Adaptive fuzzy control for a class of nonlinear systems with input constraint and unknown control direction

An indirect adaptive fuzzy control scheme is developed for a class of nonlinear systems with input constraint and unknown control direction. In this scheme, the fuzzy systems are used to proximate unknown nonlinear functions, a modified control design framework is presented for preventing the presence of input constraint from destroying the learning capabilities of the fuzzy systems, and the dynamic robustness term is used to compensate the approximation errors. The proposed design scheme guarantees that all the signals in the resulting closed-loop system are bounded, and the tracking error converges to the small neighborhood of the origin. Simulation results indicate the effectiveness of this scheme.