An Underactuated Prosthetic Hand with Coupled Metacarpophalangeal Joints

The design of a comfortable and functional prosthetic hand is still a challenge. This paper presents the design of a tendon-driven, 3D-printed, underactuated prosthetic hand. An improved structural design was developed to make the hand more flexible. Three fingers are equipped with abduction freedom at the metacarpophalangeal joints (MCP) to ensure natural enveloping for both cylinder and sphere-like objects. A force-sensing resistor (FSR) is adopted to measure the fingertip force of each finger. Experiments show that this type of structure design provides the hand with excellent dexterity, as the added abduction ensures natural enveloping grasp gestures for both cylinder and sphere-like objects. Moreover, a myoelectric control paradigm is implemented in the control system to demonstrate the feasibility.