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Journal of NeuroEngineering and Rehabilitation

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Open Access 01-12-2019 | Research

Model-based control for exoskeletons with series elastic actuators evaluated on sit-to-stand movements

Authors: Jonas Vantilt, Kevin Tanghe, Maarten Afschrift, Amber K.B.D Bruijnes, Karen Junius, Joost Geeroms, Erwin Aertbeliën, Friedl De Groote, Dirk Lefeber, Ilse Jonkers, Joris De Schutter

Published in: Journal of NeuroEngineering and Rehabilitation | Issue 1/2019

Abstract

Background

Currently, control of exoskeletons in rehabilitation focuses on imposing desired trajectories to promote relearning of motions. Furthermore, assistance is often provided by imposing these desired trajectories using impedance controllers. However, lower-limb exoskeletons are also a promising solution for mobility problems of individuals in daily life. To develop an assistive exoskeleton which allows the user to be autonomous, i.e. in control of his motions, remains a challenge. This paper presents a model-based control method to tackle this challenge.

Methods

The model-based control method utilizes a dynamic model of the exoskeleton to compensate for its own dynamics. After this compensation of the exoskeleton dynamics, the exoskeleton can provide a desired assistance to the user. While dynamic models of exoskeletons used in the literature focus on gravity compensation only, the need for modelling and monitoring of the ground contact impedes their widespread use. The control strategy proposed here relies on modelling of the full exoskeleton dynamics and of the contacts with the environment. A modelling strategy and general control scheme are introduced.

Results

Validation of the control method on 15 non-disabled adults performing sit-to-stand motions shows that muscle effort and joint torques are similar in the conditions with dynamically compensated exoskeleton and without exoskeleton. The condition with exoskeleton in which the compensating controller was not active showed a significant increase in human joint torques and muscle effort at the knee and hip. Motor saturation occurred during the assisted condition, which limited the assistance the exoskeleton could deliver.

Conclusions

This work presents the modelling steps and controller design to compensate the exoskeleton dynamics. The validation seems to indicate that the presented model-based controller is able to compensate the exoskeleton.

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Title: Model-based control for exoskeletons with series elastic actuators evaluated on sit-to-stand movements
Authors: Jonas Vantilt
Kevin Tanghe
Maarten Afschrift
Amber K.B.D Bruijnes
Karen Junius
Joost Geeroms
Erwin Aertbeliën
Friedl De Groote
Dirk Lefeber
Ilse Jonkers
Joris De Schutter
Publication date: 01-12-2019
Publisher: BioMed Central
Published in: Journal of NeuroEngineering and Rehabilitation / Issue 1/2019
Electronic ISSN: 1743-0003
DOI: https://doi.org/10.1186/s12984-019-0526-8

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Springer Medicine

Model-based control for exoskeletons with series elastic actuators evaluated on sit-to-stand movements

Abstract

Background

Methods

Results

Conclusions

Keynote webinar | Spotlight on medication adherence

Springer Medicine

Abstract

Background

Methods

Results

Conclusions

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