Asymptotic Tracking for Nonminimum-Phase Nonlinear Systems in Output Feedback Form

Global asymptotic tracking by output feedback is studied for a class of nonminimum-phase nonlinear systems in output feedback form. It is proved that the tracking problem is solvable by an n-dimensional output feedback controller under the two conditions: 1) the nonminimum-phase nonlinear system can be rendered minimum-phase by a virtual output; 2) the internal dynamics of the nonlinear system driven by a desired signal and its derivatives has a bounded solution trajectory. With the help of a new coordinate transformation, a constructive method is presented for the design of a dynamic output tracking controller. An example is given to validate the proposed output feedback tracking control scheme.