The design and development of a gloveless endoskeletal prosthetic hand

Current prosthetic hands, although functional, have the potential of being improved significantly. We report here the design and development of a nove l prosthetic hand that is lighter in weight, less expensive, and more funct ional than current hands. The new prosthesis features an endoskeleton embed ded in self-skinning foam that provides a realistic look and feel and obvia tes the need for a separate cosmetic glove. The voluntary-dosing mechanism offers variable grip strength. Placement of joints at three locations (meta carpophalangeal and proximal and distal interphalangeal) within each of fou r fingers affords realistic finger movement. High-strength synthetic cable attached to the distal phalanx of each finger is used to effect flexion. A multiposition passive thumb provides both precision and power grips. The ne w prosthesis can securely grasp objects with various shapes and sizes. Comp ared to current hands, weight has been reduced by approximately 50%, and ca ble excursion required for full finger flexion by more than 50%. The new en doskeletal prosthesis requires approximately 12-24% less force input to gra sp a variety of everyday objects, largely due to its adaptive grip. Product ion cost estimates reveal the new prosthesis to be significantly less expen sive than current prosthetic hands.