Direct adaptive fuzzy control for a class of discrete-time nonlinear systems

In this paper, a robust direct adaptive fuzzy control scheme is presented for a class of discrete-time nonlinear systems in the strict-feedback form. The fuzzy logic system (FLS) is used to approximate the unknown system function of the system, and backstepping design procedure is employed in adaptive controller and the adaptation laws design. Compared with the existing results, the proposed controller lighten the online computational burden. It is shown via Lyapunov theory that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB) and the tracking error converges to a small neighborhood of zero by choosing the design parameters ap- propriately. A simulation example is employed to illustrate the effectiveness of the proposed scheme.