Development and assessment of a powered 3D-printed prosthetic hand for transmetacarpal amputees

New proposals for prosthetic hands fabricated by means of 3D printing are either body-powered for partial hand amputees or myoelectric powered prostheses for transradial amputees. There are no current studies to develop powered 3D printed prostheses for transmetacarpal, probably because at this level of amputation there is little space to fit actuators and their associated electronics. In this work, a design of a 3D-printed hand prosthesis for transmetacarpal amputees and powered by DC micromotors is presented. Four-bar linkage mechanisms were used for the index, middle, ring and little fingers flexion movements, while a mechanism of cylindrical gears and worm drive were used for the thumb. Additionally, a method for customizing prosthetic fingers to match a user specific anthropometry is proposed. Sensors and actuators' selection is explained, and a position control algorithm was developed for each local controller by modeling the DC motors and transmission mechanisms. Finally, a basic control scheme was tested on the prototype for velocity and force evaluation.