Designing and testing a hybrid lightweight shoulder prosthesis.

Lightweight prostheses are preferred in terms of usability in daily living. However, this is not a property easy to realize, especially for shoulder prostheses. High portability, multiple degrees of freedom (DOFs) with an appropriate ROM (range of motion), sufficient end-effector power, and suitable viscoelasticity for the safe use in daily living, usually result in a heavy weight. In this paper, a hybrid shoulder prosthesis that combined servo motors and pneumatic elastic actuators, with a weight distribution scheme, was designed to meet the requirements. The prosthetic system was preliminarily tested by comparing its ADL (activities of daily living) motion data with that of an intact arm. The experiment results showed that the shoulder prosthesis could reproduce the motion of an intact arm, thus demonstrate its usability in daily living.