Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion

Abstract Background This research aims to improve the control of assistive devices for individuals with hemiparesis after stroke by providing intuitive and proportional motor control. Stroke is the leading cause of disability in the United States, with 80% of stroke-related disability coming in the...

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Main Authors: Caleb J. Thomson, Fredi R. Mino, Danielle R. Lopez, Patrick P. Maitre, Steven R. Edgley, Jacob A. George
Format: Article
Language:English
Published: BMC 2024-12-01
Series:Journal of NeuroEngineering and Rehabilitation
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Online Access:https://doi.org/10.1186/s12984-024-01529-0
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author Caleb J. Thomson
Fredi R. Mino
Danielle R. Lopez
Patrick P. Maitre
Steven R. Edgley
Jacob A. George
author_facet Caleb J. Thomson
Fredi R. Mino
Danielle R. Lopez
Patrick P. Maitre
Steven R. Edgley
Jacob A. George
author_sort Caleb J. Thomson
collection DOAJ
description Abstract Background This research aims to improve the control of assistive devices for individuals with hemiparesis after stroke by providing intuitive and proportional motor control. Stroke is the leading cause of disability in the United States, with 80% of stroke-related disability coming in the form of hemiparesis, presented as weakness or paresis on half of the body. Current assistive exoskeletonscontrolled via electromyography do not allow for fine force regulation. Current control strategies provide only binary, all-or-nothing control based on a linear threshold of muscle activity. Methods In this study, we demonstrate the ability of participants with hemiparesis to finely regulate their muscle activity to proportionally control the position of a virtual bionic arm. Ten stroke survivors and ten healthy, aged-matched controls completed a target-touching task with the virtual bionic arm. We compared the signal-to-noise ratio (SNR) of the recorded electromyography (EMG) signals used to train the control algorithms and the task performance using root mean square error, percent time in target, and maximum hold time within the target window. Additionally, we looked at the correlation between EMG SNR, task performance, and clinical spasticity scores. Results All stroke survivors were able to achieve proportional EMG control despite limited or no physical movement (i.e., modified Ashworth scale of 3). EMG SNR was significantly lower for the paretic arm than the contralateral nonparetic arm and healthy control arms, but proportional EMG control was similar across conditions for hand grasp. In contrast, proportional EMG control for hand extension was significantly worse for paretic arms than healthy control arms. The participants’ age, time since their stroke, clinical spasticity rate, and history of botulinum toxin injections had no impact on proportional EMG control. Conclusions It is possible to provide proportional EMG control of assistive devices from a stroke survivor’s paretic arm. Importantly, information regulating fine force output is still present in muscle activity, even in extreme cases of spasticity where there is no visible movement. Future work should incorporate proportional EMG control into upper-limb exoskeletons to enhance the dexterity of stroke survivors.
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spelling doaj-art-7d617662add24d05a4f19eb926b619ba2024-12-22T12:19:19ZengBMCJournal of NeuroEngineering and Rehabilitation1743-00032024-12-0121111410.1186/s12984-024-01529-0Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motionCaleb J. Thomson0Fredi R. Mino1Danielle R. Lopez2Patrick P. Maitre3Steven R. Edgley4Jacob A. George5Department of Biomedical Engineering, University of UtahDepartment of Electrical and Computer Engineering, University of UtahInterdepartmental Neuroscience Program, University of UtahDepartment of Physical Medicine and Rehabilitation, University of UtahDepartment of Physical Medicine and Rehabilitation, University of UtahDepartment of Biomedical Engineering, University of UtahAbstract Background This research aims to improve the control of assistive devices for individuals with hemiparesis after stroke by providing intuitive and proportional motor control. Stroke is the leading cause of disability in the United States, with 80% of stroke-related disability coming in the form of hemiparesis, presented as weakness or paresis on half of the body. Current assistive exoskeletonscontrolled via electromyography do not allow for fine force regulation. Current control strategies provide only binary, all-or-nothing control based on a linear threshold of muscle activity. Methods In this study, we demonstrate the ability of participants with hemiparesis to finely regulate their muscle activity to proportionally control the position of a virtual bionic arm. Ten stroke survivors and ten healthy, aged-matched controls completed a target-touching task with the virtual bionic arm. We compared the signal-to-noise ratio (SNR) of the recorded electromyography (EMG) signals used to train the control algorithms and the task performance using root mean square error, percent time in target, and maximum hold time within the target window. Additionally, we looked at the correlation between EMG SNR, task performance, and clinical spasticity scores. Results All stroke survivors were able to achieve proportional EMG control despite limited or no physical movement (i.e., modified Ashworth scale of 3). EMG SNR was significantly lower for the paretic arm than the contralateral nonparetic arm and healthy control arms, but proportional EMG control was similar across conditions for hand grasp. In contrast, proportional EMG control for hand extension was significantly worse for paretic arms than healthy control arms. The participants’ age, time since their stroke, clinical spasticity rate, and history of botulinum toxin injections had no impact on proportional EMG control. Conclusions It is possible to provide proportional EMG control of assistive devices from a stroke survivor’s paretic arm. Importantly, information regulating fine force output is still present in muscle activity, even in extreme cases of spasticity where there is no visible movement. Future work should incorporate proportional EMG control into upper-limb exoskeletons to enhance the dexterity of stroke survivors.https://doi.org/10.1186/s12984-024-01529-0MyoelectricEMGHemiparesisStrokeMotor controlExoskeleton
spellingShingle Caleb J. Thomson
Fredi R. Mino
Danielle R. Lopez
Patrick P. Maitre
Steven R. Edgley
Jacob A. George
Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion
Journal of NeuroEngineering and Rehabilitation
Myoelectric
EMG
Hemiparesis
Stroke
Motor control
Exoskeleton
title Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion
title_full Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion
title_fullStr Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion
title_full_unstemmed Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion
title_short Proportional myoelectric control of a virtual bionic arm in participants with hemiparesis, muscle spasticity, and impaired range of motion
title_sort proportional myoelectric control of a virtual bionic arm in participants with hemiparesis muscle spasticity and impaired range of motion
topic Myoelectric
EMG
Hemiparesis
Stroke
Motor control
Exoskeleton
url https://doi.org/10.1186/s12984-024-01529-0
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