Design of a 7 degree-of-freedom upper-limb powered exoskeleton

The exoskeleton is an external structural mechanism with joints and links corresponding to those of the human body. Worn by the human, the exoskeleton transmits torques from proximally located actuators through rigid exoskeletal links to the human joints. This paper presents the development of an anthropometric seven degree-of-freedom powered exoskeleton for the upper limb. The design was based on a database defining the kinematics and dynamics of the upper limb during daily living activities, as well as joint physiological and upper limb anatomical considerations, workspace analyses, and joint ranges of motion. Proximal placement of motors and distal placement of pulley reductions were incorporated into the design of a cable-driven wearable robotic arm. This design led to low inertias, high-stiffness links, and back-drivable transmissions with zero backlash. Potential applications of the exoskeleton as a wearable robot include use as: (1) a therapeutic and diagnostics device for physiotherapy, (2) an assistive (orthotic) device for human power amplifications, (3) a haptic device in virtual reality simulation, and (4) a master device for teleoperation.