Ski deflection measurement during skiing and estimation of ski direction and edge angle

T. Yoneyama, Nathan Scott, H. Kagawa, K. Osada

Research output: Contribution to journalArticlepeer-review


A new sensor for detecting ski bending and torsional deflection during an actual ski turn on the snow has been developed. It consisted of bending and torsion sensors connected by light rigid beams. This structure was fixed to the upper surface of a ski and passed through a tunnel in the central binding plate. The bending and torsion sensors were strain cells, designed to reject strain orthogonal to the desired measurement direction. The calibration factor for each sensor was determined in a jig, then the calibration of the overall sensor assembly was checked by static bending experiments and a free vibration test. A data logger recorded the strain signals synchronously with other data such as the components of the earth’s magnetic field measured by a sensor on the ski. The data set allowed reconstruction in software of the instantaneous shape, direction and edge angle of the ski. The purpose of this paper is mainly to introduce the equipment used and methods developed. Tests of the sensor performance are described. Results from a ski run on snow are presented to show how the various types of data can be combined. A skilled ski athlete performed long turns with the ski at about 60 km/h on a groomed snow surface at Shiga Kogen in Japan. The experiment on snow showed that the deformation of the ski was predominantly bending; torsional deflection, although measurable, had only a small effect on the shape of the running edge. The ski edge adopted a symmetrical circular bent shape with an unexpectedly small radius when on the outside, but was unconstrained, lightly loaded and nearly straight when on the inside.
Original languageEnglish
Pages (from-to)3-13
JournalSports Engineering
Issue number1
Publication statusPublished - 2008


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