Variable structure MRAC for a class of uncertain nonlinear systems

In this paper, a robust model reference adaptive controller based on variable-structure strategy is designed for a class of nonlinear systems with uncertain parameters and bounded external disturbances. Without a priori knowledge of bounded disturbance,both the unknown system parameters and the upper bound of external disturbance are estimated by the design of adaptive law to ensure the accessibility of sliding mode and the global stability of the closed-loop system. Theoretical analysis and simulation results show the robustness and effectiveness of this controller.