Output-feedback tracking control for a class of nonlinear non-minimum phase systems via backstepping method

In this paper, we focus on the problem of output-feedback tracking control for a class of nonlinear non-minimum phase systems. To hold the unstable internal dynamics be bounded, the method of output redefinition is introduced to let the stability of the internal dynamics depend on that of newly defined output, thus we only need to consider the new external dynamics rather than internal dynamics in the procedure of designing the control law. Under this circumstance, the backstepping method is firstly extended to deal with the issue of trajectory control of nonlinear non-minimum phase systems. The posed outputfeedback backstepping controller drives the system output to track desired trajectory asymptotically, and at the same time forces the unstable internal dynamics to follow its corresponding causal and bounded ideal internal dynamics solved via the method of stable system center. The effectiveness of the proposed controller is verified via a numerical simulation.