The Relationship Between User Perceptions Of Exoskeletons And Changes In Muscle Activity And Range Of Motion

While through the literature different objective metrics, such as kinematics and muscle activity, have been used for the evaluation of exoskeletons performance, there is less research on how these metrics represent users’ perceptions. This study aimed to find the relationships between muscle activity and joint kinematics with user perception. Muscle activity was measured using electromyography sensors, focusing on the Latissimus and Thoracolumbar muscles. Body joint kinematics measurements were taken for the knee and trunk joints. The study also investigated how users’ overall selections of exoskeletons, considering all aspects, align with their choices based on comfort and biomechanical support. A similarity index and point biserial correlation coefficient were used for finding the relationships. Four individuals performed trunk bending and weight lifting while wearing different exoskeleton configurations. Both perceived comfort (similarity index: 57%) and biomechanical support (similarity index: 62.5%) played a role in users’ overall preferences, and users prioritized one of them depending on the exoskeleton setting. Comparing the objective and subjective results revealed that muscle activity represented human perception of support to some extent (average similarity index and correlation coefficient of 49% and 0.27 across static and dynamic tasks), while trunk range of motion had a high similarity and correlation with users’ perceived comfort (similarity index: 74.2% and correlation coefficient: 0.53). In summary, this study contributed to understanding the rationale behind users’ perception across different aspects. The results highlight the necessity of future research on finding more sensitive objective metrics, leading us toward obtaining the objective function underlying users’ preferences.