Abstract: For a class of nonlinear systems with bounded disturbance uncertainties, the robust adaptive ε-output-tracking control problem is dealt with. Combining the backstepping method with robust control, a new robust output feedback controller is developed for unknown parameters and dynamic uncertainties. It is shown that the derived controller based on the Lyapunov stability theory can ensure global uniform boundedness for all states of a closed-loop system, and convergence of tracking error within an arbitrarily small neighborhood of the origin. Simulation results are provided to show effectiveness of the proposed approach.

Key words: nonlinear system, adaptive control, backstepping method, ε-output-tracking