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In this paper, we consider the event-triggered control problem for continuous-time switched linear systems. It is assumed that only the sampled information of system state and switching signal is available to the controller at each sampling instant. Based on a mode-dependent event-triggered transmission scheme, the closed-loop system is modeled as a switched system with delayed state and augmented switching signal. Then, an exponential stability condition, characterized by the dwell time and average dwell time of the switching signal, is obtained. The condition presents an extension of the multiple Lyapunov functional method based stability analysis for sampled-data control of nonswitched system. Consequently, the design methods for state-feedback controller gains and event-triggered parameters are then formulated by the properly selected quadratic Lyapunov functional. The analysis results are significant and also lead to an important step to study the event-triggered control for switched system. Finally, based on the definition of event-trigger efficiency, the effectiveness and improvement of the proposed approach are illustrated by two numerical examples. [ABSTRACT FROM AUTHOR]

This paper considers a singular problem in optimal control of continuous-time bimodal switched linear systems. A relaxed switched system with a continuous-valued switching signal is considered and the representations of singular control and singular arcs are derived. The similarity in the structure between the singular control and a stabilizing switching law is revealed and an approximation of the singular control by a well-defined switching signal is addressed. The results are demonstrated by numerical simulations. [ABSTRACT FROM AUTHOR]

We study feedback control for a discrete-time integrator with unitary delay in the presence of quantization both in the control action and in the measurement of the controlled variable. In some applications the quantization effects can be neglected, but when high precision is needed, they have to be explicitly accounted for in control design. In this paper, we propose a switched control solution for minimizing the effect of quantization of both the control and controlled variables for the considered system, that is quite common in the computing systems domain, for example, in thread scheduling, clock synchronization, and resource allocation. We show that the switched solution outperforms the one without switching, designed by neglecting quantization, and analyze necessary and sufficient conditions for the controlled system to exhibit periodic solutions in the presence of an additive constant disturbance affecting the control input. Simulation results provide evidence of the effectiveness of the approach. [ABSTRACT FROM AUTHOR]

The goal of this paper is to study the stabilizability of controlled discrete-time switched linear systems (CSLSs), where the discrete switching control input and the continuous control input coexist. For a given positive integer $h$ , we propose a quantitative metric of stabilizability, called $h$ -contraction rate ($h$ -CR), and prove that it serves as an indicator of the stabilizability in the following sense: the $h$ -CR is less than one for sufficiently large $h$ if and only if the switched linear system is stabilizable. In addition, we develop computational tools to estimate upper and lower bounds of the $h$ -CR. In particular, the upper bound estimation is expressed as a semidefinite programming problem. We derive its Lagrangian dual problem and prove that the dual problem with an additional rank constraint gives an exact characterization of the $h$ -CR. An algorithm is developed to solve the dual problem with the rank constraint. [ABSTRACT FROM AUTHOR]

This paper presents a fault-tolerant control scheme for constrained discrete-time linear systems against stuck actuators and bounded disturbances. The results proposed here are a significant generalization of a similar algorithm that has been designed only to manage healthy/out-of-service actuator units. A key feature of the proposed scheme consists of taking advantage of polyhedral algebra and computational geometry concepts in order to characterize the reconfiguration logic of the proposed fault-tolerant architecture. This is achieved by describing the plant via a set of a finite number of piecewise affine (PWA) systems capable to cover all the admissible faulty stuck scenarios. It is then proved that one-step sequences of controllable sets can be formally defined within a PWA system paradigm under the key property that each region is a polyhedron. [ABSTRACT FROM AUTHOR]

We study synchronization of coupled linear systems over networks with weak connectivity and nonuniform time-varying delays. We focus on the case where the internal dynamics are time-varying but nonexpansive (stable dynamics with a quadratic Lyapunov function). Both uniformly jointly connected and infinitely jointly connected communication topologies are considered. A new concept of quadratic synchronization is introduced. We first show that global asymptotic quadratic synchronization can be achieved over directed networks with uniform joint connectivity and arbitrarily bounded delays. We then study the case of infinitely jointly connected communication topology. In particular, for the undirected communication topologies, it turns out that the existence of a uniform time interval for the jointly connected communication topology is not necessary and quadratic synchronization can be achieved when the time-varying nonuniform delays are arbitrarily bounded. Simulation results are provided to validate the theoretical results. [ABSTRACT FROM AUTHOR]

We consider the problem of ensuring the identifiability of the parameters of a multivariable linear system by means of feedback control. It is shown that parameter identifiability can be generically ensured using time-varying (switching) controllers. Moreover, this property holds true for any, arbitrarily small, data observation window. Some practical aspects of the problem are also dealt with, including controller design and multimodel least-squares estimation. [ABSTRACT FROM PUBLISHER]

In this note, a switching-type delay-adaptive predictor feedback controller is proposed to globally stabilize linear systems with unknown input delay. The idea of our method is to take advantage of the robustness of feedback laws to delay estimate error that is sufficiently small. We first prove that, when the delay estimate is sufficiently close to the true delay, there is a Lyapunov–Krasovskii functional that is strictly decreasing, and asymptotic regulation is achievable. Then, with the help of the Lyapunov–Krasovskii functional as a supervisor, the switching logic plays the role of adjusting the estimated delay online to make it sufficiently close to the true delay. The result of this note shows that, global adaptive stabilization of linear systems with unknown input delay is achievable, with a logic-based switching control law. [ABSTRACT FROM PUBLISHER]

In this note, we study the stabilization problem of positive switched linear system (PSLS) with disturbance. By introducing a class of weak common linear copositive Lyapunov functions, we design time-dependent switching rules under which the system is asymptotically stable. Both continuous-time and discrete-time PSLS are taken into consideration, and the obtained results are also extended to nonpositive switched systems. Finally, the theoretical results are applied to consensus problem of multiagent systems with switching topologies and disturbance. [ABSTRACT FROM PUBLISHER]

This note proposes a dynamic controller for practical coordinated tracking of uncertain heterogeneous multi-agent systems. The agents are high-order linear systems subject to external disturbances and plant uncertainties, the input to the leader is not known to other agents, and the network topology is time-varying. We adopt a recently developed reduced-order disturbance observer to present a distributed tracking controller which uses only relative measurements. It is shown that the proposed controller can be tuned to ensure the ultimate boundedness of tracking error which can be chosen arbitrarily small despite the network switching, plant uncertainties, and disturbances. Simulation results are provided to show the effectiveness of the proposed controller. [ABSTRACT FROM PUBLISHER]

This note deals with the problem of controlling an uncertain discrete-time linear system by means of a hybrid controller in the form of a linear system whose parameters switch among a finite number of possible configurations, called modes. We suppose that each single controller is designed in order to individually ensure robust stability for a dual-Youla uncertainty model. Then, we show that robust stability of the switching controller can be directly related to robust stability of each single controller mode, in that it is possible to implement the switching controller so that robust stability is guaranteed for any possible switching sequence. This allows one to freely select the switching signal so as to enhance performance, for instance by selecting in real time the control mode displaying the best potential performance with respect to the current operating conditions. An application of the ideas to the problem of active disturbance attenuation is presented and simulation results are shown to validate the proposed solution. [ABSTRACT FROM PUBLISHER]

This technical note establishes a novel result for adaptive asymptotic tracking control of uncertain switched linear systems. The result exploits a recently proposed stability condition for switched systems. In particular, a time-varying positive definite Lyapunov function is used to develop a novel piecewise continuous model-reference adaptive law and a dwell-time switching law. In contrast with previous research, where asymptotic tracking was possible only in the presence of a common Lyapunov function for the reference models, in this work asymptotic tracking is shown in a more general setting. Additionally, in the presence of persistence of excitation, the controller parameter estimation errors will converge to zero asymptotically. The main contribution of this work consists in establishing a symmetry between adaptive control of classical non-switched linear systems and adaptive control of switched linear systems. A practical example with an electro-hydraulic system is adopted to illustrate the results. [ABSTRACT FROM AUTHOR]

This paper addresses the problems of determining the \mathcal H_2 norm and the root mean square (RMS) gain of continuous-time switched linear systems. A novel class of Lyapunov functions is proposed for reaching this goal, called homogeneous rational Lyapunov functions (HRLFs). It is shown that sufficient conditions for establishing upper bounds of the sought performance indexes in the case of arbitrary switching can be given in terms of linear matrix inequality (LMI) feasibility tests by searching for an HRLF of chosen degree. Moreover, it is shown that these conditions are also necessary by searching for an HRLF of degree sufficiently large. It is worth mentioning that necessary and sufficient LMI conditions have not been proposed yet in the literature for the considered problems. Hence, the paper continues by considering the case of switching with dwell time constraints, showing that analogous LMI conditions can be obtained for this case by searching for a family of HRLFs mutually constrained by the dwell time specification. Some numerical examples illustrate the proposed methodology and highlight the advantages with respect to the existing works. [ABSTRACT FROM AUTHOR]

This paper addresses the output reachable set estimation problem for continuous-time switched linear systems consisting of Hurwtiz stable subsystems. Based on a common Lyapunov function approach, the output reachable set is estimated by a union of bounding ellipsoids. Then, multiple Lyapunov functions with time-scheduled structure are employed to estimate the output reachable set for switched systems under dwell-time constraint. Furthermore, the safety verification problem of uncertain switched systems is investigated based on the result of output reachable set estimation. First, a sufficient condition ensuring the existence of an approximate bisimulation relation between two switched linear systems with a prescribed precision is proposed. Then, the safety verification for an uncertain switched system can be performed through an alternative safety verification for a switched system with exact parameters. Numerical examples are provided to illustrate our results. [ABSTRACT FROM AUTHOR]

This paper introduces the notion of common zeroing-output systems (CZOS) to analyze the stability of switched systems. The concept of CZOS allows one to verify weak zero-state detectability. It characterizes a common behavior of any individual subsystem when the output signal for each subsystem is “approaching” zero. Heuristically speaking, it removes the effect of switching behavior, and thus enables one to analyze stability properties in systems with complex switching signals. With the help of CZOS, the Krasovskii–LaSalle theorem can be extended to switched nonlinear time-varying systems with both arbitrary switching and more general restricted switching cases. For switched nonlinear time-invariant systems, the needed detectability condition is further simplified, leading to several new stability results. Particularly, when a switched linear time-invariant system is considered, it is possible to generate a recursive method, which combines a Krasovskii–LaSalle result and a nested Matrosov result, to find a CZOS if it exists. The power of the proposed CZOS is demonstrated by consensus problems in literature to obtain a stronger convergence result with weaker conditions. [ABSTRACT FROM AUTHOR]

We show that existence of a global polynomial Lyapunov function for a homogeneous polynomial vector field or a planar polynomial vector field (under a mild condition) implies existence of a polynomial Lyapunov function that is a sum of squares (sos) and that the negative of its derivative is also a sum of squares. This result is extended to show that such sos-based certificates of stability are guaranteed to exist for all stable switched linear systems. For this class of systems, we further show that if the derivative inequality of the Lyapunov function has an sos certificate, then the Lyapunov function itself is automatically a sum of squares. These converse results establish cases where semidefinite programming is guaranteed to succeed in finding proofs of Lyapunov inequalities. Finally, we demonstrate some merits of replacing the sos requirement on a polynomial Lyapunov function with an sos requirement on its top homogeneous component. In particular, we show that this is a weaker algebraic requirement in addition to being cheaper to impose computationally. [ABSTRACT FROM AUTHOR]

In this note we present connections between two celebrated tools for the design of stabilising switching laws for continuous-time and discrete-time switched linear systems, namely Lyapunov-Metzler inequalities and S-procedure. [ABSTRACT FROM AUTHOR]

This paper investigates the state observer design of a class of unknown input switched linear systems via mode-dependent dwell time switchings. The distinguishing feature of the proposed method is that strong detectability condition of subsystems of the switched systems is unnecessarily required. First, a time-varying coordinate transformation is introduced to design a suitable reduced-order observer for each subsystem. Then, computable sufficient conditions on the synthesis of the observers are proposed in the framework of a mode-dependent dwell time technique. Since the observer of an individual subsystem cannot be designed due to unavailability of strong detectability condition of the subsystem, the state of the switched system is estimated under the condition of confining the dwell time by a pair of upper and lower bounds, restricting the growth of the Lyapunov function of the active subsystem and forcing “energy” of the overall switched system to decrease at switching instants. Finally, an example is presented to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper studies the problem of stabilizing discrete-time switched linear control systems (SLCSs) using continuous input by a user against adversarial switching by an adversary. It is assumed that at each time the adversary knows the user's decision on the continuous input but not vice versa. A quantitative metric of stabilizability is proposed. Systems at the margin of stabilizability are further classified and studied via the notions of defectiveness and reducibility. Analytical bounds on the stabilizability metric are derived using (semi)norms, with tight bounds provided by extremal norms. Numerical algorithms are also developed for computing this metric. An application example in networked control systems is presented. [ABSTRACT FROM AUTHOR]

The existing results on the leaderless and leader-following consensus problems for discrete-time linear multi-agent systems subject to jointly connected switching networks are limited to undirected networks. This note will first study the stability property for a class of discrete-time linear switched systems. This stability result will then be applied to the two consensus problems for discrete-time linear multi-agent systems subject to directed jointly connected switching networks. It is shown that, in some interesting cases, the two problems are solvable by the distributed state feedback control law even if the switching networks are directed and every time disconnected. [ABSTRACT FROM AUTHOR]

This technical note focuses on stability analysis and control design of switched affine systems in discrete-time domain. The stability conditions are obtained by taking into account that the system trajectories, governed by a certain switching function, converge to a set of attraction \boldsymbol\mathcal V containing a desired equilibrium point. These conditions follow from the adoption of a general quadratic Lyapunov function whose time variation is bounded above by a concave-convex function with center determined by minimax theory. Our main contribution is to provide a stabilizing state feedback switching function and an invariant set of attraction \boldsymbol\mathcal V_* with minimum volume as far as this class of quadratic Lyapunov functions is adopted. The results are applied to sampled-data control of continuous-time switched affine systems with chattering avoidance. The speed control of a DC motor is presented. [ABSTRACT FROM PUBLISHER]

The goal of this paper is to study the exponential stabilization problem for autonomous discrete-time switched linear systems (SLSs), where only the discrete mode can be controlled. Our approach is based on periodic control Lyapunov functions whose value decreases periodically instead of at each time step as in the classical control Lyapunov functions. Using periodic control Lyapunov functions, we develop stabilizability analysis and controller synthesis conditions that are less conservative than existing results in that they apply to a larger class of SLSs. Utilizing recent results on the switched optimal control problems, a constructive way to find periodic control Lyapunov functions is presented. [ABSTRACT FROM PUBLISHER]

This paper is concerned with a class of discrete-time semi-Markov jump linear systems (S-MJLSs) subject to exponentially modulated periodic (EMP) probability density function (PDF) of sojourn time, and the problems of stability and stabilization are addressed. Setting a relatively large period, the considered systems are capable of approximating the general S-MJLSs (without any requirements on sojourn-time PDFs) for which numerically testable stability and stabilization conditions are rather difficult to obtain. Necessary and sufficient criterion for mean square stability of the general S-MJLSs is first derived, which involves an infinite number of conditions and as such not checkable. However, the developments lay a foundation to further establish the numerically testable conditions for the systems when the PDF of sojourn time is EMP albeit the sojourn time can tend to infinity. The derivations explicitly depend on the PDF of sojourn time, which circumvents the difficulty in obtaining the memory transition probabilities of S-MJLSs. The adopted Lyapunov function is sojourn-time-dependent (STD), by which the existence conditions of STD controller are developed as well using certain techniques that can eliminate the terms of power of matrices in the stability conditions. Two illustrative examples including a class of population ecological systems are presented to show the validity and applicability of the developed theoretical results. [ABSTRACT FROM AUTHOR]

The problem of designing a switching and control policy for regulating the state of a switched linear system to zero while minimizing a quadratic cost appears in numerous applications. However, obtaining the optimal policy is in general computationally intractable. Here, we propose a class of suboptimal policies that exploit information, in terms of upper or lower bounds, on the optimal cost. We analyze the performance of these novel policies, obtaining new bounds on the optimal cost which are tighter than the initial ones. The usefulness of these policies and performance bounds is illustrated in the context of resource-aware control. [ABSTRACT FROM AUTHOR]

In this work, we study the stability of an autonomous discrete-time linear switched system whose switching sequences are generated by a Muller automaton. This system arises in various engineering problems such as distributed communication and automotive engine control. The asymptotic stability of this system, referred to as regular asymptotic stability (RAS), generalizes two well-known definitions of stability of autonomous discrete-time linear switched systems, namely absolute asymptotic stability (AAS) and shuffle asymptotic stability (SAS). We also extend these stability definitions to robust versions. We show that absolute asymptotic stability, robust absolute asymptotic stability and robust shuffle asymptotic stability are equivalent to exponential stability. In addition, by using the Kronecker product, we prove that a robust regular asymptotic stability problem is equivalent to the conjunction of several robust absolute asymptotic stability problems. [ABSTRACT FROM PUBLISHER]

In this technical note, we consider the cooperative output regulation problem for linear multi-agent systems subject to communication delays and switching networks by a distributed feedforward approach. Both distributed dynamic state feedback controller and distributed dynamic measurement output feedback controller are proposed to solve the problem. In comparison with the existing result for the similar problem, our result can handle the cooperative output regulation problem subject to nonuniform time-varying communication delays and jointly connected switching communication networks. As an application of cooperative output regulation, it is shown that our main result can solve the leader-following consensus problem and includes some existing results as its special cases. [ABSTRACT FROM AUTHOR]

The problem of robust finite-time stabilization of perturbed multi-input linear system by means of generalized relay feedback is considered. A new control design procedure, which combines convex embedding technique with Implicit Lyapunov Function (ILF) method, is developed. The sufficient conditions for both local and global finite-time stabilization are provided. The issues of practical implementation of the obtained implicit relay feedback are discussed. Our theoretical result is supported by numerical simulation for a Buck converter. [ABSTRACT FROM AUTHOR]

This article investigates the stability of positive switched linear systems. We start from motivating examples and focus on the case when each switched subsystem is marginally stable (in the sense that all the eigenvalues of the subsystem matrix are in the closed left-half plane with those on the imaginary axis simple) instead of asymptotically stable. A weak excitation condition is first proposed such that the considered positive switched linear system is exponentially stable. An extension to the case without dwell time assumption is also presented. Then, we study the influence of time-varying delay on the stability of the considered positive switched linear system. We show that the proposed weak excitation condition for the delay-free case is also sufficient for the asymptotic stability of the positive switched linear system under unbounded time-varying delay. In addition, it is shown that the convergence rate is exponential if there exists an upper bound for the delay, irrespective of the magnitude of this bound. The motivating examples are revisited to illustrate the theoretical results. [ABSTRACT FROM PUBLISHER]

This work proposes a model predictive control (MPC) approach for a switching linear system where the switching signal is prescribed with unknown future values. The switching signal is known only at its current value, satisfies a minimal dwell-time restriction of $\tau$ steps between successive switchings and is otherwise arbitrary. Under such a setting, the MPC optimization problem has to allow for all admissible switching sequences within a given horizon length. Such a formulation necessitates several other features: the use of a modified returnable set as the terminal constraint; the introduction of consistency constraints on the predicted controls; a min-max optimization criterion as the cost function; the splitting of the horizon into two portions for recursive feasibility consideration and exponential stability of the closed-loop system. The proposed approach is demonstrated by a numerical example. [ABSTRACT FROM AUTHOR]

In this technical note, a necessary and sufficient stability criterion for switched linear systems under dwell-time constraint is proposed by employing a class of time-scheduled homogeneous polynomial Lyapunov functions with a sufficiently large degree. The key feature of this nonconservative condition lies in its convexity in the system matrices, which explicitly facilitates its further extension to uncertain systems. Then, in order to obtain numerically testable condition, a family of LMI conditions are presented with the aid of the idea of dividing the dwell-time interval into a finite number of segments. It is proved that the non-conservativeness can be maintained with a sufficiently large interval dividing parameter. In the end, the result is straightforwardly extended to the uncertain case in virtue of the convexity in the system matrices. Numerical examples are presented to illustrate our findings. [ABSTRACT FROM PUBLISHER]

A moment-matching method for model reduction of linear switched systems (LSSs) is presented. The method can be seen as a non-trivial extension of the Krylov subspace methods for linear time-invariant (LTI) systems. The procedure is based on the so called “nice selections,” which represent a choice of basis in the reachability or observability space of the LSS. The framework can also be used for exact matching of the input-output behavior of an LSS with a reduced order LSS for a specific switching sequence. Conditions for applicability of the method for model reduction are stated and finally the results are illustrated on numerical examples. [ABSTRACT FROM PUBLISHER]

This technical note studies switching stabilization problems for continuous-time switched linear systems. We consider four types of switching stabilizability defined under different assumptions on the switching control input. The most general switching stabilizability is defined as the existence of a measurable switching signal under which the resulting time-varying system is asymptotically stable. Discrete switching stabilizability is defined similarly but requires the switching signal to be piecewise constant on intervals of uniform length. In addition, we define feedback stabilizability in Filippov sense (respectively, sample-and-hold sense) as the existence of a feedback law under which closed-loop Filippov solution (respectively, sample-and-hold solution) is asymptotically stable. It is proved that the four switching stabilizability notions are equivalent and their sufficient and necessary condition is the existence of a piecewise quadratic control-Lyapunov function that can be expressed as the pointwise minimum of a finite number of quadratic functions. [ABSTRACT FROM PUBLISHER]

In this note, we first propose an adaptive distributed observer for a linear leader system. This observer only assumes those followers who are the children of the leader know the system matrix of the leader system. Then, we further develop a distributed adaptive controller utilizing this adaptive distributed observer to solve the leader-following consensus problem for multiple uncertain Euler-Lagrange systems without assuming that all the followers need to know the system matrix of the leader system. [ABSTRACT FROM AUTHOR]

This work deals with the problem of rendering the output of a switched linear system insensitive to a disturbance input, with the requirement that the dynamics of the closed-loop system be exponentially stable for all switching signals with a sufficiently large dwell time. A necessary and sufficient condition for the problem to have a solution is shown. A complete computational procedure to check the solvability condition and to synthesize the compensation scheme is provided. A worked-out example is presented with the aim of showing the effectiveness of the devised method. [ABSTRACT FROM AUTHOR]

A sufficient condition for the stability of arbitrary switching linear systems (SLSs) without control inputs is that the individual subsystems are stable and their evolution matrices are simultaneously triangularizable (ST). This sufficient condition for stability is known to be extremely restrictive and not robust, and therefore of very limited applicability. The situation can be radically different when control inputs are present. Indeed, previous results have established that, depending on the number of states, inputs and subsystems, the existence of feedback matrices for each subsystem so that the corresponding closed-loop matrices are stable and ST can become a generic property, i.e., a property valid for almost every set of system parameters. This note provides novel contributions along two lines. First, we give sufficient conditions for the genericity of the property of existence of feedback matrices so that the subsystem closed-loop matrices are ST (not necessarily stable). Second, we give conditions for the genericity of the property of existence of feedback matrices that, in addition to achieving ST, enable arbitrary eigenvalue selection for each subsystem's closed-loop matrix. The latter conditions are less stringent than existing ones, and the approach employed in their derivation can be interpreted as an extension to SLSs of specific aspects of the notion of eigenvalue controllability for (non-switching) linear systems. [ABSTRACT FROM AUTHOR]

In this paper, we consider the l\infty gain characterizations of linear switched systems (LSS) and present various relevant results on their exact computation and optimization. Depending on the role of the switching sequence, we study two broad cases: first, when the switching sequence attempts to maximize, and second, when it attempts to minimize the l\infty gain. The first, named as worst-case throughout the paper, can be related to robustness of the system to uncontrolled switching; the second relates to situations when the switching can be part to the overall decision making. Although, in general, the exact computation of l\infty gains is difficult, we provide specific classes, the input-output switching systems, for which it is shown that linear programming can be used to obtain the worst-case l\infty gain. This is a sufficiently rich class of systems as any stable LSS can be approximated by one. Certain applications to robust control design are provided where we show that a switched compensation independently of the plant has no advantage over a linear time invariant (LTI) compensation, and further, if the plant is strictly causal, even a switched compensation which has a matched switching with the plant does not provide a better performance over an LTI compensation. Also, we present a new necessary and sufficient condition to check the stability of LSS in form of a model matching problem. On the other hand, if one is interested in minimizing the l\infty gain over the switching sequences, we show that, for finite impulse response (FIR) switching systems the minimizing switching sequence can be chosen to be periodic. For input-only or output-only switching an exact, readily computable, characterization of the minimal l\infty gain is provided, and it is shown that the minimizing switching sequence is constant, which, as also shown, is not true for input-output switching. [ABSTRACT FROM AUTHOR]

In this paper we deal with the stabilizability property for discrete-time switched linear systems. A recent necessary and sufficient characterization of stabilizability, based on set theory, is considered as the reference for comparing the computation-oriented sufficient conditions. The classical BMI conditions based on Lyapunov-Metzler inequalities are considered and extended. Novel LMI conditions for stabilizability, derived from the geometric ones, are presented that permit to combine generality with computational affordability. For the different conditions, the geometrical interpretations are provided and the induced stabilizing switching laws are given. The relations and the implications between the stabilizability conditions are analyzed to infer and compare their conservatism and their complexity. [ABSTRACT FROM AUTHOR]

We consider discrete-time linear time-invariant (LTI) systems with state feedback, where the actuation signal is subject to switching propagation delays, due to, e.g., routing in a multi-hop communication network. We show how to model these systems as pure switching linear systems and provide an algorithm for robust stability analysis. Next, we turn to the design problem and provide an algorithm that computes in a finite number of steps the look-ahead knowledge of the delays (i.e., routing) necessary to achieve controllability and stabilizability. This generalizes well known controllability criteria for LTI systems. [ABSTRACT FROM AUTHOR]

This technical note is concerned with the problems of stability and stabilization for a class of discrete-time semi-Markov jump linear systems (S-MJLSs). The discrete-time semi-Markov kernel (SMK) is introduced, where the probability density function of sojourn-time is dependent on both current and next system mode. As a consequence, different types of distributions and/or different parameters in a same type of distribution of sojourn-time, depending on the target mode towards which the system jumps, can coexist in each mode of a SMK. The underlying S-MJLSs are therefore more general than those considered in existing studies. A new stability concept generalizing the traditional mean-square stability is proposed such that numerically testable criteria on the basis of SMK are obtained. Numerical examples are presented to illustrate the validity and advantage of the developed theoretical results. [ABSTRACT FROM PUBLISHER]

This technical note presents a novel characterization of controllability for linear time-invariant finite-dimensional systems. This characterization relates eigenvalue controllability with the continuity of the map that assigns to each closed-loop eigenvalue the smallest subspace containing the set of corresponding closed-loop eigenvectors. Application of the given characterization is illustrated on a specific case of controller-driven sampling stabilization, where the sampled system is interpreted as a discrete-time switched system and stability under arbitrary switching is ensured via simultaneous triangularization (Lie-algebraic solvability). [ABSTRACT FROM AUTHOR]

This note points out certain limitations of our results from the paper mentioned in the title, and provides a modified approach to overcome these limitations. Specifically, the observer design addressed in the aforementioned paper is, in general, only applicable to switched linear systems with invertible state reset maps and this note presents a modified algorithm for state estimation that can also handle non-invertible state reset maps. In the process, we also identify some equalities from that paper which may not hold in general for arbitrary state reset maps. [ABSTRACT FROM PUBLISHER]

Motivated by control applications relying on shared resources (such as computation time or bandwidth), we analyze the stability and robustness of discrete-time switched linear systems with stochastic commutations. We show that a wide class of shared resources control strategies can be modeled by a stochastic jump linear system involving two stochastic processes. The class of systems we study encompasses Markov chains and independent and identically distributed switching processes. For these systems, we recall existing definitions of stability and robustness, by relying on the input-to-state stability (ISS) property. We show that, for the class of systems under concern, $\delta$-moment stability is equivalent to $\delta$-moment ISS and that they both imply almost sure ISS. Several sufficient conditions are provided to guarantee these properties. Anytime control design for a translational oscillator/rotational actuator (TORA) system is used to illustrate all these concepts. [ABSTRACT FROM PUBLISHER]

In this note, the stabilization problem for a class of discrete-time switched linear systems with additive disturbances is investigated. The considered switching signals are of mode-dependent persistent dwell-time (MPDT) property and the disturbances are assumed to be amplitude-bounded. By constructing a quasi-time-varying (QTV) Lyapunov function, a QTV stabilizing controller is designed for the nominal system such that the resulting closed-loop system is globally uniformly asymptotically stable. In the presence of bounded additive disturbances, a MPDT robust positive invariant set is determined for the error system between the nominal system and disturbed system. A concept of generalized robust positive invariant (GRPI) set under admissible MPDT switching is further proposed for the error system. It is demonstrated that the disturbed system is also asymptotically stable in the sense of converging to the MPDT GRPI set that can be regarded as the cross section of a uniform tube of the disturbed system. A numerical example is provided to verify the theoretical findings. [ABSTRACT FROM AUTHOR]

In this note, a novel actuator Fault Tolerant Control strategy for constrained discrete time linear systems subject to bounded disturbances is proposed. The scheme consists of three modules: a bank of estimators, each one associated with healthy and faulty model configurations, a logic mechanism for identifying healthy-to-faulty and faulty-to-healthy transitions and an estimate based control reconfiguration unit. The idea is to abstractly describe healthy and faulty plant configurations by means of a switching paradigm and sequences of pre-computed inner approximations of one-step controllable sets. Such regions are then on-line exploited together with a switching logic to determine the current plant configuration on the basis of the state estimate provided by the observers. [ABSTRACT FROM PUBLISHER]

We investigate the stabilizability of switched linear systems of differential-algebraic equations (DAEs). For such systems we introduce a parameterized family of switched ordinary differential equations that approximate the dynamic behavior of the switched DAE. A necessary and sufficient criterion for the stabilizability of a switched DAE system using time-dependent switching is obtained in terms of these parameterized approximations. Furthermore, we provide conditions for the stabilizability of switched DAEs via fast switching as well as using solely the consistency projectors of the constituent systems. The stabilization of switched DAEs with commuting vector fields is also analyzed. [ABSTRACT FROM PUBLISHER]

In this technical note, we study the pointwise stability of a discrete-time, matrix-valued, and stationary Markovian jump linear system. When the system is restricted to a linear subspace, we show that it is pointwise convergent if and only if it is pointwise exponentially convergent under the framework of probability and symbolic dynamics. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of modes detection for switching discrete-time linear and affine systems. A unified presentation of the model-based methods with the corresponding modes detectors is carried out and a comparative study is conducted. Next, the different notions of discernibility proposed in the literature are presented. Such notions are central since they guarantee the uniqueness of the solution delivered by the modes detectors. A complete step-by-step procedure of modes detection is proposed. The paper includes, whenever necessary, some extensions of the existing results. [ABSTRACT FROM AUTHOR]

We consider a general triplet Markov Gaussian linear system (\bf X, \bf R, \bf Y), where \bf X is an hidden continuous random sequence, \bf R is an hidden discrete Markov chain, \bf Y is an observed continuous random sequence. When the triplet (\bf X, \bf R, \bf Y ) is a classical “Conditionally Gaussian Linear State-Space Model” (CGLSSM) , the mean square error optimal filter is not workable with a reasonable complexity and different approximate methods, e.g. based on particle filters, are used. We propose two contributions. The first one is to extend the CGLSSM to a new, more general model, called the “Conditionally Gaussian Pairwise Markov Switching Model” (CGPMSM), in which \bf X is not necessarily Markov given \bf R . The second contribution is to consider a particular case of CGPMSM in which (\bf R, \bf Y ) is Markov and in which an exact filter, optimal in the sense of mean square error, can be performed with linear-time complexity. Some experiments show that the proposed method and the suited particle filter have comparable efficiency, while the second one is much faster. [ABSTRACT FROM AUTHOR]

This technical note addresses the state feedback switched control design problem for discrete-time switched linear systems. More specifically, the control goal is to jointly design a set of state feedback gains and a state dependent switching function, ensuring \cal H2 and \cal H\infty guaranteed performance. The conditions are based on Lyapunov or Riccati-Metzler inequalities, which allow the derivation of simpler alternative conditions that are expressed as LMIs whenever a scalar variable is fixed. The theoretical results are well adapted to deal with the self-triggered control design problem, where the switching rule is responsible for the scheduling of multiple sampling periods, to be considered in the communication channel in order to improve performance. This method is compared to others from the literature. Examples show the validity of the proposed technique in both contexts, switched and networked control systems. [ABSTRACT FROM PUBLISHER]