2017 Volume 53 Issue Supplement2 Pages S708-S709
The objective of this study is to develop the wearable device for motion measurement which can be used anywhere without calibrated cameras, for measuring motions with transfer. We used a 9-axis sensor to measure three-dimensional acceleration, angular velocity and magnetism. The motion of the segments connected by the joint was calculated by integrating angular velocity, and the static posture was by the orientation from the gravity acceleration and environmental magnetism supposing geomagnetism. Joint angles were calculated from the relative posture of two segments in joint angle coordinate system. We performed the experiments to evaluate the measurement system. As a result, the absolute error at static posture was 1.8° on average and 7.4° at a maximum, and increased to 4.8° on average and 11.2° at a maximum by flexing 90°. Moreover, the result of experiment attaching the sensor thigh and lower thigh to measure the knee angle showed the unphysiological rotation and abduction which might be caused by the declination between the bone axis and the sensor. Eventually, our sensor system considered to be able to measure the posture of a single sensor, however, could measure just rough flexion angle and could not measure the small angle as rotation or abduction precisely when applying to human. Our future task is to correct the error between the axes of bone and sensor.
