Direct adaptive fuzzy control with state observer for a class of nonlinear systems

In this paper, we develop an observer-based direct adaptive fuzzy logic controller for a certain class of nonlinear systems. The complete states of the nonlinear system are not assumed to be available for measurement. By using an observer-based output feedback control law and adaptive law, the free parameters of the direct adaptive controller can be tuned on line based on the Lyapunov synthesis approach. A supervisory controller is designed to guarantee the boundedness of the state vector. Moreover, a robust control term is adapted to compensated for the approximation error and output disturbances of the system. The overall adaptive scheme guarantees that all signals involved are bounded. Simulation results illustrates the performance of the proposed algorithm.