Design of a passive gravity-compensation exoskeleton for elbow movement assistance

In this paper, we propose a passive elbow exoskeleton that utilizes a gravity compensation mechanism to reduce burden on users.An exoskeleton is a wearable assisting mechanism that enhances the user's task performance and mobility by supporting his/her muscular motion.The passive exoskeleton, which does not use actuators, applies spring force in the opposite direction of gravity to aid the user.Compared to mechanical springs, magnetic springs have a simpler structure and a smaller volume.Its maintenance is even easier.The proposed device utilizes a magnetic spring to generate a smooth torque profile which is well-suited for assisting human torque.The proposed passive elbow exoskeleton is designed to have relatively lightweight of 0.39 kg, and a maximum torque of 1.32 Nm.When wearing the exoskeleton and lifting burden, the average muscle activity of the biceps brachii was reduced by 16.1% compared to the non-wearing condition.Wearing the proposed exoskeleton can effectively assist the user's movements and it has potential to prevent musculoskeletal disorders.