Abstract

Exoskeletons (EXOs) are wearable assistive devices that enhance workers' physical capabilities and reduce injury risk due to overexertion. However, current devices may produce mixed outcomes, and even increase demands. Factors responsible for this gap were identified and potential design improvements were proposed to improve their adoption. A subsequent systematic review showed mixed outcomes in real-world scenarios, possibly due to challenges in conducting field evaluations. A new guideline is proposed, which can be beneficial in improving the generalizability of findings in field evaluations. Low-back is injury-prone due to repetitive trunk flexion tasks, where Back-support industrial exoskeletons (BSIEs) can be beneficial. Literature review suggests that mixed effects during field testing may result from insufficient considerations of realistic factors in lab-based studies (asymmetry, task variations, and their cyclic nature leading to fatigue). In this study, twelve participants performed intermittent bending (with sustained bending, bending/retraction, standing and rest), tasks with/without BSIE and with/without 45⁰ left asymmetry till medium-high fatigue. Each intermittent bending task was preceded and followed by 30 x repetitive bending cycles. Simultaneously, we recorded trunk movement, stability, muscle activity in back and legs, and subjective fatigue ratings. Findings showed that BSIE increased endurance by 50% and was favorably rated by participants. BSIE was beneficial to low-back during sustained portions of intermittent bending (20%) but increased leg demands with fatigue (5%). Similarly, the device reduced back activity (9-22%) during bending, but increased activity during retraction (8%-11%). Asymmetry and fatigue reduced BSIE benefits in right-back by ~8% and ~11-15% respectively. During repetitive bending, BSIE led to minimal back benefits (0-1.8%) but substantial leg benefits (10-18%). Asymmetry increased right low-back and leg demands, while fatigue increased low-back activity (8-12%). BSIE notably led to slower trunk movements and improved stability in both tasks showing no effect on fall-risk. Overall outcomes suggest that BSIE can benefit low-back in tasks with higher portions of sustained bending that require less frequent bending, with rest breaks focusing on relieving leg demands. Future studies may integrate sensing technologies for evaluating BSIEs in real-world scenarios and develop fatigue detection methods that can be used to define task cycle parameters and work-rest ratios.

Publication Date

8-2024

Document Type

Dissertation

Student Type

Graduate

Degree Name

Mechanical and Industrial Engineering (Ph.D)

Department, Program, or Center

Mechanical Engineering

College

Kate Gleason College of Engineering

Advisor

Ehsan Rashedi

Advisor/Committee Member

Esa Rantanen

Advisor/Committee Member

Kathleen Lamkin-Kennard

Campus

RIT – Main Campus

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