Robust control design of nonlinear adaptive control systems with unmodelled dynamics

In this paper, the robust adaptive control problem for a class nonlinear systems is studied in which the unknown system parameters are not required to enter the system linearly. A new design scheme for the construction of control for the nonlinear adaptive control problem is devised by using the backstepping and variable structure techniques. The control obtained will suppress the unmodeled dynamics while regulate the corresponding closed loop system to a small neighborhood of the origin globally.