Energy-Efficient Hybrid Shoulder Exoskeleton With Magnetic Spring Joints

• Published in: IEEE/ASME transactions on mechatronics Vol. 30; no. 4; pp. 3152 - 3160
• Main Authors: Lee, Hyun-Ho, Yoon, Kyung-Taek, Seo, Min-Ho, Bang, Byeong-Hoon, Kuk, Dong-Youn, Lee, Sung Q, Choi, Young-Man
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Arms; Counterbalances; Disorders; Energy efficiency; Exoskeletons; gravity compensation; Human motion; Human performance; hybrid actuation; Hybrid power systems; Magnetic shielding; magnetic spring joint; Motors; Performance tests; Shoulder; shoulder exoskeleton; Springs; surface electromyography (sEMG); Torque
• ISSN: 1083-4435; 1941-014X
• DOI: 10.1109/TMECH.2025.3570713

Shoulder disorders, a significant subset of work-related musculoskeletal disorders, are a major cause of disability among industrial workers, driving the development of preventive shoulder exoskeletons. Passive exoskeletons are lightweight and portable but provide a fixed torque profile based on shoulder angle, which limits adaptability to diverse work tasks. In contrast, active exoskeletons offer task-specific assistive torque, but are heavier and less energy-efficient, reducing their practicality in industrial settings. Hybrid exoskeletons present a promising solution by addressing the adaptability limitations of passive exoskeletons and the energy inefficiency of active exoskeletons. This article introduces a hybrid shoulder exoskeleton that integrates a magnetic spring-based counterweight mechanism with a quasi-direct-drive motor, achieving an 86.4% reduction in power consumption during arm elevation compared to a single actuator. The exoskeleton covers 90.3% of the shoulder's natural range of motion and, in human performance tests, reduces anterior deltoid muscle activation by an average of 40% during overhead and waist-level tasks.