Adaptive robust fuzzy control for output tracking

This paper gives an adaptive robust fuzzy control design for a class of nonlinear systems represented by input-output models to follow a reference trajectory in the presence of uncertainties. Direct approach to this problem by using fuzzy logic systems (FLS) to approximate the unknown ideal control law (designed when the nonlinear system is known) is followed, and the semi-global stability is established based on the Lyapunov analysis. By combining the advantages of the fuzzy logic reasoning, robust control and adaptive control techniques, the proposed control has the following features: the ability to incorporate in a transparent way an existing control experience into the controller design, robustness to a wide range of uncertainties, reduced a priori information on the nonlinear system and on-line computation load required for its implementation, and semi-global exponential output tracking to the reference signal up to an ultimately bounded error. The effectiveness of this control is demonstrated through simulations.