Comprehensive Evaluation of a Passive Upper-Limb Exoskeleton in Agricultural Tasks: Integrating Physiological, Postural, and Cognitive Measures.

This study evaluated the effects of a passive upper-limb exoskeleton in agricultural work using a repeated-measures design with 24 adult males across three exoskeleton conditions (No Exo, Prototype, and Airframe), three work directions (left, front, and right), and two work distances (near and far). Outcomes included muscle activity, center of pressure travel, task completion time, perceived exertion, body part discomfort, and usability. Airframe use significantly reduced shoulder and upper-arm muscle activity by about 25-35 percent, consistent with the mechanical sharing of shoulder elevation torque. Erector spinae activity showed a compensatory increase trend, suggesting heightened trunk stabilization demands. Center of pressure varied by direction and distance, with greater excursion for leftward and far tasks, but did not differ among exoskeleton conditions, indicating preserved postural stability. Task time was unaffected by exoskeleton and distance but was longest for leftward tasks. Perceived exertion and discomfort varied by direction and distance and tended to be lower on average with Airframe. Usability differed only in the effectiveness factor, which favored Airframe. An integrated evaluation emphasizing EMG, center of pressure, and perceived fatigue, with usability as needed, is recommended for field validation.