A Finite-Time Fault-Tolerant Control Using Non-Singular Fast Terminal Sliding Mode Control and Third-Order Sliding Mode Observer for Robotic Manipulators

Van-Cuong Nguyen,Anh-Tuan Vo,Hee-Jun Kang

doi:10.1109/access.2021.3059897

Van-Cuong Nguyen, Anh-Tuan Vo + Show 1 more

Open Access

https://doi.org/10.1109/access.2021.3059897

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Abstract

In this paper, a fault-tolerant control (FTC) method for robotic manipulators is proposed to deal with the lumped uncertainties and faults in case of lacking tachometer sensors in the system. First, the third-order sliding mode (TOSM) observer is performed to approximate system velocities and the lumped uncertainties and faults. This observer provides estimation information with high precision, low chattering phenomenon, and finite-time convergence. Then, an FTC method is proposed based on a non-singular fast terminal switching function and the TOSM observer. This combination provides robust features in dealing with the lumped uncertainties and faults, increases the control performance, reduces chattering phenomenon, and guarantees fast finite-time convergence. Especially, this paper considers both two periods of time, in which before and after the convergence process takes place. The stability and the finite-time convergence of the proposed controller-observer technique is demonstrated using the Lyapunov theory. Finally, to verify the effectiveness of the proposed controller-observer technique, computer simulation on a serial two-link robotic manipulator is performed.

Highlights

In the industrial environment, robotic manipulators have many special applications due to their ability to replace workers in difficult and dangerous activities such as moving heavy products, assembling mechanical structures, sheet metal cutting, etc
DESIGN OF THE OBSERVER The third-order sliding mode (TOSM) observer is designed for the robotic system (8) as [23]
The results show that the TOSM observer provides the estimation information with higher accuracy than that of the SOSM observer

Summary

Introduction

Robotic manipulators have many special applications due to their ability to replace workers in difficult and dangerous activities such as moving heavy products, assembling mechanical structures, sheet metal cutting, etc. They can help to improve both the product quality and quantity, saving the cost for manufacturers. Robotic manipulators have very complicated dynamic, from practical viewpoint, they are arduous or even impossible to obtain the robot’s exact dynamics, leading to model uncertainties. They are the large challenges in both theoretical and practical control. The faults are treated as additional uncertainties, the total effects of the lumped uncertainties and faults in the system are considered

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