Intention-Based Walking Support for Paraplegia Patients with Robot Suit HAL

Abstract

This paper proposes an algorithm to estimate human intentions related with walking in order to comfortably and safely support a paraplegia patient's walk. A robot suit "HAL" has been developed for an enhancement of healthy person's activities and for support of physically challenged person's daily life. Assisting method based on bioelectrical signals such as myoelectricity successfully supports healthy person's walking. These bioelectrical signals, however, cannot be measured properly from a paraplegia patient. Therefore another interface that can estimate patients' intentions without any manual controller are desired for robot control since a manual controller deprives a patient of his/her hands' freedom. Estimation of patients' intentions contributes to support not only comfortably but also safely, because an inconformity between the robot suit motion and the patient motion results in his/her stumbling or falling. The proposed algorithm, therefore, estimates patient's intentions from a floor reaction force reflecting patient's weight shift during walking and standing. The effectiveness of this algorithm is investigated through experiments on a paraplegia patient who has a sensory paralysis on both legs, especially his left leg. We show that HAL supports patient's walk properly, estimating his intentions based on floor reaction force.