A robotic walker for standing assistance with realtime estimation of a patient´s load

This paper proposes a standing assistance control for our robotic walker system. Our developing assistance system is based on a walker which is a popular assistance device for an aged person in normal daily life and realizes a standing motion using its support pad which is actuated by novel assistance manipulator mechanisms with four parallel linkages. Our system assists a standing motion using a remaining physical strength of a patient maximally in order not to decrease a force generating capacity of the patient. For realizing this function, this paper proposes the following two topics. The first topic is an estimation scheme of a patient´s load. During standing assistance, our system measures the body motion and the applied force of a patient, and our system estimates the load of pelvis, 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.