Elegant anti-disturbance control for nonlinear systems based on a robust disturbance observer

Abstract

A new elegant anti-disturbance control and estimation strategy is presented for a class of nonlinear systems subject to multiple disturbances. As a class of strong-coupled nonlinear systems, the models have measurement error, friction, varying load, and unmodelled dynamics, which can be characterized as two types of disturbances in this framework. One is supposed to be generated by an exogenous system with uncertainty, which represents the disturbance with partial known information. The other is a bounded external disturbance in the H2-norm. The nonlinear robust disturbance observer (DO) based on regional pole placement theory is constructed separately from the controller design to estimate and reject the first type of disturbance, and terminal sliding-mode (TSM) control is used to attenuate the second type of disturbance. By integrating the nonlinear robust DO with TSM control, a new elegant anti-disturbance control scheme based on a robust DO is proposed for a kind of nonlinear system, which can further improve the ability of anti-disturbance for nonlinear systems. Simulations are given to demonstrate the effectiveness of the proposed method.