著者

Ayane KUSAFUKA Naoki TSUKAMOTO Kohei MIYATA Kazutoshi KUDO

出版者

The Japan Society of Mechanical Engineers

雑誌

Mechanical Engineering Journal (ISSN:21879745)

巻号頁・発行日

pp.23-00220, (Released:2023-11-15)

参考文献数

22

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In human motion capture systems, reflective markers attached to the body have been widely used to track motion using optical cameras. However, when the speed of motion increases, because the brightness and angle of view of the camera are limited, and the markers often fall off, particularly of detailed body parts such as fingers in full-body movements, other parts of the body (palms) have been investigated. This study attempted to acquire finger movements during a high-speed throwing task without attaching markers using automatic image recognition technology based on deep learning (DeepLabCut) and verified its accuracy compared to conventional methods. As a result, the absolute distance between the 3D coordinates obtained from the two motion capture systems was an average of 15.5 to 29.4 mm depending on tracked points, and the correlation coefficients between them ranged from 0.932 to 0.999. Therefore, the shapes of the time-series profiles of the 3D coordinates obtained from the two motion- capture systems were similar. These results suggest that motion measurement using markerless motion capture is possible in environments where conventional motion capture systems are difficult to use.

著者

Hiroki Nakata Akito Miura Michiko Yoshie Takatoshi Higuchi Kazutoshi Kudo

出版者

The Japanese Society of Physical Fitness and Sports Medicine

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.3, no.4, pp.457-466, 2014-09-25 (Released:2014-10-02)

参考文献数

16

被引用文献数

4 4

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We investigated differences in trunk rotation patterns during baseball batting in eight skilled (collegiate level) players and nine unskilled novices using high-speed video cameras. The maximum angle during the backswing, angle at bat-ball impact, and angular displacement during the forward swing were analyzed for data on upper torso, pelvis, and torso-pelvis interaction (trunk twist) angles. We also noted movement variability in these angles over 10 trials, which was calculated as the standard deviation. The timing of the maximum angle during the backswing and variability was also analyzed. Statistical analysis revealed that angular displacements in the upper torso, pelvis, and torso-pelvis interaction were significantly larger in skilled players than in unskilled novices (p < 0.001, p < 0.001, and p < 0.05, respectively). The timing of the maximum pelvis angle during the backswing was significantly later in skilled players than in unskilled novices (p < 0.05). Movement variability in angular displacement during the forward swing and timing during the backswing were significantly greater in unskilled novices than skilled players. Although many previous studies reported the importance of angular velocity in trunk rotation during baseball batting, our results indicate that angular displacement and movement variability during trunk rotation are also key components for understanding the proficiency of skilled baseball players and unskilled novices.

著者

Noriaki Usui Motoki Okumura Kazutoshi Kudo

出版者

Japan Society of Physical Education, Health and Sport Sciences

雑誌

International Journal of Sport and Health Science (ISSN:13481509)

巻号頁・発行日

vol.16, pp.19-26, 2018 (Released:2018-07-24)

参考文献数

18

被引用文献数

2

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To succeed in many sports, players must not only adjust their movements during execution in response to environmental changes, but also switch to different movements altogether. Previous studies have implicated executive functions in movement switching ability. We aimed to clarify expertise differences in movement adjustment and switching, and compared performance on three tasks of target striking between expert and intermediate kendo players as participants. Task 1 was a simple strike, whereby participants struck targets at one position; Task 2 was an adjusted strike, whereby participants struck targets at three positions in a random order. Task 3 was strike-defense switching, whereby participants struck targets as in Task 2 while were also required to switch to defense when an opponent made a counter-strike. That is, the participants were required accurate strike in Task 1 and 2 close to the kendo practices, and were required accurate strike and defense in Task 3 close to the real matches. We found no differences in strike movement time and accuracy in any of the tasks between groups. However, expert players were able to execute successful strike-defense switching in Task 3, whereas intermediate players were not. These results suggest that an expertise difference exists in executive functions, and that it is essential for players to practice focused on acquisition of switching skills in order to further improve their performance.