Gait pattern generation for a power-assist device of paraplegic gait

We address a gait pattern generation on a legged locomotor device (WPAL: wearable power-assist locomotor) for paraplegics. In the gait movement with WPAL, a backward falling is a considerable problem, and a foot-floor collision during a swing movement would induce a loss of balance. In addition, adjustability of the gait parameters, such as stride length, gait cycle and maximum hight of the toe clearance, would be required for an individual paraplegic according to the degrees of his disabilities and skills. In this paper, we propose a gait pattern generation method considering the requirements of the stability and the adjustability. First, the trajectories of toe position, horizontal hip position, and foot plantar angle are calculated using a minimum jerk trajectory with the constraints of the position and velocity at via points. Second, the desired trajectories of joint angles are determined from the calculated trajectories by inverse kinematic equations. We demonstrate that generated desired trajectories for various gait parameter values and boundary conditions were satisfied with the required stability conditions.