Motion Analysis and Joint Angle Measurement of Skier Gliding on the Actual Snow Field Using Inertial Sensors

Abstract

This paper deals with the motion analysis of skier gliding on the actual snow field using inertial sensors. It is difficult to measure the motion of skier gliding on the actual snow field since the gliding velocity is fast and the measurement area is large. Therefore, few studies have analyzed ski turns in gliding on the actual snow field. It is necessary to analyze the skier gliding on the actual snow field in resolving the mechanism of ski turns. In our previous study, we developed the motion measurement method of skier using inertial and magnetic field sensors. The 3D posture is estimated by applying the sensor fusion method, and the method can estimate the 3D posture compensating the drift error of gyro sensor and reducing the effect of dynamic acceleration of accelerometer. Furthermore, we developed the sensor fusion method estimating the 3D posture in local coordinate by the information of inertial sensors attaching the body segments. The joint angle of skier in gliding on the actual snow field can be estimated by this method and inverse kinematics. We conducted the measurement experiment by skier gliding on the actual snow field. The inertial sensors and the GPS receiver were attached to the body segments and the top of skier, respectively. Skier conducted carving and skidding turns in this experiment. We calculated the joint angles of skier by the information of inertial sensors, and the switchovers of turns are estimated by the GPS receiver output. The results of motion analysis indicated the major feature of skier's motion and the difference between carving and skidding turns. Therefore, the analysis results can be used to the skill rating, the clarification of the mechanism of ski turns and the suggestion of more ideal turning form.