Adaptive fuzzy tracking control for nonlinear strict-feedback systems with unmodeled dynamics via backstepping technique

This paper considers an output tracking control problem with unmodeled dynamics for a class of nonlinear strict-feedback systems, which possess unstructured uncertainties and dynamic disturbances. Uncertain nonlinearities contain both unmeasured states and measurable output. A direct tracking controller is obtained on the basic of the backstepping and fuzzy logic system. By the use of small-gain approach, the discussed closed-loop system is proved to be input-to-state practically stable (ISpS) and all the parameter signals are semi-globally uniformly ultimately bounded. There are three adaptive parameters in the fuzzy controller. Finally, simulation examples are given to illustrate the efficiency of the proposed approach.