Development and Functional Evaluation of The PrHand V3 Soft-Robotics Prosthetic Hand

The affordability and functionality of hand prosthetics in developing countries are still very limited. This work aims to present and evaluate the new version of the PrHand affordable robotic prosthesis (PrHand V3), built with soft robotics and compliant mechanisms. PrHand V3 implements a new frictionless tendon unification system, the degree of freedom of thumb opposition was removed, and the finger flexion was improved to the previous version, PrHand V2. The study contributes by evaluating these mechanical changes and conducting the first functional assessment of PrHand V3 with an amputee user. The Anthropomorphic Hand Assessment Protocol (AHAP) dexterity test was the first evaluation in this work; it evaluated how the prosthesis performs eight different grips. PrHand V3 was compared with a PrHand V2 and a commercial robotic prosthesis A3D from Prótesis Avanzadas SAS. PrHand V3’s score on the AHAP test was 80%. This result is higher than the 69% obtained by the PrHand V2 and the 79% obtained by A3D. The Activities Measure for Upper Limb Amputees (AM-ULA) test was the second evaluation in this work; An A3D amputee user performed 23 Activities of Daily Living with PrHand V3 and an A3D. PrHand V3 obtained an average of 2.86/4 and A3D obtained an average of 2.96/4 without significant differences between the two tests. The soft actuation of PrHand V3 as an affordable prosthesis performs similarly to a commercial robotic prosthesis with the advantage of being more flexible to assist a trans-radial hand amputee.