Fuzzy-sliding mode controller design for tracking control of nonlinear system

The main purpose of this paper is to integrate fuzzy logic control and sliding mode control techniques to develop a fuzzy-sliding mode controller. In the design of the fuzzy-sliding mode controller, one can systematically determine the fuzzy control rules and predict the controlled system behavior. The sliding surface in the proposed fuzzy-sliding mode control system is a fuzzy set rather than a crisp set as given in the conventional sliding mode control system. Furthermore, it is seen that the inputs of the proposed fuzzy-sliding mode controller are fuzzy quantities of s and S˙. Hence, the number of the fuzzy-sliding mode-control rules is independent of the number of system state variables, and can be minimized. Simulation results show that the proposed fuzzy-sliding mode controller has the following advantages: 1) the fuzzy-sliding mode controller can control most of the complex systems without knowing their mathematical model; and 2) the dynamics behavior of the controlled system can be approximately dominated by a fuzzified sliding surface.