Robust adaptive nonlinear control with guaranteed transient performance

This paper considers the robust adaptive control of a class of nonlinear systems in a semi-strict feedback form. Nonlinear systems may possess both parametric uncertainties and unknown nonlinear functions which may represent modelling error and external disturbances. With a prior knowledge of the bounds of the parametric uncertainty and the bounding function of the unknown functions, a systematic way to combine backstepping adaptive control with conventional deterministic robust control is developed. The proposed method preserves the advantages of the two methods-i.e., asymptotic stability of adaptive control in the presence of parametric uncertainties and guaranteed transient performance with prescribed precision of deterministic robust control for both parametric uncertainties and unknown nonlinear functions-and, at the same time, eliminates drawbacks of each. Simulation results validate the proposed method