Measurement of Forearm Trajectory During Pitching Motion Using Elbow-mounted Sensor

• Published in: Nihon Kikai Gakkai ronbunshū. C Vol. 74; no. 738; pp. 400 - 408
• Main Authors: KONDO, Izumi, SAGAWA, Koichi, TSUKAMOTO, Toshiaki, ABO, Shuko
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society of Mechanical Engineers 2008
• Subjects: Acceleration; Angular Velocity; Bio-Motion; Forearm; Integration; Measurement; Pitching; Sensor
• ISSN: 0387-5024; 1884-8354
• DOI: 10.1299/kikaic.74.400

This paper describes a measurement method of three-dimensional (3D) forearm movement during pitching motion using an elbow-mounted sensor (3D sensor). The 3D sensor is composed of two kinds of accelerometers with the dynamic range of 4 [G] and 100 [G], and two kinds of gyroscopes with the dynamic range of 300 [deg/s] and 4 000 [deg/s], respectively, since the sensors used in the measurement of the sports activity require wide dynamic range. The 3D sensor is attached on the forearm and measures 3D acceleration and angular velocity. The 3D trajectory of the forearm is estimated by the double integration of measured acceleration which is transformed from the acceleration based on the system of moving coordinated on the forearm to that on the fixed system of coordinate. Since the estimated trajectory of the forearm is affected by the numerical integration, the error of the 3D trajectory is reduced by determining the position and posture of the forearm at the end of the pitching motion. The results of the pitching experiment show that 3D trajectory and angle of the forearm estimated by the 3D sensor agree with that measured by the video camera image with the error margin of around 10%.