Kinematic effects of a back-assistance exoskeleton during human locomotion

Abstract

In the last years, Industry 5.0 has proposed a sustainable and resilient industry model, where the human-centric approach places human needs at the center of the production process. Wearable robots have been designed to assist users, providing support for the entire body or specific regions during task performance. Ergonomic investigations are necessary to test the effects, advantages and possible drawbacks of occupational wearable devices. The present study focuses on the biomechanics of locomotion while wearing the Laevo V2.5 exoskeleton. Experimental tests involved twelve healthy volunteers. Spatio-temporal parameters, human 3D kinematics and exoskeleton 3D kinematics were compared in three settings (without exoskeleton, wearing the exoskeleton without and with passive support). These comparisons aimed to quantify the effects and the possible restrictions on user kinematics due to the interaction with the exoskeleton. Results highlighted a significant reduction in the gait speed (1.14 m/s no-exo, 1.07 m/s exo-no-support, 1.05 m/s exo-with-support) and the stride length (1.29 m no-exo, 1.24 m exo-no-support, 1.23 m exo-with-support) when wearing the exoskeleton. Human angular kinematics showed significant reductions in the range of motion for all joints when wearing the exoskeleton. However, results pointed out no significant differences between the no-support and support configurations, indicating that the primary effect is due to the exoskeleton structure rather than the support provided. Further assessment is essential to determine whether these changes in human kinematics align with ergonomic standards and reflect user adaptation, or if they fulfill acceptable limits, potentially leading to long-term negative effects.

Keywords: Human gait; Human-exoskeleton interaction; Kinematics; Occupational back-assistance exoskeletons; Passive device; Spatio-temporal parameters.