State observer based indirect adaptive fuzzy tracking control

An observer based adaptive fuzzy controller for a certain class of unknown nonlinear systems is proposed in this paper. The proposed approach employs a fuzzy system to approximate the unknown nonlinear functions in designing the adaptive controller and an observer is designed to generate an error signal for the adaptive law. Moreover, a robust H∞ control law is obtained by solving a modified Riccati-like equation in order to compensate the effect of the approximated error and external disturbance of the system. It is proved that the overall adaptive scheme guarantees the global asymptotic stability in the Lyapunov sense if all the signals involved are uniformly bounded. Simulation studies show that the proposed controller performs well and exhibits good performance.