Robust Adaptive Fuzzy Tracking Control with Two Errors of Uncertain Nonlinear Systems

This paper aims to develop robust adaptive fuzzy control techniques to improve tracking performance, where both the tracking error and the modeling error are utilized to adjust system parameters. A hybrid adaptive control scheme including a H∞ compensator is proposed which makes the tracking performance faster and more reliable. Performance analysis is given by using Lyapunov theory. In our proposed hybrid control scheme, the adaptive fuzzy controller serves as a master controller and contributes to a rough tuning of tracking control, and the H∞ compensation term turns to refine the tuning course. Simulations are carried out to illustrate controller design steps and performance evaluation aspects in detail. Results indicate that the effect of both fuzzy modeling errors and external disturbances on tracking errors can be attenuated by our proposed robust adaptive control techniques. Furthermore, it is observed that a superior tracking performance can be achieved with guaranteed closed-loop system stability.