A Novel Passive Occupational Shoulder Exoskeleton With Adjustable Peak Assistive Torque Angle For Overhead Tasks

TL;DR

This paper introduces a novel passive shoulder exoskeleton with adjustable assistive torque, designed to support various overhead tasks while maintaining natural movement and reducing muscle effort.

Contribution

It presents a new passive exoskeleton with an adjustable torque angle mechanism, enabling multi-task adaptability and improved user comfort in overhead work.

Findings

Ensures sufficient ROM in sagittal and horizontal movements

Reduces muscle activation by up to 49.6% during tasks

Improves user experience with high satisfaction scores

Abstract

Objective: Overhead tasks are a primary inducement to work-related musculoskeletal disorders. Aiming to reduce shoulder physical loads, passive shoulder exoskeletons are increasingly prevalent in the industry due to their lightweight, affordability, and effectiveness. However, they can only accommodate a specific task and cannot effectively balance between compactness and sufficient range of motion. Method: We proposed a novel passive occupational shoulder exoskeleton to handle various overhead tasks with different arm elevation angles and ensured a sufficient ROM while compactness. By formulating kinematic models and simulations, an ergonomic shoulder structure was developed. Then, we presented a torque generator equipped with an adjustable peak assistive torque angle to switch between low and high assistance phases through a passive clutch mechanism. Ten healthy participants were recruited to validate its functionality by performing the screwing task. Results: Measured range of motion results demonstrated that the exoskeleton can ensure a sufficient ROM in both sagittal (164{\deg}) and horizontal (158{\deg}) flexion/extension movements. The experimental results of the screwing task showed that the exoskeleton could reduce muscle activation (up to 49.6%), perceived effort and frustration, and provide an improved user experience (scored 79.7 out of 100). Conclusion: These results indicate that the proposed exoskeleton can guarantee natural movements and provide efficient assistance during overhead work, and thus have the potential to reduce the risk of musculoskeletal disorders. Significance: The proposed exoskeleton provides insights into multi-task adaptability and efficient assistance, highlighting the potential for expanding the application of exoskeletons.