Personalization of Passive Hip Exosuit for Efficient Human Walking

<title>Abstract</title> <p>Exosuits have proven effective in reducing the physical effort required for walking. Personalizing these exosuits can further enhance user outcomes. Current personalization primarily focuses on tuning joint torque assistance profile in the sagittal plane; however, walking involves complex, three-dimensional joint movements. Therefore, to maximize exosuits benefits, it is also important to consider the assistance in other planes during the personalization. This study investigates the effect of personalized assistance positions in a passive hip exosuit on the walking effort. We used a passive hip exosuit that provides torque assistance using the textile elastic band placed across the hip joint and human-in-the-loop personalization method to systematically identify an optimal band position for each subject (N=10). Metabolic cost was used as the objective function, and a Bayesian optimization algorithm identified the optimal position that minimized energy expenditure during walking. The results showed that the optimally positioned band significantly reduced walking metabolic cost by 8.39 ± 4.69% compared to the No exosuit condition (p &lt; 0.001) and by 4.81±3.88% compared to Fixed band position (p &lt; 0.01), which is greater than previous studies on passive exosuits (&lt;5%). EMG analysis further revealed a 7.35±6.20% (p &lt; 0.05) reduction in soleus peak activity during push-off with Optimal position compared to No exosuit. These findings suggest that optimizing assistance position in a passive hip exosuit effectively reduces physical exertion during walking and highlight the importance of optimizing assistance position. This research opens new avenues for designing high-performing assistive devices by optimizing assistance position alongside other critical parameters.</p>