Stable adaptive fuzzy control for a class of uncertain nonlinear systems with input magnitude and rate saturation constraint

In this paper, an indirect adaptive controller using fuzzy systems is presented for a class of uncertain single-input single-output nonlinear systems with input magnitude and rate saturation. The unknown system´s nonlinearities are approximated by fuzzy systems whose parameters update laws are resulting from the standard Lyapunov synthesis method. Control law and adaptation algorithms are mainly modified to avoid the problems generally caused by saturation such as performance degrading and closed-loop instability. The stability analysis of the overall closed-loop system is performed using the Lyapunov direct method. A numerical simulation example is given to demonstrate the effectiveness of the proposed adaptive control approach.