Practical issues in data-driven model-free adaptive control for an omnidirectional mobile manipulator

Chao Ren; Jingyi Zhang; Liang Hu; Shugen Ma

doi:10.1016/j.isatra.2023.07.024

Practical issues in data-driven model-free adaptive control for an omnidirectional mobile manipulator

ISA Trans. 2023 Nov:142:615-625. doi: 10.1016/j.isatra.2023.07.024. Epub 2023 Jul 22.

Authors

Chao Ren¹, Jingyi Zhang², Liang Hu³, Shugen Ma⁴

Affiliations

¹ School of Electrical and Information Engineering, Tianjin University, Tianjin, 300072, China. Electronic address: renchao@tju.edu.cn.
² School of Electrical and Information Engineering, Tianjin University, Tianjin, 300072, China. Electronic address: jingyi_zhang@tju.edu.cn.
³ School of Computer Science and Electronic Engineering, University of Essex, UK. Electronic address: l.hu@essex.ac.uk.
⁴ School of Electrical and Information Engineering, Tianjin University, Tianjin, 300072, China; Department of Robotics, Ritsumeikan University, Shiga 525-8577, Japan. Electronic address: shugen.ma@ieee.org.

PMID: 37541855
DOI: 10.1016/j.isatra.2023.07.024

Abstract

This article focuses on addressing three practical issues encountered when applying a data-driven model-free adaptive control (MFAC) approach to mobile robots. The first practical issue lies in a common assumption in MFAC schemes that the sign of all elements in pseudo-partial derivative (PPD) should be constant, while it cannot be satisfied if omnidirectional mobile manipulators (OMMs) move with platform rotation. To solve this problem, a new coordinate frame is introduced, which is crucial for applying MFAC to any mobile robots with rotation. The second one is that the initial value setting method for estimation of PPD is unclear. Improper settings may easily lead to control system instability. An initial value setting method for estimation of PPD is proposed with explicit physical interpretation. Lastly, applying the typical MFAC scheme directly to OMM fails to converge well to the desired trajectory. To tackle this, a new data-driven MFAC controller is proposed by incorporating a sliding mode control. Finally, experimental tests on an OMM are carried out to verify the effectiveness of the proposed control scheme. To the best of our knowledge, this is the first MFAC scheme that has been experimentally verified on a prototype mobile robot with rotation.

Keywords: Data-driven; Model-free adaptive control; Omnidirectional mobile robot; Trajectory tracking control.