Discrete Event-triggered Communication Scheme Research Articles

Research on Dual Security Control for a Non-Linear CPS with Multi-Objective Constraints under DoS Attack and Actuator Fault: An Active-Passive Attack-Tolerant Approach

Based on the discrete event-triggered communication scheme (DETCS), a codesign method of dual security control and communication for the non-linear cyberphysical system (CPS) with denial-of-service (DoS) attack and actuator fault is studied under multi-objective constraints. First, to effectively distinguish DoS attacks with different energy levels, the DoS attack detection method is established based on the maximum allowable delay of the system. Second, a non-linear CPS dual security control framework that integrates active-passive attack tolerance for DoS attack and active fault tolerance for actuator fault is constructed. Third, the low-energy DoS attack is regarded as a special kind of time delay, and a robust observer for the estimation of system states and actuator fault is designed, and a codesign method of passive attack tolerance, active fault tolerance, and communication is proposed. Furthermore, a correction compensation algorithm of control quantity is proposed for high-energy DoS attack based on the PID idea to make active-passive attack tolerance more effective. Finally, the effectiveness of the proposed method is verified by the simulation of a quadruple-tank model.

Event-triggered-based adaptive sliding mode control for networked linear control systems

This paper investigates the robust stabilization of the adaptive sliding mode control for a class of linear systems subjected to external disturbance via event-triggered communication (ETC) scheme. First, in order to reduce the bandwidth utilization, a discrete ETC scheme is proposed and the networked sliding mode function is derived using the ETC scheme. Based on the derived sliding mode function, a reduced-order networked sliding mode dynamics with communication delay is established. Second, by constructing a Lyapunov–Krasovskii functional (LKF), asymptotic stability and stabilization criteria of the reduced-order sliding mode dynamics are given in the form of linear matrix inequalities. According to the stabilization result, a novel event-triggered-based adaptive sliding mode controller is designed while guaranteeing the reachability of the sliding surface. Finally, simulation results illustrate the effectiveness and merit of the developed method.

Event-triggered L1 filtering for uncertain networked control systems with multiple sensor fault modes

Considering the influence of sensor fault modes on the system performance in communication network, under the discrete event-triggered communication scheme (DETCS), the problems of the robust [Formula: see text] filtering for a class of uncertain networked control systems (NCSs) with multiple sensor fault modes and persistent and amplitude-bounded disturbance constraints are investigated. A set of stochastic variables are adopted to describe the sensor faults, the filtering error system is established, which characterizes the effects of sensor faults and DETCS. By constructing an appropriate delay-dependent Lyapunov-Krasovskii functional, new results on stability and robust [Formula: see text] performance are proposed for the filtering error system according to Lyapunov theory and the integral inequality method, and the co-design method for gaining the desired [Formula: see text] filter parameters and event-triggering parameters is given in terms of linear matrix inequalities (LMIs). We notice that with the structrue of Lyapunov-Krasovskii functional which considers the piecewise-linear sawtooth structure characteristic of transmission delay, a less conservative result is obtained. Finally, three examples are provided to illustrate the feasibility of the proposed method.

Co-design between robust L 1 fault-tolerant control and discrete event-triggered communication scheme for networked control systems with transmission delay and quantisation

In order to take into account both the system performance and economical utilisation of network resources, under the discrete event-triggered communication scheme, the problems of the robust fault-tolerant control for a class of uncertain networked control systems with actuator fault constraint are investigated. In consideration with the imperfect networked environment with transmission delay and quantisation, a model of the error dependent networked closed-loop fault system is established. By constructing an appropriate delay-dependent Lyapunov–Krasovskii functional, the sufficient condition for the existence of robust fault-tolerant controller is obtained for an error dependent networked closed-loop fault system, and a co-design method for gaining the discrete event-triggered parameter and fault-tolerant controller is proposed in terms of linear matrix inequalities. Notice that the structure of Lyapunov–Krasovskii functional which considers the piecewise-linear sawtooth structure characteristic of transmission delay, a less conservative result is obtained. Finally, simulation examples are provided to illustrate the feasibility of the proposed method.

Research on Satisfactory Integrated Design of Event-Triggered Fault Accommodation and Network Communication Saving for NCSs With Actuator Saturation Under Non-Uniform Transmission

Under the non-uniform transmission period, the satisfactory integrated design problem combining active fault-tolerant control and network communication saving was studied for nonlinear network control systems (NCSs) with actuator saturation constraints based on discrete event-triggered communication scheme (DETCS). First, the model of a non-uniform transmission closed-loop fault system was established, which includes the network attribute, actuator saturation constraints, estimation value of fault and state, event-triggered condition, disturbance information and so on. Second, the method of fault estimation with H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> -performance was proposed by a continuous time state observer. Furthermore, a satisfactory integrated design method integrating event-triggered fault accommodation and network communication saving was given for non-uniform transmission nonlinear NCSs with α-stability and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> /H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> performance. Finally, a MATLAB simulation was conducted to verify the effectiveness and feasibility of the proposed method based on a nonlinear NCS example. In order to reflect the real network transmission circumstances fully, a semi entity experimental platform was also built to verify the effectiveness and feasibility of the proposed method.

Adaptive event-triggered H∞ fuzzy filtering for interval type-2 T–S fuzzy-model-based networked control systems with asynchronously and imperfectly matched membership functions

This paper is concerned with the network-based H∞ fuzzy filtering for non-linear systems with parameter uncertainties under a novel adaptive discrete event-triggered communication scheme (DETCS). Based on interval type-2 (IT2) Takagi–Sugeno (T–S) fuzzy model, the non-linear systems with parameter uncertainties are represented as a class of IT2 T–S fuzzy systems. In the design process, a novel adaptive DETCS is proposed to reduce the usage of system resources and adapt the variation of plant output, and a novel networked IT2 T–S fuzzy filter is applied to improve the flexibility of filter design. By employing the time-delay systems modeling method, the filtering-error-system is modeled as a class of interval time-varying delayed IT2 T–S fuzzy systems with asynchronously and imperfectly matched membership functions, and further conditionally expressed as a favorable form. Then, some relaxed stability criteria are established to determine that this class of delayed IT2 T–S fuzzy systems is asymptotically stable with a prescribed H∞ disturbance attenuation performance. Also, the co-design of parameter matrices of adaptive DETCS and filter is implemented. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed method.

Research on secure control and communication for cyber-physical systems under cyber-attacks

This paper investigates the co-design problem of secure control and communication quality for cyber-physical systems (CPSs) to solve unavoidable problems, in which both actuator faults and cyber-attacks occur in practical implementations of CPSs. Firstly, based on the discrete event-triggered communication scheme (DETCS), a system framework for active fault-tolerant and passive attack-tolerant control is proposed. Then, a model of a closed-loop CPS is established that integrates a triggering condition, actuator faults and cyber-attacks into a single uniform framework. Secondly, using the partition and definition of different delay functions, the appropriate Lyapunov functions are constructed based on the time-delay system theory, and design methods for a robust observer with passive attack tolerance for estimation of the state and fault, and an active fault-tolerant and passive attack-tolerant controller are developed in terms of linear matrix inequality. In this way, the co-design goal involving active fault tolerant control, passive attack-tolerant control and the communication network is achieved. Finally, a simulation experiment of a quadruple-tank is carried out to demonstrate the effectiveness of the proposed method.

Event-triggered fault detection filter design for nonlinear networked systems via fuzzy Lyapunov functions

This paper investigates the problem of event-triggered fault detection filter design for nonlinear networked control systems with both sensor faults and process faults. First, Takagi–Sugeno (T–S) fuzzy model is utilized to represent the nonlinear systems with faults and disturbances. Second, a discrete event-triggered communication scheme is proposed to reduce the utilization of limited network bandwidth between filter and original system. At the same time, considering network-induced delays and event-triggered scheme, a novel T–S fuzzy fault detection filter is constructed to generate a residual signal, which has nonsynchronous premise variables with the original T–S fuzzy system. Then, the fuzzy Lyapunov functional based approach and the reciprocally convex approach are developed such that the obtained sufficient conditions ensure that the fuzzy fault detection system is asymptotically stable with H∞ performance and is less conservative. All the conditions are given in terms of linear matrix inequalities (LMIs), which can be solved by LMI tools in MATLAB environment. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed results.

Hybrid Active-Passive Robust Fault-Tolerant Control of Event-Triggered Nonlinear NCS

In this paper, the authors aimed to analyze uncertain nonlinear networked control systems (NCS) under discrete event-triggered communication scheme (DETCS), in which an integrated design methodology between robust fault detection observer and active fault-tolerant controller is proposed. Moreover, the problem of hybrid active–passive robust fault-tolerant control, which integrated passive fault-tolerant control, fault detection, and controller reconstruction, is researched. In consideration of the impact of uncertainties and network-induced delay on system performance, a new class of uncertain nonlinear NCS fault model is established based on T-S fuzzy model. By employing Lyapunov stability theory,H∞control theory, and linear matrix inequality method, the fault detection observer and hybrid fault-tolerant controller are both appropriately designed. In addition, the sufficient condition that guaranteed the asymptotically robust stability of nonlinear NCS against any actuator failures is deduced. Finally, a numerical simulation is provided to show the effectiveness of the proposed methods.

The Multiobjective Constraint Fault-Tolerant Control of Event-Triggered Nonuniform Transmission for Networked T-S Fuzzy System

Considering the actuator saturation, the problem of multiobjective constraint fault-tolerant control is studied for networked Takagi-Sugeno (T-S) fuzzy system with nonuniform transmission period under the discrete event-triggered communication scheme (DETCS). A closed-loop T-S fuzzy model, which includes numerous factors such as actuator saturation, actuator failure, event-triggered condition, nonuniform transmission period, and time-delay, is established by transferring the effect caused by the nonuniform update period on the system performance into the effect on the system time-delay. Two stability criterions and two codesign methods for the networked closed-loop failure T-S fuzzy system are developed based on a discontinuous Lyapunov-Krasovskii function, a kind of reciprocally convex technology, a kind of linear convex combination, Jessen inequality, and Wirtinger’s inequality. A feasible experimental solution is presented to verify the effectiveness of the proposed method.

Network-based H∞ control for singular systems with event-triggered sampling scheme

In this paper, the problem of event-triggered H∞ control is investigated for networked singular systems. To make full use of the characteristics of networked control system, a discrete event-triggered communication scheme, which only needs to supervise the system state in discrete instants, is proposed. The sampling-interval is employed to unify the networked singular system and the event-triggered condition into a new time-delay system. Based on this model, sufficient criteria are derived to guarantee the networked singular system regular, impulse-free and stable with an H∞ norm bound. The corresponding state feedback controller is designed. A practical example is given to show that the proposed event-triggered scheme is more effective and useful than some existing works.

Event-triggered fuzzy filtering for a class of nonlinear networked control systems

The problem of event-triggered fuzzy filtering is investigated for a class of nonlinear networked control systems in this paper. The nonlinear networked control system is modeled as a T–S fuzzy system and a discrete event-triggered communication scheme is proposed to mitigate the utility of limited network bandwidth. A logic zero order holder is employed to choose the latest transmitted data packet and discard the disordering packet. Using time-delay system method – the discrete event-triggered communication scheme, the network-induced delay and the nonlinear system are unified into a networked T–S fuzzy time-delay system. Then, a new bounded real lemma is derived for this system based on a reciprocally convex approach. A new co-design method is developed for the triggering condition and the fuzzy filter, which guarantees the correspondent filtering error system being asymptotically stable with a prescribed disturbance attenuation level. Finally two examples are given to show the effectiveness of the proposed results.

Discrete Event-Triggered Robust Fault-Tolerant Control for Nonlinear Networked Control Systems withα-Safety Degree and Actuator Saturation

This paper deals with the discrete event-triggered robust fault-tolerant control problem for uncertain nonlinear networked control systems (NNCSs) withα-safety degree. A discrete event-triggered communication scheme (DETCS) is initially proposed, and a closed-loop fault model is subsequently established for NNCSs with actuator saturation under the DETCS. Based on an appropriately constructed delay-dependent Lyapunov–Krasovskii function, sufficient conditions are derived to guarantee the asymptotic stability of NNCSs under two different event-triggered conditions and are established as the contractively invariant sets of fault tolerance withα-safety degree. Furthermore, codesign methods between the robust fault-tolerant controller and event-triggered weight matrix are also proposed in terms of linear matrix inequality. The simulation shows that the resultant closed-loop fault NNCSs possesses a high safety margin, and an improved dynamic performance, as well as a reduced communication load. A comparative analysis of the two event-triggered conditions is discussed in the experiment section.

Robust Integrity Design for Uncertain NCS with Actuator Saturation Based on Discrete Event-Triggered Communication Scheme

This paper investigates the co-design problem of both robust integrity and the usage of communication resources for a class of actuator-saturated networked control system(NCS) based on a novel discrete event-triggered communication scheme(DETCS). First, a new model of NCS is established that parameter uncertainty, network-induced delay, actuator saturation and faults, and the state error arising from the DETCS are taken into consideration in a unified framework. Second, based on the model, the set of invariance condition of the closed-loop fault NCS with actuator saturation is proposed, which is the delay-dependent and event-dependent sufficient condition for ensuring the system stability. Then, a co-design approach which includes both robust fault-tolerant controller and the corresponding trigger weight matrix is given via linear matrix inequalities. The reciprocally convex combination lemma and the improved Jensen integral inequality are employed to deal with the derivative terms of the Lyapunov-Krasovakii functional, which can reduce the conservatism and computation of the results. Finally, a simulation example is used to demonstrate the advantage and the effectiveness of the proposed co-design approach, meanwhile, the quantitative relationship between the system performance and the communication resources is provided.

To Transmit or Not to Transmit: A Discrete Event-Triggered Communication Scheme for Networked Takagi–Sugeno Fuzzy Systems

This paper first proposes a discrete event-triggered communication scheme for a class of networked Takagi-Sugeno (T-S) fuzzy systems. This scheme has two main features: 1) Whether or not the sampled state should be transmitted is determined by the current-sampled state and the error between the current-sampled state and the latest transmitted state. Compared with those in a periodic time-triggered communication scheme, the communication bandwidth utilization is considerably reduced while preserving the desired control performance; and 2) it is a discrete event-triggered communication scheme due to the fact that the triggered conditions are only measured and checked at a constant sampling period. Compared with a continuous event-triggered communication scheme, the special hardware for continuous measurement and computation is no longer needed. Second, a networked T-S fuzzy model is delicately constructed, which not only considers nonuniform time scales in the networked T-S fuzzy model and the parallel distributed compensation fuzzy control rules but includes the aforementioned state error as well. Third, a stability criterion and a stabilization criterion about the networked T-S fuzzy system are derived, respectively. The stability criterion and stabilization criterion can provide a tradeoff to balance the required communication resource and the desired performance: Lowering the desired performance allows the network to allocate more limited bandwidth to other nodes in need. Finally, a numerical example is given to show the effectiveness of the proposed method.