Variable Structure Control For Uncertain Discrete-Time Systems And Stability Of Time-Delay Measure Large Scale Systems With Impulsive Effects

Variable structure control (VSC) is essentially a special kind of nonlinear feedback control, reflected in the control of discontinuity. VSC is the invariance of its sliding mode when systems were affected by parameter perturbation and external interference. Due to the sampling interval, the methods of VSC for discrete-time systems (DS) are greatly different from continuous time control systems. Chattering is a main obstacle to the application of VSC to DS. Therefore, the main works of this dissertation is to study the method of VSC for uncertain discrete systems. By applying the proposed reaching law to discrete variable structure control systems (DVSCS). An improved method reducing chattering is proposed and improving system performance effectively.Many evolutionary processes can be successfully described by measure large scale systems with impulsive effects and time delays also often occur in measure large scale systems with impulsive effects. The main works of this dissertation is to discuss stability of time-delay and time-varying measure large scale systems with impulsive effects and obtain a new stability conclusion of these systems.The main contents consist of several parts as follows.1. The historical development and broad research situation about VSC for DS is introduced.2. The basic definitions, principles and methods about VSC for DS are summarized. Such as, existence, accessibility, stability, quasi-sliding mode, reaching law and chattering for VSC.3. Feature of some design methods for uncertain DVSCS are discussed and an improved discrete reaching law for DVSCS is proposed with the help of sigmoid function in this paper. By applying the proposed reaching law to DVSCS, the stability of origin and steady of systems are better than the exponential rate reaching law and the variable rate reaching law. The design method can make the states of system keep one reaching behavior, which is better for designing variable structure control. With the design method, the sliding surface can be reached quickly and the system chattering can be decreased at the same time.4. The Lyapunov function, the comparison principle and some other analytical methods and techniques are employed to investigate the sufficient conditions for uniform stability and global exponential stability of time-delay and time-varying measure large scale systems with impulsive effects. At the same time, the new conclusion of stability of these systems is more universa1 and contains the existing results. Simulation results illustrate the obtained results of this dissertation is feasible and effective.