The Lightweight Delft Cylinder Hand: First Multi-Articulating Hand That Meets the Basic User Requirements

Rejection rates of upper limb prostheses are high (23%-45%). Amputees indicate that the highest design priority should be reduction of the mass of the prosthetic device. Despite all efforts, the mass of the new prosthetic hands is 35%-73% higher than that of older hands. Furthermore, current hands are thicker than a human hand, they operate slower and do not provide proprioceptive force and position feedback. This study presents the Delft Cylinder Hand, a body powered prosthetic hand which mass is 55%-68% lower than that of the lightest current prosthetic hands, operates faster, has an anthropomorphic shape, and provides proprioceptive force and position feedback. The hand has articulating fingers, actuated by miniature hydraulic cylinders. The articulating fingers adapt to the shape of the grasped object. Its functional scores are similar to that of current prosthetic devices. The hand has a higher mechanical performance than current body-powered hands. It requires 49%-162% less energy from the user and it can deliver a higher maximum pinch force (30-60 N).