Mechanical assessment of novel compliant mechanisms for underactuated prosthetic hands

Orion Ramos; Laura de Arco; Carlos A Cifuentes; Mehran Moazen; Helge Wurdemann; Marcela Múnera

doi:10.3389/fbioe.2023.985901

Mechanical assessment of novel compliant mechanisms for underactuated prosthetic hands

Front Bioeng Biotechnol. 2023 Oct 11:11:985901. doi: 10.3389/fbioe.2023.985901. eCollection 2023.

Authors

Orion Ramos¹, Laura de Arco², Carlos A Cifuentes^{1

3}, Mehran Moazen⁴, Helge Wurdemann⁴, Marcela Múnera^{3

5}

Affiliations

¹ School of Engineering, Science and Technology, Universidad Del Rosario, Bogota, Colombia.
² Telecommunications Laboratory (LABTEL), Electrical Engineering, Federal University of Espirito Santo (UFES), Vitória, Brazil.
³ Bristol Robotics Laboratory, University of the West of England, Bristol, United Kingdom.
⁴ Department of Mechanical Engineering, University College London, London, United Kingdom.
⁵ Biomedical Engineering Department, Colombian School of Engineering Julio Garavito, Bogota, Colombia.

Abstract

This paper proposes novel compliant mechanisms for constructing hand prostheses based on soft robotics. Two models of prosthetic hands are developed in this work. Three mechanical evaluations are performed to determine the suitability of the two designs for carrying out activities of daily living (ADLs). The first test measures the grip force that the prosthesis can generate on objects. The second determines the energy required and dissipated from the prosthesis to operate. The third test identifies the maximum traction force that the prosthesis can support. The tests showed that the PrHand1 prosthesis has a maximum grip force of 23.38 ± 1.5 N, the required energy is 0.76 ± 0.13 J, and the dissipated energy is 0.21 ± 0.17 J. It supports a traction force of 173.31 ± 5.7 N. The PrHand2 prosthesis has a maximum grip force of 36.13 ± 2.3 N, the required energy is 1.28 ± 0.13 J, the dissipated energy is 0.96 ± 0.12 J, and it supports a traction force of 78.48 ± 0 N. In conclusion, the PrHand1 prosthesis has a better performance in terms of energy and tensile force supported. The difference between the energy and traction force results is related to two design features of the PrHand2: fully silicone-coated fingers and a unifying mechanism that requires more force on the tendons to close the prosthesis. The grip force of the PrHand2 prosthesis was more robust than the PrHand1 due to its silicone coating, which allowed for an improved grip.

Keywords: compliant mechanism; grasping; hand prosthetics; mechanical assessment; soft-actuators.

Grants and funding

This work was supported by the Royal Academy of Engineering–Industry-Academia Partnership Programme Colombia/UK (IAPP18-19∖264), PrExHand Project. This work has been partially funded by the Engineering and Physical Sciences Research Council (Grant Number: EP/V01062X∖1).