Standing Assistance Control based on Voluntary Body Movement within Safety Tolerance

This paper proposes a novel standing assistance robot, which considers the posture tolerance of its user. In previous studies, conventional assistive robots did not require patients to use their own physical strength to stand, which leads to decreased strength in the elderly. Therefore, an assistive robot that allows patients to maximally use the physical strength they possess is required. To realize this objective, it is important that a robot assists patients according to their body movement and by their intentions. However, in previous studies, general assistive robots helped patients by using a fixed motion reference pathway in spite of their original intention, and as a result, these robots failed to use the physical strength of the patients. In our previous study, we investigated the posture tolerance during a standing motion. In this tolerance, patients could stand by own muscle strength with stable posture. Thus, as the next step, this paper proposes assistance force control scheme which considers the investigated posture tolerance. Our robot generated assistance force, which lead the voluntary movement with their remaining physical strength within investigated range, by combining position control and force control. A prototype assistive robot, based on the proposed idea was fabricated to help patients stand up safely using the maximum of their remaining physical strength.