Ergonomic evaluation of a wearable assistive device for overhead work

Abstract

Overhead work is an important risk factor for upper extremity (UE) musculoskeletal disorders. We examined the potential of a mechanical arm and an exoskeletal vest as a wearable assistive device (WADE) for overhead work. Twelve participants completed 10 minutes of simulated, intermittent overhead work, using each of three payloads (1.1, 3.4 and 8.1 kg) and with/without the WADE. Ratings of perceived discomfort (RPDs) and electromyography (EMG) were obtained for the upper arms, shoulders and low back. Using the WADE, UE RPDs decreased by ∼50% with the heavier payloads, whereas smaller (∼25%) and non-significant increases in low-back RPDs were found and were relatively independent of payload. Changes in RPDs with WADE use were consistent with physical demands indicated by EMG, though EMG-based differences in fatigue were less apparent. Participants generally preferred using the WADE, particularly with heavier payloads. These results supported the potential utility of a WADE as an intervention for overhead work.

Abstract

Practitioner Summary: A wearable assistive device for overhead work reduced physical demands on the upper extremity and had high acceptance, though some evidence suggested increased demands at the low back. While some design needs were found and field-testing is needed, this may be a useful practical intervention.

Keywords::

• shoulder
• overhead work
• wearable assistive device
• exoskeleton

Acknowledgements

This work was supported by a grant from Equipois, Inc., and in cooperation with Ford Motor Company and Boeing, Inc. These companies provided the WADE and/or initial information on overhead work characteristics in their worksites. However, they had minimal involvement in study design, and no involvement in data analysis and interpretation, or decision for publication. The contents of this paper are solely the responsibility of the authors and do not necessarily represent the official views of the sponsor. The authors thank Drs Khoirul Muslim and Nima Toosizadeh for their help during data collection.