Validating Printed Sensors for Alpine Ski Torsional Deflection Analysis in the Laboratory
Thorwartl Christoph, Tschepp Andreas, Zirkl Martin, Holzer Helmut, Stöggl Thomas (2024): Validating Printed Sensors for Alpine Ski Torsional Deflection Analysis in the Laboratory In: Book of Abstracts of the Joint Conference 25th International Congress on Snow Sport Trauma and Safety - 38th Congress of the International Society for Snowsports Medicine.
Recently, a PyzoFlex® ski prototype was developed to assess the curvature characteristics of alpine skis. This prototype not only measures curvature based on ski bending but also demonstrates potential in detecting torsional deformations. However, sensor calibration and a comparison with a gold standard have not yet been performed. Therefore, the objectives of this work were (i) to identify an appropriate printed sensor layout for torsional measurements, (ii) to calibrate the sensors with respect to torsional angle, and (iii) to assess validity of the sensor based torsional deformation concept. High correlation (r = 0.998) between the sensor-derived and encoder-captured torsional angles confirms strong validity of the proposed concept. The sensor system demonstrated a high level of accuracy, with a systematic bias of 0.12°. The signal’s precision, as indicated by standard deviation and Limits of Agreement, is suitable in the laboratory, where individual torsion levels are easily distinguishable (torsion range of ± 12°). Nevertheless, the question is whether the precision is adequate for field measurements, as field torsion angles can be very small and, consequently, more challenging to distinguish. Therefore, future snow measurements are needed to verify the approach described above. However, detecting ski deflection, both bending and torsional, is valuable not only for optimizing performance but also for ensuring safety when selecting the appropriate ski for product fitting.
