Human Gait During Level Walking With an Occupational Whole-Body Powered Exoskeleton: Not Yet a Walk in the Park

Sunwook Kim,Maury A Nussbaum,Alexander Leonessa,Divya Srinivasan

doi:10.1109/access.2021.3068836

Abstract

With rapid advancements in exoskeleton technologies, a whole-body powered exoskeleton (WB-PEXO) for augmenting human physical capacity (a “super-operator”) is generating increasing attention as an integral part of Industry 4.0. Our understanding of WB-PEXO use is lagging, however, largely due to the lack of detailed evaluations via human-subjects testing of a WB-PEXO. We examined (independently from the manufacturer of a WB-PEXO) the potential impacts of using a state-of-the-art WB-PEXO prototype (pre-alpha prototype version of the Sarcos Guardian ® XO ® ) on users ( n=5) during a common basic activity in the workplace, level walking. With emphasis on the “human”, impacts of XO use (compared to a no EXO baseline) were assessed in terms of lower limb intersegmental coordination, muscle activity, and postural dynamic stability. A larger variance between participants was observed for intersegmental coordination with XO use, and participants appeared to rely on more hip motions. When using the XO, participants exhibited higher muscle activity levels in the lower limb muscle groups monitored. Further, there was a moderate to high similarity in muscle activity profiles between the XO and no EXO conditions ( R XY (τ)=0.70-0.92), yet muscle activity profiles when using the XO were generally time-lagged from those without the XO. We discuss the results within the context of developing a mental model for walking with the XO, and aspects of human-robot interaction such as transparency of the XO and understanding user state and intention. In concluding, we outline several future research topics for occupational WB-PEXO development.

Highlights

Use of wearable robotic systems such as exoskeletons – nonpowered or powered mechanical systems that enhance/assist the strength and/or performance of the wearer – has generated great interest in occupational applications
WITHOUT XO USE Given that no information was available about how the prototype XO interacts with the user during level walking, we examined if participants had similar muscle-recruitment patterns at comparable gait phases with vs. without XO use
PCA on elevation angles (EAs) profiles showed that planarity was consistently high in both the baseline [99.2 (0.3) %] and XO [98.9 (0.5) %] conditions

Summary

Introduction

Use of wearable robotic systems such as exoskeletons – nonpowered (passive) or powered (active) mechanical systems that enhance/assist the strength and/or performance of the wearer – has generated great interest in occupational applications. Work-related musculoskeletal disorders (WMSDs) continue to be an important health issue in the workplace of many industrialized countries [1], [2]. The physical augmentation offered by (occupational) exoskeleton use is an innovative solution to control WMSDs, during physically demanding jobs [3], [4]. Lab-based studies have indicated beneficial effects of passive exoskeleton on. Though limited in quantity and comprehensiveness, several industry pilots have addressed use, acceptance, and effectiveness of passive exoskeletons (e.g., Ford [11], Toyota [12], Boeing [13]). Passive exoskeleton use is a very promising intervention approach in industrial settings, and a majority of commercially-available exoskeletons are passive (e.g., exoskeletonreport.com)

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Conclusion