INTRODUCTION: In the dynamics of ski jumping, it is necessary to measure the forces on the jumper. In the air, the jumper receives the gravity and aerodynamic force. Then the jumper produces rotational momentum. The angle of the jumper and the direction of motion change greatly. It is important to measure the body momentum during ski jumping. We developed a compact measurement device, combined accelerometer, and gyroscope. The purpose of this study is the development of an analysis system, including a measurement device, for ski jumping. METHOD: A compact measurement device (Microstome Corporation, Saku, JAPAN), which combines an accelerometer, a gyroscope, and a data logger was developed. The acceleration data in three directions and angular velocity data in three axes were sampled by 200Hz and stored in the data logger. Three jumpers performed ski jumping to prove the availability of this System. RESULTS and DISCUSSION: A set of Eular angles representation for rotation called roll, pitch, and yaw was used. The three angles were obtained by the Integration of each angular velocity data measured from the gyroscope. Figure 1 indicates a typical example of Eular angles during ski jumping. The movement of the jumper was mainly represented by pitch angle. The yaw and roll momentums were also observed. It was considered that the three momentums acted to control jumper's posture. A rotation matrix was also calculated using the angle data of roll, pitch, and yaw. The acceleration data were also converted into a global coordinate system by the rotation matrix. CONCLUSION: It became possible to obtain three-dimensional dynamic data using the analysis System.
© Copyright 2007 4th International Congress on Science and Skiing. Published by University of Salzburg. All rights reserved.