Design and development of a powered upper limb exoskeleton with high payload capacity for industrial operations

Abstract

This study presents the hardware development and low level controller structure of an upper-body exoskeleton that is equipped with high torque-to-weight ratio actuators. It is intended to be used in industrial applications. The exoskeleton can be adjusted for various arm sizes and can ideally be used by an operator that has a height within the range of 160 cm and 200 cm. The robot structure was comprised of 4 degrees of freedom, 3 of which are powered via custom-built series elastic actuators with high power-to-weight ratio and real-time torque control capability. The 4th joint, a prismatic joint, was added to accommodate for glenohumeral head elevation, enabling the system to attain a workspace that is suitable for industrial tasks. The exoskeleton is equipped with a two-piece end effector (E1 and E2) to enable the power augmentation tasks. In order to check torque controllability, initial experiments of the system were conducted on a joint level. As a result, 20 Hz of control bandwidth was achieved when the peak-to-peak torque inputs were 20 Nm.