Periodic Event-triggered Control For Networked Control Systems

With the rapid development of computer technology and network communication technology,networked control systems(NCSs)have been widely used because of their simple structure and easy expansion.Networked control system(NCS)is a kind of distributed control system.Each node in the control system is dispersed in different locations,and the communication between nodes depends on the network.However,after the network is used as a communication medium,due to the limited communication bandwidth of the network,large communication load may cause a series of problems,such as delay and packet loss,which will affect the control effect of the system,and the periodic event-triggered control(PETC)can solve this problem well.For this reason,the issue of periodic event-triggered control in networked control systems is discussed,and the co-design of periodic event-triggered mechanism and controller under different system conditions is studied.The main contents are as follows:For the networked linear system with unmeasurable state,in order to reduce the number of information transmission in the network,a model-based periodic event-triggered mechanism is introduced on the sensor side,and a new switching threshold event-triggered mechanism is introduced on the controller side.In order to facilitate the stability analysis,the original system is constructed into a new piecewise linear system by using the extended state vector method according to the signal transmission from the sensor to the controller and from the controller to the actuator.Using Lyapunov stability theorem and linear matrix inequality(LMI)theory to obtain the conditions that the controller gain,observer gain and event-triggered mechanism parameters need to meet when the closed-loop system is stable.For the networked piecewise affine(PWA)system with parameter uncertainty and time-delay,a periodic event-triggered mechanism is introduced to reduce the number of signal transmissions in the network and the number of updates to control inputs.By constructing a new system model,based on the piecewise Lyapunov function,and using the S-procedure,the LMI with constraints is transformed into LMI without constraints.Using the matrix inversion theorem,the sufficient conditions for the periodic event-triggered mechanism parameters and the piecewise robust controller gain to be satisfied when the system is asymptotically stable are derived.Finally,the LMI toolbox is used to solve the piecewise robust controller gain which is adapted to the parameters of the event-triggered mechanism set in advance.For the networked PWA system with random intermittent faults in the actuator,the periodic event-triggered mechanism is introduced.The Bernoulli distribution sequence is used to describe the occurrence of actuator fault.By constructing a new system model and based on the piecewise Lyapunov function and LMI theory,the periodic event-triggered mechanism and the passive fault-tolerant controller are designed.The designed controller can overcome the intermittent fault of the actuator and ensure that the networked PWA system is asym ptotically stable and meets certain H_?performance index.