Adaptive control of a class of nonlinear systems with fuzzy approximators

Adaptive control of a class of nonlinear systems is discussed in this paper. We employ a direct adaptive fuzzy controller that approximates an ideal optimal controller. All parameters of the fuzzy controller are tuned on-line. In order to tune these parameters, linear relationship between approximation error and parameters is established first. Then the adaptive laws of these parameters are proposed based on the Lyapunov synthesis approach. The advantage of the proposed method is that parameters of the consequences of fuzzy rules as well as those of the membership functions are tuned. As a result, a stable and flexible controller is achieved. The performance of the adaptive scheme is demonstrated through the simulation studies of a longitudinal vehicle control system.