Discovering hidden strengths: How a passive lower extremity exoskeleton boosts the isometric pulling capacity to new heights

Abstract

Wearable exoskeletons aim to balance physical work demands and individual capacity. This study assessed isometric pushing capacities in various directions using a chair-type exoskeleton (CEX) at different heights. Twenty participants of both genders underwent forward, backward, upward and sideways pushing. Using CEX increased posterior pushing by over 60%, decreased lateral pushing about 10%, but had no significant effect on anterior or superior pushing capacities. The weight distribution on the feet rose to 80% in posterior pushing and dropped to 20% in anterior pushing, while weight distribution between the feet and CEX, measured with two force plates, was about 5:5 in superior and lateral pushing. Despite increased posterior pushing, decrease in posterior stability with CEX should be considered. Workers and exoskeleton designers should be aware of this trade-off between increased pushing capacity and reduced posterior postural stability. With proper precautions to mitigate the risk of falling, introducing CEX can be especially beneficial for the workers needing to pull objects at lower levels.