Development and Analysis of a Novel Bio-syncretic Parallel Hip Exoskeleton Based on Torque Requirements

Abstract This study has developed a bio-syncretic parallel hip exoskeleton (BsPH-Exo) to address the misalignment between the rotational center of the hip joint and that of the mechanical joint. BsPH-Exo uses the hip joint as its sole motion constraint to ensure precise alignment with the hip joint center (HJC). To tackle the high costs and technical limitations of traditional methods for measuring HJC coordinates, we propose a new solution: using sensors embedded in BsPH-Exo to gather motion data from both the motors and the human leg, then processing this data through a formula to calculate the exact HJC coordinates. This approach not only simplifies the measurement process but also significantly reduces costs. Through analysis of the workspace, singularity, and maximum torque index, it was found that BsPH-Exo provides a wide range of leg motion while avoiding singularities within the rehabilitation scope. Additionally, the torque law from BsPH-Exo aligns with the torque requirements for human leg movement. In a series of wearable experiments, BsPH-Exo demonstrated its ability to meet rehabilitation training needs and showed excellent controllability in flexion/extension and adduction/abduction directions.