Continuous-time Networked Control Systems Research Articles

Decentralized event-triggered resilient control for a class of networked control systems under denial-of-service attacks

This paper studies the problem of resilient dynamic output-feedback control schemes for continuous-time networked control systems (NCSs). A decentralized hybrid strategy is utilized while network imperfections, external disturbances, and noise are considered. Moreover, during data transmission, a practical denial-of-service (DoS) jamming attack, which periodically disturbs the network channels, is considered. To preserve the network resources, a decentralized event-triggered mechanism is employed to transmit only the sampled signals that are required. It is assumed that outputs and control inputs of each subsystem are transmitted to the corresponding decentralized controllers and actuators, respectively, over the different individual channels based on independent triggering mechanisms. At first, the NCS is modeled as a decentralized hybrid system with exogenous disturbance and noise. Then, sufficient conditions that guarantee the [Formula: see text]-stability of the NCS in the presence of external disturbances and noise, which is resilient to periodic DoS attacks, are provided in terms of the linear matrix inequalities. Finally, sufficient conditions are derived to deal with the time-varying delays. It has been demonstrated that the proposed technique can be effectively applied to a well-known continuous stirred tank reactor (CSTR) as a benchmark example.

Passive Fault-Tolerant Control for NCSs Using Event-Triggered Approach

In this paper, the passive event-triggered control problem for networked control systems with actuator faults is of concern. A sufficient condition is proposed by a Lyapunov-Krasovskii functional, under which such type continuous-time Networked control systems with actuator faults are asymptotically stable and passive. The designing method of controller is developed by using Wirtinger inequality and linear matrix inequalities (LMIs). The given strategy can reduce the number of transmissions, thus saving the communication resources. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed method.

H∞ Control of Linear Networked and Quantized Control Systems With Communication Delays and Random Packet Losses

This article studies the H∞ control problem for linear networked and quantized control systems (NQCSs) with both communication delays and random packet losses. To deal with network-induced constraints and random packet dropouts, a novel discrete-time stochastic system model is developed for continuous-time networked control systems, and further overapproximated to a polytopic system with norm-bounded uncertainty. Based on the overapproximated system model, sufficient conditions are established for linear NQCSs in different cases to guarantee both input-to-state stability and H∞ performance with respect to the network-induced errors. Furthermore, we propose an algorithm to minimize the stability gain and the H∞ attenuation level simultaneously. Finally, a numerical example is given to illustrate the developed results.

Output feedback [formula omitted]-gain control of networked control systems subject to round-robin protocol

This paper considers the output feedback L2-gain control problem for continuous-time networked control systems subject to round-robin protocol. The sensors of the considered system are distributed over a network. Round-robin protocol is introduced to schedule the measurement information transmitted from sensors to the controller. Then the closed-loop system is modeled as a kind of time-delay system. According to Lyapunov–Krasovskii method, sufficient conditions are derived to guarantee the exponential stability and the prescribed L2-gain of the closed-loop system. The output feedback controller gains are determined efficiently by solving linear matrix inequalities. Finally, one example is reported to illustrate the advantages of the proposed design scheme.

Quantized Dynamic Output Feedback Control and $L_2$-Gain Analysis for Networked Control Systems: A Hybrid Approach

In this article, the problems of stabilization and L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -gain performance analysis for continuous-time networked control systems (NCSs) with quantization effects are addressed. The plant output and control input are quantized respectively by two different dynamic quantizers before being transmitted over networks. In order to deal with the dynamic behavior resulting from the dynamic quantizers, a hybrid system framework is adopted to remodel the NCSs. The hybrid model is flexible to the joint design of dynamic output feedback controller, nonequidistant samplers and dynamic quantizers. Furthermore, our method can effectively prevent the Zeno phenomenon on the instants of sampling and the updates of quantizer variables. By constructing a novel Lyapunov function, new sufficient conditions guaranteeing the uniformly globally asymptotic stability (UGAS) and L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -gain performance are presented in terms of matrix inequalities, respectively. Finally, two numerical examples illustrate the effectiveness of our proposed method.

Event-Triggered Stabilization of a Linear System With Model Uncertainty and i.i.d. Feedback Dropouts.

This article investigates the input-to-state stability (ISS) of continuous-time networked control systems with model uncertainty and bounded noise based on event triggering. The feedback loop is closed over an unreliable digital communication network. Feedback packets suffer from network delay and may be dropped in an independent and identically distributed (i.i.d.) way, which may harm to the concerned stability. This article focuses on a Lyapunov-based event-triggered control design scheme with the consideration of i.i.d. packet dropouts. By designing a state-dependent event-triggering threshold and updating methods, it can still ensure ISS for the concerned multidimensional system in the presence of i.i.d. packet dropouts and model uncertainty without exhibiting the Zeno behavior. Simulations are done to verify the effectiveness of the achieved results.

Delay-Dependent Algebraic Riccati Equation to Stabilization of Networked Control Systems: Continuous-Time Case.

In this paper, a delay-dependent algebraic Riccati equation (DARE) approach is developed to study the meansquare stabilization problem for continuous-time networked control systems. Different from most previous studies that information transmission can be performed with zero delay and infinite precision, this paper presents a basic constraint that the designed control signal is transmitted over a delayed communication channel, where signal attenuation and transmission delay occur simultaneously. The innovative contributions of this paper are threefold. First, we propose a necessary and sufficient stabilizing condition in terms of a unique positive definite solution to a DARE with Q > 0 and R > 0. In accordance with this result, we derive the Lyapunov/spectrum stabilizing criterion. Second, we apply the operator spectrum theory to study the stabilizing solution to a more general DARE with Q ≥ 0 and R > 0. By defining a delay-dependent Lyapunov operator, we propose the existence theorem of the unique stabilizing solution. It is shown that the stabilizing solution, if it exists, is unique and coincides with a maximal solution. Third, as an application, we derive the explicit maximal allowable delay bound for a scalar system. To confirm the validity of our theoretic results, two illustrative examples are included in this paper.

Robust sampled-data PI controller design for networked control systems

This paper focuses on investigating the robust stabilization problem for a class of continuous-time networked control systems (NCS) with sampled-data strategy through uncertain time-varying sampling rate via the proportional-integral (PI) control design. The main objective of this paper is to design a state feedback sample-data PI controller with time varying input delay such that the resulting closed-loop system is robustly asymptotically stable for all admissible uncertainties. Based on the Lyapunov stability theory, a new set of delay-dependent conditions is obtained in terms of linear matrix inequalities to determine the system stability and achieve the sampled-data PI control design. Finally, simulation results based on electronic-circuit system and mass–spring damped system are provided to demonstrate the effectiveness and the merit of the proposed design technique.

Event-Triggered Fault Detection Filter Design for a Continuous-Time Networked Control System.

This paper studies the problem of event-triggered fault detection filter (FDF) and controller coordinated design for a continuous-time networked control system (NCS) with biased sensor faults. By considering sensor-to-FDF network-induced delays and packet dropouts, which do not impose a constraint on the event-triggering mechanism, and proposing the simultaneous network bandwidth utilization ratio and fault occurrence probability-based event-triggering mechanism, a new closed-loop model for the considered NCS is established. Based on the established model, the event-triggered H ∞ performance analysis, and FDF and controller coordinated design are presented. The combined mutually exclusive distribution and Wirtinger-based integral inequality approach is proposed for the first time to deal with integral inequalities for products of vectors. This approach is proved to be less conservative than the existing Wirtinger-based integral inequality approach. The designed FDF and controller can guarantee the sensitivity of the residual signal to faults and the robustness of the NCS to external disturbances. The simulation results verify the effectiveness of the proposed event-triggering mechanism, and the FDF and controller coordinated design.

A Delay-Distribution Approach to Stabilization of Networked Control Systems

A novel delay-distribution approach is proposed for a continuous-time networked control system (NCS) with time-varying transmission delays and transmission intervals based on an input-delay approach. The real-time distribution of input delays is modeled as a continuous-dependent and nonidentically distributed (d.n.d.) process. By introducing multiple indicator functions, the NCS is represented as a hybrid system with multiple input delay subsystems. An improved Lyapunov-Krasovskii method is proposed and it additionally exploits the real-time distribution of input delays by means of estimating the cross-product integral terms of the infinitesimal of the Lyapunov functional using a new bounding technique. Delay-distribution-dependent sufficient conditions are derived for the deterministic exponential stability and stabilizability of the NCS, which leads to tighter bounds of input delays than existing results. The resulting controller design method is formulated as an iterative linear optimization algorithm subject to linear matrix inequality constraints. Finally, numerical examples are presented to substantiate the effectiveness and advantage of the results.

Fault detection filter design for data reconstruction-based continuous-time networked control systems

This paper is concerned with observer-based fault detection filter design for a continuous-time networked control system (NCS) by taking packet dropouts and network-induced delays into account. An observer-based fault detection filter and a reference residual model are introduced to construct a novel model for the continuous-time NCS. To reduce the time for fault detection, a new data reconstruction scheme is proposed and the corresponding closed-loop model is established. Based on the established models, new fault detection filter design criteria are derived to asymptotically stabilize the residual system. The mutually exclusive distribution characteristic of interval time-varying delays is made full use to deal with integral inequalities for products of vectors. The designed fault detection filters can guarantee the sensitivity of the residual signal to faults. Simulation results illustrate the effectiveness of the proposed observer-based fault detection filter design.

Robust reliable control design for networked control system with sampling communication

In this article, the problem of robust exponential stability and reliable stabilisation for a class of continuous-time networked control systems (NCSs) with a sample-data controller and unknown time-varying sampling rate is considered. The analysis is based on average dwell-time, Lyapunov–Krasovskii functional and linear matrix inequality (LMI) technique. The delay-dependent criteria are developed for ensuring the robust exponential stability of the considered NCSs. The obtained conditions are formulated in terms of LMIs that can easily be solved by using standard software packages. Furthermore, the result is extended to study the robust stabilisation for NCS with parameter uncertainties. A state feedback controller is constructed in terms of the solution to a set of LMIs, which guarantee the robust exponential stabilisation of NCS and the controller. Finally, numerical examples are presented to illustrate the effectiveness of the obtained results.

Fuzzy-Model-Based Quantized Guaranteed Cost Control of Nonlinear Networked Systems

This paper is concerned with the problem of guaranteed cost control for a class of continuous-time networked control systems based on the Takagi–Sugeno fuzzy model approach. In this study, network-induced transmission delays and packet dropouts are taken into simultaneous consideration. By the improved Lyapunov–Krasovskii functionals, a less-conservative delay-dependent condition is proposed for the stability analysis of the resulting closed-loop system. Furthermore, the sufficient condition under which the guaranteed cost controller exists is formulated in terms of linear matrix inequalities, and the suboptimum solution is obtained by a cone complementarity linearization algorithm. Finally, numerical examples are provided to illustrate the effectiveness of the proposed method.

The Stabilization of Continuous-Time Networked Control Systems with Data Drift

By data drift, we mean the data received by the controller may be different from that sent by the sensor, or the data received by actuator may be different from that sent by the controller. The issues of guaranteed cost control for a class of continuous-time networked control systems with data drift are investigated. Firstly, with the consideration of data drift between sensor and controller, a closed-loop model of networked control systems including network factors such as time-delay and data-dropouts is established. And then, selecting an appropriate Lyapunov function, a guaranteed cost controller in terms of linear matrix inequality (LMI) is designed to asymptotically stabilize the networked control system with data drift. Finally, simulations are included to demonstrate the theoretical results.

Modelling and observer‐based H ∞ controller design for networked control systems

This study is concerned with modelling and observer-based H∞ controller design for a continuous-time networked control system with network-induced delays and packet dropouts. A new model for an observer-based networked control system is first established by proposing a linear estimation-based delay compensation method. Then some controller design criteria are obtained by constructing an interval time-varying delay decomposition-based Lyapunov functional. A new bounding inequality is introduced to transfer non-linear matrix inequalities into a solvable optimisation problem. A numerical example is given to illustrate the merits and effectiveness of the obtained results.

Active-Varying Sampling-Based Fault Detection Filter Design for Networked Control Systems

This paper is concerned with fault detection filter design for continuous-time networked control systems considering packet dropouts and network-induced delays. The active-varying sampling period method is introduced to establish a new discretized model for the considered networked control systems. The mutually exclusive distribution characteristic of packet dropouts and network-induced delays is made full use of to derive less conservative fault detection filter design criteria. Compared with the fault detection filter design adopting a constant sampling period, the proposed active-varying sampling-based fault detection filter design can improve the sensitivity of the residual signal to faults and shorten the needed time for fault detection. The simulation results illustrate the merits and effectiveness of the proposed fault detection filter design.

Dynamic output feedback H ∞ control for continuous‐time networked control systems

This study is concerned with dynamic output feedback (DOF) H ∞ control for continuous-time networked control systems (NCSs). The packet dropouts and network-induced delays in the sensor-to-controller channel, and network-induced delays in the controller-to-actuator channel are taken into account. A linear estimation-based method is proposed to estimate the measurement output, and the non-uniform distribution characteristic of the measurement output arrival instant is taken into full consideration to establish a new model for the considered NCSs. Based on the newly established model and a new Lyapunov functional, the problem of DOF controller design is studied. A numerical example is given to illustrate the effectiveness of the proposed DOF controller design.

Communication channel sharing‐based network‐induced delay and packet dropout compensation for networked control systems

This study is concerned with the problem of dual communication channels sharing-based network-induced delay and packet dropout compensation for continuous-time networked control systems (NCSs). By introducing the dual communication channels sharing-based compensation method, a new closed-loop model for continuous-time NCSs, which can receive more than one control input during a control input updating time interval, is established. Based on the newly established model and a new Lyapunov functional, an effective controller design criterion is derived to optimise the H ∞ performance of the considered systems. Even for NCSs without considering network-induced delay and packet dropout compensation, the newly derived controller design method is also applicable. Two numerical examples are given to illustrate the merits and effectiveness of the proposed compensation method.

Delay-dependent H ∞ stabilisation criterion for continuous-time networked control systems with random delays

This article mainly addresses the H ∞ stabilisation problem for a class of networked control systems (NCSs) with random input delays in the continuous-time domain. A Markov jump linear system (MJLS) model with two jump parameters is developed which takes both the sensor-to-controller and controller-to-actuator delays into account. Based on such a MJLS, a new Lyapunov–Krasovskii functional is proposed to establish a delay-dependent H ∞ stabilisation criterion in terms of linear matrix inequalities (LMIs), and a mode-dependent state-feedback controller of NCSs can be determined. Two numerical examples are included to illustrate the derived result.

Robust H ∞ model reference tracking control for networked control systems with communication constraints

This paper studies the problem of H∞ model reference tracking control for continuous time networked control systems (NCSs) with communication constraints. By using the continuous Jensen inequality, linear matrix inequality (LMI)-based H∞ model reference tracking controller design for nominal NCSs with controller-to-actuator communication constraints is presented, and a new method is proposed to design H∞ model reference tracking controllers for NCSs with both controller-toactuator and sensor-to-controller communication constraints. The results are also extended to NCSs with norm-bounded parameter uncertainties. The merits of the proposed methods lie in their less computational complexity and less conservatism, which are achieved by adopting continuous Jensen inequality and proposing new controller design methods, respectively. The simulation results illustrate the effectiveness of the proposed H∞ model reference tracking controller design for NCSs with communication constraints.