Composite adaptive anti-disturbance control for MIMO nonlinearly parameterized systems with mismatched general periodic disturbances

In this paper, the problem of anti-disturbance control for a class of multi-input and multi-output (MIMO) nonlinearly parameterized systems with mismatched general periodic disturbances is investigated via a composite adaptive anti-disturbance control scheme. The composite adaptive anti-disturbance control method is presented by using disturbance observer technique, back-stepping method and adaptive control approach. A novel disturbance observer is designed to estimate the disturbances generated by a linear system with nonlinear output function. Rigorous stability analysis for the augmented closed-loop system is developed by direct Lyapunov stability theory. It is shown that the system outputs asymptotically converge to zero in the presence of mismatched general periodic disturbances. Finally, a simulation example is given to demonstrate the effectiveness of the proposed method.