Reinforcement learning control of a biomechanical model of the upper extremity

Abstract Among the infinite number of possible movements that can be produced, humans are commonly assumed to choose those that optimize criteria such as minimizing movement time, subject to certain movement constraints like signal-dependent and constant motor noise. While so far these assumptions h...

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Autores principales: Florian Fischer, Miroslav Bachinski, Markus Klar, Arthur Fleig, Jörg Müller
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Lenguaje:EN
Publicado: Nature Portfolio 2021
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Acceso en línea:https://doaj.org/article/33d3fa44c29842128b53c1355182dbf9
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spelling oai:doaj.org-article:33d3fa44c29842128b53c1355182dbf92021-12-02T16:14:10ZReinforcement learning control of a biomechanical model of the upper extremity10.1038/s41598-021-93760-12045-2322https://doaj.org/article/33d3fa44c29842128b53c1355182dbf92021-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-93760-1https://doaj.org/toc/2045-2322Abstract Among the infinite number of possible movements that can be produced, humans are commonly assumed to choose those that optimize criteria such as minimizing movement time, subject to certain movement constraints like signal-dependent and constant motor noise. While so far these assumptions have only been evaluated for simplified point-mass or planar models, we address the question of whether they can predict reaching movements in a full skeletal model of the human upper extremity. We learn a control policy using a motor babbling approach as implemented in reinforcement learning, using aimed movements of the tip of the right index finger towards randomly placed 3D targets of varying size. We use a state-of-the-art biomechanical model, which includes seven actuated degrees of freedom. To deal with the curse of dimensionality, we use a simplified second-order muscle model, acting at each degree of freedom instead of individual muscles. The results confirm that the assumptions of signal-dependent and constant motor noise, together with the objective of movement time minimization, are sufficient for a state-of-the-art skeletal model of the human upper extremity to reproduce complex phenomena of human movement, in particular Fitts’ Law and the $$\frac{2}{3}$$ 2 3 Power Law. This result supports the notion that control of the complex human biomechanical system can plausibly be determined by a set of simple assumptions and can easily be learned.Florian FischerMiroslav BachinskiMarkus KlarArthur FleigJörg MüllerNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-15 (2021)
institution DOAJ
collection DOAJ
language EN
topic Medicine
R
Science
Q
spellingShingle Medicine
R
Science
Q
Florian Fischer
Miroslav Bachinski
Markus Klar
Arthur Fleig
Jörg Müller
Reinforcement learning control of a biomechanical model of the upper extremity
description Abstract Among the infinite number of possible movements that can be produced, humans are commonly assumed to choose those that optimize criteria such as minimizing movement time, subject to certain movement constraints like signal-dependent and constant motor noise. While so far these assumptions have only been evaluated for simplified point-mass or planar models, we address the question of whether they can predict reaching movements in a full skeletal model of the human upper extremity. We learn a control policy using a motor babbling approach as implemented in reinforcement learning, using aimed movements of the tip of the right index finger towards randomly placed 3D targets of varying size. We use a state-of-the-art biomechanical model, which includes seven actuated degrees of freedom. To deal with the curse of dimensionality, we use a simplified second-order muscle model, acting at each degree of freedom instead of individual muscles. The results confirm that the assumptions of signal-dependent and constant motor noise, together with the objective of movement time minimization, are sufficient for a state-of-the-art skeletal model of the human upper extremity to reproduce complex phenomena of human movement, in particular Fitts’ Law and the $$\frac{2}{3}$$ 2 3 Power Law. This result supports the notion that control of the complex human biomechanical system can plausibly be determined by a set of simple assumptions and can easily be learned.
format article
author Florian Fischer
Miroslav Bachinski
Markus Klar
Arthur Fleig
Jörg Müller
author_facet Florian Fischer
Miroslav Bachinski
Markus Klar
Arthur Fleig
Jörg Müller
author_sort Florian Fischer
title Reinforcement learning control of a biomechanical model of the upper extremity
title_short Reinforcement learning control of a biomechanical model of the upper extremity
title_full Reinforcement learning control of a biomechanical model of the upper extremity
title_fullStr Reinforcement learning control of a biomechanical model of the upper extremity
title_full_unstemmed Reinforcement learning control of a biomechanical model of the upper extremity
title_sort reinforcement learning control of a biomechanical model of the upper extremity
publisher Nature Portfolio
publishDate 2021
url https://doaj.org/article/33d3fa44c29842128b53c1355182dbf9
work_keys_str_mv AT florianfischer reinforcementlearningcontrolofabiomechanicalmodeloftheupperextremity
AT miroslavbachinski reinforcementlearningcontrolofabiomechanicalmodeloftheupperextremity
AT markusklar reinforcementlearningcontrolofabiomechanicalmodeloftheupperextremity
AT arthurfleig reinforcementlearningcontrolofabiomechanicalmodeloftheupperextremity
AT jorgmuller reinforcementlearningcontrolofabiomechanicalmodeloftheupperextremity
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