An Under-Actuated Hand Prosthesis with Finger Abduction and Adduction for Human Like Grasps

Loss of a hand can severely limit the functions of Activities in Daily Living (ADL). Hand prostheses replace the missing hands and enable the lost hand functions. Dexterity of the hand prosthesis depends on the achievable finger motions by the hand prosthesis. However, the dexterity of a hand prosthesis is reduced due to the absence of the finger Abduction/ Adduction (Abd/ Add) motion. In this paper an active prosthetic hand is proposed with a novel mechanism for finger Abd/Add motion (except for the middle finger). The proposed under-actuated hand prosthesis has 15 Degrees of Freedom (DoF) designed to obtain flexion/ extension (F/E) motion for all five fingers, opposition/ reposition (Opp/Rep) of the thumb finger and compound Abd/ Add of four fingers. Furthermore, an EMG based prosthesis controller with Multilayer Perceptron Neural Network is used to control the proposed hand prosthesis. Experiments have been carried out to validate the effectiveness of the hand prosthesis in generating grasping patterns for ADL and to measure the effectiveness of the implemented prosthesis controller for different prosthesis users.