Hybrid Soft-Rigid Elbow Exosuit: Theory, Mechatronic Design, and Experimental Assessment

Hybrid wearable robotics, combining soft and rigid elements, offer a promising solution for upper limb assistance by balancing comfort and functionality. This study evaluates a hybrid soft-rigid elbow exosuit designed for elbow movement support in dynamic and endurance tasks, focusing on biomechanical impact, user perception, and ergonomics. A theoretical model guided the design, optimizing device dynamics and assistive force delivery. A generic interaction controller, combined with fixed system parameters, provided effective assistance across participants without the need for subject-specific tuning, simplifying deployment in practical settings. During dynamic tasks, the exosuit significantly reduced biceps muscle activity compared to the unassisted condition, with an average reduction of 28.40%. In endurance tasks, it reduced infraspinatus activity by an average of 44.55% and mitigated increased muscle activation during load-carrying. Subjective assessments indicated lower perceived physical demand, while the System Usability Scale confirmed high usability and acceptance. These findings highlight the exosuit's ability to reduce physical effort and improve muscle coordination while maintaining comfort. The robust mechatronic design enabled effective assistance through a generic controller, emphasizing the importance of hardware reliability.