床反力計を用いた立位時の質量中心の運動の推定

（前額面モデルへの適用）

抄録

In order to evaluate the balance ability and diagnose the disease, it is necessary to measure the standing motion easily and accurately. The purpose of this study is to estimate small motion of human body from force plates during standing on swaying support surface. This paper discusses a posture estimation method for the frontal plane. Accurate posture estimation method from the force plates requires an appropriate kinematic chain representing the lower body. We defined a three-link chain as a mechanical model of lower body and single-link as a model of upper body. Assuming that subjects stand with their stance parallel and movement of upper body synchronizes with lower body, we can simplified the mechanical chain to an single-degree of freedom system. Based on the equation of motion, the present method can estimate the posture angle and the angular acceleration of the body from shearing force and center of pressure measured by force plate and acceleration of support surface. To verify the validity of the estimation method, we conducted sway test using an electric board equipped with two force plates. Comparing the posture estimated from the force plates by the present method with that from motion capture system, it was found that sufficient estimation accuracy can be obtained by the proposed method.