Design of a Lightweight Passive Shoulder Exoskeleton with Variable Stiffness Mechanisms

In this paper, a new design of shoulder exoskeleton for overhead tasks is proposed. This exoskeleton is mechanically-powered, also known as passive exoskeleton. It does not has any energized actuators, which has advantages in achieving lightweight and portable design. In our work, a standalone torque generator mounted away the arm structure is constructed, and Bowden cables are used for force transmission from the torque generator to the shoulder joints. Based on the new design, the exoskeleton has a extra lightweight arm structure. The torque generator is designed with variable stiffness mechanisms (VSMs), which allow to adjust torque-deflection characteristics achieving shoulder assistance level changes. A prototype is constructed, and preliminary tests evaluate the usability of the exoskeleton.