Assessment of a Modular Upper-Limb Exoskeleton with Powered Assistance

Upper extremity exoskeletons can provide support to workers for carrying tasks while reducing workers' muscle fatigue and the prevalence of work-related musculoskeletal disorders in workers' elbows. Nevertheless, current upper-limb exoskeletons suffer from issues like excessive weight, inconvenient wearability, high rigidity, poor human-machine interaction, and limited modularity. To address these issues, this study introduces a design for a lightweight, powered-assistive, and modular upper-limb exoskeleton. The research developed a prototype specifically tailored for the elbow joint. The experiment encompassed three control modes (Constant torque, Gravity compensation, and Impedance control) to assess the efficacy of the exoskeleton. Subjects engaged in 'pick-hold-drop' tasks with varying loads (4kg, 3kg, 2kg), simulating real load-bearing scenarios, performed five times. The experimental results indicate that the proposed design provided effective assistance to the subjects. During the 'hold' phase, the EMG Maximum Voluntary Contraction (MVC) values of the subjects' biceps muscles notably decreased, averaging a reduction of 9.29%.