Fault Detection And Robust Prediction Control Of The Network Control System With Data Packet Loss And Time Delay

With the integration and development of Internet application technology and communication technology,networked control systems(NCSs)have gradually become the focus of automation and industrial research due to their advantages of resource sharing,low cost and high reliability.The problem of time delay and packet loss in the information transmission process of the network itself not only lead to the deterioration of the system performance,but also make the system lose stability and can not work properly.In this thesis,we apply the Lyapunov stability theory,linear matrix inequality and robust model predictive control for fault detection and controller design for NCSs time lag and packet loss problems.Firstly,for a class of networked control systems that suffer packet loss on both sensor to filter and controller to actuator channels,a fault detection method based on the H_∞index is studied.The Bernoulli distribution sequence is used to describe the random packet loss models on both sensor to filter and controller to actuator channels,and a fault detection filter with robust H_∞performance is desinned.Based on the Lyapunov stability theory,sufficient conditions for system stability are derived,and the fault detection filter parameters are found so that the system can accurately detect faults in the presence of disturbances.By constructinn a residual evaluation function and comparinn the value of the residual evaluation function with a predetermined threshold,this method detects whether a fault has occurred.Finally,the effectiveness of the method is verified based on the simulation of the three-capacity water tank example,and the simulation results show that the proposed method can accurately and quickly detect the fault of the system.Second,a robust model predictive control method is investinated for a class of NCSs with random packet loss and time-varyinn time lans.Describinn the packet loss model from sensor to controller usinn Bernoulli distribution sequences,desinninn Lyapunov function for specific time lan compensation,dealinn with external disturbances by Lipschitz nonlinear theorem,usinn Lyapunov stability theory and linear matrix inequality technique,transforminn the complex optimization problem into a convex optimization problem with linear matrix inequality,and derivinn the stability condition based on the constrained form of linear matrix inequality.The simulation results show that the proposed controller can reduce the effects of packet loss and time-varyinn delay on the system and realize the stability of the system.