Direct adaptive fuzzy output tracking control of nonlinear systems

A stable direct adaptive fuzzy output tracking control scheme is developed for the single-input-single-output (SISO) unknown nonlinear systems, Using a high-gain observer. the proposed adaptive fuzzy algorithm does not require the state variables to be measurable, First, a direct adaptive fuzzy state controller is constructed with the aid of its H-infinity control technique to achieve the H-infinity tracking performance. After-wards, a high-gain observer is used to estimate the system states, by which the above adaptive fuzzy state controller becomes an adaptive fuzzy output feedback control. The proposed control scheme can guarantee the stability of the closed-loop system and the good tracking performance as well. (C) 2002 Elsevier Science B.V. All rights reserved.