The change of gait motion when curving a corner owing to the motion restriction caused by a wearable device

Many wearable robots are not fully capable of fitting the motion of the wearer, owing to their limited degrees-of-freedom (DOF). This limitation disturbs motions such as corner curving, which are required in daily life. In this study, the effect of the DOF restriction on the corner curving motion was observed and analyzed. The gait motions, when curving a round corner with and without the restriction of out-of-sagittal plane motion, were compared using a wearable device which could restrict hip adduction/abduction and rotation. The result suggested that the restriction not only decreased the range of motion of hip adduction/abduction and rotation, but also changed the center of mass (COM) trajectory. Owing to the disturbance applied during the stepping motion of the outer leg, the COM trajectory moved further from the corner in the trials with restriction. Thus, the distance between COM and the base of support of the inner foot became larger during the swing phase of the outer leg, which possibly increased the risk of loss of balance. Furthermore, it was also suggested that an assistive torque, which does not consider curving motion, possibly increases such risk.