Impact of Hip Exoskeleton Assistance on Human Gait: A Kinematic Study

Wearable robotic devices such as lower-limb exoskeletons have been recently proposed to support mobility, assist activities of daily living, and even aid rehabilitation. Understanding and quantifying the quality of interaction between human and robot is essential to ensure physiological and effective support. In this study, we evaluated a transparent (i.e., non-assisting) modality and two levels of assistance (low and high) of the Hypershell-X hip exoskeleton during overground walking in a cohort of 16 healthy individuals. Our goal was to characterize the impact of the assistance on physiological gait from a kinematic perspective. The results suggest that the exoskeleton preserved natural gait characteristics across conditions: no significant changes were found in spatiotemporal parameters, and joint profiles on the sagittal plane remained highly correlated (r > 0.9). Significant alterations emerged at the highest assistance level, which mainly affected the hip joint, where the assistive torque is directly applied. However, even in this experimental condition, the overall gait biomechanics was preserved. These findings indicate that the Hypershell-X provides functional and effective assistance without relevant alteration of the physiological structure of gait.