A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model
The ski deflection with the associated temporal and segmental curvature variation can be considered as a performance-relevant factor in alpine skiing. Although some work on recording ski deflection is available, the segmental curvature among the ski and temporal aspects have not yet been made an obj...
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| Format: | Article |
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MDPI AG
2021-07-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/21/14/4848 |
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| author | Christoph Thorwartl Josef Kröll Andreas Tschepp Philipp Schäffner Helmut Holzer Thomas Stöggl |
| author_facet | Christoph Thorwartl Josef Kröll Andreas Tschepp Philipp Schäffner Helmut Holzer Thomas Stöggl |
| author_sort | Christoph Thorwartl |
| collection | DOAJ |
| description | The ski deflection with the associated temporal and segmental curvature variation can be considered as a performance-relevant factor in alpine skiing. Although some work on recording ski deflection is available, the segmental curvature among the ski and temporal aspects have not yet been made an object of observation. Therefore, the goal of this study was to develop a novel ski demonstrator and to conceptualize and validate an empirical curvature model. Twenty-four PyzoFlex<sup>®</sup> technology-based sensor foils were attached to the upper surface of an alpine ski. A self-developed instrument simultaneously measuring sixteen sensors was used as a data acquisition device. After calibration with a standardized bending test, using an empirical curvature model, the sensors were applied to analyze the segmental curvature characteristic (m<sup>−1</sup>) of the ski in a quasi-static bending situation at five different load levels between 100 N and 230 N. The derived curvature data were compared with values obtained from a high-precision laser measurement system. For the reliability assessment, successive pairs of trials were evaluated at different load levels by calculating the change in mean (CIM), the coefficient of variation (CV) and the intraclass correlation coefficient (ICC 3.1) with a 95% confidence interval. A high reliability of CIM −1.41–0.50%, max CV 1.45%, and ICC 3.1 > 0.961 was found for the different load levels. Additionally, the criterion validity based on the Pearson correlation coefficient was R<sup>2</sup> = 0.993 and the limits of agreement, expressed by the accuracy (systematic bias) and the precision (SD), was between +9.45 × 10<sup>−3</sup> m<sup>−1</sup> and −6.78 × 10<sup>−3</sup> m<sup>−1</sup> for all load levels. The new measuring system offers both good accuracy (1.33 × 10<sup>−3</sup> m<sup>−1</sup>) and high precision (4.14 × 10<sup>−3</sup> m<sup>−1</sup>). However, the results are based on quasi-static ski deformations, which means that a transfer into the field is only allowed to a limited extent since the scope of the curvature model has not yet been definitely determined. The high laboratory-related reliability and validity of our novel ski prototype featuring PyzoFlex<sup>®</sup> technology make it a potential candidate for on-snow application such as smart skiing equipment. |
| first_indexed | 2024-03-10T09:23:31Z |
| format | Article |
| id | doaj.art-321d4a7be43b463db687eae8897dc02f |
| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-10T09:23:31Z |
| publishDate | 2021-07-01 |
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| spelling | doaj.art-321d4a7be43b463db687eae8897dc02f2023-11-22T04:56:56ZengMDPI AGSensors1424-82202021-07-012114484810.3390/s21144848A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature ModelChristoph Thorwartl0Josef Kröll1Andreas Tschepp2Philipp Schäffner3Helmut Holzer4Thomas Stöggl5Department of Sport and Exercise Science, University of Salzburg, Schlossallee 49, 5400 Hallein/Rif, AustriaDepartment of Sport and Exercise Science, University of Salzburg, Schlossallee 49, 5400 Hallein/Rif, AustriaJoanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Straße 30, 8160 Weiz, AustriaJoanneum Research Forschungsgesellschaft mbH, Franz-Pichler-Straße 30, 8160 Weiz, AustriaAtomic Austria GmbH, Atomic Strasse 1, 5541 Altenmarkt, AustriaDepartment of Sport and Exercise Science, University of Salzburg, Schlossallee 49, 5400 Hallein/Rif, AustriaThe ski deflection with the associated temporal and segmental curvature variation can be considered as a performance-relevant factor in alpine skiing. Although some work on recording ski deflection is available, the segmental curvature among the ski and temporal aspects have not yet been made an object of observation. Therefore, the goal of this study was to develop a novel ski demonstrator and to conceptualize and validate an empirical curvature model. Twenty-four PyzoFlex<sup>®</sup> technology-based sensor foils were attached to the upper surface of an alpine ski. A self-developed instrument simultaneously measuring sixteen sensors was used as a data acquisition device. After calibration with a standardized bending test, using an empirical curvature model, the sensors were applied to analyze the segmental curvature characteristic (m<sup>−1</sup>) of the ski in a quasi-static bending situation at five different load levels between 100 N and 230 N. The derived curvature data were compared with values obtained from a high-precision laser measurement system. For the reliability assessment, successive pairs of trials were evaluated at different load levels by calculating the change in mean (CIM), the coefficient of variation (CV) and the intraclass correlation coefficient (ICC 3.1) with a 95% confidence interval. A high reliability of CIM −1.41–0.50%, max CV 1.45%, and ICC 3.1 > 0.961 was found for the different load levels. Additionally, the criterion validity based on the Pearson correlation coefficient was R<sup>2</sup> = 0.993 and the limits of agreement, expressed by the accuracy (systematic bias) and the precision (SD), was between +9.45 × 10<sup>−3</sup> m<sup>−1</sup> and −6.78 × 10<sup>−3</sup> m<sup>−1</sup> for all load levels. The new measuring system offers both good accuracy (1.33 × 10<sup>−3</sup> m<sup>−1</sup>) and high precision (4.14 × 10<sup>−3</sup> m<sup>−1</sup>). However, the results are based on quasi-static ski deformations, which means that a transfer into the field is only allowed to a limited extent since the scope of the curvature model has not yet been definitely determined. The high laboratory-related reliability and validity of our novel ski prototype featuring PyzoFlex<sup>®</sup> technology make it a potential candidate for on-snow application such as smart skiing equipment.https://www.mdpi.com/1424-8220/21/14/4848bending sensorsflexionPyzoFlexski bendingski deflection |
| spellingShingle | Christoph Thorwartl Josef Kröll Andreas Tschepp Philipp Schäffner Helmut Holzer Thomas Stöggl A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model Sensors bending sensors flexion PyzoFlex ski bending ski deflection |
| title | A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model |
| title_full | A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model |
| title_fullStr | A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model |
| title_full_unstemmed | A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model |
| title_short | A Novel Sensor Foil to Measure Ski Deflections: Development and Validation of a Curvature Model |
| title_sort | novel sensor foil to measure ski deflections development and validation of a curvature model |
| topic | bending sensors flexion PyzoFlex ski bending ski deflection |
| url | https://www.mdpi.com/1424-8220/21/14/4848 |
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