CORA hand: a 3D printed robotic hand designed for robustness and compliance

This work presents design and experimental evaluation of CORA (COmpliant Robotic hAnd), a robotic hand designed for easy manufacturing and maintenance, and for robustness and compliance in real operational environments. It takes advantage of recent soft-polymer printable filaments to obtain intrinsic compliance during grasping and accidental contacts. All parts are designed and optimized for manufacturing with conventional fused deposition modeling 3D printers, in order to allow simple fabrication and replacement of parts. In this paper design of the CORA hand is presented, focusing on specific design solutions adopted for improving robustness of the final 3D printed parts and for obtaining compliance in interaction with the environment. A prototype of the CORA hand was built and experimentally tested in terms of grasping capabilities, measuring contact forces and the distributed grasping pressure. Compliance introduced by soft polymer links was evaluated with finite element method simulation and experimental bending tests. A collision test evidenced robustness of the finger mechanism and transmission to pronounced passive deformations, induced by lateral contacts possibly occurring in common manipulation tasks.