Implementation of a Long-Lasting, Untethered, Lightweight, Upper Limb Exoskeleton

To prevent muscle fatigue or disorder due to long-term or repetitive arm-lifting in scenarios that heavily rely on manual operations, various exoskeletons have been developed previously. However, the exoskeletons with motors suffer from heavy mass and high cost, while previous passive exoskeletons possess poor adaptability to different arm angles, tasks, and users. To solve this problem, we designed a lightweight (3.1 kg) upper limb exoskeleton capable of providing a self-adaptable support force to the upper limbs based on linkage mechanisms and gas springs and a tunable maximum force (10-130 N) based on small motors and sensors. By altering the supporting angle and distance, the force curvature is adjustable by motors to adapt to the load in the hands. Since the motors adjust the dimension of the mechanical structure, instead of directly supporting the arms, the power consumption is low (1.85 W), and the exoskeleton operation duration is very long (11 h) using a 3000 mAh battery. The experimental results show that the measured surface electromyogram activities reduced up to 43.84% and 46.23% for static and dynamic tests, respectively.