An Angle Measurement Method by Using Terrestrial Magnetism Sensors on a Ski Jumper´s Motion Monitoring System

We are developing a ski jumper´s motion monitor system employing terrestrial magnetism and acceleration sensors. On this development, we have confirmed that terrestrial magnetism and acceleration sensors are useful to measure ski jumper´s in run descending speed and taking-off positions using a model of ski jumping ramp. Also, we gathered required measurement by inquiring a ski jumping athlete and his coach. As this result, we confirmed following measurement: in run descending speed, jumper´s style and posture at jumping point, and slant of body of the jumper when he is flying. We are developing a ski jumper´s motion monitoring system using terrestrial magnetism, acceleration sensors and a video camera. To monitor ski jumper´s jumping styles, angles of ski jumper´s joints must be measured. In this paper, we describe a method to measure an angle of a joint to monitor ski jumper´s style using terrestrial magnetism sensors. Also, we show measured angles using actual ski jumpers´ data gathered at ski jumping hill, and we discuss on usefulness of the system.