Robust adaptive dynamic surface control for nonlinear systems with output unmodeled dynamics

This paper presents a robust adaptive output-feedback dynamic surface control for a class of nonlinear systems with output unmodeled dynamics. A new relation ship between the output and the state of the output unmodeled dynamics is established while the unmodeled dynamics is input-to-state practically stable. With such relationship, it is shown that all the signals of the closed-loop system are bounded and the tracking error can be made arbitrarily small. Simulation results are presented to demonstate the efficiency of the proposed scheme.