An arm for a leg: Adapting a robotic arm for gait rehabilitation

The purpose of this study was to adapt a multipurpose robotic arm for gait rehabilitation. An advantage of this approach is versatility: a robotic arm can be attached to almost any point on the body to assist with lower- and upper-extremity rehabilitation. This may be more cost-effective than purchasing and training rehabilitation staff to use several specialized rehabilitation robots. Robotic arms also have a more human-like morphology, which may make them less intimidating or alien to patients. In this study a mechanical interface was developed that allows a fast, secure, and safe attachment between a robotic arm and a human limb. The effectiveness of this interface was assessed by having two healthy subjects walk on a treadmill with and without a robotic arm attached to their legs. The robot´s ability to follow the subjects´ swinging legs was evaluated at slow and fast walking speeds. Two different control schemes were evaluated: one using the standard manufacturer-provided control algorithm, and another using a custom algorithm that actively compensated for robot-human interaction forces. The results showed that both robot control schemes performed well for slow walking. There were negligible differences between subjects´ gait kinematics with and without the robot. During fast walking with the robot, similar results were obtained for one subject; however, the second subject demonstrated noticeable gait modifications. Together, these results show the feasibility of adapting a multipurpose robotic arm for gait rehabilitation.