Event-triggered And Self-triggered Control For Networked Control Systems:A Switched System Approach

In the past decade,the rapid development of communication,control and computer technology has greatly affected the structure of the control systems.With the increasing complexity of the control objects and the expanded distribution area,the traditional point-to-point control systems architecture presents a series of problems,such as,complex wiring,maintenance difficulties,poor scalability and high cost,which is difficult to meet the continuously improved performance requirements of the control systems.It is in this context,Networked Control Systems(NCSs)came into being.In the NCSs,the control nodes through the shared communication network exchange the information between controllers,actuators,sensors and other nodes,which brings some new problems.Among them,the most prominent problems are the network-induced delay and the limited communication channel bandwidth.In the network environment,under certain conditions to ensure the performance of the system,the event-triggered mechanism,self-triggered mechanism can reduce the amount of data transmission in the network,thereby saving network resources,reducing energy consumption and solving the problems of network traffic constraints,network congestion,wasting of resources.Therefore,the research on event-triggered control and self-triggered control of NCSs is of great theoretical and practical significance.In this article,we study the event-triggered and self-triggered control of the networked control systems with short network-induced delay and packet loss.By using the Lyapunov function,linear matrix inequality,we co-design the state feedback controller and the event-triggered generator.The exponential stability of the closed-loop event-triggered networked control systems is studied,mainly including the following two aspects:Firstly,we study the event-triggered and self-triggered control of NCSs with short time-varying delay.In considering the presence of a short network-induced delay,we use the switched systems modeling method to model the system into a discrete-time switched system with finite sub-systems.Based on this model,we use the Lyapunov function,the linear matrix inequality technique and the average dwell time method to co-design the triggered condition and the discrete-time controller,and study the exponential stability of the closed-loop event-triggered networked control systems.The proposed event-triggered conditions are changed with the subsystem switching which means the varying of the network-induced delays and only need to compare the state information of the adjacent discrete sampling instants without paying attention to the state information between the sampling intervals,simultaneously avoid the Zeno phenomenon.Then based on this,we propose the self-triggered condition to guarantee the exponential stability of the system.Finally,the simulation results verify the correctness and efficiency of the results.Secondly,we discuss the design of event-triggered mechanism,self-triggered mechanism and switching controller when both the packet loss and short network-induced delay in the network transmission environment.We also use the switched systems method to describe the uncertainty and time-varying characteristics of the network-induced delay.We derive the co-design conditions on the existing of the hybrid state feedback controller and event-triggered mechanism based on the average dwell-time method.The proposed event-triggered condition in this section also can avoid the Zeno phenomenon.Then we design a self-triggered mechanism,under which,the system is exponentially stable.Finally,the feasibility of the proposed co-design method is verified by the simulation example.