Robust adaptive control for uncertain nonlinear non-minimum-phase system

A robust adaptive controller was developed in this paper, since the conventional adaptive robust controller cannot be directly applied on the nonlinear non minimum-phase system. An appropriate coordinate transformation was given to transform the uncertain nonlinear system with unstable zero-dynamics into an equivalent system whose zero-dynamics is stable. Considering unknown parameter and uncertainty, the robust adaptive controller for the equivalent system was developed based on robust passivity principle and Lyapunov theory. An example was designed to illustrate the effectiveness of the method investigated by this paper.