SKISPRUNG - Precise Trajectory and Velocity Determination in Ski Jumping

The most important indicators for the flight performance of a ski jumper are the flight trajectory itself and the corresponding velocity. Due to the fact that an accurate position and velocity information along the flight trajectory is available for coaches and athletes shortly after the jump, new and important analysis methods of the jump performance are made possible. Therefore, the main objective of the project SKISPRUNG is the precise determination of these two indicators - the position and the velocity along the flight trajectory at each epoch.

Short Description

Furthermore, a demonstrator system for the immediate processing and analysis of the measured data should be provided. The system requires a position accuracy in the cm-level and a velocity accuracy of 0.5 km/h.

During the project, a "passive" and an "active" system are developed. The passive system consists of several high- frequency and high-resolution cameras which are able to track a label with an accuracy in the cm-level. The label is attached to the jumper’s dress according to the centre of mass of the jumper. Thus, the position and the height of trajectory points can be measured if the position and the orientation of the cameras are known.

Since the recording is done with a high frame rate, the velocity can be determined and assigned to the corresponding trajectory points. The use of a passive system has the advantage that the athlete is not irritated by the measurement equipment and, therefore, the system can also be used during competitions. The active system uses GPS phase measurements in the relative- positioning mode.

The receiver module is mounted between the inner and outer shell of the helmet with the GPS antenna on top of the helmet. An important basic condition is the equipment’s weight. It should be less than 200 grams, since the equipment should not be a handicap for the ski jumper. A second GPS receiver is located at a reference point beside the ski-jumping platform. The jump trajectory is determined in post-processing mode.

On the one hand, the GPS data are used to provide the necessary verification of the passive system. On the other hand, the active GPS system is designed as a stand-alone application for training sessions. Its advantage is that is is easy to install. Thus, it can be easily used at different ski-jumping sites and is the proper tool to compare all the jumps of the athletes.

Project Partners

Coordinator

Institute of Navigation und Satellite Geodesy, University of Technology Graz
- Manfred Wieser

Partners

Institute of Digital Image Processing, JOANNEUM RESEARCH - Gerhard Paar
Institute of Sports Science, University of Innsbruck - Werner Nachbauer
Österreichischer Skiverband - Werner Nachbauer

Contact Address

Institute of Navigation und Satellite Geodesy
University of Technology Graz
Manfred Wieser
Steyrergasse 30
A-8010 Graz
E-Mail: wieser@geomatics.tu-graz.ac.at
Web: www.inas.tugraz.at