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Designing and testing lightweight shoulder prostheses with hybrid actuators for movements involved in typical activities of daily living and impact absorption

Authors Sekine M, Kita K, Yu W

Received 1 March 2015

Accepted for publication 21 April 2015

Published 6 July 2015 Volume 2015:8 Pages 279—294

DOI https://doi.org/10.2147/MDER.S83756

Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Scott Fraser


Masashi Sekine,1,2 Kahori Kita,1 Wenwei Yu1

1Center for Frontier Medical Engineering, 2Graduate School of Engineering, Chiba University, Chiba, Japan


Abstract: Unlike forearm amputees, transhumeral amputees have residual stumps that are too small to provide a sufficient range of operation for their prosthetic parts to perform usual activities of daily living. Furthermore, it is difficult for small residual stumps to provide sufficient impact absorption for safe manipulation in daily living, as intact arms do. Therefore, substitution of upper limb function in transhumeral amputees requires a sufficient range of motion and sufficient viscoelasticity for shoulder prostheses under critical weight and dimension constraints. We propose the use of two different types of actuators, ie, pneumatic elastic actuators (PEAs) and servo motors. PEAs offer high power-to-weight performance and have intrinsic viscoelasticity in comparison with motors or standard industrial pneumatic cylinder actuators. However, the usefulness of PEAs in large working spaces is limited because of their short strokes. Servo motors, in contrast, can be used to achieve large ranges of motion. In this study, the relationship between the force and stroke of PEAs was investigated. The impact absorption of both types of actuators was measured using a single degree-of-freedom prototype to evaluate actuator compliance for safety purposes. Based on the fundamental properties of the actuators identified, a four degree-of-freedom robotic arm is proposed for prosthetic use. The configuration of the actuators and functional parts was designed to achieve a specified range of motion and torque calculated from the results of a simulation of typical movements performed in usual activities of daily living. Our experimental results showed that the requirements for the shoulder prostheses could be satisfied.

Keywords: shoulder prosthesis, hybrid actuation, pneumatic elastic actuator, antagonistic mechanism, compliance

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