Development of an Underactuated Finger Mechanism for a Hand Prosthesis

This works shows the conceptual development of a finger mechanism for a prothestic hand. Three degrees of freedom of the finger are actuated by single DC motor, characterizing therefore an underactuated mechanical system. Mechanical torque developed by the motor is transmitted to the phalanges through tendons and is converted into flexion and extension torques by means of small pulleys. The tendon is fixed on the tip of the distal phalange and conducted up to the motor pulley by passing around each pulley. The chosen servo motor is able to provide movement of the finger phalanges at an acceptable speed, as well as a reasonable amount of prehension force.