Direct adaptive fuzzy tracking control for a class of perturbed strict-feedback nonlinear systems

In this paper, a novel direct adaptive fuzzy tracking control scheme is presented for a class of perturbed strict-feedback nonlinear systems with unknown virtual control coefficients. Based on the Mamdani-type fuzzy logic system online approximation capability, a direct adaptive fuzzy tracking controller is developed by using the backstepping approach. The proposed design scheme guarantees that all the signals in the resulting closed-loop system are uniform ultimate bounded, and the tracking error converges to an arbitrarily small neighborhood of the origin. In addition, the number of the online adaptive parameters is not more than the order of the considered system and the possible controller singularity problem is removed by introducing the modified integral Lyapunov functions. Finally, two simulation examples are used to demonstrate the effectiveness of the proposed control scheme.