A Robust Noise-Free Linear Control Design for Robot Manipulator with Uncertain System Parameters

Yi-Liang Yeh

doi:10.3390/act10060121

Abstract

In robot control, the sliding mode control is known for its robustness against external disturbances and system uncertainties. However, it has the disadvantage of control chattering, which can damage the actuator and degrade system performance. With a new stability proof, this paper presents an alternative simple linear feedback control that can cope with large system uncertainties and suppress large external disturbances, doing so as effectively as sliding mode control does. The advantage of using linear control is that the control law is simple and control chattering can be avoided. Moreover, a noise-free control scheme is proposed as an improvement of the feedback control; the modified design preserves the advantages of linear control and generates a chattering-free control signal even in a noisy environment.

Highlights

The tracking control of robot manipulators is a mature field but still has many research possibilities, and a straightforward control scheme is known as computed-torque control [1]
The purpose of this paper is to demonstrate that simple linear control can deal with system uncertainties and external disturbances as effectively as sliding mode control can, especially in the robot control task
The goal of this paper is to show that (1) given any large Lipschitz nonlinearity ∆ f (x), one can always stabilize the closed-loop system with the proposed simple linear control (11) and (2) the simple linear control is sufficient to suppress the effects of large disturbance d on the system

Summary

Introduction

The tracking control of robot manipulators is a mature field but still has many research possibilities, and a straightforward control scheme is known as computed-torque control [1]. When uncertainties and unknown disturbances occur, conventional robust stability analysis shows that if the nominal system is exponentially stable, the system can tolerate “small” system uncertainties and external disturbances [2], restricting the application of linear control to robot manipulators, which is a highly nonlinear system. In this case, adaptive control [3,4,5], sliding-mode control [6,7,8,9,10,11], and neural network control [12,13,14] were proposed to solve the problem.

Problem Description Consider the dynamic equation of an n-DOF link robot

Preliminary

Stability Analysis

Noise-Free Control Design

Application to a Two DOF Robot Manipulator

Conclusions