A Practical Sensing Interface for Exoskeleton Evaluation in Workplaces Using Interface Forces*

This paper presents a novel approach to evaluating back support exoskeletons (BSEs) in workplace settings, addressing the limitations of traditional methods like electromyography (EMG), which are impractical due to their sensitivity to external disturbances and user sweat. Variability in BSE performance among users, often due to joint misalignment and anthropomorphic differences, can lead to discomfort and reduced effectiveness. To overcome these challenges, we propose integrating a compact load cell into the exoskeleton's thigh cuff. This small load cell provides precise force measurements without significantly altering the exoskeleton's kinematics or inertia, enabling real-time assessment of exoskeleton assistance in both laboratory and workplace environments. Experimental validation during load-lifting tasks demonstrated that the load cell effectively captures interface forces between the BSE and human subjects, showing stronger correlations with the user's muscle activity when the BSE provides effective assistance. This innovative sensing interface offers a stable, practical alternative to EMG and respiratory gas measurements, facilitating more accurate and convenient evaluation of BSE performance in real-world industrial and laboratory settings. The proposed method holds promise for enhancing the adoption and effectiveness of BSEs by providing reliable, real-time feedback on their assistance capabilities.