MICRO-TECHNOLOGY

These three published articles will provide you with the most recent information regarding the use of technology to assess performance in elite-level half-pipe snowboarding.  Use the links provided to read the full papers and you can also download the PDF versions of these three papers from the PDF download page.

img_34052. Feature Extraction of Performance Variables in Elite Half-Pipe Snowboarding Using Body Mounted Inertial Sensors 

Harding JW, Small JW, James DA. (2007) Feature Extraction of Performance Variables in Elite Half-Pipe Snowboarding Using Body Mounted Inertial Sensors. In BioMEMS and Nanotechnology III, edited by Dan V. Nicolau, Derek Abbott, Kourosh Kalantar-Zadeh, Tiziana Di Matteo, Sergey M. Bezrukov, Proceedings of SPIE Vol. 6799 (SPIE, Bellingham, WA, 2007) 679917.

Recent analysis of elite-level half-pipe snowboard competition has revealed a number of sport specific key performance variables (KPV’s) that correlate well to score1. Information on these variables is difficult to acquire and analyse, relying on collection and labour intensive manual post processing of video data. This paper presents the use of inertial sensors as a user-friendly alternative and subsequently implements signal processing routines to ultimately provide automated, sport specific feedback to coaches and athletes. The author has recently shown that the key performance variables (KPV’s) of total air-time (TAT) and average degree of rotation (ADR) achieved during elite half-pipe snowboarding competition show strong correlation with an athlete’s subjectively judged score1. Utilising Micro-Electrochemical System (MEMS) sensors (tri-axial accelerometers) this paper demonstrates that air-time (AT) achieved during half-pipe snowboarding can be detected and calculated accurately using basic signal processing techniques. Characterisation of the variations in aerial acrobatic manoeuvres and the associated calculation of exact degree of rotation (DR) achieved is a likely extension of this research. The technique developed used a two-pass method to detect locations of half-pipe snowboard runs using power density in the frequency domain and subsequently utilises a threshold based search algorithm in the time domain to calculate air-times associated with individual aerial acrobatic manoeuvres. This technique correctly identified the air-times of 100 percent of aerial acrobatic manoeuvres within each half-pipe snowboarding run (n = 92 aerial acrobatic manoeuvres from 4 subjects) and displayed a very strong correlation with a video based reference standard for air-time calculation  (r = 0.78 ± 0.08; p value < 0.0001; SEE = 0.08 ×/÷ 1.16; mean bias = -0.03 ± 0.02s) (value ± or ×/÷ 95% CL).   Read Full Paper …

img_07723.  Classification of Aerial Acrobatics in Elite Half-Pipe Snowboarding Using Body Mounted Inertial Sensors. 

Harding JW, Mackintosh CG, Hahn AG, James DA. (2008) Classification of Aerial Acrobatics in Elite Half-Pipe Snowboarding Using Body Mounted Inertial Sensors. In The Engineering of Sport 7, Estivalet, M., Brisson, P. Springer-Verlag France., Vol. 2, 447 – 456.

We have previously presented data indicating that the two most important objective performance variables in elite half-pipe snowboarding competition are air-time and degree of rotation. Furthermore, we have documented that air-time can be accurately quantified by signal processing of tri-axial accelerometer data obtained from body mounted inertial sensors. This paper adds to our initial findings by describing how body mounted inertial sensors (specifically tri-axial rate gyroscopes) and basic signal processing can be used to automatically classify aerial acrobatic manoeuvres into four rotational groups (180, 360, 540 or 720 degree rotations). Classification of aerial acrobatics is achieved using integration by summation. Angular velocity (ωi, j, k) quantified by tri-axial rate gyroscopes was integrated over time (t = 0.01s) to provide angular displacements (θi, j, k) at ith sample points. Absolute angular displacements for each orthogonal axes (i, j, k) were then accumulated over the duration of an aerial acrobatic manoeuvre to provide the total angular displacement achieved in each axis over that time period. The total angular displacements associated with each orthogonal axes were then summed to calculate a composite rotational parameter called Air Angle (AA). We observed a statistically significant difference between AA across four half-pipe snowboarding acrobatic groups which involved increasing levels of rotational complexity (P = 0.000, n = 216). The signal processing technique documented in this paper provides sensitive automatic classification of aerial acrobatics into terminology used by the snowboarding community and subsequently has the potential to allow coaches and judges to focus on the more subjective and stylistic aspects of half-pipe snowboarding during either training or elite-level competition.  Read Full Paper …

2176771281_d80b6bff21_b-resized5.  Automated Scoring for Elite Half-Pipe Snowboard Competition – Important Sporting Development or Techno Distraction? 

Harding JW, Mackintosh CG, Martin DT, Hahn AG, James DA.  Automated Scoring for Elite Half-PIpe Snowboard Competition – Important Sporting Development or Techno Distraction?  Sports Technology 2008; 1 (6), 277 – 290.

The authors have previously reported a strong relationship between video based objective data (air-time and degree of rotation) and subjectively judged scores awarded during elite half-pipe snowboard competition.  Advancements in sports monitoring technologies now provide the capacity to accurately and automatically quantify this objective information. This may assist current subjective coaching and competition judging protocols provided the integration process imparts a large element of control to key players within the sport.  The authors therefore recently hosted an invitational half-pipe snowboard competition (2007 Australian Institute of Sport (AIS) Micro-Tech Pipe Challenge) designed to evaluate whether the snowboard community would embrace a competition where results were in part determined by automated objectivity, explore the practical, logistical and technical challenges associated with conducting such an event and evaluate the relationship between subjective judging and results predicted from objective information to see if prior research had ecological validity.  Ten elite male half-pipe snowboarders were instrumented with inertial sensors throughout this competition.  A prediction equation using previously established weightings of average air-time and average degree of rotation accounted for 74% of the shared variance in subjectively judged scores awarded during this competition.  Although our predictions of overall scores and rankings were good there was still 26% of the total variance unexplained.  This should not be considered a weakness of this approach but a strength as the subjective components of style and execution should never be removed from the sport.  The future of half-pipe snowboarding however may be best guided a judging protocol that incorporates both objective and subjective criteria.  Read Full Paper …

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