Design Method System Of Sliding Mode Variable Structure Control System

The sliding mode variable structure control that is brought in 50's is attention- getting because of its ideal robustness. The sliding mode movement of variable structure system holds the invariance for the change of system parameters, outside disturbance, uncertain mode and model uncertainty of the system. Its flaw is that after the system state getting to the sliding plane, it will produce high frequency chattering around the sliding plane and the control variable of the system will also produce high frequency chattering.The paper makes some research for the design method of sliding mode variable structure control, and does some works for the existent problems at present. The simulation shows that better control effect can be achieved. The main works are summarized as follows:Firstly, this thesis relatively fully refers to the literature in the field of sliding mode variable structure control, and summarizes the development history and characteristics of sliding mode variable structure control, and particularly introduces the elementary concepts and elementary definitions and design method.Secondly, based on the principle of sliding mode control and fuzzy control a new design method of fuzzy sliding mode control is put forward for a class of SISO nonlinear systems in the presence of uncertainties. The reaching condition of the method becomes exponent load-frequency and fuzzy measure gene of switch function is adaptively adjusted through fuzzy rules. Simulation results show that the fuzzy sliding mode system ulteriorly increases the speed to the sliding plane, and that the systemerrors are improved ulteriorly and the control precision is advanced when avoiding the chattering phenomenon that is inherent to sliding mode variable structure systems.Thirdly, with the simplest single-input discrete system as the model, we analyze and discuss the effects for control-delay on the discrete variable structure control systems, and bring forward the design method of discrete variable structure control based on the system state forecast; Simulations show that the above solution avoids adverse influences for Control-delay on the performance of variable structure control systems with control-delay, and control effect is fine. In addition, we discuss the effects for the errors of system parameters on the discrete sliding mode variable structure control systems that are designed by means of above solution based on the system state forecast, and put forward the variable structure design method with on-line arithmetic, and achieve favorable control effect.