Robust Control And Its Application In Networked Control Systems

In this dissertation, we focus on the linear time-invariant controlled plant, considering the main problems of networked time-induced delay, disturbance and perturbations of the controller parameter in NCS. The problems of modeling, stability analysis, robust control, H-infinity control, performance guaranteed control and non-fragile control for NCS are discussed surrounding the quality of its performance. The main contributions of this thesis are as follows:Firstly, it is modeled to a discrete system for a class of networked control systems with short transmission delay and external disturbance. Under the considerations of a quadratic cost index and the disturbance attenuationγ,a sufficient condition for the existence of the robust H_∞state feedback guaranteed cost controller is derived based on the Lyapunov theory and linear matrix inequality approach. Then the solving method of the suboptimal guaranteed cost controller is turned to a convex optimization problem with linear matrix inequalities constraints.Secondly, the problem of robust and non-fragile state feedback guaranteed cost controller design for NCS with networked-induced delay less than or equals to one sampling period and perturbations on controller is considered. This class of NCS is transformed into the linear discrete model with uncertainties. On this basis, the non-fragile theory is introduced. Sufficient conditions of the existence of the controller with two kinds of controller gain perturbations and the controller design method are presented. Furthermore, the design problem of the optimal guaranteed cost controller is turned to a convex optimization problem with linear matrix inequalities constraints. The perturbation problem of the controller parameter appears in the engineering practice is solved at a certain extent.At last, an Ethernet-based networked control system simulation platform is achieved by software and hardware to simulate a real network environment. The results of the study are carried out on the platform and the algorithms have been proved to be effective and feasible. The controller design method presented in this essay is applied to metering pump stroke adjustment system, and the desired control effect is achieved.