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A networked output feedback loop subject to packetized transmissions of the output signal is considered. Based on the small gain theorem, an easy‐to‐use stability criterion covering two important cases is presented. In the first case a packet numbering mechanism is employed whereas in the second case neither packet numbering nor synchronization between sender and receiver is assumed. The analysis makes use of acausal subsystems and deduces the optimal constant time delay with respect to the minimization of the ℓ2 gain due to uncertain packet delays. This additional delay is then used in a nominal controller design such that additional admissible packet delay variations introduced by the network are maximized. A simulation example of a networked control system with a filtered Smith predictor illustrates the application of the proposed criterion. It is shown that the proposed novel technique is less‐conservative than existing stability criteria based on the small gain theorem.

This article concerns the event‐triggered fuzzy filter design for Takagi‐Sugeno (T‐S) fuzzy systems subject to deception attacks under the stochastic multiple time‐varying delays. A sequen...

This paper mainly focuses on the optimal control and stabilization for networked control systems with packet dropout, measurement delay and input delay. The main contributions are two‐fold...

Summary Further on the controllability of networked multiple-input–multiple-output systems, an efficient, necessary, and sufficient condition is derived, where the network topology is directed and weighted and the nodes are higher-dimensional linear time-invariant systems. The new condition is easier to verify, which explicitly shows the effects of the network topology, node-system dynamics, external control inputs, and inner interactions on the controllability of the whole networked system. For networked multiple-input–multiple-output systems in several specific topologies, the corresponding conditions are expressed more precisely. The effectiveness of the conditions is demonstrated through several examples.

Summary This paper presents an event-triggered predictive control approach to stabilize a networked control system subject to network-induced delays and packet dropouts, for which the states are not measurable. An observer-based event generator is first designed according to the deviation between the state estimation at the current time and the one at the last trigger time. A predictive control scheme with a selector is then proposed to compensate the effect of network-induced delays and packet dropouts. Sufficient conditions for stabilization of the networked control system are derived by solving linear matrix inequalities and the corresponding gains of the controller and the observer are obtained. It is shown that the event-triggered implementation is able to realize reduction in communication and save bandwidth resources of feedback channel networks. A simulation example of an inverted pendulum model illustrates the efficacy of the proposed scheme.

Summary In this work, a new self-triggered model predictive control (STMPC) algorithm is proposed for continuous-time networked control systems. Compared with existing STMPC algorithms, the proposed STMPC is implemented based on linear interpolation (first-order hold) rather than the standard zero-order hold, which helps further reduce the difference between the self-triggered control signal and the original time-triggered counterpart and thus reduce the rate of triggering. Based on the first-order hold implementation, a self-triggering condition is derived and the corresponding theoretical properties of the closed-loop system are analyzed. Finally, the comparison between the proposed algorithm and the zero-order hold–based STMPC is carried out through both theoretical analysis and a simulation example to illustrate the effectiveness of the proposed method.

To manage with large communication delays in the presence of scheduling protocols from sensors to actuators, the time-delay approach to continuous-time decentralized NCSs has been developed in Chap. 7. The results of Chap. 7 are confined to stability analysis. This chapter is devoted to extend the time-delay approach to decentralized stabilization and \(H_{\infty }\) control of large-scale discrete-time systems with multiple local communication networks connecting sensors, controllers and actuators.

Summary This paper is devoted to the problem of designing a sparsely distributed sliding mode control for networked systems. Indeed, this note uses a distributed sliding mode control framework by exploiting (some of) other subsystems' information to improve the performance of each local controller so that it can widen the applicability region of the given scheme. To do so, different from the traditional schemes in the literature, a novel approach is proposed to design the sliding surface, in which the level of required control effort is taken into account during the sliding surface design based on the ℋ2 control. We then use this novel scheme to provide an innovative less-complex procedure that explores sparse control networks to satisfy the underlying control objective. Besides, the proposed scheme to design the sliding surface makes it possible to avoid unbounded growth of control effort during the sparsification of the control network structure. Illustrative examples are presented to show the effectiveness of the proposed approach.

A method is proposed for scheduling sensor accesses to the shared network in a networked control system. The proposed method determines the access...

The paper proposes a new robust networked controller, for example suitable for packet data transfer control in wireless sensor networks with uncertain delays. The method adjusts a linear H2 loop-shaping design towards consistency with a long delay and a saturation in the feedback loop, where the saturation results because of the one-directional packet flow. Feedforward from a measurable disturbance is integrated in the design. By formally extending recently derived sensitivity function constraints to include feedforward, a subset of the L2 stability region is pre-computed using the stability inequality of the Popov criterion. A robustly stable controller is then selected in the stability region. The new controller design method is applied to internet data flow control supporting 5G wireless connectivity. The results indicate a possible enhancement of the robustness against feedback delay uncertainty with a factor of 3-4. Such robustness should be beneficial for example for packet data relying with variable routing over ad hoc wireless sensor networks.

Summary In this paper, the multi-tasking optimal control problem is addressed in the delta-domain for a class of networked control systems (NCSs) with external disturbances. A delta-domain model is proposed to describe the NCSs with random packet dropouts and long-time delay, and the so-called e-Nash equilibrium is employed to quantify the impacts from the disturbances on the underlying NCSs. The multi-tasking optimal control strategies are developed and the upper bound for the e-Nash equilibrium is provided explicitly. Some simulation results on the two-area load frequency control system are given to show the validity and applicability of the proposed method. Copyright © 2016 John Wiley & Sons, Ltd.

This article is concerned with observer and controller design for networked control systems, where the considered plant refers to a class of discrete-time communication delay Markovian jump systems. In the study, random packet losses and output quantization are considered simultaneously. The packet losses considered here includes sensor to controller and controller to actuator sides, which are modeled as two Bernoulli distributed white sequences, respectively. An observer-based control scheme is developed to stabilize the closed-loop systems. Finally, an illustrative example is provided to show the applicability of the proposed control method. © 2016 Wiley Periodicals, Inc. Complexity, 2016

Summary This paper proposes a separation method of a transmission delay and data packet dropouts from a lumped input delay in the stability problem of a networked control system, where both the transmission delay and the data packet dropouts are involved. By modeling data packet dropouts as sampling processes and the transmission delay as a state delay, the networked control system is represented as a sampled-data system with aperiodic sampling and a state delay. In order to separate the state delay and the sampling, the sampled-data system is transformed into a new system with an integral operator, where the sampling is embedded into the integral operator. By investigating the integral operator's gain and passivity, a novel Lyapunov functional is constructed to address the stability problem. The obtained stability results are dependent on both the data packet dropouts and the time delay. A numerical example is provided to demonstrate that the stability results are less conservative than some existing ones. Copyright © 2016 John Wiley & Sons, Ltd.

Summary In this paper, we investigate the problems of stabilization of networked control systems with quantization and actuator saturation via delta operator approach. The definition of the domain of attraction for delta operator systems is introduced to analyze the stochastic stability of the closed-loop networked control systems. The quantizer is a uniform one with arbitrary quantization regions, and the packet dropout process is modeled as a Bernoulli process. On the basis of the zoom strategy and Lyapunov theory in delta domain, sufficient conditions are given for the closed-loop delta operator systems to be mean square stable, and the feedback controllers are designed to ensure the stability of networked control systems. A single link direct joint driven manipulator model is presented to show the effectiveness of the main results. Copyright © 2016 John Wiley & Sons, Ltd.

Summary The problem of H∞ output tracking control over networked control systems (NCSs) with communication limits and environmental disturbances is studied in this paper. A wide range of time-varying stochastic problem arising in networked tracking control system is reduced to a standard convex optimization problem involving linear matrix inequalities (LMIs). The closed-loop hybrid NCS is modeled as a Markov jump linear system in which random time delays and packet dropouts are described as two stochastic Markov chains. Gridding approach is introduced to guarantee the finite value of the sequences of transmission delays from sensor to actuator. Sufficient conditions for the stochastic stabilization of the hybrid NCS tracking system are derived by the LMI-based approach through the computation of the optimal H∞ performance. The mode-dependent robust H∞ output tracking controller is obtained by the optimal iteration method. Numerical examples are given to demonstrate the effectiveness of the proposed robust output tracking controller for NCS. Copyright © 2016 John Wiley & Sons, Ltd.

This paper addresses the design of a model-based event-triggered sliding mode control strategy of adaptive type. The overall proposal can be regarded as a networked control scheme, because one of the design objectives is to reduce the number of transmissions of the plant state over the network used to construct the control loop. The key idea consists in using the actual plant state or the state of a suitably updated nominal model of the plant to generate the control variable, depending on the magnitude of the sliding variable. The proposed adaptive control scheme proves to be capable of steering the sliding variable to a boundary layer of the sliding manifold in finite time, in spite of the presence of bounded uncertainties with unknown bounds. When the sliding variable is confined within the boundary layer, the nominal model state is used to compute the control variable. Then, a continuous control can be analytically determined and applied, which provides a beneficial chattering alleviation effect. The proposed networked control scheme is theoretically analyzed and assessed in simulation with satisfactory results. Copyright © 2016 John Wiley & Sons, Ltd.

The problem of a guaranteed cost controller design of networked control systems under transmission control protocol TCP is derived. To improve the overall performance of the networked control system, a scheme to simultaneously control the plant and the network is presented. An analytical TCP model is used to design active queue management AQM to achieve the desired queue length, which is helpful in reducing the variation of the network induced delay. Moreover, a new closed loop model of networked control systems is obtained by augmenting the TCP communication model with the control plant. The guaranteed cost controller is addressed in terms of a linear matrix inequality LMI to render the system asymptotically stable based on Lyapunov-Krasovskii theory and weighted technology. Finally, numerical simulations are included to demonstrate the theoretical results.

A multi-hop control network (MHCN) is a control system in which plants and controllers are connected through a multi-hop wireless network modeled by a directed graph. In this paper, based on the MLD (mixed logical dynamical) framework, which is one of the powerful methods in hybrid systems control, we propose a modeling method and an optimal control method of MHCNs. First, a directed graph in MHCNs and a switch of the control input are modeled by a pair of a linear state equation and a linear inequality with binary variables. Thus, the MLD model expressing a given MHCN is derived. Next, using the MLD model, the optimal control problem is transformed into a mixed integer quadratic programming problem. Finally, numerical examples are presented. The proposed method provides us a basic result for control of MHCNs. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Summary In this paper, an event-triggered model predictive networked scheme is proposed to control traffic in freeway networks. The freeway network is a spatially distributed system in which sensors and actuators act locally on portions of the overall system; measurements and control actions are transmitted to/from the feedback controllers via a shared communication network. In this sense, the considered plant can be properly controlled by relying on a design framework typical of networked control systems, a major feature of which is the necessity of taking care of both the computational effort and the communication effort. The proposed control scheme allows to reduce the computational load with a feedback model predictive controller in which suitable triggering conditions are defined. As for the communication effort, local triggering conditions are included in sensors, inducing transmissions of the system state only when such conditions are verified. The robustness properties of the controlled system are investigated in the paper by analyzing the input-to-state practical stability of the plant under the action of the proposed control strategy. The effectiveness of this proposal is also analyzed via simulation. Copyright © 2015 John Wiley & Sons, Ltd.

This article deals with the problem of nonfragile H∞ output tracking control for a kind of singular Markovian jump systems with time-varying delays, parameter uncertainties, network-induced signal transmission delays, and data packet dropouts. The main objective is to design mode-dependent state-feedback controller under controller gain perturbations and bounded modes transition rates such that the output of the closed-loop networked control system tracks the output of a given reference system with the required H∞ output tracking performance. By constructing a more multiple stochastic Lyapunov–Krasovskii functional, the novel mode-dependent and delay-dependent conditions are obtained to guarantee the augmented output tracking closed-loop system is not only stochastically admissible but also satisfies a prescribed H∞-norm level for all signal transmission delays, data packet dropouts, and admissible uncertainties. Then, the desired state-feedback controller parameters are determined by solving a set of strict linear matrix inequalities. A simple production system example and two numerical examples are used to verify the effectiveness and usefulness of the proposed methods. © 2015 Wiley Periodicals, Inc. Complexity, 2015

In this paper, we consider a multi-sensor networked control configuration with linear plant which is affected by a bounded additive disturbance. Shared network is used for the communication between sensors and controller. It is assumed that the sensors are prone to abrupt faults, while the controller's input may be updated with a varying time-delay. In order to identify and isolate the sensors providing faulty information, we equip the controller with a set-based detection and isolation routine. Furthermore, in the case when the network induces time-delays, control is performed based on the knowledge we have on the mathematical model of the plant. In the presence of model inaccuracies or disturbance, such a control action may not guarantee satisfying performance of the system. Therefore, a stabilising controller with delay compensation has been designed. The functioning of the proposed control algorithm has been illustrated through an example. Copyright © 2015 John Wiley & Sons, Ltd.

Summary In this paper, the problem of H∞ output tracking control for networked control systems with random time delays and system uncertainties is investigated. Effective sampling instant that is tightly related with transmission delay from sensor to actuator is proposed to ensure that the random variable time delay is always shorter than one effective sampling period. By using both active time-varying sampling period strategy and hybrid node-driven mechanism, the switching instant is coincided with the effective sampling instant. An augmented time-varying networked tracking system model is provided by including the output tracking error as an additional state. However, random transmission delay causes indeterminate sampling period, which induces infinite subsystems. Gridding approach is introduced to transform the continuous time axis into discrete-time sequences, which guarantees the finite number of switching rules. By employing multiple Lyapunov–Krasovskii functions, linear matrix inequality (LMI)-based output tracking H∞ performance analysis is presented, and robust switching H∞ model reference tracking controller for networked control systems with communication constraints and system uncertainties is designed to guarantee asymptotic tracking of prescribed reference outputs while rejecting disturbances. Finally, simulation results illustrate the correctness and effectiveness of the proposed approaches. Copyright © 2015 John Wiley & Sons, Ltd.

Summary In this paper, the stabilization problem of a class of nonlinear networked systems with time-delay and quantization through sampled-data control is investigated. With sampled-data control, sufficient conditions to guarantee the trivial solution of the nonlinear networked system to be asymptotically stable without any quantization or with uniform quantization are derived. Finally, an example of a continuous-time nonlinear system controlled through a digital controller and a communication channel is given to illustrate the effectiveness of the proposed control methods. Copyright © 2015 John Wiley & Sons, Ltd.

Summary The problem of resilient controller design for a class of networked control system based on passivity theory is presented. By using the Lyapunov–Krasovskii stability theory and linear matrix inequality approach, a set of sufficient conditions for the existence of state feedback controllers is derived. The networked control system under consideration is modeled by taking the network-induced imperfections like packet dropouts and transmission delays as a single time-varying delay. The controller is considered with a stochastic fluctuations in its gain matrix by using the Bernoulli distributed white sequence with time-varying probability measures. The probability-dependent sufficient conditions are established to guarantee the resulting closed-loop system to be stochastically stable with a prescribed mixed and passivity performance criterion. The results are expressed in the form of convex optimization problem subject to the set of LMIs, which can be easily solved by using some standard numerical packages. Finally, a numerical example by using the high-incidence research model is presented to illustrate the effectiveness and applicability of the theoretical results. Copyright © 2015 John Wiley & Sons, Ltd.

The problem of stabilization for wireless networked control system (NCS) with packet dropout and time delay is studied in this article. The impulsive control law for the NCS is defined with time delay and impulse. Using a switching model, the network-induced imperfections can be treated as three switching subsystems. Therein, in the case of packet dropout, the control law use the previous state via the first-order hold. The impulsive control law is designed using the switched system approach and the average dwell time method. The obtained sufficient conditions which can guarantee the exponential stability of switched system are in the form of linear matrix inequalities. Finally, a numerical example is used to demonstrate the merits and applicabilities of the proposed method. © 2015 Wiley Periodicals, Inc. Complexity, 2015

This paper is concerned with fuzzy decentralized control of a class of large-scale networked dynamic systems with network-induced time delays, missing measurements and external disturbances. Nonlinear systems are modeled in Takagi-Sugeno T-S form. Fuzzy decentralized state feedback controllers are developed. A sufficient condition on stochastic stability with prescribed H∞ performance for the closed-loop control system is obtained by using the Lyapunov function method. The constructive design of the controller is expressed in terms of linear matrix inequalities. Finally, numerical simulations are provided to illustrate the results of this paper.

In this paper, a new model is proposed to describe networked control systems NCS with delays and quantization errors. Firstly, the non-idealizations are unified in the classic robust control framework and the entire system is modeled as a discrete system closed via a block uncertainty. Then, the stability criteria are derived using small gain theorem, µ tool and integral quadratic constraint IQC method, respectively. Finally, a simulation and a numerical example are provided to demonstrate the effectiveness of the proposed methods. This work is supported by the Science Foundation of China University of Petroleum, Beijing No.YJRC-2013-11 and National Natural Science Foundation NNSF of China under Grant 61374033.

Summary The problem of H∞ control for networked Markovian jump system under event-triggered scheme is studied in this paper. In order to reduce the utilization of limited network bandwidth, a dynamic discrete event-triggered scheme to choose the transmitted data is designed. A Markovian jump time-delay system model is employed to describe the event-triggered scheme and the network related behavior, such as transmission delay, data package dropout, and disorder. Furthermore, a sufficient condition is derived to guarantee that the resulting closed-loop system is stable and has a prescribed performance index. A co-design method for the H∞ controller and the event-triggered scheme is then proposed. The effectiveness and potential of the theoretic results obtained are illustrated by a simulation example. Copyright © 2014 John Wiley & Sons, Ltd.

Summary This paper investigates the stabilization problem for networked control systems (NCSs) with communication constraint and packet loss. The communication constraint considered is that only one network node is allowed to access a shared communication channel during one time-slot, and a feedback control is performed with only partially available measurements and control inputs. By taking random packet loss into consideration, a stochastic switched system model is presented to describe the NCS. A sufficient condition is derived for the NCS to be mean-square exponentially stable, and it is shown that the system performance specified by the exponential decay rate critically depends on the network accessing rates (NARs) of the network nodes and the packet loss probability. The state feedback controller and scheduling protocol, which allocates the NARs, are co-designed such that the NCS achieves a minimal decay rate. Finally, an illustrative example is given to show the effectiveness of the proposed design approach. Copyright © 2014 John Wiley & Sons, Ltd.

This article studies the problem of observer-based dissipative control problem for wireless networked control systems NCSs. The packet loss and time delay in the network are modeled by a set of switches, using that a discrete-time switched system is formulated. First, results for the exponential dissipativity of discrete-time switched system with time-varying delays are proposed by using the average dwell time approach and multiple Lyapunov-Krasovskii function. Then, the results are extended to drive the controller design for considered wireless NCS. The attention is focused on designing an observer-based state feedback controller which ensures that, for all network-induced delay and packet loss, the resulting error system is exponentially stable and strictly Q,S,R dissipative. The sufficient conditions for existence of controllers are formulated in the form of linear matrix inequalities LMIs, which can be easily solved using some standard numerical packages. Both observer and controller gains can be obtained by the solutions of set of LMIs. Finally, numerical examples are provided to illustrate the applicability and effectiveness of the proposed method. © 2014 Wiley Periodicals, Inc. Complexity 21: 297-308, 2015

In this paper we study the fault tolerant control FTC problem on wireless networked control systems WNCSs which have been aware of a bright and broad prospect and taken as a development trend of automation industry. We aim at finding an FTC strategy which makes the WNCSs satisfy a quadratic cost function. The FTC law is designed to be related with the system state and the fault. Considering the system state and the fault may be physically unaccessible in the actual control process, an estimation scheme is proposed to estimate the system state and fault simultaneously. Finally, an experimental application is presented to demonstrate the effectiveness of the proposed method.

Summary This paper focuses on a new H∞ controller design issue for networked control systems with external disturbance as well as random time delays and packet dropouts in forward and feedback channels, which are modeled by multiple Markov chains in a unified style. The output feedback controller is designed to stabilize the networked control system and also achieves the prescribed H∞ disturbance attenuation level. The addressed controller design problem is transformed into a nonlinear minimization problem with LMI constraints. An illustrative example is provided to show the effectiveness of the proposed methods. Copyright © 2014 John Wiley & Sons, Ltd.

SUMMARY The paper studies the problem of mixed H2/H∞ control for a class of nonlinear discrete-time networked control systems. By using the indicator function method, random network-induced delays and stochastic packet dropouts are taken into account in a unified framework in the designed mixed H2/H∞ controller. In the presences of random transmission delays, stochastic packet dropouts and all admissible disturbances, the resulting closed-loop system is stochastically stable in mean square and attains the prescribed H2 and H∞ performances. The designed mixed H2/H∞ controller can be obtained by solving a set of feasible linear matrix inequalities. Finally, a numerical example is provided to show the usefulness and effectiveness of the developed method. Copyright © 2014 John Wiley & Sons, Ltd.