Composite disturbance-observer-based control and terminal sliding mode control for non-linear systems with disturbances

TLDR

Disturbances in the considered MIMO nonlinear systems comprise an uncertain exogenous component that can model harmonic signals and a bounded‑H₂ component. The paper proposes a novel control architecture that fuses disturbance‑observer‑based control with terminal sliding‑mode control for such systems. Disturbance observers are designed via regional pole placement and D‑stability theory independently of the controller, and the observers are integrated with TSM laws to form the overall controller. The integrated DOBC–TSM scheme rejects and attenuates both disturbance types, achieving finite‑time performance for both known and unknown nonlinear dynamics, as confirmed by flight‑control and hard‑disk‑drive simulations that outperform prior methods.

Abstract

A novel type of control scheme combining the disturbance-observer-based control (DOBC) with terminal sliding mode (TSM) control is proposed for a class of multiple-input–multiple-output (MIMO) continuous non-linear systems subject to disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modelling perturbations. The other is supposed to have the bounded H 2 norm. The disturbance observers based on regional pole placement and D-stability theory are presented, which can be constructed separately from the controller design. By integrating DOBC with TSM control laws, the disturbances can be rejected and attenuated, simultaneously, and the desired dynamic performances can be guaranteed for non-linear systems in finite time with known and unknown non-linear dynamics, respectively. Two simulation examples for a flight control system and a hard disk drive actuator are given respectively to demonstrate the effectiveness of the proposed control schemes compared with the previous schemes.