Impact of a Lower Limb Exosuit Anchor Points on Energetics and Biomechanics

TL;DR

This study investigates how different anchor point placements in a lower limb exosuit affect gait biomechanics, muscle activation, and energy use, highlighting the importance of personalized configurations for optimal assistance.

Contribution

It provides experimental evidence on how anchor point positions influence exosuit performance, emphasizing the need for personalized adjustments based on individual biomechanics.

Findings

Posterior knee anchor reduces hip flexor activation by up to 10.21%

Certain configurations decrease metabolic expenditure by up to 18.45%

Anchor point placement affects kinematics of knee and ankle joints

Abstract

Anchor point placement is a crucial yet often overlooked aspect of exosuit design since it determines how forces interact with the human body. This work analyzes the impact of different anchor point positions on gait kinematics, muscular activation and energetic consumption. A total of six experiments were conducted with 11 subjects wearing the XoSoft exosuit, which assists hip flexion in five configurations. Subjects were instrumented with an IMU-based motion tracking system, EMG sensors, and a mask to measure metabolic consumption. The results show that positioning the knee anchor point on the posterior side while keeping the hip anchor on the anterior part can reduce muscle activation in the hip flexors by up to 10.21\% and metabolic expenditure by up to 18.45\%. Even if the only assisted joint was the hip, all the configurations introduced changes also in the knee and ankle kinematics. Overall, no single configuration was optimal across all subjects, suggesting that a personalized approach is necessary to transmit the assistance forces optimally. These findings emphasize that anchor point position does indeed have a significant impact on exoskeleton effectiveness and efficiency. However, these optimal positions are subject-specific to the exosuit design, and there is a strong need for future work to tailor musculoskeletal models to individual characteristics and validate these results in clinical populations.