Design and Evaluation of a Passive Cable-driven Occupational Shoulder Exoskeleton.

Exoskeleton technologies have the potential to reduce the prevalence of work-related musculoskeletal disorders. Despite the fast-growing industrial exoskeleton market, several bottlenecks have prevented their wide application, namely the lack of wearability, the amount of assistance they deliver and their usefulness in various working scenarios, outside of those they were specifically designed to perform. In this work we present the design, realization and evaluation of a new wearable shoulder exoskeleton that is kinematically compatible with the glenohumeral joint and features a new passive remote actuation system (pRAS). The latter has a twofold function: it delivers assistance only when needed and allows for a more convenient repositioning of the exoskeleton components, reducing the exoskeleton's footprint and limiting the weight on the user's arm. A test bench has been designed to validate the mechanical performance of the shoulder exoskeleton and experiments have been conducted to investigate its effect on users while executing overhead working tasks. Based on the muscle activity monitored in six subjects, we conclude that our exoskeleton reduces anterior deltoid activity by 22% during the execution of overhead work. This preliminary study suggests that our device can successfully provide relief at the level of the shoulder without hindering the subject.