Development of Skill Scoring System for Ski and Snowboard

Observation of dynamic posture during sports activity is one of the most important factors to give absolute evaluation to the player’s performance. The sports like the figure skating and the skiing have difficulty in evaluation of skill because the evaluation depends mostly on the observation from the third person. The training method for such sports inevitably needs feedback comments from the experts. However, it is hard for all players of the sports to receive such expensive feedbacks at any time when they need. In order to overcome the inconvenience to perform self-training without the third experts, this paper focuses on development of a training system using smartphone device that gives a clear guide for body balance control in the skier and the snowboarder. The system gives scores and comments for the ski’s parallel turn. The system automatically scores skill for body balance control regarding three aspects: the tempo at turns of body balance movements between the right and the left in the skiing, the distribution of body balance, and the angle between the snow slope and the body of the skier. This paper also performs a preliminary evaluation of the system in the case of snowboard. The system brings a new method to know the skills of body balance control in skiing and snowboarding from the absolute data measured by sensor devices.

This research is partially supported by Tateishi Science and Technology Foundation. And also this work is partially supported by KAKENHI (24240085) Grant-in-Aid for Scientific Research (A). We thank to Prof. Yuji Yamamoto at Nagoya University, Japan for his proofreading of this paper content. We also thank to the participants of the experiments Prof. Kawahara, Prof. Ueno, Dr. Hisamitsu and all other ski experts.

Authors and Affiliations

1. Faculty of Engineering, Information and Systems, University of Tsukuba, Tsukuba, Japan

   Shinichi Yamagiwa & Hiroyuki Ohshima

2. Exercise Physiology, Health Education, Graduate School of Education, Hokkaido University, Sapporo, Japan

   Kazuki Shirakawa

Corresponding author

Correspondence to Shinichi Yamagiwa .

Editors and Affiliations

1. Norwegian School of Sport Sciences, Oslo, Norway

   Jan Cabri

2. Universidade de Lisboa, Cruz Quebrada, Portugal

   João Barreiros

3. Universidade de Lisboa, Cruz Quebrada, Portugal

   Pedro Pezarat Correia

Appendix

The approximation line for the balance angle is calculated using the least squares method. For any accelerometer data of X and Y axis represented by (\(x_i\), \(y_i\)) where i is \(0\le i<N\), we calculate a that makes minimal of;

Because \(S'(a)=0\),

The scoring equation for the balance angle uses the data in the right side to calculate \(a_R\) and the one of the left side to calculate the \(a_L\). The calculation for the score uses the absolute values of \(a_R\) and \(a_L\).

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