Standing motion assistance on a robotic walker based on the estimated patient´s load

This paper proposes a standing assistance control with a patient´s load estimation for our robotic walker system. Our developing robotic walker realizes a standing assistance using its support pad which is actuated by novel assistance manipulator mechanisms on its body with four parallel linkages. Our system assists a standing motion using a remaining physical strength of patients maximally in order not to decrease their force generating capacity. For realizing this function, this paper proposes the following two topics. The first topic is an load estimation scheme of a patient who uses our assistance system. Our developed system measures a body motion and the applied force of a patient during standing assistance, and our system estimates the load of trunk, knee and ankle joint using a linkage model which approximates the human body. The second topic is a combination of force and position control. According to the estimated load of a patient during standing motion, our control system selects more appropriate control method from them and realizes the standing assistance using the physical strength of the patient. The performance of our system is verified by experiments using our prototype.