Improved integral fuzzy sliding mode control for a class of nonlinear uncertain systems

For the conventional sliding mode control of a class of nonlinear uncertain systems, the ranges of sliding mode error and steady-state error are deduced. In order to reduce the steady-state error while anti-windup, an improved integral sliding surface is designed, and an improved integral fuzzy sliding mode control approach is proposed based on this sliding surface. In this approach, the integral action is reduced through adjust factor when the sliding variable outside the boundary layer. Then, the large overshoots due to the large initial errors can be avoided. When sliding variable inside the boundary layer, the integral action is conventional in order to reduce the steady-state error. The adjust factor is automatically tuned by real time fuzzy inference. Finally, an inverted pendulum control is used to illustrate the effectiveness and robustness of the proposed approach.