Composite anti-disturbance control for a class of uncertain nonlinear systems via disturbance observer and adaptive backstepping method

A new anti-disturbance control scheme is proposed for a class of nonlinear systems subjecting to multi-source disturbances in this paper. The uncertain multi-source disturbances are classified into two parts, one is the harmonic or constant disturbance with partial known information, which can be formulated by an exogenous system, another one is unknown time-varying disturbances. The nonlinear disturbance observer(NDO) is constructed separately from the controller design to estimate the first kind of disturbance. By integrating NDO with adaptive backstepping technique, a novel composite anti-disturbance control scheme is proposed for the nonlinear systems. Then the stability analysis of all signals of the closed-loop system is presented. Simulation for a numerical example is given to demonstrate the effectiveness of the results.