Overground gait patterns changed by modulating hip stiffness with a robotic exoskeleton

Abstract

Lower-limb exoskeletons have shown great potential to assist human locomotion. However, effective methods for modulating aspects of gait behavior beyond reducing metabolic effort, such as stride time and gait kinematics, are still needed, especially for individuals with impaired gait. Using the Samsung GEMS-H exoskeleton, we studied the effect on healthy gait behavior of applying hip stiffness during overground walking. We found that applying positive stiffness did not affect stride time, but it did reduce hip range of motion. We also found that applying negative stiffness increased both stride time and hip range of motion. Additional analyses showed that the effect of applied hip stiffness on hip range of motion during overground walking was similar to that observed during treadmill walking. The effect of positive stiffness on stride time was similar during overground and treadmill walking, but the increase in stride time in response to the application of negative stiffness was greater during treadmill walking than in overground walking. Lastly, we found no evidence to indicate that neural adaptation or learning occurred when hip stiffness was applied. These results suggest that applying joint stiffness may be a promising approach to restoring healthy gait kinematics.