A-29 A study on estimation of body information for motion analysis using inertial sensor

Abstract

The aim of this study is to establish the method for improving the performance of body motion analysis by inertial sensor. The position vector must be measured before the experiment in the previous studies using inertial sensor. In the previous study, we developed the estimation method for the position information of the attached sensors. The method estimates the position vectors from the accelerometer to the joint position by the centrifugal and tangential accelerations included to the accelerometer output. This method is established by the Extended Kalman filter. The nonlinear state equation consists of the relational equation between the Roll-Pitch-Yaw angles and the angular velocity, and the position vectors from the accelerometer position to the joint position, and the measurement equation consists of the rotational matrix from the sensor coordinate to the global coordinate and the gravity acceleration. Furthermore, we extended the method for estimating the inclination parameter of body shape in this study. We conducted the measurement experiment to confirm the performance of the method by using the experimental setup installing the rotary encoders and attaching the inertial sensor system. We estimated the 3D posture by the sensor fusion compensating the effect of centrifugal and tangential acceleration established by the previous study. The calculation of centrifugal and tangential acceleration is used to the estimated position vectors and the inclination parameter. The estimated 3D posture showed higher accuracy than the 3D posture without compensation. The method can be used to the development of more simply motion measurement method and the improvement of accuracy in the motion analysis by inertial sensor system.