Adaptive fuzzy control for a class of perturbed strict-feedback nonlinear systems with unknown time-varying delays

In this paper, a novel fuzzy adaptive backstepping design procedure is proposed for a class of perturbed strict-feedback nonlinear systems with unknown time-varying delays. The fuzzy logic systems are used to approximate the nonlinear uncertainties, then, the adaptive fuzzy tracking controller is constructed by combining Lyapunov-Krasovskii functionals and the backstepping approach. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output converges to a small neighborhood of the desired reference signal. The main advantage of the scheme is that the controller can handle system with time-varying delays. Finally, simulation studies are given to demonstrate the effectiveness of the proposed design scheme.