Analysis And Synthesis Of Uncertain Networked Control Systems With Time-delay

Network Control Systems(NCSs) is the integrated communication network and control system into together, forming network real time closed-loop feedback control system, where all the information in the sensor, controller and actuator is transmitted over the network. NCSs brings about more advantages at the same time, but the existence of the network will inevitably cause the problem of delay, packet loss, packet disordering, and modeling system for the inherent uncertainty and actuator saturation characteristics, made the system analysis and synthesis due to complex implementation. In this dissertation, for reducing the negative influence from these network issues and inherent system problems, we apply some methodologies such as time delay system theory, Lyapunov stability theory, linear matrix inequality theory to discuss the stability and controller design for NCSs. The main contents are as follows:(1) The stability and state-feedback controller design for a class of NCSs with time-variant delay and the H∞problem for the same system are discussed. Firstly, the stability and controller design problem of networked control systems with time-variant delay is investigated based on the improved free weighting matrix approach, gives a less conservative stability results and controller design method, and verify the effectiveness of the proposed method by numerical analysis. Secondly, the H∞problem of networked control systems with time-variant delay is studied based on the improved integral inequality approach, in order to reduce the conservatism of the system, gives a new integral inequality, combined with the Lyapunov stability theory and linear matrix inequality method, obtained stability conditions and the H∞controller. Through numerical simulation, the method depresses the influence of time delay and reduces the conservatism of the system.(2)The stability and state-feedback controller design for a class of NCSs with multiple-delay, uncertainty and unknown actuator parameters is discussed. First of all, with the Newton-Leibniz formula and free weighting matrix application, the sufficient stabilization criteria and controller design for networked control systems with multiple-delay and unknown actuator parameters are presented by the improved integral inequality. Furthermore, we apply the results to the NCSs with multiple-delay, uncertainty and unknown actuator parameters. According to the norm bounded uncertainties characteristics, we give the sufficient stabilization conditions and the controller design strategy. Finally, numerical examples demonstrate the validity and the effectiveness of the proposed techniques. (3)A class of NCSs with time delay, uncertainty and input saturation is studied. Considering the time delay, uncertainty and input saturation with the sector nonlinear saturation function, the networked control system is modeled as a linear system with time delay, uncertainty and input saturation. By the Jensen integral inequality method and linear matrix inequality theory, sufficient conditions for the stability of the closed-loop network control system are obtained. Through solving the linear matrix inequalities, the control laws that depend on the Parameters of the saturation limit and the value of the time delay are obtained.