Comparison between rigid and soft poly-articulated prosthetic hands in non-expert myo-electric users shows advantages of soft robotics

Cristina Piazza,Giorgio Grioli,Patricia Capsi-Morales,Elena Fiaschi,Lisa Schiavon,Antonio Bicchi,Manuel G Catalano

doi:10.1038/s41598-021-02562-y

Abstract

Notwithstanding the advancement of modern bionic hands and the large variety of prosthetic hands in the market, commercial devices still present limited acceptance and percentage of daily use. While commercial prostheses present rigid mechanical structures, emerging trends in the design of robotic hands are moving towards soft technologies. Although this approach is inspired by nature and could be promising for prosthetic applications, there is scant literature concerning its benefits for end-users and in real-life scenarios. In this work, we evaluate and assess the role and the benefits of soft robotic technologies in the field of prosthetics. We propose a thorough comparison between rigid and soft characteristics of two poly-articulated hands in 5 non-expert myo-electric prosthesis users in pre- and post-therapeutic training conditions. The protocol includes two standard functional assessments, three surveys for user-perception, and three customized tests to evaluate the sense of embodiment. Results highlight that rigid hands provide a more precise grasp, while soft properties show higher functionalities thanks to their adaptability to different requirements, intuitive use and more natural execution of activities of daily living. This comprehensive evaluation suggests that softness could also promote a quick integration of the system in non-expert users.

Highlights

Notwithstanding the advancement of modern bionic hands and the large variety of prosthetic hands in the market, commercial devices still present limited acceptance and percentage of daily use
To evaluate the performance and functionalities of the two systems we considered 2 standard assessments, the Box and Blocks test (BBT) and the Assessment for Capacity of Myoelectric Control (ACMC)
The average of the group is reported for each prosthetic hand

Summary

Introduction

Notwithstanding the advancement of modern bionic hands and the large variety of prosthetic hands in the market, commercial devices still present limited acceptance and percentage of daily use. Results highlight that rigid hands provide a more precise grasp, while soft properties show higher functionalities thanks to their adaptability to different requirements, intuitive use and more natural execution of activities of daily living This comprehensive evaluation suggests that softness could promote a quick integration of the system in non-expert users. Just like humans modify their hands to match different task requirements (e.g. wearing gloves to increase hand traction, or using specialized tools), each prosthetic technology could favour the execution of specific activities and may be preferred depending on the context and situations Thanks to their simplicity and ruggedness, hooks are well suited for precision g rips[9] and for coarse e nvironments[10]. Myo-electric prostheses are less cumbersome and offer more dexterous capabilities, so that they are preferred for light duties, office work, and social o uting[12]

Methods

Results

Conclusion