論文 - 仰木　裕嗣

Aerodynamic study of ski jumping flight based on inertia sensors (171)

Yuji Ohgi, Nobuyuki Hirai, Masahide Murakami, Kazuya Seo

ENGINEERING OF SPORT 7, VOL 2 （SPRINGER VERLAG PARIS）  7 （ 2 ） 157 - + 2008年

査読有り

　概要を見る

Aerodynamic forces, drag and lift were estimated by the body attached inertia sensors and high speed videography in ski jumping. Last ISEA conference, the authors presented our new method for the aerodynamic study on ski Jumping. In this paper, we propose more robust and reliable measurement system by using wireless technology. Wireless 6DOF inertia sensor platform, which has a built-in tri-axial accelerometer and three single axial gyroscopes, was attached on the jumper's low back. The authors adopted IEEE802.15.4 for the start trigger and real time monitoring during long training session. Sensor also has a flush memory inside for one hour data storage at 250Hz. The primary target of the present study is to extract the aerodynamic force data during real jumping flight. Angular velocity on the sagittal plane was directly measured from the gyroscope. Then we could obtain the jumper's body pitch angle by its time integration. The accelerations with respect to the body local coordinate system which was determined by the body pitch angle, indicated the drag and lift forces. The assessment of the aerodynamic forces of ski jumping was examined by both of the sensor data and the kinematical data in this study.

Aerodynamic study of ski jumping flight based on inertia sensors (171)

Yuji Ohgi, Nobuyuki Hirai, Masahide Murakami, Kazuya Seo

ENGINEERING OF SPORT 7, VOL 2 （SPRINGER VERLAG PARIS）  7 （ 1 ） 157 - + 2008年

査読有り

　概要を見る

Aerodynamic forces, drag and lift were estimated by the body attached inertia sensors and high speed videography in ski jumping. Last ISEA conference, the authors presented our new method for the aerodynamic study on ski Jumping. In this paper, we propose more robust and reliable measurement system by using wireless technology. Wireless 6DOF inertia sensor platform, which has a built-in tri-axial accelerometer and three single axial gyroscopes, was attached on the jumper's low back. The authors adopted IEEE802.15.4 for the start trigger and real time monitoring during long training session. Sensor also has a flush memory inside for one hour data storage at 250Hz. The primary target of the present study is to extract the aerodynamic force data during real jumping flight. Angular velocity on the sagittal plane was directly measured from the gyroscope. Then we could obtain the jumper's body pitch angle by its time integration. The accelerations with respect to the body local coordinate system which was determined by the body pitch angle, indicated the drag and lift forces. The assessment of the aerodynamic forces of ski jumping was examined by both of the sensor data and the kinematical data in this study.

1814 内蔵型加速度センサによる飛翔球の運動学変量推定(S18 スポーツ流体工学,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

小柳 玲乃, 仰木 裕嗣

年次大会講演論文集 （一般社団法人日本機械学会）  2008   149 - 150 2008年

　概要を見る

The purpose of this research is to estimate the velocity, angular velocity and direction of the rotational axis of the flying ball by the accelerometer. A subject performed pitching by using the sensor ball. And, the closed up release point image was acquired using the high speed cameras. The distance from the release point to the switch is measured image analysis and the velocity of each trial was estimated by the flight time of the ball. The angular velocity was estimated from the gravitational and the translational acceleration. The direction of the rotational axis was estimated from the component of the centrifugal acceleration. Each estimated value was compared to the value calculated by the high speed cameras. The velocity difference between the estimation value and the calculation value was about 1.85 (m/s). The difference of the angular velocity was about 0.57 (rad). The difference of the rotational axis was about 0.41 (rad). And it was observed that the rotational axis on the sensor coordinate system changed during flight phase.

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Measurement of the forces on ball in flight using built-in accelerometer (P138)

R. Koyanagi, Y. Ohgi

ENGINEERING OF SPORT 7, VOL 2 （SPRINGER VERLAG PARIS）  7 （ 2 ） 1 - + 2008年

査読有り

　概要を見る

In this study, tri-axial accelerometer was installed in a ball to measure the acrodynamic forces during the ball's flight. The control experiments to validate were conducted besides the pitching experiment, to examine ball linear or angular velocity components independently. These were performed using a turntable and free fall test, respectively. The acceleration data of the throwing experiment showed a semi-sinusoidal wave pattern. Oil the other hand, this wave pattern was not observed in the acceleration data of both the rotational table experiment and free-fall experiment. It was revealed that the change of the orientation vectors of the gravitational acceleration and the translation acceleration on the sensor coordinate system caused the sinusoidal acceleration pattern.

Modelling swimmers' speeds over the course of a race

Hideyasu Shimadzu, Ritel Shibata, Yuji Ohgi

JOURNAL OF BIOMECHANICS （ELSEVIER SCI LTD）  41 （ 3 ） 549 - 555 2008年

査読有り,  ISSN  0021-9290

　概要を見る

A stochastic model of swimming speed over the course of a male 200 m freestyle swimming race is proposed. It builds on a dynamical model reflecting the trade-off between drag and propulsion in swimming. The parameters of the model are estimated from elapsed time data observed at several points along the pool. The model fits the data well and also provides a good description of the swimming strategies of each swimmer from phase to phase in the race. An individual factor measuring how much faster or slower the individual swims relative to the average swimming speed of the race is simultaneously estimated in the course of fitting the model. This factor is, as expected, closely related to the final outcome of the race. (c) 2007 Elsevier Ltd. All rights reserved.

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Aerodynamic forces computation from high-speed video image of ski jumping flight

Masahide Murakami, Nobuyuki Hirai, Kazuya Seo, Yuji Ohgi

The impact of Technology on Sport II    397 - 402 2007年09月

査読有り

Aerodynami forces acting in ski jumping

仰木 裕嗣,瀬尾和哉, 平井伸幸, 村上正秀

Journal of Biomechanics （International Biomechanics Society）  40 （ sup.2 ） S402 2007年07月

研究論文（研究会，シンポジウム資料等）, 単著

B30 高速度ビデオカメラの画像解析を用いたスキージャンプの空力解析(スキー・リュージュ)

平井 伸幸, 村上 正秀, 瀬尾 和哉, 仰木 裕嗣

ジョイント・シンポジウム講演論文集：スポーツ工学シンポジウム：シンポジウム：ヒューマン・ダイナミックス （一般社団法人日本機械学会）  2007   348 - 353 2007年

　概要を見る

A ski jumping flight analysis was attempted on the basis of the high-speed digital video image taken at Hakuba Ski Jumping Stadium in Japan. Initial 40m of flights of 120-m jumping after take-off were recorded by a fixed high-speed video camera at a frame rate of 250 frames/s. After some corrections, a number of time series data were extracted for the loci of key parts of a jumper such as the waist, the ski boots and the ski tip as well as for key angles representing a jumper posture such as the ski angle and the forward leaning angle. It is demonstrated that the aerodynamic force data during real jumping flights, in particular in the early phase of a flight can be derived from video image.

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Measurement of Jumper's Body Motion in Ski Jumping

Yuji Ohgi, Kazuya Seo, Nobuyuki Hirai, Masahide Murakami

The Engineering of Sports 6 1   275 - 280 2006年07月

査読有り

慣性センサを使った人間の運動計測

仰木 裕嗣

ライフサポート （The Society of Life Support Engineering）  18   14 - 14 2006年

ISSN  1341-9455

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Pulling Straight to the End of the Pool

仰木 裕嗣

Science 306   43 2004年10月

研究論文（その他学術会議資料等）, 共著

Meeting - Engineering of sport - Pulling straight to the end of the pool

A Cho

SCIENCE （AMER ASSOC ADVANCEMENT SCIENCE）  306 （ 5693 ） 43 - 43 2004年10月

ISSN  0036-8075

水泳中の手首加速度・角加速度計測-3軸加速度・3軸ジャイロｓコープセンサデータロガーの開発

仰木 裕嗣

スポーツ工学 5 （国際スポーツ工学会）  5 （ 1 ） 536-542 2004年09月

研究論文（研究会，シンポジウム資料等）, 単著, 査読有り

ピエゾ抵抗型3軸加速度センサーを用いたゴルフスイング技能評価システムの開発

仰木 裕嗣,馬場敏之,坂口勇夫

日立金属技報 20   45-50 2004年01月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0916--930

DandDによるスポーツ競技支援

仰木 裕嗣　島津秀康

日本統計学会講演報告集 （日本統計学会）     372-374 2003年09月

研究論文（学術雑誌）, 共著

Stroke phase discrimination in breaststroke swimming using a tri-axial acceleration sensor device

仰木 裕嗣,市川　浩, 本間　正信, 宮地　力

International Journal of Sports Engineering 6 （ 2 ） 111-121 - 121 2003年06月

研究論文（学術雑誌）, 共著, 査読有り

Microcomputer-based acceleration sensor device for swimming stroke monitoring

Yuji Ohgi, Hiroshi Ichikawa, Chikara Miyaji

JSME International Journal, Series C: Mechanical Systems, Machine Elements and Manufacturing 45 （ 4 ） 960 - 966 2002年12月

査読有り,  ISSN  1344-7653

　概要を見る

The purpose of this study was to develop a microcomputer-based acceleration logger device for the swimming stroke monitoring. The authors measured the swimmer's tri-axial wrist acceleration and applied this device for the fatigue evaluation of the swimmers. The experimental protocol led the swimmers exhausted after the crawl stroke interval training. Every single stroke was determined by the impact acceleration peak, which appeared on the x and z-axis acceleration. The change of the underwater stroke phases was identified by the characteristics of the acceleration peaks. In their exhaustion, the y-axis acceleration, which was longitudinal forearm acceleration decreased at the beginning of the upsweep phase. At that time, the swimmer could not extend his elbow joint. Since the developed acceleration data logger could provide us the information about the underwater stroke phases and it would be a helpful tool in the swimming training.

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Application of a mathematical model of arm motion in front crawlswimming to kinematical analysis using an accelerometer

いちかわひろし, おおぎゆうじ, みやじちから, のむらたけお

The Engineering of Sport 4 （'Ujihashi, S. and Haake S. J. eds.,/Blackwell Publishing'）  4   644-650 2002年09月

研究論文（学術雑誌）, 共著

Microcomputer-based data logging device for accelerometry in swimming

おおぎゆうじ, いちかわひろし

The Engineering of Sport 4 （'Ujihashi, S. and Haake S. J. eds., Blackwell Publishing'）  4   637-643 2002年09月

研究論文（学術雑誌）, 共著

　概要を見る

' The authors developed a microcomputer-based data logging device to evaluate the swimming stroke motion. This newly developed device enabled observation of the tri-axial wrist accelerations in swimming over a one hour-period with no-restrictions. In this study, we looked at the change in wrist acceleration affected by swimmer's fatigue during intensive interval training. The direct linear transformation method was used for kinematical quantitative evaluation. A blood lactate test was used as a physical quantitative evaluation of the swimmer's fatigue. It was observed that swimmers' stroke motion changed with increased exhaustion. And these changes were also observed in acceleration patterns.'

'Microcomputer-based Acceleration Sensor Device for Sports Biomechanics,-Stroke Evaluation by using Swimmer's Wrist Acceleration-'

おおぎゆうじ

Proceedings of IEEE Sensors Conference 2002 （IEEE）  2002年06月

研究論文（学術雑誌）, 単著

　概要を見る

'Swimmer's propulsive force is maily produced by his arm strokes. Swimmers and coaches are very interested in underwater arm stroke motion. However, so far, in order to examine stroke motion, we had to prepare underwater cameras for the kinematical observation. Although we could prepare those facilities, it was very difficult for us to detect which stroke phase would be improved, or which underwater phase would be changed by their fatigue. The authors reported that the swimmer's wrist acceleration has several characteristics of their swimming styles. Some are common between subjects and the others are swimmer's own characteristics. In addition, swimmer's skill level is appeared their wrist acceleration. The authors developed microcomputer-based data logging device for swimming research. This newly developed device make us observe tri-axial swimmer's wrist acceleration in swimming over an hour with non-restricted. We applied it for the evaluation of swimming stroke motion. Especially, in this study, we focused on the change of the wrist acceleration by swimmer's fatigue during intensive interval training. We took three dimensional motion analysis for the kinematical quantitative evaluation and blood lactate test as a physical quantitative evaluation of the swimmer's fatigue. As a result, swimmers' stroke motion had changed under their exhaustion. And those change were also observed in acceleration patterns.'