Robust adaptive control for a class of nonlinear time-delay systems with unknown control coefficient

The robust control is considered for a class of nonlinear time-delay systems with unknown control coefficient in this paper. By constructing an appropriate observer and using backstepping method, an output-feedback controller is designed. The theory of Nussbaum function is successfully applied to coping with unknown control coefficient, and the ideal of changing supply functions is used so as to design Lyapunov function for the whole closed-loop system. It is shown that the presented controller can make system output tend to zero while keeping all signals bounded.