Event-triggered Dynamic Output Feedback Control Research Articles

Decentralized stabilization of a class of large scale networked control systems based on modified event-triggered scheme

In this paper, a new method is proposed to design a decentralized $$H_\infty $$ dynamic output feedback controller for a class of large scale event-triggered networked control systems. The networked control system is modeled based on a modified event-triggered scheme. In addition to the time interval between triggers, the characteristics of network communication are also considered. The time delay and packet loss are two important phenomena and are inevitable in networked control systems. A time delay model is presented to collect all types of delay and packet loss in the event-triggered networked control system. Also, dynamic delays between subsystems are considered. Based on this model, some new sufficient conditions are given to guarantee the stability and the $$H_\infty $$ performance, based on LKF and integral estimation. The mixed Wirtinger–Jensen inequality is proposed to derive less conservative synthesis conditions in terms of linear matrix inequalities. A decentralized event-triggered dynamic output feedback controller is designed based on the required stability conditions. Simulation results of a two coupled inverted pendulum and continuous stirred-tank reactors show the effectiveness of the proposed method, which guarantees the asymptotical stability with less number of data packets and the more maximum allowable time interval between packet releases, in comparison with the common networked control schemes.

Event-triggered output feedback control for discrete Markov jump systems under deception attack

An event-triggered dynamic output feedback control (DOFC) problem for discrete Markov jump systems is considered, where both measurement and control channel are under the deception attacks. To reduce the data traffic in the channel and the control actions against attack, two event-triggered schemes (ETSs) are implemented on sensor and controller node asynchronously. And two quantizers are installed independently. Sufficient criterions for ensuring asymptotic stability of the networked control systems (NCSs) are obtained by deriving the Lyapunov functional, and the co-design of DOFC with ETSs can be acquired in terms of the linear matrix inequality (LMI). An application on DC motor is utilized to prove the feasibility of this method.

Cooperative Output Regulation of Linear Multiagent Systems: An Event-Triggered Adaptive Distributed Observer Approach

This article investigates the cooperative output regulation problem for heterogeneous linear multiagent systems by event-triggered control, where the system matrix of the exosystem is not available to all agents. First, an event-triggered adaptive distributed observer is designed for each agent to estimate both the state and the system matrix of the exosystem. Then, a fully distributed event-triggered dynamic output feedback control law is proposed for each agent. Meanwhile, a fully distributed event-triggering mechanism is proposed such that each agent can determine when to broadcast its information to its neighbors. It is shown that with the proposed event-triggered control strategy, the cooperative output regulation problem is solved by intermittent communication in a fully distributed manner in the sense that no global information, such as the eigenvalues of the Laplacian matrix or the number of the agents, is used. It is also shown that Zeno behavior is excluded for each agent. Finally, a numerical example is given to illustrate the effectiveness of the proposed event-triggered control strategy.

Event-Triggered Dynamic Output Feedback Control for Switched Systems With Frequent Asynchronism

This paper addresses the event-triggered dynamic output feedback control for switched linear systems with frequent asynchronism. Different from existing work, which limits at most once switching during an interevent interval, we adopt the average dwell time approach without limiting the minimum dwell time of each subsystem, and thus frequent switching is allowed to happen in an interevent interval. Since the difficulty in acquiring the full information of system states, the dynamic output feedback controller is taken into account to stabilize the switched system. By employing a controller-mode-dependent Lyapunov functional, stability criterion is proposed for the resulting closed-loop system, based on which the dynamic output feedback controller together with the mode-dependent event-triggered mechanism is codesigned. Besides, the existence of the lower bound on interevent intervals is attentively discussed, which gets rid of the Zeno behavior. Finally, the effectiveness of the proposed method is illustrated by numerical simulations.

Improved co-design of event-triggered dynamic output feedback controllers for linear systems

This paper presents a less conservative co-design method of output feedback law and event-triggering condition for linear systems in a networked control scenario. The previous work added three constraints to obtain linear matrix inequalities (LMI) from bilinear matrix inequalities (BMI). However, the additional constraints introduce the conservatism of the LMI condition. In this study, we relax the conservativeness induced by the additional constraints by replacing it with other constraints with free variables. As a result, the feasible set obtained by the proposed condition encompasses that of the previously published one. A convex optimization problem is provided for the co-design of the output feedback law and event-triggering condition to reduce the number of transmissions. A numerical example shows the effectiveness of the proposed method.

Dynamic output feedback control for network‐based switched linear systems with performance dependent event‐triggering strategies

This study investigates the dynamic output feedback L ∞ control for network-based switched linear systems subject to communication delay and quantisation. To reasonably configure the network communication resources according to the dynamic and steady-state characteristics of the system, the performance dependent event-triggering strategies are proposed. Moreover, the quantiser and dynamic output feedback controllers are applied, and the time-delay closed-loop switched system models corresponding to the system dynamic and steady-state processes are developed using a transformation technique. Subsequently, by utilising the average dwell time and piecewise Lyapunov functional techniques, sufficient conditions are derived to render the state of the time-delay closed-loop switched system globally uniformly ultimately bounded with an L ∞ performance level. In particular, the coupling between the switching instants and the data updating instants in the actuator is analysed during the system performance analysis. Furthermore, the design conditions of the event-triggered dynamic output feedback controllers are presented. Finally, numerical simulations verify the effectiveness of the proposed approach.

Distributed Dynamic Event-Triggered Control for Cooperative Output Regulation of Linear Multiagent Systems.

This paper investigates the cooperative output regulation problem for heterogeneous linear multiagent systems under fixed communication graphs via event-triggered control. A fully distributed event-triggered dynamic output feedback control law is proposed based on the feedforward design approach. At the same time, a fully distributed dynamic event-triggering mechanism is designed so that each agent can determine when to broadcast its information to its neighbors. Compared with existing related results, both the control law and the event-triggering mechanism in this paper are independent of any global information. It is shown that with the proposed dynamic event-triggered control strategy, the cooperative output regulation problem can be solved in a fully distributed manner by intermittent communication. Moreover, Zeno behavior can be strictly ruled out for each agent. Finally, the effectiveness of the proposed dynamic event-triggered control strategy is validated by a numerical example.

Event-Triggered Control for T–S Fuzzy Systems Under Asynchronous Network Communications

This paper is concerned with the event-triggered dynamic output feedback control problem for Takagi–Sugeno (T–S) fuzzy systems under asynchronous network communications. Compared with the existing event-triggered output feedback results for the T–S fuzzy systems, two event-triggered mechanisms are predefined independently to check in an asynchronous manner whether the measurement output and the control input should be transmitted over networks or not. Consequently, network resources can be further saved. By introducing an auxiliary function in modeling, a delay system model is constructed. Then, a new stability criterion is presented such that the resulting closed-loop system is asymptotically stable. Furthermore, event-triggered parameters and controller gains can be codesigned if the related linear matrix inequalities are feasible. Finally, the validity of the theoretical result is illustrated by two examples.

Decentralized event-triggered output feedback control for a class of interconnected large-scale systems

This paper is concerned with the problem of decentralized event-triggered dynamic output feedback control for large-scale systems with unknown interconnections. By using a modified cyclic-small-gain condition and introducing a free-matrix-based integral inequality, a novel sufficient condition is derived to ensure that the overall closed-loop system is asymptotically stable with a prescribed H∞ performance. Based on this condition, a convex condition is presented to design the controller gains and the event-triggered parameters simultaneously. In contrast with the existing event-triggered results, the derived stability criterion can be applied to the large-scale systems with unmatched unknown interconnections. The effectiveness of the proposed control strategy is demonstrated by a double-inverted pendulum model.

Periodic event-triggered dynamic output feedback control of switched systems

This paper considers the problem of co-design of a dynamic output feedback controller and a periodic event-triggering mechanism for control of switched systems under limited communication resources. The dynamic output feedback controller is designed to utilize quantized output measurements which can reduce the load on communication; a logarithmic quantizer model is assumed. The event-triggering mechanism is designed to detect events periodically which can significantly reduce sampling frequency and preclude the occurrence of Zeno behavior due to continuous-time sampling. The governing equations of the physical system combined with the equations of the dynamic output feedback controller and the event-triggering mechanism are formulated as a switched delay system. For the closed-loop switched delay system, sufficient conditions in terms of Linear Matrix Inequalities (LMIs) are obtained to achieve exponential stability with a prescribed L2−L∞ attenuation performance with respect to an exogenous disturbance; both weighted and non-weighted performance can be achieved with the proposed approach. Tools and techniques from delay-dependent Lyapunov theory, free-weighting matrices, Singular Value Decomposition (SVD), and average dwell time for switched systems are used to obtain the main results. A synthesis procedure is provided for obtaining the dynamic output feedback controller gains, event-triggering condition parameters, and a lower bound on the average dwell time of the switching signal. Numerical simulation results on a switched boost converter circuit system are provided to evaluate the proposed design and results.

Dynamic output feedback control for stochastic networked control systems based on a periodic event-triggered mechanism

In this paper, the event-triggered dynamic output feedback control for stochastic networked control systems is investigated. The measurement output signal is periodically sampled but aperiodically transmitted. The time-delay system method is utilized to model the stochastic networked control system under the periodic event-triggered mechanism, then the corresponding stability criteria are obtained. Based on the stability criteria, the suitable output-based controller and event-triggered parameters are co-designed. Two air vehicle systems are presented to illustrate the efficiency of the proposed control method.

Dynamic Output Feedback Control of Discrete Markov Jump Systems based on Event-Triggered Mechanism

This paper is devoted to the co-design strategy of event-triggered scheme and dynamic output feedback controller for a class of discrete-time networked control systems (NCSs) with random time delay. An event-triggered mechanism is given to ease the information transmission. Both the sensor and controller are set with mode-dependent quantizers in the system. A Markov process is used to model the time delay which is used to describe the quantization density. By employing the Lyapunov-Krasovskii functional and linear matrix inequality (LMI), sufficient conditions are obtained for the system. A specific example is given to demonstrate the proposed approach.

Event-triggered dynamic output feedback control for networked control systems with probabilistic nonlinearities

This paper investigates the problem of dynamic output feedback control for networked nonlinear systems. A novel event-triggered mechanism (ETM) is proposed, in which a new event-triggering condition is introduced. Compared with some existing ETMs, the proposed ETM has at least three merits: i) The data-releasing rate can be further decreased, leading to a reduction of network loads; ii) During the time when the system is disturbed by external signals, this ETM can release more sampled data to the controller so that some better closed-loop performance can be achieved; and iii) Wrong decision-making on data-releasing can be avoided due to a new definition of the related error. By employing the Lyapunov–Krasovskii functional method, sufficient conditions are derived to design both controller gains and ETM parameters. An example with four cases is given to show the effectiveness and superiority of the proposed method.

Robust event-triggered control for networked control systems

This paper is concerned with event-triggered dynamic output feedback control for networked control systems subject to communication delays. Two event-triggered conditions are predefined independently to check in an asynchronous matter if sampled signals from the sensor and control input signals from the controller should be transmitted to the controller and the actuator, respectively. As a result, communication resources can be further saved. Then, under the proposed framework, the closed-loop system is modeled as a switched system with a time-delay, based on which a novel exponential stability criterion is derived. This criterion is of less conservatism due to that the chosen Lyapunov–Krasovskii functional is not necessarily decreased. Moreover, the control gains and event-triggered parameters can be co-designed if the related linear matrix inequalities are feasible. The effectiveness of the proposed method is demonstrated via two numerical examples.

Event-Triggered Dynamic Output Feedback Control for Networked T-S Fuzzy Systems With Asynchronous Premise Variables

This paper investigates the problem of event-triggered dynamic output feedback control for networked Takagi-Sugeno (T-S) fuzzy systems with asynchronous premise variables. Our attention is focused on the design of an event-triggered fuzzy dynamic output feedback controller that guarantees that the closed-loop system is asymptotically stable. First, with consideration of the limited bandwidth and restricted network resource, an event-triggered communication scheme is proposed to save the limited network resource. Second, different from the existing results in the literature, a fuzzy dynamic output feedback controller with asynchronous premise variables is constructed such that the premise membership functions are not necessarily the same as the networked T-S fuzzy systems. Then, by using the Wirtinger inequality and some slack matrices, a less conservative stability and stabilization conditions for the existence of fuzzy dynamic output feedback controller are derived in the form of linear matrix inequalities, which can be solved by the standard MATLAB toolbox. Finally, an example is given to demonstrate the effectiveness of the designed event-triggered fuzzy dynamic output feedback controller.

Event-triggered fuzzy control for nonlinear networked control systems

This paper investigates the problem of event-triggered (ET) dynamic output feedback controller (DOFC) design for nonlinear networked control systems (NCSs) in the framework of interval type-2 (IT2) fuzzy systems. The parameter uncertainties in the nonlinear plant can be captured effectively by utilizing the membership functions with upper and lower bounds. To reduce the utilization of limited network bandwidth, an ET communication mechanism is applied. A novel type of DOFC subject to parameter uncertainties, ET communication mechanism and transmission delay is proposed, where the membership functions are different from those of the fuzzy models. Consequently, the closed-loop system is with mismatched membership functions, which hampers the stability analysis and controller design. To promote the stability analysis and achieve a better control performance, the information of membership functions and slack matrices are utilized for obtaining the main results. Finally, a simulation example is employed to demonstrate the effectiveness of the proposed mechanism.

Event-Triggered Decentralized Dynamic Output Feedback Control for LTI Systems

In this paper we investigate event-triggered controllers for dynamic output feedback control of Linear Time Invariant (LTI) systems. We propose a systematic methodology for designing implicitly verified event-triggered dynamic output feedback controllers for LTI systems that are observable and controllable. Event-triggering conditions for sampled-data implementation of the observer and the controller are proposed for a decentralized architecture. The output of each sensor and actuator are asynchronously sampled by event-triggers that depend only on local information. The proposed controllers are shown to guarantee global asymptotic stability of the closed loop system, and provide global lower-bounds on inter-communication times. The proposed design methodology is illustrated through simulation results.