Electromyographic Assessment of a Shoulder Support Exoskeleton During on-Site Job Tasks

OCCUPATIONAL APPLICATIONS

We performed an ergonomic assessment of a passive upper body exoskeleton at on-site job tasks, using surface electromyography (EMG) to quantify muscular demands at the shoulder. Six workers were assessed during cab assembly, hydraulic assembly, parts painting, parts hanging, and frame welding tasks, both with and without an exoskeleton. Workers were evaluated during consecutive job tasks, at beginning and at end of a shift. EMG amplitudes were measured and compared to recommended threshold limit values (TLVs) to determine fatigue risk values. Wearing the exoskeleton significantly reduced anterior deltoid EMG amplitudes and fatigue risk values during the consecutive job cycles, with no significant effects on the biceps brachii, superior trapezius, or lumbar erector spinae. Reduced EMG amplitudes were found at five of the six job tasks, and in three of the tasks fatigue risk values were reduced from above the TLV without the exoskeleton to below the TLV with the exoskeleton. Workers indicated that they would recommend the exoskeleton to others who perform overhead job tasks, but expressed concern that it might interfere with tasks that involve tight spaces, sitting, and bending over. We suggest evaluating specific job tasks when making decisions about exoskeleton usage.

Keywords:

• electromyography
• exoskeleton
• overhead work
• shoulder
• threshold limit values

ACKNOWLEDGMENTS

The authors wish to thank Terry Butler for his assistance coordinating communications between Levitate Technologies and John Deere. The authors also wish to thank Dan Wisner, Chad Neumayer, and Bethany Henning of John Deere for their assistance organizing the on-site data collections.

CONFLICT OF INTEREST

Levitate Technologies provided the upper body exoskeletons that were tested during this study and paid a fee-for-service for the EMG assessment, but had no influence on the interpretation of the results, the contents of this article.