Variable Interlock Mechanism Joining Shoulder Rotation and Elbow Flexion for Body-Powered Upper Limb Prostheses

Akira Kato, Masato Hirabayashi, Masakatsu G. Fujie, Shigeki Sugano

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    People with upper limb amputations wearing body-powered prostheses perform elbow joint flexion and opening/closing the terminal device by pulling one control cable with the contralateral shoulder. When moving the terminal device close to the mouth during eating, the socket obstructs shoulder rotation motion. In this paper, we developed the variable interlock mechanism to realize shoulder rotation and elbow flexion simultaneously by pulling only one control cable for a body-powered prosthesis. We propose a mechanism consisting of a differential bevel gear and a continuous variable transmission (CVT) unit with a conical cone and roller. With the CVT unit, the user can change the interlocking relationship without multiple steps. The number of teeth of the bevel gear, the radius of conical cone, and roller were designed to realize the interlocking motion of the inner rotation of the shoulder joint at 80° when the elbow flexion angle is 145°. We measure the terminal device trajectory and each joint angle by fixing the prosthesis with the proposed mechanism in an aluminum frame and by pulling the control cable from the top using a motion capture system. For the two conditions of the designed CVT ratio (kσ=1.00, 3.46), the measured CVT ratio becomes ki=1.04, 1.54. We confirm the interlocking motion of our mechanism, and the error between designed and measured CVT ratio can be improved by reducing the backlash of the bevel gear and the slip between the conical cone and the roller at the CVT unit.

    Original languageEnglish
    Title of host publication2018 World Automation Congress, WAC 2018
    PublisherIEEE Computer Society
    Pages312-317
    Number of pages6
    Volume2018-June
    ISBN (Print)9781532377914
    DOIs
    Publication statusPublished - 2018 Aug 8
    Event2018 World Automation Congress, WAC 2018 - Stevenson, United States
    Duration: 2018 Jun 32018 Jun 6

    Other

    Other2018 World Automation Congress, WAC 2018
    CountryUnited States
    CityStevenson
    Period18/6/318/6/6

    Keywords

    • body-powered prosthesis
    • continuous variable transmission
    • differential gear
    • variable interlocking mechanism

    ASJC Scopus subject areas

    • Control and Systems Engineering

    Fingerprint Dive into the research topics of 'Variable Interlock Mechanism Joining Shoulder Rotation and Elbow Flexion for Body-Powered Upper Limb Prostheses'. Together they form a unique fingerprint.

  • Cite this

    Kato, A., Hirabayashi, M., Fujie, M. G., & Sugano, S. (2018). Variable Interlock Mechanism Joining Shoulder Rotation and Elbow Flexion for Body-Powered Upper Limb Prostheses. In 2018 World Automation Congress, WAC 2018 (Vol. 2018-June, pp. 312-317). [8430445] IEEE Computer Society. https://doi.org/10.23919/WAC.2018.8430445