Integrated active and passive gravity compensation method for a cable-actuated elbow rehabilitation robot

In this paper, a cable actuated elbow rehabilitation robot with integrated active and passive gravity compensation method is proposed. Passive method compensates for the weight of the robot and patient forearm, but full gravity compensation for different patient needs spring stiffness to be adjusted. It seems unreasonable to equip the rehabilitation robot with a different spring for each patient. Here, an active method through controller effort is used to eliminate the defective gravity compensation. Thus, the performance of proposed robust controller is compared to the proportional-derivative controller through computer simulation. Simulation results illustrate the ability of the proposed robust control algorithm in eliminating the unpleasant reaching transient of passive gravity compensation and tracking error despite uncertainties and external disturbance. Integrated gravity compensation method effectively improves inherent safety of the elbow rehabilitation robot.