Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques

Alejandro Moya Esteban; Ronald C. Van 'T Veld; Christopher P. Cop; Guillaume Durandau; Massimo Sartori; Alfred C. Schouten

doi:10.1109/EMBC.2019.8856423

Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques

Alejandro Moya Esteban, Ronald C. Van 'T Veld, Christopher P. Cop, Guillaume Durandau, Massimo Sartori, Alfred C. Schouten

Biomechatronics & Human-Machine Control

Research output: Chapter in Book/Conference proceedings/Edited volume › Conference contribution › Scientific › peer-review

8 Citations (Scopus)

51 Downloads (Pure)

Abstract

An important goal in the design of next-generation exoskeletons and limb prostheses is to replicate human limb dynamics. Joint impedance determines the dynamic relation between joint displacement and torque. Joint stiffness is the position-dependent component of joint impedance and is key in postural control and movement. However, the mechanisms to modulate joint stiffness are not fully understood yet. The goal of this study is to conduct a systematic analysis on how humans modulate ankle stiffness. Time-varying stiffness was estimated for six healthy subjects under isometric, as well as quick and slow dynamic conditions via system identification techniques; specifically, an ensemble-based algorithm using short segments of ankle torque and position recordings. Our results show that stiffness had the lowest magnitude under quick dynamic conditions. Under isometric conditions, with fixed position and varying muscle activity, stiffness exhibited a higher magnitude. Finally, under slow dynamic conditions, stiffness was found to be the highest. Our results highlight, for the first time, the variability in stiffness modulation strategies across conditions, especially across movement velocity.

Original language	English
Title of host publication	Proceedings of the 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2019)
Place of Publication	Piscataway, NJ, USA
Publisher	IEEE
Pages	2119-2122
ISBN (Electronic)	978-1-5386-1311-5
DOIs	https://doi.org/10.1109/EMBC.2019.8856423
Publication status	Published - 2019
Event	EMBC 2019: 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society - Berlin, Germany Duration: 23 Jul 2019 → 27 Jul 2019 Conference number: 41st

Conference

Conference	EMBC 2019
Country/Territory	Germany
City	Berlin
Period	23/07/19 → 27/07/19

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

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10.1109/EMBC.2019.8856423

Estimation_of_Time-Varying_Ankle_Joint_Stiffness_Under_Dynamic_Conditions_via_System_Identification_TechniquesFinal published version, 1.18 MB

Cite this

Esteban, A. M., Van 'T Veld, R. C., Cop, C. P., Durandau, G., Sartori, M., & Schouten, A. C. (2019). Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques. In Proceedings of the 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2019) (pp. 2119-2122). IEEE. https://doi.org/10.1109/EMBC.2019.8856423

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title = "Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques",

abstract = "An important goal in the design of next-generation exoskeletons and limb prostheses is to replicate human limb dynamics. Joint impedance determines the dynamic relation between joint displacement and torque. Joint stiffness is the position-dependent component of joint impedance and is key in postural control and movement. However, the mechanisms to modulate joint stiffness are not fully understood yet. The goal of this study is to conduct a systematic analysis on how humans modulate ankle stiffness. Time-varying stiffness was estimated for six healthy subjects under isometric, as well as quick and slow dynamic conditions via system identification techniques; specifically, an ensemble-based algorithm using short segments of ankle torque and position recordings. Our results show that stiffness had the lowest magnitude under quick dynamic conditions. Under isometric conditions, with fixed position and varying muscle activity, stiffness exhibited a higher magnitude. Finally, under slow dynamic conditions, stiffness was found to be the highest. Our results highlight, for the first time, the variability in stiffness modulation strategies across conditions, especially across movement velocity.",

author = "Esteban, {Alejandro Moya} and {Van 'T Veld}, {Ronald C.} and Cop, {Christopher P.} and Guillaume Durandau and Massimo Sartori and Schouten, {Alfred C.}",

note = "Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.; EMBC 2019 : 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society ; Conference date: 23-07-2019 Through 27-07-2019",

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doi = "10.1109/EMBC.2019.8856423",

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Esteban, AM, Van 'T Veld, RC, Cop, CP, Durandau, G, Sartori, M & Schouten, AC 2019, Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques. in Proceedings of the 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2019). IEEE, Piscataway, NJ, USA, pp. 2119-2122, EMBC 2019, Berlin, Germany, 23/07/19. https://doi.org/10.1109/EMBC.2019.8856423

Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques. / Esteban, Alejandro Moya; Van 'T Veld, Ronald C.; Cop, Christopher P. et al.
Proceedings of the 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2019). Piscataway, NJ, USA: IEEE, 2019. p. 2119-2122.

Research output: Chapter in Book/Conference proceedings/Edited volume › Conference contribution › Scientific › peer-review

TY - GEN

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AU - Esteban, Alejandro Moya

AU - Van 'T Veld, Ronald C.

AU - Cop, Christopher P.

AU - Durandau, Guillaume

AU - Sartori, Massimo

AU - Schouten, Alfred C.

N1 - Conference code: 41st

PY - 2019

Y1 - 2019

N2 - An important goal in the design of next-generation exoskeletons and limb prostheses is to replicate human limb dynamics. Joint impedance determines the dynamic relation between joint displacement and torque. Joint stiffness is the position-dependent component of joint impedance and is key in postural control and movement. However, the mechanisms to modulate joint stiffness are not fully understood yet. The goal of this study is to conduct a systematic analysis on how humans modulate ankle stiffness. Time-varying stiffness was estimated for six healthy subjects under isometric, as well as quick and slow dynamic conditions via system identification techniques; specifically, an ensemble-based algorithm using short segments of ankle torque and position recordings. Our results show that stiffness had the lowest magnitude under quick dynamic conditions. Under isometric conditions, with fixed position and varying muscle activity, stiffness exhibited a higher magnitude. Finally, under slow dynamic conditions, stiffness was found to be the highest. Our results highlight, for the first time, the variability in stiffness modulation strategies across conditions, especially across movement velocity.

AB - An important goal in the design of next-generation exoskeletons and limb prostheses is to replicate human limb dynamics. Joint impedance determines the dynamic relation between joint displacement and torque. Joint stiffness is the position-dependent component of joint impedance and is key in postural control and movement. However, the mechanisms to modulate joint stiffness are not fully understood yet. The goal of this study is to conduct a systematic analysis on how humans modulate ankle stiffness. Time-varying stiffness was estimated for six healthy subjects under isometric, as well as quick and slow dynamic conditions via system identification techniques; specifically, an ensemble-based algorithm using short segments of ankle torque and position recordings. Our results show that stiffness had the lowest magnitude under quick dynamic conditions. Under isometric conditions, with fixed position and varying muscle activity, stiffness exhibited a higher magnitude. Finally, under slow dynamic conditions, stiffness was found to be the highest. Our results highlight, for the first time, the variability in stiffness modulation strategies across conditions, especially across movement velocity.

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BT - Proceedings of the 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2019)

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ER -

Esteban AM, Van 'T Veld RC, Cop CP, Durandau G, Sartori M, Schouten AC. Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques. In Proceedings of the 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2019). Piscataway, NJ, USA: IEEE. 2019. p. 2119-2122 doi: 10.1109/EMBC.2019.8856423

Estimation of time-varying ankle joint stiffness under dynamic conditions via system identification techniques

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