over the complex plane. A customized optimization algorithm is outlined to solve the equivalent non-convex problem whose solution is ensured to be a stationary point of the original problem. The method is further utilized to address the optimal placement of actuators by maximizing the network robust controllability index and simultaneously regularizing the number of actuators in the network graph. The proposed framework is implemented efficiently using convex optimization solvers and offers a fast and reliable tool for the assessment of robust controllability and optimal selection of control nodes. Analogous results can be established for robust observability and optimal sensor placement. © 2019 Elsevier B.V.

Carreño, N., Cerpa, E., Mercado, A.
Boundary controllability of a cascade system coupling fourth- and second-order parabolic equations
(2019) 133, art. no. 104542, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072763215&doi=10.1016%2fj.sysconle.2019.104542&partnerID=40&md5=563e6843debf5b4420c381f74fd10e5d
AFFILIATIONS: Departamento de Matemática, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile
ABSTRACT: A control system coupling fourth- and second-order parabolic equations is considered in this paper. The main topic is the study of the control properties of this system when we only control the second-order partial differential equation through a boundary condition. Depending on the choice of the diffusion coefficients, we obtain positive and negative results for approximate- and null-controllability. In particular, we prove that for any given positive time T0, we can find some diffusion coefficients such that the system is null-controllable in time T if T>T0 and is not null-controllable if T<T0. © 2019 Elsevier B.V.

Meng, T., Xie, Y., Lin, Z.
Consensus of second-order multi-agent systems under unknown but bounded measurement noises
(2019) 133, art. no. 104517, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072194954&doi=10.1016%2fj.sysconle.2019.104517&partnerID=40&md5=4e32f01f5a45497cc215b59d77769bbe
AFFILIATIONS: Charles L. Brown Department of Electrical and Computer Engineering, University of Virginia, P.O. Box 400743, Charlottesville, VA  22904-4743, United States; 
Department of Automation, Shanghai Jiao Tong University, Shanghai, 200240, China
ABSTRACT: In this paper, we investigate the static ϵ-consensus problem of multi-agent systems with double-integrator agent dynamics over a connected undirected communication topology. It is assumed that only noisy measurements of neighbors’ states are available. We propose two types of consensus protocols using and without using neighbors’ velocity information, respectively. With the knowledge of the bounds of measurement noises, we show that, under these consensus protocols, the velocities of all agents achieve consensus at zero and the positions of all agents achieve ϵ-consensus. Numerical examples are shown to illustrate the theoretical results. © 2019 Elsevier B.V.

Alaeddini, A., Morgansen, K.A., Mesbahi, M.
Augmented state feedback for improving observability of linear systems with nonlinear measurements
(2019) 133, art. no. 104520, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072184411&doi=10.1016%2fj.sysconle.2019.104520&partnerID=40&md5=5c64ec035e37542b580345fdf21b0433
AFFILIATIONS: Institute for Disease Modeling, Bellevue, WA  98005, United States; 
University of Washington, William E. Boeing Department of Aeronautics and Astronautics, Seattle, WA  98195, United States
ABSTRACT: This paper is concerned with the design of an augmented state feedback controller for finite-dimensional linear systems with nonlinear observation dynamics. Most of the theoretical results in the area of (optimal) feedback design are based on the assumption that the state is available for measurement. In this paper, we focus on finding a feedback control that avoids state trajectories with undesirable observability properties. In particular, we introduce an optimal control problem that specifically considers an index of observability in the control synthesis. The resulting cost functional is a combination of LQR-like quadratic terms and an index of observability. The main contribution of the paper is presenting a control synthesis procedure that on one hand, provides closed loop asymptotic stability, and addresses the observability of the system – as a transient performance criterion – on the other. © 2019 The Author(s)

Haak, B., Hoang, D.-T., Ouhabaz, E.-M.
Controllability and observability for non-autonomous evolution equations: The averaged Hautus test
(2019) 133, art. no. 104524, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072156663&doi=10.1016%2fj.sysconle.2019.104524&partnerID=40&md5=aa104bf9a8d5543fc4c4f7d32e0dac54
AFFILIATIONS: Institut de Mathématiques de Bordeaux, UMR CNRS 5251, Université de Bordeaux, 351 cours de la Liberation, Talence, 33405, France
ABSTRACT: We consider the observability problem for non-autonomous evolution systems (i.e., the operators governing the system depend on time). We introduce an averaged Hautus condition and prove that for skew-adjoint operators it characterizes exact observability. Next, we extend this to more general class of operators under a growth condition on the associated evolution family. We give an application to the Schrödinger equation with time dependent potential and the damped wave equation with a time dependent damping coefficient. © 2019 Elsevier B.V.

Pyrkin, A., Bobtsov, A., Ortega, R., Vedyakov, A., Aranovskiy, S.
Adaptive state observers using dynamic regressor extension and mixing
(2019) 133, art. no. 104519, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071872672&doi=10.1016%2fj.sysconle.2019.104519&partnerID=40&md5=d9ca190b8bc8dd60ae64d35789f70f10
AFFILIATIONS: School of Automation, Hangzhou Dianzi University, Xiasha Higher Education Zone, Hangzhou, Zhejiang, China; 
ITMO UniversitySt. Petersburg, Russian Federation; 
Center for Technologies in Robotics and Mechatronics Components, Innopolis University, Innopolis, Russian Federation; 
Laboratoire des Signaux et Systèmes, CNRS-SUPELEC, Plateau du Moulon, Gif-sur-Yvette, 91192, France; 
CentraleSupélec – IETR, Avenue de la Boulai, Cesson-Sévigné, 35576, France
ABSTRACT: In this paper we propose an adaptive state observer for a class of nonlinear systems with unknown parameters. Assuming that the system variables satisfy an algebraic constraint, a linear regression involving unknown parameters and unmeasurable states is established. The design proceeds adopting a gradient descent approach to minimize a quadratic criterion that is suggested by this regression. To separate the problems of state and parameter estimation we use the recently proposed dynamic regressor extension and mixing approach, whose main feature is that it allows to generate, out of an N-dimensional, linear vector regression, N scalar regression models. Moreover, under a weak interval excitation assumption, it ensures finite-time parameter convergence. It is shown that the proposed observer is applicable to several practically interesting physical systems. © 2019 Elsevier B.V.

Zhang, C.
Finite-time internal stabilization of a linear 1-D transport equation
(2019) 133, art. no. 104529, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071845293&doi=10.1016%2fj.sysconle.2019.104529&partnerID=40&md5=1b50931738bc5248c45205379cf3d86d
AFFILIATIONS: Laboratoire Jacques-Louis Lions, Sorbonne Université, Boîte courrier 187, 75252 Paris Cedex 05 Université Paris-Diderot SPC, CNRS, INRIA équipe Cage, Paris, France
ABSTRACT: We consider a 1-D linear transport equation on the interval (0,L), with an internal scalar control. We prove that if the system is controllable in a periodic Sobolev space of order greater than 1, then the system can be stabilized in finite time, and we give an explicit feedback law. © 2019

Kotyczka, P., Lefèvre, L.
Discrete-time port-Hamiltonian systems: A definition based on symplectic integration
(2019) 133, art. no. 104530, . Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071839209&doi=10.1016%2fj.sysconle.2019.104530&partnerID=40&md5=338ea502c29e0374eaee06d694f493ec
AFFILIATIONS: Technical University of Munich, Department of Mechanical Engineering, Chair of Automatic Control, Boltzmannstraß,e 15, Garching, 85748, Germany; 
Univ. Grenoble Alpes, LCIS, 50 rue Barthélémy de Laffémas, Valence, 26902, France
ABSTRACT: We introduce a new definition of discrete-time port-Hamiltonian (PH) systems, which results from structure-preserving discretization of explicit PH systems in time. We discretize the underlying continuous-time Dirac structure with the collocation method and add discrete-time dynamics by the use of symplectic numerical integration schemes. The conservation of a structural discrete-time energy balance – expressed in terms of the discrete-time Dirac structure – extends the notion of symplecticity of geometric integration schemes to open systems. We discuss the energy approximation errors in the context of the presented definition and show that their order for linear PH systems is consistent with the order of the numerical integration scheme. Implicit Gauss–Legendre methods and Lobatto IIIA/IIIB pairs for partitioned systems are examples for integration schemes that are covered by our definition. The statements on the numerical energy errors are illustrated by elementary numerical experiments. © 2019 Elsevier B.V.

Shi, S., Shi, Z., Fei, Z.
Asynchronous control for switched systems by using persistent dwell time modeling
(2019) 133, art. no. 104523, . Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071722279&doi=10.1016%2fj.sysconle.2019.104523&partnerID=40&md5=b9774596190bc312e2d1e27e1b2496c5
AFFILIATIONS: Research Institute of Intelligent Control and Systems, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: This work is concerned with stability and control for continuous-time switched systems with asynchronous switching. The persistent dwell time (PDT) switching is used to model the asynchronous characteristic in switched systems. Compared with the common dwell time or average dwell time switching widely studied in the existing literature, the PDT switching is known to be more general. The stability and L2-gain analysis are derived firstly for the switched system with PDT switching, and the Lyapunov-like function is allowed to increase during the mismatched period between the controller and the system mode. Then, the corresponding controller design scheme is proposed. Finally, the effectiveness of the provided method is illustrated with two examples. © 2019 Elsevier B.V.

Gaudio, J., Amin, S., Jaillet, P.
Exponential convergence rates for stochastically ordered Markov processes under perturbation
(2019) 133, art. no. 104515, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071720088&doi=10.1016%2fj.sysconle.2019.104515&partnerID=40&md5=144f062a89b14fa3494d0d9983bdd3b6
AFFILIATIONS: Operations Research Center, Massachusetts Institute of Technology, 1 Amherst St., Cambridge, MA  02142, United States; 
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, United States; 
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, United States
ABSTRACT: In this technical note we find computable exponential convergence rates for a large class of stochastically ordered Markov processes. We extend the result of Lund, Meyn, and Tweedie (1996), who found exponential convergence rates for stochastically ordered Markov processes starting from a fixed initial state, by allowing for a random initial condition that is also stochastically ordered. Our bounds are formulated in terms of moment-generating functions of hitting times. To illustrate our result, we find an explicit exponential convergence rate for an M/M/1 queue beginning in equilibrium and then experiencing a change in its arrival or departure rates, a setting which has not been studied to our knowledge. © 2019 Elsevier B.V.

Asl, H.J., Narikiyo, T., Kawanishi, M.
Saturated input consensus algorithms for perturbed double-integrator systems without velocity measurements
(2019) 133, art. no. 104528, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071693919&doi=10.1016%2fj.sysconle.2019.104528&partnerID=40&md5=8b9305320cfecd108d4ca87965d6f749
AFFILIATIONS: Control System Laboratory, Department of Advanced Science and Technology, Toyota Technological Institute, Japan
ABSTRACT: This study addresses the consensus problem of perturbed double-integrator systems. Specifically, we propose consensus algorithms for these systems that simultaneously account for input saturation, lack of velocity information, and existence of time-varying external disturbances; in this sense, we extend some of existing results in the literature. The designs have been developed by means of introduction of auxiliary dynamics for each agent. First, we propose a leaderless consensus algorithm and then deal with the leader–follower consensus and consensus with reference velocity. Sufficient control gain conditions and upper bounds of the consensus errors are derived for each case by considering both bidirectional and unidirectional communication topologies. The effectiveness of the algorithms is evaluated through simulation studies. © 2019 Elsevier B.V.

Ren, W., Xiong, J.
Stability analysis for stochastic impulsive switched time-delay systems with asynchronous impulses and switches
(2019) 133, art. no. 104516, . Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071671353&doi=10.1016%2fj.sysconle.2019.104516&partnerID=40&md5=66f2317bdafaa4b8dc0e4f1cf1f32ca9
AFFILIATIONS: Division of Decision and Control Systems, EECS, KTH Royal Institute of Technology, Stockholm, SE-10044, Sweden; 
Department of Automation, University of Science and Technology of China, Hefei, 230026, China
ABSTRACT: This paper studies stability of a general class of impulsive switched systems under time delays and random disturbances using multiple Lyapunov functions and average dwell-time. In the studied system, impulses and switches are allowed to occur asynchronously. As a result, the switching may occur in impulsive intervals and the impulses could also occur in switching intervals, which affect system stability greatly. Although the switches do no bring about the change of system state, multiple Lyapunov functions do not decrease at the switching times. Therefore, we study two cases: the stable continuous dynamics case and the stable impulsive dynamics case. Based on multiple Lyapunov functions and average dwell-time condition, sufficient stability conditions are derived. Finally, the obtained results are demonstrated through a numerical example from complex switched networks. © 2019 Elsevier B.V.

Li, X., Wang, R., Yin, G.
Moment bounds and ergodicity of switching diffusion systems involving two-time-scale Markov chains
(2019) 132, art. no. 104514, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071305126&doi=10.1016%2fj.sysconle.2019.104514&partnerID=40&md5=c9591935a2fcab4000d58d7f61af00a5
AFFILIATIONS: School of Mathematics and Statistics, Northeast Normal University, Jilin, Changchun  130024, China; 
Department of Economics, University of Kansas, Lawrence, KS  66045, United States; 
Department of Mathematics, Wayne State University, DetroitMI  48202, United States
ABSTRACT: This work is concerned with stochastic differential equations with regime switching modulated by a two-time-scale Markov chain involving fast and slow motions. Using the perturbed Lyapunov function methods and stochastic analysis, we obtain moment boundedness. Then we further provide sufficient conditions under which the measures of the original system converge to the invariant measure of the limiting system. © 2019 Elsevier B.V.

Zhou, B., Speyer, J.L.
ℋ2 control of SISO fractional order systems
(2019) 132, art. no. 104511, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070959408&doi=10.1016%2fj.sysconle.2019.104511&partnerID=40&md5=9c611aa7223f8a69499b7f17790bc596
AFFILIATIONS: Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA  90095, United States
ABSTRACT: In this paper, we propose a systematic method to design the optimal ℋ2 output feedback controller for single input, single output plants of fractional order based on Wiener–Hopf spectral factorization. The plant is allowed to be unstable, non-minimum-phase, and incommensurate order. Using the fractional order Youla parameterization, the resulting controller satisfies the closed-loop internal stability requirement. Because of the branch point singularities associated with fractional order transfer functions, the spectral decompositions are effected via an integral technique. An example is provided to demonstrate the design procedure. © 2019 Elsevier B.V.

Wang, Y., Wu, F., Mao, X.
Stability in distribution of stochastic functional differential equations
(2019) 132, art. no. 104513, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070928420&doi=10.1016%2fj.sysconle.2019.104513&partnerID=40&md5=83dc57c8af779f55378f53f073dcb993
AFFILIATIONS: School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; 
Department of Mathematics and Statistics, University of Strathclyde, Glasgow, G1 1XH, United Kingdom
ABSTRACT: In this paper we investigate the stability in distribution for a class of stochastic functional differential equations (SFDEs), which include stochastic differential delay equations (SDDEs). Although stability in distribution has been studied by several authors recently, there is so far no stability-in-distribution criterion on SFDEs where the terms involved the delay components are highly nonlinear (not bounded by linear functions). In this paper we will establish the sufficient criteria on the stability in distribution for a class of highly nonlinear SFDEs. Two examples will be given to illustrate our new results. We also explain the reason why the existing stability-in-distribution criteria are not applicable by these two examples. © 2019 Elsevier B.V.

Gershon, E., Shaked, U.
Robust predictor based control of state multiplicative noisy retarded systems
(2019) 132, art. no. 104499, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070864644&doi=10.1016%2fj.sysconle.2019.104499&partnerID=40&md5=3a863c2d3c82daac199cafaca47e0816
AFFILIATIONS: School of Electrical Engineering, Tel-Aviv University, Tel-Aviv, 69978, Israel; 
Department of Electrical Engineering, Medical Electronics, Holon Institute of Technology (HIT), Holon, Israel
ABSTRACT: Linear, continuous-time systems with stochastic uncertainties and delayed input are considered. The problems of H∞ state-feedback control and static output-feedback control are solved, for nominal systems, applying a Luenberger-type predictor. The two problems are solved via the input–output approach, where the system is replaced by a non-retarded system with deterministic norm-bounded uncertainties. The cost function in these two problems is the expected value of the standard H∞ performance index with respect to the stochastic parameters. The above problems are solved also for the case where the deterministic parameters of the system encounter either norm-bounded or polytopic-type uncertainties. In the uncertain state-feedback control problem the solution is obtained by applying a vertex-dependent approach that is based on the Finsler lemma. An illustrative example is given that compares several control solution methods. An additional example of practical process control problem is also solved. © 2019

Gomez, M.A., Egorov, A.V., Mondié, S., Zhabko, A.P.
Computation of the Lyapunov matrix for periodic time-delay systems and its application to robust stability analysis
(2019) 132, art. no. 104501, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070565224&doi=10.1016%2fj.sysconle.2019.104501&partnerID=40&md5=4aabaa3b66bc041410cf0ec2507f4c36
AFFILIATIONS: Department of Computer Science, KU Leuven, Leuven, Belgium; 
Department of Automatic Control, CINVESTAV-IPN, Mexico City, Mexico; 
St. Petersburg State University, St. Petersburg, Russian Federation
ABSTRACT: A new procedure for computing the delay Lyapunov matrix for periodic time-delay systems that is based on the numerical solution of a partial differential equations (PDE) system is presented. The introduction of a new set of boundary conditions that are satisfied by the PDE system allows us to propose a new methodology for computing the initial conditions required by the implemented numerical scheme. The potential of the presented results is demonstrated by obtaining robust stability conditions depending on the delay Lyapunov matrix with respect to the system parameters, the delay and the frequency. The theoretical results are applied to the widely known delayed Mathieu equation. © 2019 Elsevier B.V.

Li, C., Dong, H., Li, J., Wang, F.
Distributed Kalman filtering for sensor network with balanced topology
(2019) 131, art. no. 104500, . Cited 9 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073707000&doi=10.1016%2fj.sysconle.2019.104500&partnerID=40&md5=a1eb14bf87e998531fc25f1acefe2944
AFFILIATIONS: College of Electrical Engineering, Zhejiang University, Hangzhou, 310027, China; 
Research Center of Satellite Technology, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: In this paper, we study the distributed Kalman filtering for sensor network with mild assumption on communication topology and local observability. To this end, a new peer-to-peer distributed Kalman filtering is proposed, where each sensor communicates with its connected neighbors to achieve average consensus on weighted measurements and inverse-covariance matrices. Then, a consensus strategy is introduced to reduce the error produced by embedded dynamic consensus method. In addition, the convergence and steady-state performance of the proposed algorithm are also investigated, and we prove rigorously that the biased estimates are bounded and controllable. Numerical simulations validate the theoretical contributions of this paper. © 2019 Elsevier B.V.

Aliseyko, A.N.
Lyapunov matrices for neutral time-delay systems with exponential kernel
(2019) 131, art. no. 104497, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069712886&doi=10.1016%2fj.sysconle.2019.104497&partnerID=40&md5=a6604a567482b4397462fff9d9232493
AFFILIATIONS: Department of Control Theory, St. Petersburg State University, St. Petersburg, Russian Federation
ABSTRACT: In this contribution we study the problem of finding a Lyapunov matrix for neutral-type systems with distributed delay and exponential kernel. In previous works an attempt was made to reduce this problem to the computation of solutions to an auxiliary delay-free system with boundary conditions. In this paper we propose new boundary conditions allowing a significant extension of existing results. It is established that the new auxiliary boundary value problem has a unique solution if and only if there exists a unique Lyapunov matrix. © 2019 Elsevier B.V.

Bucolo, M., Buscarino, A., Fortuna, L., Frasca, M.
Forward action to make time-delay systems positive-real or negative-imaginary
(2019) 131, art. no. 104495, . Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069708642&doi=10.1016%2fj.sysconle.2019.104495&partnerID=40&md5=d4166151f5b09b23efcaa8ab00cc8658
AFFILIATIONS: Dipartimento di Ingegneria Elettrica Elettronica e Informatica, University of Catania, Italy; 
CNR-IASI, Italian National Research Council-Institute for Systems Analysis and Computer Science “A. Ruberti”, Rome, Italy
ABSTRACT: Positive-real and negative-imaginary systems are characterized by properties which make them particularly important in modeling physical devices, such as large-scale flexible structures or electric networks. This paper focuses on a strategy developed in order to ensure the positive-real or negative-imaginary property to systems with external time-delays. A forward action is taken into consideration in order to make systems with time-delay positive-real or negative-imaginary, guaranteeing also closed-loop stability performance. Numerical examples are included. © 2019 Elsevier B.V.

Gugat, M., Gerster, S.
On the limits of stabilizability for networks of strings
(2019) 131, art. no. 104494, . Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069569540&doi=10.1016%2fj.sysconle.2019.104494&partnerID=40&md5=070e8a49ea56d04944e0da06b28f0396
AFFILIATIONS: Lehrstuhl für Angewandte Mathematik 2, Department Mathematik, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstr.11, 91058, Erlangen, Germany; 
IGPM, RWTH Aachen University, Templergraben 55, Aachen, 52062, Germany
ABSTRACT: An example by Bastin and Coron illustrates that the boundary stabilization of 1-d hyperbolic systems with certain source terms is only possible if the length of the space interval is sufficiently small. We show that related phenomena also occur for networks of vibrating strings that are governed by the wave equation with a certain source term. It turns out that for a tree of strings with Neumann velocity feedback control at one boundary node and a homogeneous Dirichlet boundary condition at at least one boundary node and homogeneous Dirichlet or Neumann conditions at the other boundary nodes, boundary feedback stabilization is not possible if one of the strings is sufficiently long. However, if the number of strings in the tree is sufficiently large, also for arbitrarily short strings for certain parameters in the source term stabilization is not possible. The wave equation with source term that we consider is equivalent to a certain 2 ×2 system. For the examples that illustrate the limits of stabilizability, the matrix of the source term is not positive definite. However if the system parameters are chosen in such a way that the matrix is positive semi-definite, the tree of strings can be stabilized exponentially fast by the boundary feedback control for arbitrary long space intervals. © 2019

Zhang, X., Lu, X.
On stability analysis of nonlinear time-delay systems on time scales
(2019) 131, art. no. 104498, . Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069564066&doi=10.1016%2fj.sysconle.2019.104498&partnerID=40&md5=7fca68a3778302c7d0b7f583c068e10b
AFFILIATIONS: School of Control Science and Engineering, Shandong University, Jinan, 250061, China
ABSTRACT: This paper is concerned with the stability problems of a more general class of nonlinear time-delay systems, called time-scale time-delay systems, which can include not only the traditional continuous and discrete ones, but also some other cases, such as systems on hybrid time domains. As far as we know, the only existing approach for analyzing stability of such systems is the Razumikhin-type stability theorem. To enrich the stability results for such systems, this paper proposes the Lyapunov–Krasovskii theorem. Firstly, a conservative stability criterion is provided by requiring the time-scale time derivative of relating Lyapunov functional to be negative. Then, by introducing the time-scale type uniformly stable function and uniformly asymptotically stable function, a more relaxed stability theorem is proposed, in which the time-scale time derivative of Lyapunov functional is allowed to be non-negative. A numerical example about non-continuous and non-discrete time-delay systems is given to illustrate the effectiveness and general applicability of the theoretic results. © 2019 Elsevier B.V.

Kim, D., Jeong, J.-M., Cho, S.H.
Approximate controllability for semilinear retarded control equations using surjectivity results
(2019) 131, art. no. 104496, . 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069551259&doi=10.1016%2fj.sysconle.2019.104496&partnerID=40&md5=7feda7b544876aef1dfa1c848d7fee39
AFFILIATIONS: Department of Mathematics Education, Seowon University, Chungbuk, South Korea; 
Department of Applied Mathematics, Pukyong National University, Busan, South Korea
ABSTRACT: Sufficient conditions for approximate controllability of semilinear retarded functional control equations are obtained under general conditions on nonlinear terms. To get the main result, we transform the controllability problem into surjectivity results similar to Fredholm alternative for nonlinear operators under restrictive assumptions. Finally, a simple example to which our main result can be applied is given. © 2019 Elsevier B.V.

Briat, C.
Co-design of aperiodic sampled-data min-jumping rules for linear impulsive, switched impulsive and sampled-data systems
(2019) 130, pp. 32-42. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068923722&doi=10.1016%2fj.sysconle.2019.06.003&partnerID=40&md5=9f1571c047b70f6ce2ac2691790a01b4
AFFILIATIONS: NCIS, Basel, Switzerland
ABSTRACT: Co-design conditions for the design of a jumping-rule and a sampled-data control law for impulsive and impulsive switched systems subject to aperiodic sampled-data measurements are provided. Semi-infinite discrete-time Lyapunov–Metzler conditions are first obtained. As these conditions are difficult to check and generalize to more complex systems, an equivalent formulation is provided in terms of clock-dependent (infinite-dimensional) matrix inequalities. These conditions are then, in turn, approximated by a finite-dimensional optimization problem using a sum of squares based relaxation. It is proven that the sum of squares relaxation is non conservative provided that the degree of the polynomials is sufficiently large. It is emphasized that acceptable results are obtained for low polynomial degrees in the considered examples. © 2019 Elsevier B.V.

Tegling, E., Sandberg, H.
Noise-induced limitations to the scalability of distributed integral control
(2019) 130, pp. 23-31. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068851331&doi=10.1016%2fj.sysconle.2019.06.005&partnerID=40&md5=aed3b152839eccd1ed8a3f2332008f3a
AFFILIATIONS: School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm, SE-100 44, Sweden
ABSTRACT: We study performance limitations of distributed feedback control in large-scale networked dynamical systems. Specifically, we address the question of how the performance of distributed integral control is affected by measurement noise. We consider second-order consensus-like problems modeled over a toric lattice network, and study asymptotic scalings (in network size) of H2 performance metrics that quantify the variance of nodal state fluctuations. While previous studies have shown that distributed integral control fundamentally improves these performance scalings compared to distributed proportional feedback control, our results show that an explicit inclusion of measurement noise leads to the opposite conclusion. The noise's impact on performance is shown to decrease with an increased inter-nodal alignment of the local integral states. However, even though the controller can be tuned for acceptable performance for any given network size, performance will degrade as the network grows, limiting the scalability of any such controller tuning. In particular, the requirement for inter-nodal alignment increases with network size. We show that this may in practice imply that very large and sparse networks will require any integral control to be centralized, rather than distributed. In this case, the best-achievable performance scaling, which is shown to be that of proportional feedback control, is retrieved. © 2019

Jafarizadeh, S.
Fastest mixing reversible Markov chain on friendship graph: Trade-off between transition probabilities among friends and convergence rate
(2019) 130, pp. 13-22. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068831517&doi=10.1016%2fj.sysconle.2019.07.001&partnerID=40&md5=c98ff58ba4ccdd68a7816951da4a5657
AFFILIATIONS: Rakuten Institute of Technology, Rakuten Crimson House, Tokyo, Japan
ABSTRACT: A long-standing goal of social network research has been to alter the properties of network to achieve the desired outcome. In doing so, DeGroot's consensus model has served as the popular choice for modeling the information diffusion and opinion formation in social networks. Achieving a trade-off between the cost associated with modifications made to the network and the speed of convergence to the desired state has shown to be a critical factor. This has been treated as the Fastest Mixing Markov Chain (FMMC) problem over a graph with given transition probabilities over a subset of edges. Addressing this multi-objective optimization problem over the friendship graph, this paper has provided the corresponding Pareto optimal points or the Pareto frontier. In the case of friendship graph with at least three blades, it is shown that the Pareto frontier is reduced to a global minimum point which is same as the optimal point corresponding to the minimum spanning tree of the friendship graph, i.e., the star topology. Furthermore, a lower limit for transition probabilities among friends has been provided, where values higher than this limit do not have any impact on the convergence rate. © 2019 Elsevier B.V.

Fu, J., Lv, Y., Huang, T.
Distributed anti-windup approach for consensus tracking of second-order multi-agent systems with input saturation
(2019) 130, pp. 1-6. Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068514298&doi=10.1016%2fj.sysconle.2019.06.002&partnerID=40&md5=9e643091ba5a1da967964a1705c4e3fa
AFFILIATIONS: The School of Mathematics, Southeast University, Nanjing, 210096, China; 
Texas A&M University at Qatar, Doha, Qatar
ABSTRACT: In this paper, we study the global consensus tracking problem for second-order multi-agent systems with input saturation under general directed communication graphs. A controller design approach based on distributed anti-windup control is proposed to handle the input saturation constraint. We generalize the traditional two step anti-windup control methodology to multi-agent systems and solve the input constrained consensus tracking problem based on distributed anti-windup compensator design. Some simulation examples are provided to illustrate the effectiveness of the proposed control strategy. © 2019 Elsevier B.V.

Bartosiewicz, Z.
Minimal positive continuous-time realizations of positive response maps
(2019) 130, pp. 7-12. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85068504029&doi=10.1016%2fj.sysconle.2019.06.004&partnerID=40&md5=d1827831c6d851beab126bae38dbefc5
AFFILIATIONS: Faculty of Computer Science, Bialystok University of Technology, Wiejska 45A, Bialystok, 15-351, Poland
ABSTRACT: Positive nonlinear continuous-time local realizations of positive response maps are studied. The realizations are minimal if they are positively reachable and positively observable. Necessary and sufficient conditions for a response map to have a minimal positive local realization are provided. It is also shown that a minimal positive local realization has the minimal dimension among all positive local realizations of the given response map and that it is unique up to an isomorphism of systems. © 2019 Elsevier B.V.

Xu, S., Li, C.
On instability of LS-based self-tuning systems with bounded disturbances
(2019) 129, pp. 51-55. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069086556&doi=10.1016%2fj.sysconle.2019.06.001&partnerID=40&md5=672ee6314831ee3f97025b7666a3def7
AFFILIATIONS: Key Laboratory of Systems and Control, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, 100190, PR China; School of Mathematical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, PR China
ABSTRACT: It is well known that discrete-time linear systems can be stabilized by a least-squares (LS) based self-tuning regulator (STR), as long as noises are absent. However, this note shows that once the discrete-time linear systems are disturbed, the LS-based STR is always running the risk of failing in stabilizing the systems, no matter how small the noises are. © 2019

Zhang, M., Zhu, Q.
New criteria of input-to-state stability for nonlinear switched stochastic delayed systems with asynchronous switching
(2019) 129, pp. 43-50. Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066796049&doi=10.1016%2fj.sysconle.2019.05.004&partnerID=40&md5=3354733f81b3dbbf060d7c6babdb44aa
AFFILIATIONS: School of Mathematical Sciences and Institute of Mathematics, Nanjing Normal University, Nanjing, 210023, China; 
MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, Hunan, 410081, China
ABSTRACT: In this paper, we discuss the problems of input-to-state stability (ISS), integral-ISS (iISS) and eλt-ISS for a class of switched stochastic delayed systems under asynchronous switching. Asynchronous switching refers to that the switching of candidate controllers does not coincident with the system modes. Different from existing works, we allow the coefficients of the estimated upper bound for the diffusion operator of a Lyapunov function to be time-varying and increasing during the matched time interval and unmatched time interval, respectively. Meanwhile, by using the methods of Razumikhin technique, average dwell-time (ADT) approach together with comparison equation, some desired ISS-type properties are obtained. Especially, our results improve existing results regarding asynchronous switching in the literature. An example is used to demonstrate the applicability of the results. © 2019 Elsevier B.V.

Lopez-Ramirez, F., Efimov, D., Polyakov, A., Perruquetti, W.
Conditions for fixed-time stability and stabilization of continuous autonomous systems
(2019) 129, pp. 26-35. Cited 8 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066448863&doi=10.1016%2fj.sysconle.2019.05.003&partnerID=40&md5=7e8281f78a673f38c09a41da94abbf5b
AFFILIATIONS: Inria, University of Lille, CNRS, UMR 9189 - CRIStAL, Lille, F-59000, France; 
ITMO University, 49 Kronverkskiy av., Saint Petersburg, 197101, Russian Federation; 
École Centrale de Lille, Cité Scientifique, 59651 Villeneuve d'Ascq Cedex, France
ABSTRACT: This work presents Lyapunov analysis conditions for fixed-time stability, a property where all the system's trajectories converge exactly to zero in a finite amount of time that is independent of the system's initial condition. Necessary and sufficient conditions for fixed-time stability without taking into account the regularity of the settling-time function are presented first. Next, a characterization for fixed-time stability with continuous settling-time functionis introduced. A particular form of the characterizing functions follows, it allows to establish more constructive conditions and in order to obtain a converse result, the concept of complete fixed-time stability is introduced. A set of academic examples and an example of allocation of mobile agents illustrate the given concepts. Finally, a sufficient condition for fixed-time stabilization of nonlinear affine systems is obtained. © 2019 Elsevier B.V.

Barrau, A., Bonnabel, S.
Linear observed systems on groups
(2019) 129, pp. 36-42. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066443951&doi=10.1016%2fj.sysconle.2019.05.005&partnerID=40&md5=0849deb17a7051686ac1933923beb77c
AFFILIATIONS: SAFRAN TECH, Groupe Safran, Rue des Jeunes Bois - Châteaufort, 78772 Magny Les Hameaux CEDEX, France; 
MINES ParisTech, PSL Reasearch University, centre for Robotics, 60 bd Saint-Michel, Paris, 75006, France; 
Université de la Nouvelle-Calédonie, Institut de Sciences Exactes et Appliquées, Nouméa Cedex, 98851, France
ABSTRACT: We propose a unifying and versatile framework for a class of discrete time systems whose state is an element of a general group G, that we call linear observed systems on groups. Those systems strictly mimic linear systems in the sense that ＋ is replaced with group multiplication, and linear maps with automorphisms. We argue they are the true generalization of linear systems of the form Xn+1=FnXn+Bnun in the context of state estimation, since 1—when G=RN the latter systems are recovered, 2—they are proved to possess the “preintegration” property, a characteristic property of linear systems that relates continuous time to discrete time, and has recently proved extremely useful in robotics applications, and 3—we can build observers that ensure the evolution between the true state and estimated state does not depend on the followed trajectory, a characteristic feature of Luenberger (and invariant)observers. The theory is applied to a 3D inertial navigation example. Interestingly, this example cannot be put in the form of an invariant system and the proposed generalization is required. © 2019 Elsevier B.V.

van der Woude, J., Commault, C., Boukhobza, T.
A dynamic graph characterisation of the fixed part of the controllable subspace of a linear structured system
(2019) 129, pp. 17-25. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066405929&doi=10.1016%2fj.sysconle.2019.05.002&partnerID=40&md5=82d22e0fd66516838d958f4ccc492175
AFFILIATIONS: DIAM, EWI, Delft University of Technology, Van Mourik Broekmanweg 6, 2628 XE, Delft, Netherlands; 
Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, Grenoble, 38000, France; 
Université de Lorraine, CNRS, CRAN, Nancy, F-54000, France
ABSTRACT: In this paper we study linear structured systems described by means of system matrices of which only the zero/non-zero structure is known and where the non-zeros are supposed to have independent values. The structure of linear structured systems can be represented by means of various types of graphs, like directed graphs or dynamic graphs. Here we use both type of graphs because they enable us to formulate and study certain controllability properties in a uniform and straightforward way. In this paper we extend the results of a previous paper containing a partial characterisation of the fixed part of the controllable subspace of linear structured systems. This fixed part is defined as the part of the controllable subspace that is independent of the values to the non-zeros, and therefore can be seen as the robust part of the controllable subspace. It turns out that, by considering the generic dimension of the controllable subspace, a characterisation of the fixed part can be obtained. The latter dimension equals the size of the minimal set of nodes in the dynamic graph that separates between the set of input nodes and the set of final state nodes. Computing the supremal of such minimal separating sets, we are capable of characterising the fixed part. In the paper we indicate how this supremal minimal separating set can be obtained insightfully and efficiently using the recursive nature of the dynamic graph. Our results are illustrated by some meaningful examples. © 2019 Elsevier B.V.

Wang, T., Huang, Y., Chen, Z.
Dichotomy theorem for control sets
(2019) 129, pp. 10-16. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066083007&doi=10.1016%2fj.sysconle.2019.05.001&partnerID=40&md5=a2af1069eb7800f02c2359fe5e57dc83
AFFILIATIONS: School of Mathematics, Sun Yat-sen University, GuangZhou, 510275, China; 
School of Mathematics and Systems Science, Guangdong Polytechnic Normal University, Guangzhou, 510665, China
ABSTRACT: We introduce two notions of equi-invariant sets and unstable sets for control systems and show that a control set with dense interior is either equi-invariant or unstable. This is the analogy to the well-known dichotomy theorem for topological transitive dynamical systems. An illustrative example is given to show that both of the two situations can occur. © 2019 Elsevier B.V.

Yan, C., Fang, H.
A new encounter between leader–follower tracking and observer-based control: Towards enhancing robustness against disturbances
(2019) 129, pp. 1-9. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065924314&doi=10.1016%2fj.sysconle.2019.04.010&partnerID=40&md5=0367aec4f0ba8244705d438ba4f58994
AFFILIATIONS: Department of Mechanical Engineering, University of Kansas, LawrenceKS  66045, United States
ABSTRACT: This paper studies robust tracking control for a leader–follower multi-agent system (MAS) subject to disturbances. A challenging problem is considered here, which differs from those in the literature in two aspects. First, we consider the case when all the leader and follower agents are affected by disturbances, while the existing studies assume only the followers to suffer disturbances. Second, we assume the disturbances to be bounded only in rates of change rather than magnitude as in the literature. To address this new problem, we propose a novel observer-based distributed tracking control design. As a distinguishing feature of our approach, the followers can cooperatively estimate the disturbance affecting the leader to adjust their maneuvers accordingly, which is enabled by the design of the first-of-its-kind distributed disturbance observers. We build specific tracking control approaches for both first- and second-order MASs and prove that they can lead to bounded-error tracking, despite the challenges due to the relaxed assumptions about disturbances. We further perform simulation to validate the proposed approaches. © 2019 Elsevier B.V.

Oliva, G., Panzieri, S., Setola, R., Gasparri, A.
Gossip algorithm for multi-agent systems via random walk
(2019) 128, pp. 34-40. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065551044&doi=10.1016%2fj.sysconle.2019.04.009&partnerID=40&md5=42b956b97fe0aee71877778c05dfbe06
AFFILIATIONS: Complex Systems & Security Laboratory, University Campus Bio-Medico, via A. del Portillo 21, Rome, 00128, Italy; 
University Roma Tre, Via della Vasca Navale 79, Rome, 00146, Italy
ABSTRACT: This paper proposes an asynchronous gossip framework where agents move according to independent random walks over a location graph and interactions may occur only when two agents share the same location. Our goal is to investigate how average consensus may be achieved when agents’ motion occurs over a set of discrete locations with topological constraints. This could be used to model the spreading of information across moving crowds or the coordination of agents monitoring a discrete set of points of interest. © 2019 Elsevier B.V.

Timoshin, S.A., Aiki, T.
Control of biological models with hysteresis
(2019) 128, pp. 41-45. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065535327&doi=10.1016%2fj.sysconle.2019.04.003&partnerID=40&md5=ec391db2b54fea9ef703667af837319f
AFFILIATIONS: Fujian Province University Key Laboratory of Computational Science, School of Mathematical Sciences, Huaqiao University, Quanzhou, 362021, China; 
Matrosov Institute for System Dynamics and Control Theory, Russian Academy of Sciences, Lermontov str. 134, Irkutsk, 664033, Russian Federation; 
Department of Mathematical and Physical Sciences, Faculty of Science, Japan Women's University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, 112-8681, Japan
ABSTRACT: This article presents a control problem in population dynamics when diffusive and hysteretic effects in the evolution of population are taken into account. Namely, we consider a diffusive prey–predator model, in a bounded domain, with a parameter corresponding to the quantity of food for the preys. In the model, the evolution of the food density is described by a hysteresis operator of the generalized play type whose inputs are the densities of preys/predators. Roughly speaking, the rate of change of the food density depends not only on the present state of preys/predators, but also on their immediately preceding density history. Our main concern is to extend the previous research of this model by controlling the food supply and to study the well-posedness of the corresponding dynamical control problem. © 2019 Elsevier B.V.

Huang, B., Meng, Z.
Cooperative output regulation for a group of nonlinear systems with limited information exchange: A distributed observer approach
(2019) 128, pp. 46-55. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065533348&doi=10.1016%2fj.sysconle.2019.04.007&partnerID=40&md5=3641108315d9713c0a169faee87ae4d4
AFFILIATIONS: Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
ABSTRACT: In this paper, the cooperative output regulation problem of nonlinear multi-agent system is studied. Both the cases of a linear exosystem and a nonlinear exosystem are considered. We focus on the situation of limited information exchange, i.e., only partial set of followers have access to the exosystem information and each follower exchanges the information with only its local neighbors. We first relax the classical manifold assumption on the regulator equations. In particular, the regulator equations are rebuilt and the zero-output manifold is provided not by the dynamics of the exosystem as given in the current literatures, but by exosystem signal and its higher-order derivatives. Then, a high-gain based distributed observer is designed to estimate the exosystem signal and its higher-order derivatives for the case of a linear exosystem. In the second place, a sliding-mode based distributed observer is proposed to estimate the exosystem signal and its higher-order derivatives for the case of a nonlinear exosystem. Based on the proposed distributed observers, nonlinear controllers are designed such that the cooperative output regulation is achieved with a global convergence property. Finally, simulations are provided to validate the theoretical results. © 2019 Elsevier B.V.

Li, C., Chen, S., Li, J., Wang, F.
Distributed multi-step subgradient optimization for multi-agent system
(2019) 128, pp. 26-33. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065518074&doi=10.1016%2fj.sysconle.2019.04.008&partnerID=40&md5=7851ead5fb6444a50617f8e3bf03fa61
AFFILIATIONS: College of Electrical Engineering, Zhejiang University, Hangzhou, 310027, China; 
Research Center of Satellite Technology, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: This paper proposes a novel multi-step subgradient scheme to solve distributed optimization problem with a balanced digraph. To this end, matrix diameter and radius are first introduced to describe the convergence rate of the adjacency matrix. Then, we propose a hierarchical and recursive observer to estimate the desired optimal solution, and we prove that the proposed strategy can asymptotically obtain an optimal solution, while all networked systems achieve a consensus among estimates in a finite-time. Simulation results verified the effectiveness of the proposed algorithm. © 2019 Elsevier B.V.

Formentin, S., Mazzoleni, M., Scandella, M., Previdi, F.
Nonlinear system identification via data augmentation
(2019) 128, pp. 56-63. Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065501252&doi=10.1016%2fj.sysconle.2019.04.004&partnerID=40&md5=1035b29ca676d5517e8ebaabd030b7cc
AFFILIATIONS: Dept of Electronics, Information and Bioengineering, Politecnico di Milano, Via G. Ponzio 34/5, Milano, 20133, Italy; 
Dept of Management, Information and Production Engineering, University of Bergamo, Via G. Marconi 5, 24044 Dalmine (BG), Italy
ABSTRACT: This paper presents a novel nonparametric approach to the identification of nonlinear dynamical systems. The proposed methodology exploits the potential of manifold learning on an artificially augmented dataset, obtained without running new experiments on the plant. The additional data are employed for approximating the manifold where input regressors lie. The knowledge of the manifold acts as a prior information on the system, that induces a proper regularization term on the identification cost. The new regularization term, as opposite to the standard Tikhonov one, enforces local smoothness of the function along the manifold. A graph-based algorithm tailored to dynamical systems is proposed to generate the augmented dataset. The hyperparameters of the method, along with the order of the system, are estimated from the available data. Numerical results on a benchmark Nonlinear Finite Impulse Response (NFIR)system show that the proposed approach may outperform the state of the art nonparametric methods. © 2019 Elsevier B.V.

Sánchez, C.J., Yuz, J.I.
On the relationship between spline interpolation, sampling zeros and numerical integration in sampled-data models
(2019) 128, pp. 1-8. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065088144&doi=10.1016%2fj.sysconle.2019.04.006&partnerID=40&md5=e88cadff63f15957258ed562e67b4e28
AFFILIATIONS: Department of Electronic Engineering, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile
ABSTRACT: Real systems are usually modeled in continuous-time by differential equations. In practice, however, we have to deal with them using discretized models and sampled data. These models, however, have more zeros than the continuous-time model. In this paper we show that there is a specific relation between these sampling zeros and the smoothness of the continuous-time input to the plant generated by a hold device using spline interpolation. On the other hand, in numerical analysis, ordinary differential equations are solved using numerical integration methods such as Runge–Kutta. In this paper we also characterize the asymptotic sampling zeros of approximate sampled-data models when using a Runge–Kutta method of a given order under uniform sampling and the input signal is obtained by spline interpolation. These results show the strong connections between the presence and characterization of sampling zeros, spline interpolation and numerical integration techniques. Moreover, the results presented in the paper provide additional insights about the impact of the details of the sampling process on the resulting discrete-time model. © 2019 Elsevier B.V.

Yang, H., Li, Y., Dai, L., Xia, Y.
MPC-based defense strategy for distributed networked control systems under DoS attacks
(2019) 128, pp. 9-18. Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065072005&doi=10.1016%2fj.sysconle.2019.04.001&partnerID=40&md5=8830ae2fd1b558336c2261fc6cbd9a0f
AFFILIATIONS: Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin, 300072, China; 
Department of Automation, Xiamen University, Xiamen, 361102, China; 
School of Automation, Beijing Institute of Technology, Beijing, 100081, China
ABSTRACT: In this paper, a distributed stochastic model predictive controller is designed for a networked control system subject to stochastic disturbances and denial-of-service (DoS) attacks. Each subsystem is constrained by actuator saturation and all of them are coupled via probabilistic constraints. By using the information on stochastic disturbances and considering the loss of data packet resulting from DoS attacks explicitly, an observer is designed to reconstruct the states and coupling probabilistic constraints are transformed into coupled deterministic constraints. By adopting the update strategy that only one subsystem is optimized at each time step, while others are setting feasible solutions as their control inputs, the constraints are further transformed into local deterministic constraints. To mitigate performance degradation due to DoS attacks, a performance constraint is introduced such that the optimal performance is not much worse than when the networks work perfectly. Constraints satisfaction, recursive feasibility and quadratic stability can be ensured despite the presence of DoS attacks. A numerical simulation is given to demonstrate the efficiency of the proposed algorithm. © 2019 Elsevier B.V.

Hastir, A., Califano, F., Zwart, H.
Well-posedness of infinite-dimensional linear systems with nonlinear feedback
(2019) 128, pp. 19-25. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065042437&doi=10.1016%2fj.sysconle.2019.04.002&partnerID=40&md5=8b48e8c8ab37a13c6b54f1980ef0c309
AFFILIATIONS: University of Namur, Department of Mathematics and Namur Institute for Complex Systems (naXys), Rempart de la vierge, 8, Namur, B-5000, Belgium; 
University of Twente, Robotics and Mechatronics (RAM), P.O. Box 217, 7500 AE, Enschede, Netherlands; 
University of Twente, Department of Applied Mathematics, P.O. Box 217, Enschede, 7500 AE, Netherlands; 
Eindhoven University of Technology, Department of Mechanical Engineering, P.O. Box 513, Eindhoven, 5600 MB, Netherlands
ABSTRACT: We study existence of solutions, and in particular well-posedness, for a class of inhomogeneous, nonlinear partial differential equations (PDE's). The main idea is to use system theory to write the nonlinear PDE as a well-posed infinite-dimensional linear system interconnected with a static nonlinearity. By a simple example, it is shown that in general well-posedness of the closed-loop system is not guaranteed. We show that well-posedness of the closed-loop system is guaranteed for linear systems whose input to output map is coercive for small times interconnected to monotone nonlinearities. This work generalizes the results presented in [1], where only globally Lipschitz continuous nonlinearities were considered. Furthermore, it is shown that a general class of linear port-Hamiltonian systems satisfies the conditions asked on the open-loop system. The result is applied to show well-posedness of a system consisting of a vibrating string with nonlinear damping at the boundary. © 2019 Elsevier B.V.

Copp, D.A., Vamvoudakis, K.G., Hespanha, J.P.
Distributed output-feedback model predictive control for multi-agent consensus
(2019) 127, pp. 52-59. Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064884466&doi=10.1016%2fj.sysconle.2019.04.005&partnerID=40&md5=9d203636d94d042a5d20f96741c80ce4
AFFILIATIONS: Sandia National Laboratories, AlbuquerqueNM  87185-1108, United States; 
The Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA  30332-0150, United States; 
Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA  93106-9560, United States
ABSTRACT: We propose a distributed output-feedback model predictive control approach for achieving consensus among multiple agents. Each agent computes a distributed control action based on an output-feedback measurement of a local neighborhood tracking error and communicates information only to its neighbors, according to a communication network modeled as a directed graph. Each agent computes its distributed control action by solving a local min–max optimization problem that simultaneously computes a local state estimate and control input under worst-case assumptions on unmeasured input disturbances and measurement noise. Under easily verified controllability and observability assumptions, this distributed output-feedback model predictive control approach provides an upper bound on the group consensus error, thereby ensuring practical consensus in the presence of unmeasured disturbances and noise. A numerical example with four agents connected in a directed graph is given to illustrate the results. © 2019 Elsevier B.V.

Borgioli, F., Michiels, W., Lu, D., Vandereycken, B.
A globally convergent method to compute the real stability radius for time-delay systems
(2019) 127, pp. 44-51. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064695453&doi=10.1016%2fj.sysconle.2019.03.009&partnerID=40&md5=5ad44c286fcebb46a3e2189a631ab437
AFFILIATIONS: Department of Computer Science, KU Leuven, Leuven, 3001, Belgium; 
Section of Mathematics, University of Geneva, Geneva, 1227, Switzerland
ABSTRACT: This paper presents a novel algorithm to compute the real stability radius for a linear delay system of retarded type with multiple delays. The real stability radius is the distance to instability, measured as the minimal real-valued perturbation that renders the system unstable. Our method is based on characterizing this distance to instability as the inverse of the global maximum of a real structured singular value function. We develop a criss-cross type algorithm that globally converges to this maximum, and whose convergence rate seems to be superlinear and sometimes quadratic in numerical experiments. The algorithm exploits that the intersections of these singular value functions with constant functions can be written as purely imaginary eigenvalues of certain delay eigenvalue problems (DEP) with positive and negative delays. This is an extension of the well-known linear case (without delays) where this results in algebraic eigenvalue problems. In addition, a novel numerical solver to compute all the imaginary eigenvalues of this DEP is also presented. It combines an approximation using spectral discretizations and an automatic procedure to determine the required number of discretization points. Finally, due to the presence of multiple eigenvalues at the maximum, these approximations are corrected with a block-Newton algorithm for nonlinear eigenvalue problems. © 2019 Elsevier B.V.

Alpago, D., Ferrante, A.
Families of solutions of algebraic Riccati equations
(2019) 127, pp. 35-38. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064644584&doi=10.1016%2fj.sysconle.2019.03.012&partnerID=40&md5=3b45d70765d7ccf97a2c252f499849ce
AFFILIATIONS: Dipartimento di Ingegneria dell'Informazione, Università di Padova, via Gradenigo 6/B, Padova, 35131, Italy
ABSTRACT: We consider Homogeneous Algebraic Riccati Equations in the general situation when the matrix of the dynamics can be mixed. We show that in this case the equation may have infinitely many families of solutions. An analysis of these families is carried over and an explicit formula is derived. When the matrix of the dynamics is unmixed, this formula provides an explicit parametrization of the whole set of the solutions. We finally show that there are situations in which the equation has spurious solutions that do not belong to any of the families and derive sufficient conditions under which, on the contrary, the union of the families covers the whole set of solutions. © 2019 Elsevier B.V.

Ammari, K., Crépeau, E.
Well-posedness and stabilization of the Benjamin–Bona–Mahony equation on star-shaped networks
(2019) 127, pp. 39-43. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064605202&doi=10.1016%2fj.sysconle.2019.03.005&partnerID=40&md5=6b17ec94960d7ca647520e320c41516c
AFFILIATIONS: UR Analysis and Control of PDEs, UR 13ES64, Department of Mathematics, Faculty of Sciences of Monastir, University of Monastir, Tunisia; 
LMV/UVSQ, Université Paris-Saclay, France; 
LMV, UVSQ, CNRS, Université Paris-Saclay, Versailles, 78035, France
ABSTRACT: We study the stabilization issue of the Benjamin–Bona–Mahony (BBM) equation on a finite star-shaped network with a damping term acting on the central node. In a first time, we prove the well-posedness of this system. Then thanks to the frequency domain method, we get the asymptotic stabilization result. © 2019 Elsevier B.V.

Yousefi, M., van Heusden, K., Mitchell, I.M., Dumont, G.A.
Model-invariant viability kernel approximation
(2019) 127, pp. 13-18. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064324777&doi=10.1016%2fj.sysconle.2019.03.010&partnerID=40&md5=39314628cba9cec7cecc8648bb8cfdd3
AFFILIATIONS: Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, BC, Canada; 
Department of Computer Science, The University of British Columbia, Vancouver, BC, Canada
ABSTRACT: Discussion of safety preserving control in the presence of uncertainty has mostly focused on stochastic and additive uncertainty. Multiplicative uncertainty can be represented as additive uncertainty, however, this may lead to very conservative solutions. We recently introduced a model-invariant safety-preserving control scheme for multiplicative uncertainty with multi-model description in linear time-invariant systems. This scheme relies on an approximation of the model-invariant viability kernel, which is a set of initial states for which there exists a control input that keeps the states of an uncertain system within a set of viability constraints. In previous work, we showed that the model-invariant viability kernel is the intersection of the viability kernels of all members of a model set representing model-uncertainty. Calculating this intersection is computationally expensive if the number of members in the set is large. In this paper, we propose an efficient approach to under-approximate the model-invariant viability kernel without the need to calculate the viability kernel of all individual set members. This extends the practical applicability of our previous work to multi-model uncertainty descriptions with a large or infinite number of models as well as models with continuous uncertainty. © 2019 Elsevier B.V.

Formentin, S., Campi, M.C., Carè, A., Savaresi, S.M.
Deterministic continuous-time Virtual Reference Feedback Tuning (VRFT) with application to PID design
(2019) 127, pp. 25-34. Cited 13 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064319731&doi=10.1016%2fj.sysconle.2019.03.007&partnerID=40&md5=4762e090eb78865b1ba5f044a4b7da37
AFFILIATIONS: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, P.zza L. da Vinci 32, Milano, 20133, Italy; 
Dipartimento di Ingegneria dell'Informazione, University of Brescia, via Branze 38, Brescia, 25123, Italy
ABSTRACT: In this paper, we introduce a data-driven control design method that does not rely on a model of the plant. The method is inspired by the Virtual Reference Feedback Tuning approach for data-driven controller tuning, but it is here entirely developed in a deterministic, continuous-time setting. A PID autotuner is then developed out of the proposed approach and its effectiveness is tested on an experimental brake-by-wire facility. The final performance is shown to outperform that of a benchmark model-based design method. © 2019 Elsevier B.V.

Melchor-Aguilar, D.
On Lyapunov functionals for linear functional difference equations
(2019) 127, pp. 1-5. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064319127&doi=10.1016%2fj.sysconle.2019.03.008&partnerID=40&md5=bbd6c1e124add4a01366b6013d528fa5
AFFILIATIONS: Division of Applied Mathematics, IPICYT, San Luis Potosí, SLP78216, Mexico
ABSTRACT: This paper presents new Lyapunov results for investigating the exponential stability property of general classes of linear functional difference equations by means of continuous and differentiable functionals. The results generalize some existing ones for the exponential stability of difference equations in continuous time with discrete and discrete plus distributed delays. © 2019 Elsevier B.V.

de Oliveira Souza, F.
Imaginary characteristic roots of neutral systems with commensurate delays
(2019) 127, pp. 19-24. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064277053&doi=10.1016%2fj.sysconle.2019.03.011&partnerID=40&md5=dcc636566b44e3b70eae23eb80c2f7b7
AFFILIATIONS: Department of Electronics Engineering, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, MG  31270-010, Brazil
ABSTRACT: This paper concentrates on stability analysis of neutral linear time-invariant (LTI) delay systems with multiple commensurate time-delays. A new numerical procedure is offered for the determination of purely imaginary characteristic roots of neutral delay systems, which plays a crucial role in assessing the system stability. Based on simple linear algebra it is shown that the imaginary characteristic roots of such a system can be found by calculating the generalized eigenvalues of an associated matrix pair. If the system is of retarded type we just need to determine the eigenvalues of a single matrix. The results extend previously known work on neutral delay systems subject to a single delay for neutral systems subject to multiple commensurate delays. In the light of the main result of this paper we present a new method to determine the largest first time-delay interval for which a neutral delay system preserves its stability. The paper is closed by showing numerical examples that illustrate the applicability and effectiveness of the proposed method. © 2019 Elsevier B.V.

Gajardo, P., Hermosilla, C.
The viability kernel of dynamical systems with mixed constraints: A level-set approach
(2019) 127, pp. 6-12. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064243656&doi=10.1016%2fj.sysconle.2019.03.006&partnerID=40&md5=8f6dc4481af608cbcdd1b066d248a8c9
AFFILIATIONS: Departamento de Matemática, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso, Chile
ABSTRACT: This paper deals with control systems with mixed (state-control) constraints and dynamics in discrete-time. We aim at providing a practical method for computing the viability kernel for such systems. We take a standard approach via optimal control theory, that is, we identify the viability kernel as the effective domain of the value function of a suitable optimal control problem. A dynamic programming principle can be established in order to compute that value function. However, from a practical point of view this may turn out in a slow scheme for such computation, because at each step the mixed constraints need to be verified. In this work we take a different path which has been inspired by the level-set approach studied for optimal control problems with (pure) state constraints. An algorithm is proposed for computing the viability kernel and some numerical examples are shown to demonstrate the proposed method. © 2019 Elsevier B.V.

Wang, Y., Rajamani, R., Zemouche, A.
A quadratic matrix inequality based PID controller design for LPV systems
(2019) 126, pp. 67-76. Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063622857&doi=10.1016%2fj.sysconle.2019.02.006&partnerID=40&md5=74625fc5bd38b6d50191365d3cee29d1
AFFILIATIONS: Department of Mechanical Engineering, University of Minnesota, Twin Cities, Minneapolis, MN  55455, United States; 
University of Lorraine, CRAN CNRS UMR 7039, Cosnes et Romain, 54400, France
ABSTRACT: This paper develops a robust gain-scheduled proportional–integral–derivative (PID) controller design method for a linear-parameter-varying (LPV) system with parametric uncertainty. It is recognized in the literature that the robust fixed-order controller design can be formulated as a feasibility problem of a bilinear matrix inequality (BMI) constraint. Unfortunately, the search for a feasible solution of a BMI constraint is an NP hard problem in general. Previous researchers have applied a linearization method, such as a variable change technique or a congruence transformation, to transform the BMI into a LMI. The applicability of the linearization method depends on the specific structure of the problem at hand and cannot be generalized. This paper instead formulates the gain-scheduled PID controller design as a feasibility problem of a quadratic matrix inequality (QMI) constraint, which covers the BMI constraint as a special case. An augmented sequential LMI optimization method is proposed to search for a feasible solution of the QMI constraint iteratively. As an illustrative application, a vehicle lateral control problem is presented to demonstrate the applicability of the proposed algorithm to a real-world output feedback control design system. © 2019 Elsevier B.V.

Hernandez Vicente, B.A., Trodden, P.A.
Stabilizing predictive control with persistence of excitation for constrained linear systems
(2019) 126, pp. 58-66. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063509246&doi=10.1016%2fj.sysconle.2019.03.003&partnerID=40&md5=50b89d505ecc9bd0e2ca1cbc706d3d48
AFFILIATIONS: Department of Automatic Control & Systems Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom
ABSTRACT: A new adaptive predictive controller for constrained linear systems is presented. The main feature of the proposed controller is the partition of the input in two components. The first part is used to persistently excite the system, in order to guarantee accurate and convergent parameter estimates in a deterministic framework. An MPC-inspired receding horizon optimization problem is developed to achieve the required excitation in a manner that is optimal for the plant. The remaining control action is employed by a conventional tube MPC controller to regulate the plant in the presence of parametric uncertainty and the excitation generated for estimation purposes. Constraint satisfaction, robust exponential stability, and convergence of the estimates are guaranteed under design conditions mildly more demanding than that of standard MPC implementations. © 2019 Elsevier B.V.

Xiao, Z.-H., Jiang, Y.-L., Qi, Z.-Z.
Finite-time balanced truncation for linear systems via shifted Legendre polynomials
(2019) 126, pp. 48-57. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063338982&doi=10.1016%2fj.sysconle.2019.03.004&partnerID=40&md5=6cbcc2ad753b0027eab37c2e13788636
AFFILIATIONS: School of Information and Mathematics, Yangtze University, Jingzhou, Hubei, 434023, China; 
School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China; 
School of Mathematics, Northwest University, Xi'an, Shaanxi, 710127, China
ABSTRACT: In this paper, we present a finite-time model order reduction method for linear systems via shifted Legendre polynomials. The main idea of the approach is to use finite-time empirical Gramians, which are constructed from impulse responses by solving block tridiagonal linear systems, to generate approximate balanced system for the large-scale system. The balancing transformation is directly computed from the expansion coefficients of impulse responses in the space spanned by shifted Legendre polynomials, without individual reduction of the Gramians and a separate eigenvector solve. Then, the reduced-order model is constructed by truncating the states corresponding to the small approximate Hankel singular values (HSVs). The stability preservation of the reduced model is briefly discussed. And in combination with the dominant subspace projection method, we modify the reduction procedure to alleviate the shortcomings of the above method, which may unexpectedly lead to unstable systems even though the original one is stable. Furthermore, the properties of the resulting reduced models are considered. Finally, numerical experiments are given to demonstrate the effectiveness of the proposed methods. © 2019 Elsevier B.V.

Zhu, Q., Lin, W.
Stabilizing Boolean networks by optimal event-triggered feedback control
(2019) 126, pp. 40-47. Cited 7 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063270717&doi=10.1016%2fj.sysconle.2019.03.002&partnerID=40&md5=87456618b32e40647ec965b82d652db4
AFFILIATIONS: School of Mathematical Sciences, Fudan University, Shanghai, 200433, China; 
Centre for Computational Systems Biology and ISTBI, Fudan University, Shanghai, 200433, China; 
Shanghai Key Laboratory for Contemporary Applied Mathematics, LNMS (Fudan University) and LCNBI (Fudan University), Shanghai, 200433, China
ABSTRACT: In this paper, we focus on the topic of stabilizing the Boolean control network (BCN) by an optimal event-triggered feedback control. By routinely transforming the BCN into its algebraic form, constructing the (reverse) weighted digraph and the hypergraph for the BCN, applying the shortest path algorithm to the hypergraph, we obtain an optimal event-triggered control strategy that can stabilize the BCN starting from any given initial state to a priorly-specified approachable equilibrium and simultaneously can minimize a quality index combining control time with control variability. To avoid the case where the obtained optimal strategy is dependent on the initial state, we establish necessary and sufficient conditions for finding a unified control law which can steer the BCN starting from all initial states to the given equilibrium with a minimal quality index. Furthermore, all the existence results are extended further to the BCNs under the control laws of event-triggered delayed state feedback, event-triggered output feedback, and the event-triggered delayed output feedback. Particularly, the control law of event-triggered delayed feedback can cope with the optimization problem that the unified control law without delay cannot address. Additionally, we derive the necessary and sufficient condition under which the event-triggered state (resp., output) feedback control law degenerates into the conventional state (resp., output) feedback control law. Finally, we provide an illustrative example of biological significance to demonstrate the potential usefulness of the obtained analytical results. © 2019 Elsevier B.V.

Batista, P., Silvestre, C., Oliveira, P.
Attitude observer on the special orthogonal group with Earth velocity estimation
(2019) 126, pp. 33-39. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063084084&doi=10.1016%2fj.sysconle.2019.03.001&partnerID=40&md5=3200fd128845c1dbd96a9efa12e0b586
AFFILIATIONS: Institute for Systems and Robotics, LARSyS, Instituto Superior Técnico, Universidade de Lisboa, Portugal; 
Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau; 
Institute for Systems and Robotics, LARSyS, Institute of Mechanical Engineering, LAETA, Universidade de Lisboa, Portugal
ABSTRACT: This paper proposes a new nonlinear attitude observer based on high-grade rate gyros and single body-fixed vector measurements of a constant inertial vector, in contrast with typical solutions that require two of these vectors. The structure is cascaded, where in the first block a vector that is related to the angular velocity of the Earth is estimated and in the second block the attitude itself is obtained. The attitude is directly estimated on the special orthogonal group and the estimation error is shown to converge to zero, with a region of convergence that is best described as semi-global, with local exponential convergence. Simulation results illustrate the achievable performance of the proposed solution and the robustness to sensor noise. © 2019 Elsevier B.V.

Guo, S., Jiang, B., Zhu, F., Wang, Z.
Luenberger-like interval observer design for discrete-time descriptor linear system
(2019) 126, pp. 21-27. Cited 15 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062855702&doi=10.1016%2fj.sysconle.2019.02.005&partnerID=40&md5=787bb8904e8d4d89e103fdb00c9e61d4
AFFILIATIONS: College of Electronics and Information Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China; 
College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 211106, China; 
College of Electronics and Information Engineering, Tongji University, Shanghai, 201804, China; 
School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: In this paper, the problem of Luenberger-like interval observer design for discrete-time descriptor linear system is investigated. In the first place, two ways in which the original descriptor system is transformed into general systems are given and the detectability of the equivalent general systems is discussed in detail. A new equivalent general system construction is developed and we prove that the detectability can be kept under this new equivalent transformation. After this, based on the new equivalent general system, a Luenberger-like interval observer is proposed. Finally, two simulation examples are given to demonstrate the correctness and the effectiveness of the proposed interval observer. © 2019 Elsevier B.V.

Chen, J.-H.
Infinite-time exact observability of Volterra systems in Hilbert spaces
(2019) 126, pp. 28-32. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062855119&doi=10.1016%2fj.sysconle.2019.02.004&partnerID=40&md5=34289cc8b1a7ef55023f5ada6ea921a8
AFFILIATIONS: School of Mathematical and Computational Science, Hunan University of Science and Technology, Xiangtan, Hunan  411201, China; 
School of Mathematics and Statistics, Central South University, Changsha, Hunan, 410075, China
ABSTRACT: We study infinite-time exact observability of Volterra systems in Hilbert spaces. Sufficient conditions are established under which infinite-time exact observability of a Volterra system follows from that of the corresponding Cauchy system without convolution term. This is done by combining the composition operator method with a result about bounded below composition operators on the Hardy space. © 2019 Elsevier B.V.

Padula, F., Ntogramatzidis, L., Garone, E.
MIMO tracking control of LTI systems: A geometric approach
(2019) 126, pp. 8-20. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062462008&doi=10.1016%2fj.sysconle.2019.02.003&partnerID=40&md5=b2594de40e4df156f7dbed791c994181
AFFILIATIONS: Department of Mathematics and Statistics, Curtin University, Perth, Australia; 
Department SAAS, Université Libre de Bruxelles, Brussels, Belgium
ABSTRACT: This paper addresses the tracking problem of constant references for multiple-input multiple-output linear time-invariant systems. We provide necessary and sufficient conditions for the solvability of the problem under the minimal set of assumptions that guarantee the well-posedness of every control problem requiring stability. Our approach allows to solve tracking problems for systems which are possibly nonright-invertible, simply (not asymptotically) stabilizable, and possibly with invariant zeros at the origin. Our methodology is constructive and results in the design of a stabilizing feedback matrix and a feedforward signal which solve the problem. © 2019 Elsevier B.V.

Li, Y., Chen, C.S., Wong, W.S.
Power control for multi-sensor remote state estimation over interference channel
(2019) 126, pp. 1-7. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062154353&doi=10.1016%2fj.sysconle.2019.01.007&partnerID=40&md5=ebccef14598f6cb19f2bb555e936e241
AFFILIATIONS: State Key Laboratory of Synthetical Automation for Process Industries, Northeastern University, Shenyang, 110004, China; 
Mathematics of Dynamic Systems, Nokia Bell Labs, Nozay, 91620, France; 
Department of Information Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
ABSTRACT: In this paper, we investigate a multi-sensor transmission power control problem for remote state estimation over interference channel. There are N sensors measuring a dynamic process at the same time and the sensors send their measurements to a remote state estimator for data fusion through a shared packet-dropping channel, where the packet drop rate is related to their transmission power. Traditionally, the transmission power design problem does not consider the situation where the communication process of each sensor may be affected by the interference power from other sensors. To address this issue, we consider a signal-to-interference-and-noise-ratio (SINR)-based channel model to describe the simultaneous transmission process and formulate such a power control problem into a stochastic programming problem. A certainty-equivalent problem is proposed to tackle the difficulties brought by the implicit expression of the objective function and the non-linearity/non-convexity of the original problem. By utilizing an approximated SINR quantity, a sub-optimal solution to the optimal power control problem is also obtained by solving a standard convex optimization problem. An event-based power controller, a heuristic power controller, and the power control problem with a threshold-based channel model are also discussed. Performance analysis of the sub-optimal controller and the comparison with other power controllers are demonstrated to show the effectiveness of our methods. © 2019 Elsevier B.V.

Zheng, Y., Zhao, Q., Ma, J., Wang, L.
Second-order consensus of hybrid multi-agent systems
(2019) 125, pp. 51-58. Cited 24 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061834716&doi=10.1016%2fj.sysconle.2019.01.009&partnerID=40&md5=6f0122c043267b5539827a0a44d5d8ef
AFFILIATIONS: Key Laboratory of Electronic Equipment Structure Design of Ministry of Education, School of Mechano-electronic Engineering, Xidian University, Xi'an, 710071, China; 
Center for Complex Systems, School of Mechano-electronic Engineering, Xidian University, Xi'an, 710071, China; 
School of Mathematics and Statistics, Ningxia University, Yinchuan, 750021, China; 
Center for Systems and Control, College of Engineering, Peking University, Beijing, 100871, China
ABSTRACT: It is well known that heterogeneity is an important feature of multi-agent systems. In this paper, we consider the second-order consensus of hybrid multi-agent system which is composed of continuous-time and discrete-time dynamic agents. By analyzing the interactive mode of different dynamic agents, two kinds of effective consensus protocols are proposed for the hybrid multi-agent system. The analysis tool developed in this paper is based on algebraic graph theory and system transformation method. Some necessary and sufficient conditions are established for solving the second-order consensus of hybrid multi-agent system. Two examples are also provided to demonstrate the effectiveness of the theoretical results. © 2019 Elsevier B.V.

Wei, Q.
Mean–semivariance optimality for continuous-time Markov decision processes
(2019) 125, pp. 67-74. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061809995&doi=10.1016%2fj.sysconle.2019.02.001&partnerID=40&md5=dcae3bee7d0387274361ddd167cdd9b9
AFFILIATIONS: School of Economics and Finance, Huaqiao University, Quanzhou, 362021, China
ABSTRACT: In this paper we study the mean–semivariance problem for continuous-time Markov decision processes with Borel state and action spaces and unbounded cost and transition rates. The optimality criterion is to minimize the semivariance of the discounted total cost over the set of all policies satisfying the constraint that the mean of the discounted total cost is equal to a given function. Under reasonable conditions, we show that the semivariance optimal value function is a solution to the optimality equation of the mean–semivariance criterion by an iteration approach. Moreover, we obtain the existence of mean–semivariance optimal policies from the optimality equation. Furthermore, we give a value iteration algorithm to compute approximately an optimal policy and the optimal value, and analyze the convergence of the algorithm. © 2019 Elsevier B.V.

Kanellopoulos, A., Vamvoudakis, K.G.
Non-equilibrium dynamic games and cyber–physical security: A cognitive hierarchy approach
(2019) 125, pp. 59-66. Cited 9 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061785110&doi=10.1016%2fj.sysconle.2019.01.008&partnerID=40&md5=a0d7c84e6694d17f92e6e1542f8ddb39
AFFILIATIONS: Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA  30332, United States
ABSTRACT: This paper considers the problem of identifying the cognitive capabilities of agents having bounded rationality in a cyber–physical system operating in an uncertain and/or adversarial environment. To categorize the adversaries, we introduce an iterative method of optimal responses that determine the policy of an agent with a level-k intelligence. We then, formulate a model-free learning algorithm to train the different intelligence levels without any knowledge about the physics of the system while quantifying the optimality. By sequential interaction with the adversaries, we learn the true distribution of their levels. Rigorous mathematical proofs show stability of the equilibrium point of the closed-loop system and convergence to the Nash equilibrium as the level of intelligence tends to infinity. Finally, simulation results show the efficacy of our proposed approach. © 2019 Elsevier B.V.

Arabi, E., Yucelen, T., Gruenwald, B.C., Fravolini, M., Balakrishnan, S., Nguyen, N.T.
A neuroadaptive architecture for model reference control of uncertain dynamical systems with performance guarantees
(2019) 125, pp. 37-44. Cited 15 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061543733&doi=10.1016%2fj.sysconle.2019.01.005&partnerID=40&md5=08f0932ba571479b16f39b427f28d84f
AFFILIATIONS: Department of Mechanical Engineering, University of South Florida, Tampa, FL, United States; 
Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO, United States; 
Department of Electronic and Information Engineering, Perugia University, Perugia, Italy; 
NASA Ames Research Center, Moffett FieldCA, United States
ABSTRACT: Neuroadaptive control systems have the capability to approximate unstructured system uncertainties on a given compact set using neural networks. Yet, a challenge in their design is to guarantee the closed-loop system trajectories stay in this set such that the universal function approximation property is satisfied and the overall system stability is achieved. To address this challenge, we present and analyze a new neuroadaptive architecture in this paper for model reference control of uncertain dynamical systems with strict performance guarantees. Specifically, the proposed architecture is predicated on a novel set-theoretic framework and has the capability to keep the closed-loop system trajectories within an a-priori, user-defined compact set without violating the universal function approximation property. A transport aircraft example is also given to complement the presented theoretical results. © 2019 Elsevier B.V.

Khan, G.D., Chen, Z., Meng, H.
Output synchronization of nonlinear heterogeneous multi-agent systems with switching networks
(2019) 125, pp. 45-50. Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061534893&doi=10.1016%2fj.sysconle.2019.01.006&partnerID=40&md5=b72b6eb7e4328a1c7ecbb28164d8cf9d
AFFILIATIONS: School of Electrical Engineering and Computing, The University of Newcastle, NSW, Callaghan  2308, Australia
ABSTRACT: In this paper, the output synchronization problem for nonlinear heterogeneous multi-agent systems is studied in a switching network of time-varying directed graphs. The scenario under consideration is complicated in the sense that none of the graphs is assumed to be connected (containing a spanning tree). Within a two-step framework for output synchronization of nonlinear heterogeneous multi-agent systems, the main technical challenge lies in the existence of switching strategies under which a class of switched unstable subsystems subject to external perturbation can be input-to-state stabilized. A controller design approach is proposed in this paper for guarantee of the existence of such switching strategies. © 2019 Elsevier B.V.

Yu, Y., Pei, H.-L., Xu, C.-Z.
Identification of water depth and velocity potential for water waves
(2019) 125, pp. 29-36. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061042055&doi=10.1016%2fj.sysconle.2018.12.010&partnerID=40&md5=6659db1224adb83be6af4f983d5a0966
AFFILIATIONS: Key Laboratory of Autonomous Systems and Networked Control, Ministry of Education, Unmanned Aerial Vehicle Systems Engineering Technology Research Center of Guangdong, South China University of Technology, Guangzhou, 510640, China; 
LAGEP, Batiment CPE, University Claude Bernard-Lyon 1, 43 Boulevard du 11 Novembre 1918, Villeurbanne Cedex, F-69622, France
ABSTRACT: The purpose of this paper is to investigate the identification of the water depth and the water velocity potential in a coastal region by using the linearized water wave equation (LWWE). Existence and uniqueness of the solutions to the partial differential equation LWWE are shown by using the semigroup theory. Moreover the analytical solution is found by the separation of variables method. We assume that the surface wave elevation is measurable. We like to recover the water depth and the water velocity potential from the measurement. This identification problem is shown to be well-posed by proving the parameters’ identifiability by the surface elevation. Based on the classical gradient descent method we elaborate an identification algorithm to recover simultaneously both the water depth and the velocity potential. Numerical simulations are carried out to illustrate effectiveness of the algorithm. © 2019 Elsevier B.V.

Casini, M., Criscuoli, M., Garulli, A.
A discrete-time pursuit–evasion game in convex polygonal environments
(2019) 125, pp. 22-28. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061032346&doi=10.1016%2fj.sysconle.2018.12.008&partnerID=40&md5=bb2b235ce1c5eb050e57ae7be62e770f
AFFILIATIONS: Dipartimento di Ingegneria dell'Informazione e Scienze Matematiche, Università di Siena, Via Roma 56, Siena, 53100, Italy
ABSTRACT: This paper studies a discrete-time pursuit–evasiongame within a convex polygonal environment. Building on solutions of the classic lion-and-man problem, two strategies are proposed for the pursuer, which guarantee exact capture in finite time and provide upper bounds on the time-to-capture at each move of the game. A numerical procedure for updating the so-called center of the game, which is instrumental for computing the lion's move, is devised. Numerical simulations show that optimizing the center position, with respect to a suitable cost function taking into account the structure of the environment, allows one to remarkably reduce the number of moves required to capture the evader. © 2019 Elsevier B.V.

Buscarino, A., Fortuna, L., Frasca, M.
Nyquist plots under frequency transformations
(2019) 125, pp. 16-21. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060954594&doi=10.1016%2fj.sysconle.2019.01.004&partnerID=40&md5=37b047932305c04e9406ab7a1f85dbb5
AFFILIATIONS: Dipartimento di Ingegneria Elettrica Elettronica e Informatica, University of Catania, Italy; CNR-IASI, Italian National Research Council - Institute for Systems Analysis and Computer Science “A. Ruberti” Rome, 00185, Italy
ABSTRACT: The relevance of odd, and in particular loss-less, frequency transformations is well established in analog filter design. A loss-less frequency transformation s←F(s), in fact, allows to design multi-bandpass multi-bandstop filters as transformed systems G̃(s)=G(F(s)) from an original prototype lowpass filter G(s), by properly selecting F(s). In this paper the invariance of the shape of the Nyquist plot for linear time-invariant continuous-time systems under a class of odd frequency transformations is proved. This result allows to determine closed-loop stability conditions for this class of transformed systems on the basis of the Nyquist's criterion referred to the original, lower order, system. © 2019 Elsevier B.V.

Befekadu, G.K.
Large deviation principle for dynamical systems coupled with diffusion–transmutation processes
(2019) 125, pp. 9-15. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060947380&doi=10.1016%2fj.sysconle.2019.01.003&partnerID=40&md5=017d94266fc49cf6938d1903d61d9c57
AFFILIATIONS: Department of Electrical & Computer Engineering, Morgan State University, 1700 E. Cold Spring Lane, Schaefer Engr. Bldg. 331, Baltimore, MD  21251, United States
ABSTRACT: In this paper, we introduce a mathematical apparatus that is relevant for understanding a dynamical system with small random perturbations and coupled with the so-called transmutation process — where the latter jumps from one mode to another, and thus modifying the dynamics of the system. In particular, we study the exit problem, i.e., an asymptotic estimate for the exit probabilities with which the corresponding processes exit from a given bounded open domain, and then formally prove a large deviation principle for the exit position joint with the type occupation times as the random perturbation vanishes. Moreover, under certain conditions, we also determine the exit place and the type of distribution at the exit time and, as a consequence of this, such information also give the limit of the Dirichlet problem for the corresponding partial differential equation systems with a vanishing small parameter. © 2019 Elsevier B.V.

Vu, N.M.T., Lefèvre, L., Maschke, B.
Geometric spatial reduction for port-Hamiltonian systems
(2019) 125, pp. 1-8. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060945048&doi=10.1016%2fj.sysconle.2019.01.002&partnerID=40&md5=f7a600e3dc90d1f8537c8434322a20b9
AFFILIATIONS: Univ. Grenoble Alpes, Grenoble INP, LCIS, Valence, 26000, France; 
Laboratoire d'Automatique et Génie des Procédés, Université Claude Bernard Lyon1, Lyon, France
ABSTRACT: A geometric spatial reduction method is presented in this paper. It applies to port Hamiltonian models for open systems of balance equations. It is based on projections which make use of the spatial symmetries in the model and preserve the “natural” power pairing. Reductions from 3D to 2D and 1D domains are illustrated via two examples. The first one is a vibro-acoustic system with cylindrical symmetry where 3D–2D reduction is applied. The second one is the system of two coupled parabolic equations describing the poloidal magnetic flux diffusion and heat radial transport in tokamak reactors. In this latter example the toroidal symmetry allows to perform a 3D–1D reduction. Obtained reduced models are compared with the common control models found in the literature for these two examples. © 2019 Elsevier B.V.

Jiang, Y., Liu, C., Zhang, Q., Zhao, T.
Two side observer design for singular distributed parameter systems
(2019) 124, pp. 112-120. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060352849&doi=10.1016%2fj.sysconle.2019.01.001&partnerID=40&md5=0d9cb4b99f131b95a2ded0304d63fa9f
AFFILIATIONS: Institute of System Science, Northeastern University, Shenyang, 110004, China; 
State Key Laboratory of Integrated Automation of Process Industry, Shenyang, 110004, China; 
School of Mathematics and Statistics, Northeastern University at Qinhuangdao, Qinhuangdao, 066004, China
ABSTRACT: We consider the problem of state observation for singular distributed parameter system (SDPS) with singular derivative term. For the nonhomogeneous boundary, we define the SDPS observer and investigate the exponential stability of the error SDPS with SDPS theory. Considering the uncertainty, the robustness of proposed SDPS observer is investigated by singular system theory. As an application, the state observation of distributed building automatic temperature system is considered. © 2019 Elsevier B.V.

Liu, Y., Wang, L., Lu, J., Cao, J.
Sampled-data stabilization of probabilistic Boolean control networks
(2019) 124, pp. 106-111. Cited 16 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060209200&doi=10.1016%2fj.sysconle.2018.12.012&partnerID=40&md5=44addd533217c31f0afb3b7c73ff8459
AFFILIATIONS: Jiangsu Provincial Key Laboratory of Networked Collective Intelligence, School of Mathematics, Southeast University, Nanjing, 210096, China; 
Department of Mathematics, Zhejiang Normal University, Jinhua, 321004, China; 
School of Electrical Engineering, Nantong University, Nantong, 226000, China
ABSTRACT: Probabilistic Boolean networks (PBNs) are discrete-time systems composed of a family of Boolean networks (BNs), between which the PBN switches in a stochastic fashion. In this paper, we address the stabilization of probabilistic Boolean control networks (PBCNs) via a sampled-data state feedback controller (SDSFC). Based on the algebraic representation of logical functions, a necessary and sufficient condition is derived for the existence of SDSFCs for the global stabilization of PBCNs, and the controller is further designed. A biological example is presented to illustrate the effectiveness of the obtained results. © 2019 Elsevier B.V.

Tan, A.H., Godfrey, K.R.
Direct synthesis signal sets for multi-input system identification
(2019) 124, pp. 92-98. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059843674&doi=10.1016%2fj.sysconle.2018.12.009&partnerID=40&md5=356d0154ab7d535b9605679cf83eb5f7
AFFILIATIONS: Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya, 63100, Malaysia; 
School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom
ABSTRACT: The design of correlated direct synthesis signal sets for the identification of multi-input systems is considered. These signals possess favorable characteristics for identification tests. Firstly, they do not contain power at harmonic multiples of two and three; this allows the reduction of the effects of nonlinear distortion on the linear estimate. Secondly, the signals are ternary which simplifies physical implementation. Existing results on the properties of individual direct synthesis signals are extended to the investigation of pairs of signals. The peak crosscorrelations are derived and it is shown that they depend on the generating signal class. The theoretical results provide a basis for the selection of signal sets with small peak crosscorrelations; this improves the estimation accuracy in identification tests. An important advantage of the proposed design over the conventional design using uncorrelated signal sets is the greater uniformity in the estimation accuracy of the different channels in the multi-input system. This is achieved by having all the signals in a set sharing the same power spectrum. © 2018 Elsevier B.V.

Gray, W.S., Venkatesh, G.S.
Relative degree of interconnected SISO nonlinear control systems
(2019) 124, pp. 99-105. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059840262&doi=10.1016%2fj.sysconle.2018.12.011&partnerID=40&md5=4d9995e8d78d18fdf92c28ff8b264d83
AFFILIATIONS: Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA  23529, United States
ABSTRACT: The concept of relative degree plays an important role in nonlinear control theory. It provides, for example, a necessary and sufficient condition for the existence of a feedback linearizing control law for a single-input, single-output (SISO) input-affine nonlinear state space system. It also gives a sufficient condition under which a left inverse exists. In applications it is common for systems to be composed of smaller interconnected subsystems. It is known that various feedback structures preserve relative degree, but it is largely unknown how to compute the relative degree of interconnected systems using only their properties. So the goal of this paper is to determine the relative degree of two nonlinear control systems interconnected in a variety of different ways. A collection of illustrative examples is given. © 2018 Elsevier B.V.

Fridman, E., Shaikhet, L.
Simple LMIs for stability of stochastic systems with delay term given by Stieltjes integral or with stabilizing delay
(2019) 124, pp. 83-91. Cited 15 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059457231&doi=10.1016%2fj.sysconle.2018.12.007&partnerID=40&md5=e60b09ccab7f4c3e368fecf9472a3d5c
AFFILIATIONS: School of Electrical Engineering, Tel-Aviv University69978, Tel-Aviv, Israel
ABSTRACT: This paper introduces stability conditions in the form of linear matrix inequalities (LMIs) for general linear retarded systems with a delay term described by Stieltjes integral. The derived LMIs provide in the unified form conditions for both discrete and distributed delays. Two Lyapunov-based methods for the asymptotic mean square stability of stochastic linear time-invariant systems are presented. The first one employs neutral type model transformation and augmented Lyapunov functionals. Differently from the existing LMI stability conditions based on neutral type transformation, the proposed conditions do not require the stability of the corresponding integral equations. Moreover, it is shown that in the simplest existing LMIs based on non-augmented Lyapunov functionals, the stability analysis of the integral equation can be omitted. The second method is based on a stochastic extension of simple Lyapunov functionals depending on the state derivative. The same two methods are further applied to delay-induced stability analysis of stochastic vector second-order systems, simplifying the recent results via neutral type transformation and leading to new conditions for stochastic systems via the second method. Numerical examples give comparison of results via different methods. © 2018 Elsevier B.V.

Zhai, C., Xiao, G., Chen, M.Z.Q.
Distributed sweep coverage algorithm of multi-agent systems using workload memory
(2019) 124, pp. 75-82. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059334949&doi=10.1016%2fj.sysconle.2018.12.006&partnerID=40&md5=215e57043eb2ea075d29d7b5de67aecb
AFFILIATIONS: Institute of Catastrophe Risk Management and School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore; 
Future Resilient Systems, Singapore-ETH Centre, 1 Create Way, CREATE Tower, Singapore, 138602, Singapore; 
School of Automation, Nanjing University of Science and Technology, Nanjing, Jiangsu, 210094, China
ABSTRACT: This paper addresses the sweep coverage problem of multi-agent systems in the uncertain environment. A novel formulation of distributed sweep coverage is proposed for multiple agents to cooperatively complete the workload in the coverage region. To save the sweep time, each agent takes part in partitioning the whole region using its partition bar while sweeping its own subregion at a constant rate. The trajectories of partition bars form the boundaries between adjacent subregions. Essentially, the partition operation is carried out by means of workload memory in order to balance the workload in each subregion. In particular, it is proved that the dynamics of multi-agent system is input-to-state stable. Theoretical analysis is conducted to obtain the upper bound of the error between the actual sweep time and the optimal sweep time. Moreover, a sufficient condition is provided to avoid the collision of partition bars during the partition. Finally, numerical simulations demonstrate the effectiveness of the proposed approach. © 2018 Elsevier B.V.

Souza, J.A.
Sufficient conditions for dispersiveness of invariant control affine systems on the Heisenberg group
(2019) 124, pp. 68-74. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059267160&doi=10.1016%2fj.sysconle.2018.12.004&partnerID=40&md5=fe9cad356856c13c4239dedc9e5c69f2
AFFILIATIONS: Departamento de Matemática Universidade Estadual de Maringá, Maringá-PR, 87020-900, Brazil
ABSTRACT: The notion of dispersiveness in control systems is characterized by the absence of recursive properties. It implies uncontrollability and Poisson instability. The present manuscript exhibits sufficient conditions for an invariant control affine system on the Heisenberg group to be dispersive. For a control affine system with pairwise commutative matrices, the condition for dispersiveness is the drift not depend linearly on the controlled matrices. For a general control affine system, with bounded control range, the condition is the drift not be an affine transformation of the controlled matrices. These results consequently yield necessary conditions for controllability. © 2018 Elsevier B.V.

Chen, G., Yang, Q.
Distributed constrained optimization for multi-agent networks with nonsmooth objective functions
(2019) 124, pp. 60-67. Cited 9 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059173276&doi=10.1016%2fj.sysconle.2018.12.005&partnerID=40&md5=2f4355d610a668fc2ead9e305e1f7394
AFFILIATIONS: The key Laboratory of Dependable Service Computing in Cyber Physical Society, Ministry of Education, Chongqing University, Chongqing, 400044, PR China; School of Automation, Chongqing University, Chongqing, 400044, PR China
ABSTRACT: This paper investigates the distributed constrained optimization problem in multi-agent systems, where agents cooperatively minimize an objective function being the sum of each agent's objective function while meeting equality and inequality constraints. By virtue of nonsmooth analysis and graph theory, a novel distributed continuous-time algorithm is proposed to solve such a kind of optimization problems. Different from existing continuous-time results relying on the differentiability or strict (strong) convexity of local objective functions, the proposed approach considers more general local objective functions which are only convex and not necessarily smooth. In addition, the proposed approach considers more general local constraints, not just box constraints considered in most existing studies. The optimality of the proposed algorithm is ensured under certain initial condition. Based on set-valued LaSalle invariance principle, the convergence of the proposed scheme is rigorously proved. Finally, simulation examples are applied to validate the effectiveness of the proposed algorithm. © 2018 Elsevier B.V.

Embree, M.
Unstable modes in projection-based reduced-order models: How many can there be, and what do they tell you?
(2019) 124, pp. 49-59. 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059038947&doi=10.1016%2fj.sysconle.2018.11.010&partnerID=40&md5=21f5d05a8b54d155bfd8e32b1ad75823
AFFILIATIONS: Department of Mathematics and Computational Modeling and Data Analytics Division, Academy of Integrated Science, Virginia Tech, Blacksburg, VA  24061, United States
ABSTRACT: Projection methods provide an appealing way to construct reduced-order models of large-scale linear dynamical systems: they are intuitively motivated and fairly easy to compute. Unfortunately, the resulting reduced models need not inherit the stability of the original system. How many unstable modes can these reduced models have? This note investigates this question, using theory originally motivated by iterative methods for linear algebraic systems and eigenvalue problems, and illustrating the theory with a number of small examples. From these results follow rigorous upper bounds on the number of unstable modes in reduced models generated via orthogonal projection, for both continuous- and discrete-time systems. Can anything be learned from the unstable modes in reduced-order models? Several examples illustrate how such instability can helpfully signal transient growth in the original system. © 2018 Elsevier B.V.

Dimassi, H., Winkin, J.J., Vande Wouwer, A.
A sliding mode observer for a linear reaction–convection–diffusion equation with disturbances
(2019) 124, pp. 40-48. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058955658&doi=10.1016%2fj.sysconle.2018.11.014&partnerID=40&md5=5f6217838f98a787985199557ab70842
AFFILIATIONS: University of Sousse, High Institute of applied sciences and technology of Sousse, Cité Taffala (Ibn Khaldoun), Sousse, 4003, Tunisia; 
University of Namur, naXys and Department of Mathematics, 8 Rempart de la Vierge, Namur, B-5000, Belgium; 
University of Mons, Laboratoire d'Automatique 31, Boulevard Dolez, Mons, B-7000, Belgium
ABSTRACT: A sliding mode observer is designed and analyzed for a linear reaction–convection–diffusion equation subject to external disturbances. Based on a discontinuous input, the proposed observer ensures both state estimation and disturbance rejection using only one boundary measurement. An appropriate Lyapunov function is used to prove the asymptotic convergence of the observation error. The performance of the proposed observer is illustrated by some numerical simulation results. © 2018 Elsevier B.V.

Hoshino, K., Nishimura, Y., Yamashita, Y.
Convergence rates of stochastic homogeneous systems
(2019) 124, pp. 33-39. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058947932&doi=10.1016%2fj.sysconle.2018.11.013&partnerID=40&md5=25786712685f43f5a119fcd9d09bb354
AFFILIATIONS: Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara-city, Kanagawa, Japan; 
Kagoshima University, 1-21-40 Korimoto, Kagoshima-city, Kagoshima, Japan; 
Hokkaido University, N14W9, Sapporo, Hokkaido, Japan
ABSTRACT: This study considers stochastic homogeneous systems and focuses on the relation between their homogeneity and the convergence rates. We give a definition of stochastic homogeneous systems with weighted dilations as an extension of deterministic homogeneous systems. We also introduce the stability properties, such as exponential, rational, and finite-time stability with respect to homogeneous norms. As a main result, we show that their homogeneous degrees imply the convergence rates of asymptotically stable systems. Based on the result, we also deal with the stabilization of stochastic homogeneous control systems. We provide a design method of homogeneous feedback laws with homogeneous control Lyapunov functions, which guarantees the convergence rates. © 2018 Elsevier B.V.

Kvasnica, M., Bakaráč, P., Klaučo, M.
Complexity reduction in explicit MPC: A reachability approach
(2019) 124, pp. 19-26. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058812267&doi=10.1016%2fj.sysconle.2018.12.002&partnerID=40&md5=2bb59989612314bc29591a6af3407e97
AFFILIATIONS: Slovak University of Technology in Bratislava, Slovakia
ABSTRACT: We propose to reduce the complexity of explicit MPC controllers by removing regions that will never be reached during the closed-loop evolution from a given set of initial conditions. The identification of such regions is done by solving a reachability analysis problem, formulated as a mixed-integer feasibility program. The procedure directly accounts for possible discrepancies between the prediction model and the actual plant dynamics by, among other things, considering a case where state measurements are affected by an unknown, but bounded measurement noise. The result of the procedure is the reduction of explicit MPC complexity without sacrificing closed-loop performance. © 2018 Elsevier B.V.

Cortez, K.L., Rosenblueth, J.F.
The broken link between normality and regularity in the calculus of variations
(2019) 124, pp. 27-32. Cited 3 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058805614&doi=10.1016%2fj.sysconle.2018.12.003&partnerID=40&md5=520904e52a7f1ca3e6ec6fafece74b8b
AFFILIATIONS: IIMAS, Universidad Nacional Autónoma de México, Apartado Postal 20-126DF 01000, Mexico
ABSTRACT: There is a link between two well-known constraint qualifications in nonlinear programming, namely, normality (implying a positive cost multiplier) and regularity (the tangent cone and the set of tangential constraints coincide): the former implies the latter. This fact has been crucial and a cornerstone for establishing second order conditions in terms of tangential constraints. For problems in the calculus of variations involving equality and inequality constraints, one can derive second order conditions in terms of the tangent cone and state a conjecture, based on tangential constraints, which is the counterpart of that in nonlinear programming. However, as we show in this paper, the link mentioned above between normality and regularity, in the infinite dimensional case, may fail to hold. © 2018 Elsevier B.V.

Naghnaeian, M., Hirzallah, N.H., Voulgaris, P.G.
Security via multirate control in cyber–physical systems
(2019) 124, pp. 12-18. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058679725&doi=10.1016%2fj.sysconle.2018.12.001&partnerID=40&md5=609c8994fba29498ecb39fdf6a435ab2
AFFILIATIONS: Mechanical Science and Engineering Department, University of Illinois, Urbana, IL, United States; 
Electrical and Computer Engineering Department, University of Illinois, Urbana, IL, United States; 
Aerospace Engineering Department and the Coordinated Science Laboratory, University of Illinois, Urbana, IL, United States
ABSTRACT: We consider malicious attacks on actuators and sensors of a feedback system which can be modeled as additive, possibly unbounded, disturbances at the digital (cyber) part of the feedback loop. We precisely characterize the role of the unstable poles and zeros of the system in the ability to detect unbounded stealthy attacks in the context of the sampled data implementation of the controller in feedback with the continuous (physical) plant. We show that, if there is a single sensor that is guaranteed to be secure and the plant is observable from that sensor, then there exists a class of multirate sampled data controllers that ensures that all attacks remain detectable. These dual rate controllers are sampling the output faster than the zero order hold rate that operates on the control input and as such, they can even provide better nominal performance than single rate, at the price of higher sampling of the continuous output. © 2018 Elsevier B.V.

Chen, X., Xu, H., Feng, M.
H2 performance analysis and H2 distributed control design for systems interconnected over an arbitrary graph
(2019) 124, pp. 1-11. Cited 9 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058517232&doi=10.1016%2fj.sysconle.2018.11.011&partnerID=40&md5=50f0f0af9f44424fa763cd04650f3788
AFFILIATIONS: School of Science, Nanjing University of Science and Technology, Nanjing, Jiangsu, 210094, China
ABSTRACT: This paper is concerned with the H2 performance analysis and H2 distributed controller design problem of the interconnected system which consists of heterogeneous subsystems connected arbitrarily over an undirected graph. The classical definition of the H2 performance of one-dimensional temporal system is extended to the interconnected system for the first time. A sufficient condition for the well-posedness, asymptotic stability and evaluating the H2 performance of the interconnected system is presented in this paper and this condition is in terms of individual subsystems. Based on this condition, a sufficient condition is given for the existence of the H2 distributed output-feedback controller and a constructive method is then presented for the design of optimal H2 distributed controller. A practical example is included to illustrate the applicability and effectiveness of the proposed H2 distributed control design methodology in this paper. © 2018 Elsevier B.V.

Slyn'ko, V.I., Tunç, O., Bivziuk, V.O.
Application of commutator calculus to the study of linear impulsive systems
(2019) 123, pp. 160-165. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058679004&doi=10.1016%2fj.sysconle.2018.10.015&partnerID=40&md5=0f664a8bce456f74725c6b074f8e551e
AFFILIATIONS: Stability of Processes Department, S.P. Timoshenko Institute of Mechanics of NAS of Ukraine, Nesterov str. 3, 03680, MSP, Kiev 57, Ukraine; 
Department of Mathematics, Faculty of Sciences, Van Yuzuncu Yil University -Campus, Van-Turkey, 65080, Turkey; 
Department of Algebra and Mathematical Analysis, Bohdan Khmelnytsky National University of Cherkasy, Cherkasy, Ukraine
ABSTRACT: In this paper, the formulas of commutator calculus are applied to the investigation of the stability of linear impulsive differential equations. It is assumed that the moments of impulse action satisfy the average dwell-time (ADT) condition. Sufficient conditions for the asymptotic stability of linear impulsive differential equations in a Banach space are obtained. In the Hilbert space, the stability of the original linear differential equation is reduced to the investigation of a linear differential equation with equidistant moments of impulse action and perturbed discrete dynamics. This reduction simplifies the application of Lyapunov's direct method and the construction of Lyapunov functions. We give examples in the spaces R2 and X=C[0,l] to illustrate the effectiveness of results obtained. Finally, a sufficient generality of the obtained results on the dynamic properties of linear operators of the linear impulsive differential equation is established. © 2018 Elsevier B.V.

Bitar, E., Khargonekar, P., Poolla, K.
On the marginal value of electricity storage
(2019) 123, pp. 151-159. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058467764&doi=10.1016%2fj.sysconle.2018.09.007&partnerID=40&md5=224797b3786e1c4a88b8dee618fdbd9a
AFFILIATIONS: School of Electrical and Computer Engineering, Cornell University, Ithaca, NY  14853, United States; 
Department of Electrical Engineering and Computer Science, University of California, Irvine, CA  92697, United States; 
Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA  94704, United States
ABSTRACT: We investigate the problem of characterizing the economic value of energy storage capacity to a wind power producer (WPP) that sells its energy in a conventional two-settlement electricity market. The WPP can offer a forward contract to supply power in the day-ahead market, subject to financial penalties for imbalances between the contracted power and the power that is delivered in real-time. We consider the setting in which the WPP has access to a co-located energy storage system, and can thus reshape its wind power production subject to its storage capacity constraints. Modeling wind power as a random process, we show that the problem of determining optimal forward contract offerings—given recourse with storage—is convex. We further establish that the maximum expected profit is concave and non-decreasing in the energy storage capacity, which reveals that the greatest marginal benefit from energy storage is derived from initial investment in small storage capacity. We provide a characterization of the marginal value of small energy storage capacity to the WPP. The formulae we derive shed light on the relationship between the value of storage and certain statistical measures of variability in the underlying wind power process. © 2018 Elsevier B.V.

Auriol, J., Di Meglio, F.
An explicit mapping from linear first order hyperbolic PDEs to difference systems
(2019) 123, pp. 144-150. Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058366662&doi=10.1016%2fj.sysconle.2018.11.012&partnerID=40&md5=86bace13364c5065994022a47ca84379
AFFILIATIONS: MINES ParisTech, PSL Research University, CAS—Centre automatique et systèmes, 60 bd St Michel 75006 Paris, France
ABSTRACT: In this paper, we prove that the space generated by the solutions of a general class of first-order hyperbolic PDEs is isomorphic to the space generated by the solutions of a difference equation with distributed delays. This difference equation is obtained using a backstepping approach (combining a Volterra transformation of the second kind and an invertible Fredholm transformation) and the method of characteristics. Moreover, we prove that the stability properties are equivalent between the two systems. An important by-product is the design of a delay-robust stabilizing control law. © 2018 Elsevier B.V.

Zhao, D., Yan, S., Matsushita, S., Xu, L.
An approach to multidimensional Fornasini–Marchesini state-space model realization w.r.t. columns of transfer matrices
(2019) 123, pp. 116-123. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058186035&doi=10.1016%2fj.sysconle.2018.11.008&partnerID=40&md5=65bba5c97b8d37bc9a3f3613428c2b01
AFFILIATIONS: Department of Intelligent Mechatronics, Akita Prefectural University, Akita, Japan; 
School of Information Science and Engineering, Lanzhou University, Lanzhou, China
ABSTRACT: This paper proposes a new approach that can generate a low-order Fornasini–Marchesini (F–M) model realization for a given n-D system by taking into account the column structural properties of its transfer matrix. Specifically, a new necessary and sufficient realization condition is developed for the F–M model realization based on a resolvent invariant space associated with the Gleason's problem specified by the given n-D transfer matrix. Then, a new constructive procedure with respect to the columns of a given transfer matrix is proposed for constructing a low-order F–M model realization. In order to apply this procedure to the multiple-input multiple-output case more effectively, an improved realization procedure based on a polynomial description is also proposed. It will be shown, by both algorithmic analysis and illustrative examples, that for a transfer matrix having more rows than columns the proposed realization approach may generate a much lower realization order than the existing one with respect to the rows of a given n-D transfer matrix recently developed by Cheng et al. Particularly, for a given scalar transfer function, our new approach always generates an F–M model realization with lower order than the existing methods. © 2018 Elsevier B.V.

Mazenc, F., Burlion, L., Malisoff, M.
Backstepping design for output feedback stabilization for a class of uncertain systems
(2019) 123, pp. 134-143. Cited 2 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058183306&doi=10.1016%2fj.sysconle.2018.11.007&partnerID=40&md5=332cf1bed94b822cbbf78c28b4799053
AFFILIATIONS: Laboratoire des signaux et systemes, L2S-CNRS-CentraleSupelec, 3 rue Joliot-Curie, Gif sur Yvette cedex, 91192, France; 
Onera - The French Aerospace Lab, Toulouse, F-31055, France; 
Department of Mathematics, Louisiana State University, Baton Rouge, LA  70803-4918, United States
ABSTRACT: We construct bounded globally asymptotically stabilizing output feedbacks for a family of nonlinear systems, using a dynamic extension and a converging-input-converging-state assumption. We provide sufficient conditions for this assumption to hold, in terms of Lyapunov functions. The novelty is that our construction provides formulas for the control bounds while allowing uncertainties that prevent the use of classical backstepping, and cases where only part of the state variable is available for measurement, without requiring the time lagged states in the feedback control that were required in the artificial delays approach. We illustrate the relevance of our work to engineering in an application to a single-link direct-drive manipulator. © 2018 Elsevier B.V.

Zahedi, Z., Arefi, M.M., Khayatian, A.
Fast convergence to Nash equilibria without steady-state oscillation
(2019) 123, pp. 124-133. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058145110&doi=10.1016%2fj.sysconle.2018.11.009&partnerID=40&md5=0f781f1466d820088cf55b67f96a1df2
AFFILIATIONS: Department of Power and Control Engineering, School of Electrical and Computer Engineering, Shiraz University, Shiraz, Iran
ABSTRACT: The problem of fast convergence to Nash equilibrium without steady state oscillation in static non-cooperative games with N players is considered in this paper. In this regard, players can generate their actions to achieve Nash equilibrium only by measuring their own payoff values, which means that the players do not need any information about the details of payoff function or other players’ actions. Additionally, in contrast to the most classical extremum seeking algorithms, this algorithm can converge to Nash equilibria without steady state oscillation and faster, because the amplitude of excitation sinusoidal signal in the conventional extremum seeking is adjusted to converge to zero, so the deleterious effects of steady state oscillation will be eliminated. Moreover, since each player can possess a dynamic, the actions are filtered before applying to the payoff function, which can make this algorithm appealing to many applications such as mobile sensor networks. In addition, the details of convergence to Nash equilibria are provided. Finally, we illustrate the application of this algorithm to solve the formation control problem of non-holonomic unicycles, and evasion of jammer attacks on unmanned autonomous vehicles (UAVs), which clearly shows the effectiveness and superiority of this algorithm through simulation results. © 2018 Elsevier B.V.

Cacace, F., Conte, F., d'Angelo, M., Germani, A.
Feedback polynomial filtering and control of non-Gaussian linear time-varying systems
(2019) 123, pp. 108-115. Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058029124&doi=10.1016%2fj.sysconle.2018.11.004&partnerID=40&md5=11a5e53a5602f2959ba14e4f6f74399a
AFFILIATIONS: Università Campus Bio-Medico di Roma, Italy; 
DITEN, Università Degli Studi di Genova, Genova, Italy; 
DIAG, Sapienza Università di Roma, Roma, Italy; 
DISIM, Università degli Studi dell'Aquila, L'Aquila, Italy
ABSTRACT: This paper deals with the optimal filtering and optimal output-feedback control of discrete-time, linear time-varying non-Gaussian systems. In the hypothesis that the time-varying and non-Gaussian distributions of the state and measurement noises have bounded and known moments up to a given order, this work extends previous results about polynomial filtering and optimal control to the time-varying case. The properties of the resulting filtering and control algorithms are discussed in the light of a stable recursive representation of the Kronecker powers of the system obtained through a suitable rewriting of the system with an output injection term. The resulting sub-optimal algorithm inherits the structure and the properties of the classical LQG approach but with enhanced performance. © 2018 Elsevier B.V.

Tang, W., Wang, Z., Shen, Y.
Interval estimation for discrete-time linear systems: A two-step method
(2019) 123, pp. 69-74. Cited 12 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057825057&doi=10.1016%2fj.sysconle.2018.11.001&partnerID=40&md5=820dd4253e679e55859dfdc90455a0ae
AFFILIATIONS: School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: This paper proposes a two-step interval estimation method for discrete-time linear systems by integrating robust observer design with reachability analysis. The proposed method is designed based on a new observer structure which can provide more degrees of design freedom. For improving estimation accuracy, H∞ technique is used in observer design to attenuate the effects of disturbances and noise. Based on the obtained observer, interval estimation can be achieved via reachability analysis. The proposed method provides an intuitive design paradigm for interval estimation and is effective in controlling the wrapping effect, which refers to the additional growth of the constructed sets resulting from the propagations of overestimations at each step. Simulation results are given to demonstrate the performance of the proposed method. © 2018 Elsevier B.V.

Zhang, L., Prieur, C., Qiao, J.
PI boundary control of linear hyperbolic balance laws with stabilization of ARZ traffic flow models
(2019) 123, pp. 85-91. Cited 15 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057801496&doi=10.1016%2fj.sysconle.2018.11.005&partnerID=40&md5=1b05321366c3dcb54648e42542bedb78
AFFILIATIONS: Faculty of Information Technology, Beijing University of Technology, Beijing, 100124, China; 
Key Laboratory of Computational Intelligence and Intelligent Systems, Beijing, 100124, China; 
Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, Grenoble, F-38000, France
ABSTRACT: This paper investigates the proportional–integral (PI) boundary feedback control for the linear hyperbolic systems of balance laws which control and output measures are located at the boundaries. We address the issue of feedback stabilization by means of PI boundary controllers. By constructing a new weighted Lyapunov function, the sufficient conditions in terms of matrix inequalities are developed for the exponential stability of closed-loop systems. These results are illustrated by the linearized Aw–Rascle–Zhang (ARZ) traffic flow model. We design a PI boundary controller to stabilize the oscillations of the traffic parameters of a freeway segment and evaluate the performance with numerical simulations. © 2018 Elsevier B.V.

Sanjaroon, V., Farhadi, A., Khalaj, B.H., Motahari, A.S.
Estimation and stability over AWGN channel in the presence of fading, noisy feedback channel and different sample rates
(2019) 123, pp. 75-84. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057771487&doi=10.1016%2fj.sysconle.2018.11.002&partnerID=40&md5=cc3cb2c6e0d94e041c3853e2d0c46fd4
AFFILIATIONS: Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran; 
School of Computer Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran; 
Department of Computer Engineering, Sharif University of Technology, Tehran, Iran
ABSTRACT: This paper is concerned with estimation and stability of control systems over communication links subject to limited capacity, power constraint, fading, noisy feedback, and different transmission rate rather than system sampling rate. A key issue addressed in this paper is that in the presence of noisy feedback associated with channel, which models transmission of finite number of bits over such links as is the case in most practical scenarios, the well-known eigenvalues rate condition is still a tight bound for stability. Based on an information theoretic analysis, necessary conditions are derived for stability of discrete-time linear control systems via the distant controller in the mean square sense. By construction of a specific coding scheme and by the design of a proper controller, the tight sufficient conditions for stability of control systems are also derived for linear discrete-time control systems over both Additive White Gaussian Noise (AWGN) and fading channels. This implies that the proposed coding scheme is efficient. The results are presented with the mismatch assumption between channel symbol and plant sample rates. As one key result of this paper, it is shown that if the channel symbol rate is less than the system sample rate, the control system is still stabilizable via increasing the transmission power. © 2018 Elsevier B.V.

Wei, Y., Lin, Z.
Time-varying low gain feedback for linear systems with unknown input delay
(2019) 123, pp. 98-107. Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057619460&doi=10.1016%2fj.sysconle.2018.10.016&partnerID=40&md5=69a1d3cc90bf3176ef057253abc05054
AFFILIATIONS: Charles L. Brown Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA  22904-4743, United States
ABSTRACT: In this paper, the traditional low gain feedback design with a time-invariant feedback parameter is generalized to time-varying parameter design for linear systems with delayed input. For an unknown delay with a known upper bound, a time-varying low gain feedback law, constructed by using the parametric Lyapunov equation based approach, globally regulates a system with all open loop poles at the origin as long as the time-varying low gain parameter has a continuous second derivative and approaches a sufficiently small constant with its derivative approaching zero as time goes to infinity. Improvement of the closed-loop performance is addressed in a convergence rate analysis and then observed in simulation compared with the traditional constant parameter low gain design. © 2018 Elsevier B.V.

Maarouf, H.
On enlarging the set of admissible initial states for the double integrator under asymmetrical constraints
(2019) 123, pp. 92-97. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057588458&doi=10.1016%2fj.sysconle.2018.11.006&partnerID=40&md5=9246538d1850c48592e08710c0726bfc
AFFILIATIONS: Modeling and Combinatorics Laboratory, Department of Mathematics and Computer Sciences, Poly-Disciplinary Faculty of Safi, Cadi Ayyad University, Morocco
ABSTRACT: In this paper we determine the maximal polyhedral domain which is positively invariant inside the set of the constraints for the double integrator plant. This polyhedral domain is then used to determine the set of all admissible initial states without violating the constraints on the control inputs. © 2018 Elsevier B.V.

Tan, C., Yang, L., Zhang, F., Zhang, Z., Wong, W.S.
Stabilization of discrete time stochastic system with input delay and control dependent noise
(2019) 123, pp. 62-68. Cited 5 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057305146&doi=10.1016%2fj.sysconle.2018.11.003&partnerID=40&md5=3906dcb33ae70e0000d4a9eb2035c737
AFFILIATIONS: College of Engineering, QuFu Normal University, Shandong, Rizhao  276800, China; 
Department of Information Engineering, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong; 
School of Electrical Engineering, Zhengzhou University, Zhengzhou, 450001, China
ABSTRACT: In this paper, we introduce a delay dependent Lyapunov equation (DDLE) approach to study the mean square stabilization for discrete time stochastic system with both input delay and control dependent noise. The innovative contributions of this paper are twofold. First, for a general stochastic system with input delay and multiplicative noises, we derive a necessary stabilizing condition based on a coupled Lyapunov equation (CLE). Second, we present a set of necessary and sufficient stabilizing conditions for the considered stochastic system. We show that the stochastic system is stabilizable is equivalent to that the DDLE has a positive definite solution. In this case, the constructed CLE is equivalent to the DDLE. Moreover, based on the Lyapunov stabilizing result, we further derive a spectrum stabilizing criterion. To confirm the effectiveness of our theoretic results, two illustrative examples are included. © 2018 Elsevier B.V.

Monshizadeh, N., Monshizadeh, P., Ortega, R., van der Schaft, A.
Conditions on shifted passivity of port-Hamiltonian systems
(2019) 123, pp. 55-61. Cited 6 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057297649&doi=10.1016%2fj.sysconle.2018.10.010&partnerID=40&md5=30c904d2cbd5bf04712a4035cebf824a
AFFILIATIONS: Engineering and Technology Institute, University of Groningen9747AG, Netherlands; 
Johann Bernoulli Institute for Mathematics and Computer Science, University of GroningenAK  9700, Netherlands; 
Laboratoire des Signaux et Systèmes, CNRS-SUPELEC, Plateau du Moulon, Gif-sur-Yvette, 91192, France
ABSTRACT: In this paper, we examine the shifted passivity property of port-Hamiltonian systems. Shifted passivity accounts for the fact that in many applications the desired steady-state values of the input and output variables are nonzero, and thus one is interested in passivity with respect to the shifted signals. We consider port-Hamiltonian systems with strictly convex Hamiltonian, and derive conditions under which shifted passivity is guaranteed. In case the Hamiltonian is quadratic and state dependency appears in an affine manner in the dissipation and interconnection matrices, our conditions reduce to negative semidefiniteness of an appropriately constructed constant matrix. Moreover, we elaborate on how these conditions can be extended to the case when the shifted passivity property can be enforced via output feedback, thus paving the path for controller design. Stability of forced equilibria of the system is analyzed invoking the proposed passivity conditions. The utility and relevance of the results are illustrated with their application to a 6th order synchronous generator model as well as a controlled rigid body system. © 2018 Elsevier B.V.

Zholbaryssov, M., Fooladivanda, D., Domínguez-García, A.D.
Resilient distributed optimal generation dispatch for lossy AC microgrids
(2019) 123, pp. 47-54. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057290927&doi=10.1016%2fj.sysconle.2018.10.007&partnerID=40&md5=6577e6cd2a96078c2773a6172aff66f2
AFFILIATIONS: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL  61801, United States
ABSTRACT: In this paper, we consider the problem of designing a distributed algorithm, resilient against communication delays and packet drops, for coordinating the response of distributed energy resources (DERs) in AC microgrids so as to minimize electrical line losses and generation cost, and to ensure that the microgrid network constraints are satisfied. The proposed algorithm can be utilized as a secondary or tertiary controller for frequency regulation in islanded microgrids, or to coordinate DERs for providing frequency regulation services to the bulk grid when microgrid is in grid-connected mode. We validate the practical usefulness of the theoretical results through numerical simulations involving the IEEE 39-bus system. © 2018 Elsevier B.V.

Gyurkovics, É., Takács, T.
Comparison of some bounding inequalities applied in stability analysis of time-delay systems
(2019) 123, pp. 40-46. Cited 1 time.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057156367&doi=10.1016%2fj.sysconle.2018.10.017&partnerID=40&md5=8c898aee432616656057f68d6d0004b4
AFFILIATIONS: Mathematical Institute, Budapest University of Technology and Economics, Műegyetem rkp. 3, Budapest, Hungary; 
Corvinus University of Budapest, 8 Fővám tér, H-1093, Budapest, Hungary
ABSTRACT: This paper gives comparisons of several bounding inequalities proposed recently for the estimation of integrals and sums of quadratic functions, which plays an important role in stability analysis of time delay systems via the Lyapunov–Krasovskii approach. The equivalences of several known variants of the free matrix based inequalities and their generalized and simplified forms are shown. Secondly, the relationship between the (simplified) free matrix based inequality and the combination of the Bessel-based inequality with different bounding inequalities affine in the length of the intervals are investigated. Finally, we shall demonstrate the theoretical results with the application of the various estimations for the stability analysis of a linear system with time-varying delay using the same Lyapunov–Krasovskii functional. © 2018 Elsevier B.V.

Han, X., Chen, Z., Su, R.
Synthesis of minimally restrictive optimal stability-enforcing supervisors for nondeterministic discrete event systems
(2019) 123, pp. 33-39. Cited 8 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057140335&doi=10.1016%2fj.sysconle.2018.10.014&partnerID=40&md5=779b3d2d58cfc7419a6e65d4639c13bc
AFFILIATIONS: College of Electronic Information and Automation, Tianjin University of Science and Technology, Tianjin, 300222, China; 
College of Artificial Intelligence, Nankai University, Tianjin, 300350, China; 
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
ABSTRACT: In this paper, we investigate stability-enforcing supervisory control of nondeterministic discrete event systems (DESs) from a brand-new angle. First, the dynamics of a discrete event system (DES) are converted into an algebraic equation in the framework of Boolean semi-tensor product. Using it, several necessary and sufficient conditions are presented to verify whether a DES is stable or not. Second, effective verification criteria are provided for the stabilization problem of DESs. Further, a cost function of disabling controllable events at corresponding states is defined. A matrix-based methodology of finding all minimally restrictive optimal stability-enforcing supervisors is presented. Finally, two examples are provided to illustrate the theoretical results. © 2018 Elsevier B.V.

Yu, H., Hao, F., Chen, X.
On event-triggered control for integral input-to-state stable systems
(2019) 123, pp. 24-32. Cited 8 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057123438&doi=10.1016%2fj.sysconle.2018.10.013&partnerID=40&md5=74382a7e2d29d0209d3f4de34497d9f4
AFFILIATIONS: The Seventh Research Division, School of Automation Science and Electrical Engineering, Beihang University, Beijing, 100191, China; 
School of Automation Engineering, Qingdao University of Technology, Qingdao, 266520, China
ABSTRACT: In this paper, the stabilization of nonlinear systems by means of event-triggered control is studied. Two kinds of triggering conditions are proposed for a class of systems that only satisfy the integral input-to-state stability with respect to measurement errors. A constant threshold of measurement errors is involved in the first kind of triggering conditions to ensure the ultimately bounded stability, while the second type of triggering conditions is constructed by using a decreasing extra signal as the threshold. The conditions on the extra signal are proposed to guarantee asymptotic stability and exclude Zeno behavior. Moreover, the relationship, between the proposed results and those based on the input-to-state stability, is discussed. Finally, numerical examples are provided to illustrate the efficiency and feasibility of the obtained results. © 2018 Elsevier B.V.

Tilli, A., Bosso, A., Conficoni, C.
Towards sensorless observers for sinusoidal electric machines with variable speed and no mechanical model: A promising approach for PMSMs
(2019) 123, pp. 16-23. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057042037&doi=10.1016%2fj.sysconle.2018.10.011&partnerID=40&md5=50a1216e6be43f4226ca63fb48f05e33
AFFILIATIONS: Department of Electrical, Electronic and Information Engineering (DEI), University of Bologna, Viale Risorgimento, 2, Bologna, 40136, Italy
ABSTRACT: One of the major issues in developing sensorless observers for AC Sinusoidal Machines, and for all kinds of Electric Machines, is to deal with variable speed relying only on the electromagnetic model, without using any mechanical information. In this paper, the case of Permanent Magnet Synchronous Machines is considered as first benchmark. A novel and promising design strategy is presented to develop a simple sixth-order observer for estimating rotor speed/position and magnetic flux amplitude, in the context of non-zero variable speed, with unknown constant sign and bounded derivative. This framework does not cover yet any arbitrarily-varying mechanical speed, but it goes far beyond the typical simplifying assumption of “slowly-varying speed”, which is actually meant as “constant speed” in the common theoretical analysis. In the proposed method, the rotation dynamics of the machine back-electromotive force is represented by means of the Lie Groups formalism, and no open-loop integration of stator voltages and currents is adopted. Lyapunov-like and Singular Perturbations techniques are then exploited to achieve regional practical asymptotic stability, with a very wide region of attraction. The mild limitations on such stability domain are carefully analyzed and discussed. Numerical simulations are provided to show the effectiveness of the proposed observer, under heavily variable mechanical speed. Finally, taking cue from the features of the presented approach, future steps are outlined in order to further weaken the restrictions on the speed variations and to extend the results to other electric machines. © 2018 Elsevier B.V.

Zhu, Y., Krstic, M., Su, H.
PDE output feedback control of LTI systems with uncertain multi-input delays, plant parameters and ODE state
(2019) 123, pp. 1-7. Cited 4 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056783460&doi=10.1016%2fj.sysconle.2018.10.012&partnerID=40&md5=048e937f4046d28d6d3331aa8a761895
AFFILIATIONS: School of Civil and Environmental Engineering, Nanyang Technological University, Singapore; 
Department of Mechanical and Aerospace Engineering, University of California, San Diego, United States; 
State Key Laboratory of Industrial Control Technology, Institute of Cyber-Systems and Control, Zhejiang University, China
ABSTRACT: In this paper we propose the control design of linear time-invariant (LTI) system with distinct multi-input delays. A variety of techniques to deal with different uncertainty collections are synthesized into a unified framework, from which readers can make its own selection to address a vast class of relevant problems. © 2018 Elsevier B.V.

Gao, Y., Liu, J., Sun, G., Liu, M., Wu, L.
Fault deviation estimation and integral sliding mode control design for Lipschitz nonlinear systems
(2019) 123, pp. 8-15. Cited 37 times.
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056750682&doi=10.1016%2fj.sysconle.2018.08.006&partnerID=40&md5=5ae1b9312ab510df1b15c1998adb3bc8
AFFILIATIONS: School of Astronautics, Harbin Institute of Technology, Harbin, 150001, China; 
Research Center of Satellite Technology, Harbin Institute of Technology, Harbin, 150001, China
ABSTRACT: This paper is concerned with the problems of observer-based sliding mode control and fault estimation for Lipschitz nonlinear systems. The concerned plants are characterized with an actuator fault deviation existing in state dynamics and measured outputs. It represents a more general faulty plant case than those considered in the existing literature. Comparing with existing results on the sliding mode control procedure design, we propose new techniques to overcome the difficulty caused by parametric perturbation and measured noise existing in system output. For precisely estimating the plant states and the faults simultaneously, a novel estimation technique is developed to tackle the influence from the fault deviation. Based on the state estimation, an integral-type sliding mode control scheme by the utilization of an augmented sliding mode observer is presented for the stabilization of the faulty plants. Finally, an electromechanical system is applied to validate the availability and applicability of the presented control methods. © 2018 Elsevier B.V.