Aminian, Kamiar

Fasel, Benedikt

Göpfert, Caroline

Lindinger, Stefan

Rapp, Walter

Infoscience - École polytechnique fédérale de Lausanne

Pdf Export for Submission_91 ConfidentialVALIDATION OF RELATIVE COM DISPLACEMENTIN V2 SKATING OBTAINED WITH INERTIALSENSORS – A FEASIBILITY STUDY Fasel, B. (1) ; Göpfert, C. (2) ; Rapp, W. (3) ; Lindinger, S. (2) ; Aminian, K. (1)(1) Laboratory of Movement Analysis and Measurement, EPFL, Switzerland; (2) Department of SportScience and Kinesiology, University of Salzburg, Austria; (3) Institut für Sport und Sportwissenschaft,Albert-Ludwigs-Universität Freiburg, GermanyKeywords: v2 skating, center of mass, inertial sensors, validationINTRODUCTIONFor precise estimation of the athlete’s CoM during skiing 3D video analysis isrequired. Such systems are complex to set up and cannot be used on snow forcovering large distances. Alternative solutions using inertial sensors have beenproposed but were too simple for taking into account arm movement(Myklebust et al., 2015). The aim of this project was to design and validate aninertial sensor based algorithm for estimating CoM displacement where limbmotion was also considered.METHODSThe full body model designed for alpine ski racing (Fasel et al., 2016) wasextended to include upper limbs. 10 inertial sensors (500Hz) were attached toshanks, thighs, sacrum, C7, arms, and wrists. Segment inertial parameterswere taken from (Dumas et al., 2007). Reference CoM was derived from thePlug-In Gait marker setup extended to cross-country skiing (Göpfert et al.,n.d.). One female athlete performed the V2 skating technique on treadmill at8km/h and 12km/h. For validation purpose the CoM was expressed relative tothe mid-point between left and right antero-superior iliac spine. The anterior-posterior (AP) axis was defined to be parallel to the treadmill, pointing forwardsand the medio-lateral (ML) axis was pointing horizontally to the left.RESULTSErrors were similar for both speeds. For the 8km/h condition accuracy (meanerror) was -70mm (AP axis), 23mm (ML axis), -95mm (vertical axis). Precision(error standard deviation) was 10mm, 17mm and 5mm for the three axes withcorrelation coefficients of 0.96, 0.28, 0.83. Average cycle-by-cycle range ofmotion (RoM) of relative CoM displacement had a precision of 6.7mm, 2.7mm,3.5mm.DISCUSSIONThe proposed method allowed computing relative CoM movement for the APand vertical axes with high precision. The high correlation and precisiondemonstrated that arm movement can be measured. Nevertheless, due tolimitations of the used body model only RoM values and curves should bePdf Export for Submission_91 Confidentialused instead of absolute CoM values.CONCLUSIONThe study showed that inertial sensors can be used for measuring relativeCoM displacement in V2 skating. However, before using the system avalidation on a large population is required.REFERENCESDumas, R., Chèze, L., & Verriest, J.-P. (2007). Adjustments to McConville etal. and Young et al. body segment inertial parameters. J Biomech, 40(3),543–53.Fasel, B., Spörri, J., Gilgien, M., Boffi, G., Chardonnens, J., Müller, E., &Aminian, K. (2016). Three-Dimensional Body and Centre of Mass Kinematicsin Alpine Ski Racing Using Differential GNSS and Inertial Sensors. Rem Sens,8(671).Göpfert, C., Pohjola, M., Linnamo, V., Ohtonen, O., Rapp, W., & Lindinger, S.(n.d.). Forward acceleration of the centre of mass during ski skating calculatedfrom force and motion capture date. Submitted to Sports Eng.Myklebust, H., Gloersen, O., & Jostein, H. (2015). Validity of Ski SkatingCenter of Mass Displacement Measured by a Single Inertial MeasurementUnit. J Appl Biomech, 31(6), 492–8.Powered by TCPDF (www.tcpdf.org)

Validation of relative CoM displacement in V2 skating obtained with inertial sensors - a feasibility study

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Validation of relative CoM displacement in V2 skating obtained with inertial sensors - a feasibility study

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