Development of upper limb exoskeleton with high braking torque density and low power consumption

In industrial and healthcare scenarios, long-term or repetitive tasks often lead to work-related musculoskeletal disorders (WMSDs), negatively affecting worker health and productivity. This paper introduces a passive upper limb exoskeleton designed to enhance endurance and provide mechanical support, thereby mitigating the risk of WMSDs. Kinematic models of both the exoskeleton and the human upper limb indicate that 99% of the upper limb’s range of motion is preserved when the exoskeleton is worn. The magnetorheological brake of the exoskeleton weighs only 450 g, delivers a peak locking torque of 110.38 Nm, and boasts a high braking torque density while consuming just 6 W. Muscle endurance and upper limb support capabilities were validated through three aspects, using electromyographic signals as references. The results of shoulder joint testing demonstrated the auxiliary support ability of the exoskeleton shoulder joint in three dimensions. In experiments involving heavy holding, overhead tasks, and patient transfers, the exoskeleton demonstrated outstanding assistive effects, significantly reducing muscle fatigue. The results indicate that the exoskeleton can effectively enhance endurance and prevent WMSDs. Additionally, experiments aimed at surpassing human limitations suggest that this passive exoskeleton can increase user endurance limitations by improving load holding weight.