Abstract :
In this paper, the fuzzy approximator and sliding mode control (SMC) scheme are considered. We propose two methods of adaptive SMC schemes that the fuzzy logic systems (approximators) are used to approximate the unknown system functions in designing the SMC of nonlinear system. In the first method, a fuzzy logic system is utilized to approximate the unknown function f of the nonlinear system xn= f(x, t)+b(x, t)u and the robust adaptive law is proposed to reduce the approximation errors between the true nonlinear functions and 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 stabilities of proposed control schemes are proved and these schemes are applied to an inverted pendulum system. The comparisons between the proposed control schemes are shown in simulations
Keywords :
adaptive control; control system synthesis; fuzzy control; nonlinear control systems; robust control; variable structure systems; adaptive fuzzy sliding mode control; approximation error reduction; approximation error robustness; fuzzy approximator; fuzzy logic systems; inverted pendulum system; nonlinear system; robust adaptive law; Adaptive control; Approximation error; Control systems; Fuzzy control; Fuzzy logic; Fuzzy systems; Nonlinear systems; Programmable control; Robustness; Sliding mode control;
