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Robust adaptive super twisting controller: methodology and application of a human-driven knee joint orthosis

Rihab Bkekri (Laboratory of Automatic Signal and Image Processing, National Higher Engineering School of Tunis, University of Tunis, Tunis, Tunisia)
Anouar Benamor (Department of Electrical Engineering, Laboratory of Automatic Signal and Image Processing, National Engineering School of Monastir, Monastir, Tunisia)
Mohamed Amine Alouane (Laboratory of Images, Signals and Intelligent Systems (LISSI), University of Paris-Est Créteil, Vitry sur seine, France)
Georges Fried (LISSI/UPEC, Vitry Sur Seine, France)
Hassani Messaoud (Laboratory of Automatic Signal and Image Processing, National Engineering School of Monastir, Monastir, Tunisia)

Industrial Robot

ISSN: 0143-991x

Article publication date: 20 June 2019

Issue publication date: 5 August 2019

Abstract

Purpose

The application of the sliding mode control has two obstacle phenomena: chattering and high activity of control action. The purpose of this paper concerns a novel super-twisting adaptive sliding mode control law of a human-driven knee joint orthosis. The proposed control approach consists of using dynamically adapted control gains that ensure the establishment, in a finite time, of a real second-order sliding mode. The efficiency of the controller is evaluated using an experimental set-up.

Design/methodology/approach

This study presents the synthesis of a robust super-twisting adaptive controller for the control of a lower limb–orthosis system. The developed control strategy will take into consideration the nonlinearities as well as the uncertainties resulting from the dynamics of the lower limb–orthosis system. It must also guarantee a good follow-up of the reference trajectory.

Findings

The authors first evaluated on a valid subject, the performances of this controller which were studied and compared to several criteria. The obtained results show that the controller using the Adaptive Super-Twisting algorithm is the one that guarantees the best performance. Validation tests involved a subject and included robustness tests against external disturbances and co-contractions of antagonistic muscles.

Originality/value

The main contribution of this paper is in developing the adaptation super-twisting methodology for finding the control gain resulting in the minimization of the chattering effect.

Keywords

Acknowledgements

The authors extend sincere thanks to LISSI laboratory for providing the opportunity to use the EICOSI manipulation. The authors would like to express deepest gratitude to Professor Samer Mohammed for his encouragement and invaluable support of this research, as well as all members of LISSI for their comments and respect.

Citation

Bkekri, R., Benamor, A., Alouane, M.A., Fried, G. and Messaoud, H. (2019), "Robust adaptive super twisting controller: methodology and application of a human-driven knee joint orthosis", Industrial Robot, Vol. 46 No. 4, pp. 481-489. https://doi.org/10.1108/IR-09-2018-0198

Publisher

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Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited