Sliding Mode Control of Flexible Articulated Manipulator Based on Robust Observer.

Yanghua Gao,Hailiang Lu

doi:10.1155/2022/2440770

Abstract

In this paper, a robust observer-based sliding mode control algorithm is proposed to address the modelling and measurement inaccuracies, load variations, and external disturbances of flexible articulated manipulators. Firstly, a sliding mode observer was designed with exponential convergence to observe system state accurately and to overcome the measuring difficulty of the state variables, unmeasurable quantities, and external disturbances. Next, a robust sliding mode controller was developed based on the observer, such that the output error of the system converges to zero in finite time. In this way, the whole system achieves asymptotic stability. Finally, the convergence conditions of the observer were theoretically analyzed to verify the convergence of the proposed algorithm, and simulation was carried out to confirm the effectiveness of the proposed method.

Highlights

Flexible manipulators are increasingly applied in industrial and aerospace fields, such as welding robots, industrial production lines, mechanical arms of aircraft, and so on, owing to their energy efficiency, high speed, and low contact impact
More and more attention has been paid to the research of flexible manipulators, along with the development of aerospace technology, robotics, marine engineering, and industrial engineering
Based on unknown input observer (UIO), Wang et al [15] put forward a novel funnel nonsingular terminal sliding mode control (FNTSMC) method for servomechanisms with unknown dynamics, e.g., nonlinear friction, uncertainties, and external disturbances

Summary

Introduction

Flexible manipulators are increasingly applied in industrial and aerospace fields, such as welding robots, industrial production lines, mechanical arms of aircraft, and so on, owing to their energy efficiency, high speed, and low contact impact. Based on unknown input observer (UIO), Wang et al [15] put forward a novel funnel nonsingular terminal sliding mode control (FNTSMC) method for servomechanisms with unknown dynamics, e.g., nonlinear friction, uncertainties, and external disturbances. He et al [16] created a full-state feedback neural network (NN) control to mitigate the uncertainties and enhance the robustness of the dynamic system of a flexible-joint manipulator. Rahmani and Belkheiri [17] came up with a novel approach for adaptive control of flexible multilink robots in the joint space, proved that the approach is valid for a class of highly uncertain systems with arbitrary but bounded dimensions, and realized trajectory tracking by developing a stable inversion for robot dynamics using only joint angle measurements.

The Observer and Controller Design

Design and Analysis of Observer-Based Sliding

Results and Discussion