ADAPTIVE FUZZY SLIDING MODE CONTROL OF NONLINEAR-SYSTEM

In this paper, the fuzzy approximator and sliding mode control (SMC) s cheme are considered, We propose two methods of adaptive SMC schemes t hat the fuzzy logic systems (approximators) are used to approximate th e unknown system functions in designing the SMC of nonlinear system. I n the first method, a fuzzy logic system is utilized to approximate th e unknown function f of the nonlinear system x((n)) = f((x) under bar, t) + b((x) under bar, t)u and the robust adaptive law is proposed to reduce the approximation errors between the true nonlinear functions a nd fuzzy approximators, In the second method, two fuzzy logic systems are utilized to approximate the f and b, respectively, and the control law, which is robust to approximation error is also designed, The sta bilities of proposed control schemes are proved and these schemes are applied to an inverted pendulum system. The comparisons between the pr oposed control schemes are shown in simulations.