Title: Non-cylindrical wrapping rods and compliant adapters for multi-mode twisting string actuation

Authors: Nicolas Mouazé; Thanh Nguyen; Lionel Birglen

Addresses: Department of Mechanical Engineering, Polytechnique Montréal, QC H3T 1J4 Montréal, QC, Canada ' Department of Mechanical Engineering, Polytechnique Montréal, QC H3T 1J4 Montréal, QC, Canada ' Department of Mechanical Engineering, Polytechnique Montréal, QC H3T 1J4 Montréal, QC, Canada

Abstract: In this paper, improvements of the basic twisting string actuation commonly found in the literature are demonstrated based on the addition of two types of passive elements in order to optimise mechanical efficiency. First, the motion speed is increased with non-cylindrical rigid wrapping. Secondly, passive compliant load adjusters are added to improve the overall mechanical advantage of the transmission in reaction to varying loads. A mathematical model of the new system is first detailed in the paper and provides numerical simulations subsequently validated with experimental results. The impact on the important characteristics of the transmission of the design parameters are shown in details and the simulations highlight several improvements of our proposed design compared to existing twisting wire systems. Finally, this novel transmission with a compliant adjuster is used to drive an underactuated robotic finger to demonstrate its effectiveness.

Keywords: actuation system; power transmission; twisting string mechanism; compliant mechanism.

DOI: 10.1504/IJMRS.2021.115156

International Journal of Mechanisms and Robotic Systems, 2021 Vol.5 No.1/2, pp.93 - 110

Received: 31 Jul 2020
Accepted: 29 Jan 2021

Published online: 08 May 2021 *

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