A Compliant Four-bar Linkage Mechanism that Makes the Fingers of a Prosthetic Hand More Impact Resistant
Kyung Yun Choi, Aadeel Akhtar and Timothy Bretl
Presented at IEEE International Conference on Robotics and Automation (ICRA) 2017
Abstract:
Repeated mechanical failure due to accidental impact is one of the main reasons why people with upper- limb amputations abandon commercially-available prosthetic hands. To address this problem, we present the design and evaluation of a compliant four-bar linkage mechanism that makes the fingers of a prosthetic hand more impact resistant. Our design replaces both the rigid input and coupler links with a monolithic compliant bone, and replaces the follower link with three layers of pre-stressed spring steel. This design behaves like a conventional four-bar linkage but adds lateral compliance and eliminates a pin joint, which is a main site of failure on impact. Results from free-end and fixed-end impact tests show that, compared to those made with a conventional four-bar linkage, fingers made with our design absorb up to 11% more energy on impact with no mechanical failure. We also show the integration of these fingers in a prosthetic hand that is low- cost, light-weight, and easy to assemble, and that has grasping performance comparable to commercially-available hands.
Kyung Yun Choi and Timothy Bretl are with the Dept. of Aerospace Engineering, Aadeel Akhtar is with the Neuroscience Program and Medical Scholars Program, University of Illinois at Urbana-Champaign