Design of a quasi-passive ankle-foot prosthesis with biomimetic, variable stiffness

Max K. Shepherd; Elliott J. Rouse

doi:10.1109/ICRA.2017.7989788

Design of a quasi-passive ankle-foot prosthesis with biomimetic, variable stiffness

Max K. Shepherd, Elliott J. Rouse

Biomedical Engineering

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

41 Scopus citations

Abstract

Modern passive ankle-foot prostheses do not exhibit appropriate biomechanics during walking, and are unable to adjust their mechanics for other mobility tasks, such as stair traversal or quiet standing. In this paper, we introduce a quasi-passive ankle-foot prosthesis that addresses these challenges; the ankle has a customizable, nonlinear torque-angle curve, and the overall stiffness can be varied continuously between mobility tasks. The variation in mechanics is accomplished by integrating two mechanisms: a cam-based transmission, in which rotation of the ankle joint causes deflection of a leaf spring, and an active sliding support beneath the leaf spring, which can modify the spring's effective stiffness. In addition to introducing the design, we present the mathematics to calculate the cam profile for any arbitrary torque-angle curve, and experimentally characterize the system for a desired curve based on human walking. Lastly, we demonstrate the full range of stiffness levels available and stiffness transition time.

Original language	English (US)
Title of host publication	ICRA 2017 - IEEE International Conference on Robotics and Automation
Publisher	Institute of Electrical and Electronics Engineers Inc.
Pages	6672-6678
Number of pages	7
ISBN (Electronic)	9781509046331
DOIs	https://doi.org/10.1109/ICRA.2017.7989788
State	Published - Jul 21 2017
Event	2017 IEEE International Conference on Robotics and Automation, ICRA 2017 - Singapore, Singapore Duration: May 29 2017 → Jun 3 2017

Publication series

Name	Proceedings - IEEE International Conference on Robotics and Automation
ISSN (Print)	1050-4729

Other

Other	2017 IEEE International Conference on Robotics and Automation, ICRA 2017
Country/Territory	Singapore
City	Singapore
Period	5/29/17 → 6/3/17

Funding

ACKNOWLEDGMENT The authors would like to thank Gordon Composites for donating the fiberglass spring. This work made use of the Central Laboratory for Materials Mechanical Properties supported by the MRSEC program of the National Science Foundation (DMR-1121262) at the Northwestern University Materials Research Science and Engineering Center.

ASJC Scopus subject areas

Software
Artificial Intelligence
Electrical and Electronic Engineering
Control and Systems Engineering

Access to Document

10.1109/ICRA.2017.7989788

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Shepherd, M. K., & Rouse, E. J. (2017). Design of a quasi-passive ankle-foot prosthesis with biomimetic, variable stiffness. In ICRA 2017 - IEEE International Conference on Robotics and Automation (pp. 6672-6678). Article 7989788 (Proceedings - IEEE International Conference on Robotics and Automation). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ICRA.2017.7989788

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abstract = "Modern passive ankle-foot prostheses do not exhibit appropriate biomechanics during walking, and are unable to adjust their mechanics for other mobility tasks, such as stair traversal or quiet standing. In this paper, we introduce a quasi-passive ankle-foot prosthesis that addresses these challenges; the ankle has a customizable, nonlinear torque-angle curve, and the overall stiffness can be varied continuously between mobility tasks. The variation in mechanics is accomplished by integrating two mechanisms: a cam-based transmission, in which rotation of the ankle joint causes deflection of a leaf spring, and an active sliding support beneath the leaf spring, which can modify the spring's effective stiffness. In addition to introducing the design, we present the mathematics to calculate the cam profile for any arbitrary torque-angle curve, and experimentally characterize the system for a desired curve based on human walking. Lastly, we demonstrate the full range of stiffness levels available and stiffness transition time.",

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Shepherd, MK & Rouse, EJ 2017, Design of a quasi-passive ankle-foot prosthesis with biomimetic, variable stiffness. in ICRA 2017 - IEEE International Conference on Robotics and Automation., 7989788, Proceedings - IEEE International Conference on Robotics and Automation, Institute of Electrical and Electronics Engineers Inc., pp. 6672-6678, 2017 IEEE International Conference on Robotics and Automation, ICRA 2017, Singapore, Singapore, 5/29/17. https://doi.org/10.1109/ICRA.2017.7989788

Design of a quasi-passive ankle-foot prosthesis with biomimetic, variable stiffness. / Shepherd, Max K.; Rouse, Elliott J.
ICRA 2017 - IEEE International Conference on Robotics and Automation. Institute of Electrical and Electronics Engineers Inc., 2017. p. 6672-6678 7989788 (Proceedings - IEEE International Conference on Robotics and Automation).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

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N2 - Modern passive ankle-foot prostheses do not exhibit appropriate biomechanics during walking, and are unable to adjust their mechanics for other mobility tasks, such as stair traversal or quiet standing. In this paper, we introduce a quasi-passive ankle-foot prosthesis that addresses these challenges; the ankle has a customizable, nonlinear torque-angle curve, and the overall stiffness can be varied continuously between mobility tasks. The variation in mechanics is accomplished by integrating two mechanisms: a cam-based transmission, in which rotation of the ankle joint causes deflection of a leaf spring, and an active sliding support beneath the leaf spring, which can modify the spring's effective stiffness. In addition to introducing the design, we present the mathematics to calculate the cam profile for any arbitrary torque-angle curve, and experimentally characterize the system for a desired curve based on human walking. Lastly, we demonstrate the full range of stiffness levels available and stiffness transition time.

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Design of a quasi-passive ankle-foot prosthesis with biomimetic, variable stiffness

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