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This paper studies the global output tracking problem for a class of unknown time-varying nonlinear systems in strict-feedback form. By utilizing the barrier functions, a universal adaptive state-feedback control strategy is proposed that achieves asymptotic tracking performance. Unlike the existing results in the literature, the proposed control scheme utilizes the barrier functions to ensure the unknown system nonlinearities to be the bounded “disturbance-like” terms, which are adaptively compensated at each step, this enables any approximation structures are not needed. Furthermore, the “explosion of complexity” issue in backstepping-like approaches is avoided without using additional filtering. Simulation results are presented to demonstrate the effectiveness of the proposed methodology.

This paper is concerned with the problem of dynamic surface asymptotic tracking for a class of uncertain nonlinear systems preceded by Bouc–Wen type of hysteresis nonlinearity. By introducing the nonlinear filters with a positive time-varying integral function, a novel robust adaptive control algorithm is presented without constructing the hysteresis inverse. Unlike some existing adaptive control schemes for systems with input hysteresis, the proposed controller not only solves the issue of “explosion of complexity” inherent in the recursive procedure, but also produces the asymptotic tracking in spite of input hysteresis and external disturbances. Finally, two simulation examples are presented to confirm the effectiveness of the developed control strategy.

In this paper, the global output tracking is investigated for a class of uncertain nonlinear hysteretic systems with nonaffine structures. By combining the solution properties of the hysteresis model with the novel backstepping approach, a robust adaptive control algorithm is developed without constructing a hysteresis inverse. The proposed control scheme is further modified to tackle the bounded disturbances by adaptively estimating their bounds. It is rigorously proven that the designed adaptive controllers can guarantee global stability of the closed-loop system. Two numerical examples are provided to show the effectiveness of the proposed control schemes.