Design of a Gravity Balanced Upper Limb Exoskeleton with Bowden Cable Actuators

This paper presents a design of gravity balanced upper limb exoskeleton used for the stroke patients to regain their motor function. Bowden cable actuators have a high power-weight ratio and can significantly reduce the mass, inertial and power consumption of the device. The gravity balancing of the device is achieved by a hybrid strategy, which uses zero free-length springs and auxiliary parallel links to locate the COM (center of mass) of the robot and keep the total potential energy of the system invariant with all configurations. The balance torques caused by the variation of body weight and height are calculated. The exoskeleton is proved to be robust with the users of different weights and heights.