Discrete Systems With Variable Structure Control And Its Simulation Study

Variable structure control(VSC) are well known for their robustness to system parameter variations and external disturbances. VSC have been widely used in many applications, such as robots, aircrafts, power generator and DC and AC motors and so on. In the recent years, with the development of microcomputer technology and the needs of industrial automation. We use computer to realize the control algorithm. But during the time of realizing the VSC, because of the limits of sampling, the ideal sliding mode does not exist. The state trajectory of system is chattering, which restrict it's actual applications. In the circumstances, the arrival condition and the existence condition have been changed .It is significant to study discrete-time VSC (DVSC )to reduce chattering of sliding mode.In this dissertation, the present status, both the DVSC and VSC with time-delay are analyzed all round. The basic definitions and properties are proposed. The main contents in this dissertation include:1. The background related to the subject is summarized.2. The related definitions of DVSC are proposed. After analyzing the arrival condition, the existence condition and stabilization of sliding mode in DVSC.3. Detailed analyzing the reason for the discrete reaching law to cause system chattering is given and the discrete reaching law is developed.4. After analyzing the causes of chattering, two improved strategies are developed. Using the proposed two strategies, the simulations are performed respectived.5. In the end, a conclusion is made and the future research are prospected.