A standing assistance based on a load estimation considering with a muscle arrangements at the human leg

In our previous research, we have developed a novel standing assistance system, which uses a remaining physical strength of an elderly person. For realizing it, the assistance system needs to estimate the load of a patient and in many cases, the previous researchers use a joint traction which can be derived by a human linkages model kinematically for evaluating it. However, human body motions are generated by many muscles and a joint traction, which muscles can generate, changes according to the relative position between the muscles and links. This means there is not always mutual relation between a muscle activity and a joint traction, and it is difficult to evaluate the muscular power of a patient during a standing motion simply using a joint traction. Therefore, in this paper, we propose a load estimation scheme which consider the muscle functionality of the patient. Our key idea is a load estimation using the human musculo-skeletal model of a lower limb, which expresses a biarticular muscle function. In general, the human generates a natural standing motion using the biarticular muscle function. This model enables the standing assistance system to estimate a load of the subject without biosensors such as an electromyograph and to assist the standing motion using a remaining physical strength of the subject maximally.