Disturbance Observer-Based Chattering-Attenuated Terminal Sliding Mode Control for Nonlinear Systems Subject to Matched and Mismatched Disturbances

Duc Giap Nguyen,Duc Thien Tran,Kyoung Kwan Ahn

doi:10.3390/app11178158

Abstract

This work presents a new disturbance observer-based chattering-attenuated terminal sliding mode control for a class of nonlinear systems in the presence of both mismatched and matched disturbances. A nonlinear disturbance observer is typically employed to accurately estimate mismatched disturbances. In this study, a terminal sliding mode control was designed, based on the disturbance estimation results, to counter the effects of disturbances and ultimately stabilize the target system. The utilization of a chattering-attenuated full-order terminal sliding mode structure satisfactorily resolves both chattering and singularity problems in controller design. It was shown by theoretical analyses that both the disturbance estimation error and the system state converge to the equilibrium point in finite time. Two simulation studies, namely a numerical example and an application to an electro hydrostatic actuator system, were conducted to examine the characteristics and to verify the effectiveness of the proposed algorithm.

Highlights

Sliding mode control (SMC) is a popular control algorithm and possesses several desirable characteristics, such as design simplicity, ease of implementation, and robustness to external disturbances, model uncertainties, and parameter variations
Terminal sliding mode control (TSMC) can drive system states both to the sliding mode surface and to the equilibrium point in finite time [26]
The conventional terminal sliding mode control (TSMC) inherits the robustness characteristic from its predecessor, it still suffers from the chattering phenomenon and is prone to the singularity problem as the control signal instantly jumps to infinity

Summary

Introduction

Sliding mode control (SMC) is a popular control algorithm and possesses several desirable characteristics, such as design simplicity, ease of implementation, and robustness to external disturbances, model uncertainties, and parameter variations. Significant efforts have been made in the literature to attenuate this problem, including the boundary layer [19], second and higher-order SMC [20,21,22], low-pass filtering [23,24], and the disturbance observer [25]. Another problem found in the conventional SMC is that system states can only asymptotically converge to the equilibrium point. A chattering-free full-order TSMC was developed in [30] that satisfactorily resolves both the chattering and singularity problems mentioned above

Objectives

Results

Conclusion