H_∞Control Design For A Class Of Networked Control Systems With Communication Constraints

With the continuous development of computer technology, control technology, network technology and communication technology, the research of networked control systems (NCSs) has become one of the important areas in modern control theory. Networked control systems have many advantages such as low cost, easy to extend, resource sharing and flexible structure. Due to the unreliability of communication network, it inevitably brings many problems such as transmission delays, packet dropouts and communication constraints, which directly affect the performance of the systems. How to decrease the affection that these problems bring to networked control systems has theoretical and practical significance.In this thesis, we study the problem of H∞control design of networked control systems with communication constraints. The main results are as follows:Firstly, the problem of H∞control of networked control systems with communication constraints is studied, in which we assume that networked control systems are running without packet dropouts or network-induced delays. According to the characteristics of communication constraints, we describe the discretized closed-loop networked control systems as a class of discrete-time switched systems. We use the average dwell time method to discuss the exponential stability of the systems. Then, we use the linear matrix inequality method to design a state feedback controller to ensure a prescribed H∞disturbance attenuation level y.Secondly, on the basis of the situation above, we consider a class of networked control systems with communication constraints and uncertain time-invariant delays. We describe the discretized closed-loop networked control systems as a class of discrete-time switched systems with uncertainty by converting the uncertainty of time delays to the uncertainty of the parameter matrix in state equation of systems. We give the exponentially stable conditions by the average dwell time method when all the subsystems are stable. Furthermore, a robust H∞guaranteed cost controller is designed by using linear matrix inequality approach to ensure that the closed-loop networked control systems have the upper bound of quadratic performance index and a prescribed H∞disturbance attenuation level y. Then we give the simulation results to illustrate the correctness and feasibility of the conclusions.Finally, the results of this thesis are summarized. Moreover, the further research problems of networked control systems are pointed out.