Initial static, dynamic, and cognitive fit evaluation of three passive shoulder exoskeletons while performing simulated manufacturing tasks

Abstract

Musculoskeletal Disorders of the shoulder have been associated with repetitive overhead work and manual lifting tasks. Upper-limb assistive devices, such as passive exoskeletons, have promise for reducing exposure to risk factors associated with shoulder injuries. The adoption of passive exoskeletons is adversely affected by fit concerns, particularly women, who are often at a disadvantage due to a lack of gender-specific design considerations.We conducted a pilot study evaluating initial static, dynamic, and cognitive fit of various upper-limb exoskeletons for use in manufacturing settings. In a repeated-measures laboratory study, 24 participants (sex-balanced) performed a series of exercises, including a range of motion task, simulated manufacturing activities (e.g., overhead wrenching, lifting and lowering a 10 kg box), and test of visual attention, task switching, and speeded set shifting. Three passive shoulder exoskeletons (Levitate AIRFRAME, Ekso Bionics EVO, and Ottobock), as well as a no-exoskeleton control condition, were analyzed. Subjective musculoskeletal discomfort ratings were collected periodically throughout the testing.The preliminary results revealed minimal sex-based differences in discomfort across body parts in both the control and exoskeleton conditions. Dynamic fit was associated with higher discomfort in the shoulders and elbows, with 20.8% and 8.3%, respectively, of Levitate wearers experiencing >2-point increase on a 10-point visual analog scale. Differences of <1 unit were found for the Ottobock (shoulder: 95.8%, elbow: 91.6%) and Ekso Bionic (shoulder: 87.5%, elbow: 83.3%). Moderate range of motion restrictions were reported by 70.8% of Levitate wearers and 50% of both Ekso Bionics and Ottobock users.