Wyniki wyszukiwania - Biblioteka Nauki

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Wykonywanie nagrań za pomocą systemu akwizycji ruchu oraz urządzenia mobilnego z synchronizacją wyzwalania nagrań

100%

Walczyna K. , Jasiński B. , Smołka J. , Miziołek M.

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tom Vol. 10

5--11

PL

Głównym problemem podczas przeprowadzania badania z użyciem systemu motion capture wraz z urządzeniem mobilnym jest brak możliwości jednoczesnego startu nagrywania z systemu akwizycji ruchu, jak i z urządzenia przenośnego typu smartfon. Na potrzeby rozwiązania problemu zostały opracowane dwie metody synchronizacji nagrań. Pierwsza z nich to metoda rozpoczynająca nagrywanie po stronie urządzenia mobilnego, natomiast druga to metoda wychwytująca rozpoczęcie nagrywania w systemie akwizycji ruchu. Obie metody zostały porównane pod kątem opóźnień oraz korelacji zebranych danych pochodzących z urządzenia mobilnego oraz systemu Vicon Nexus.

EN

The main problem during research with a motion capture system and mobile device is lack of possibility to simultaneously begin recording on the motion capture system and a mobile device. Two methods were developed to solve this problem. In the first method the recording is started on the mobile phone and the motion capture system is notified, in the second method the motion capture system starts recording and notifies the mobile device. Both of them were compared for lags and correlation of data form the mobile device and the motion capture system.

2

Stereophotogrammetry measurement of kinematic target effect as speed accuracy benchmark indicator for kicking performance in martial arts

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Wąsik J. , Mosler D. , Ortenburger D. , Góra T.

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tom Vol. 23, no. 4

117--125

EN

Purpose: The development of a motion capture system leads to fast and accessible ways of precise testing of athletes and their motor abilities. The striking performance in martial arts and combat sports requires measuring velocity in the context of successful contact with the target. The aim of this study was to present the novel kinematic target effect coefficient and its possible use as a speed accuracy benchmark of performance based on the example of taekwon-do roundhouse and frontal kicks. Methods: The stereophotogrammetry motion capture setup consists of 10 infrared cameras (NIR Vicon MX-T40). Analysis includes 180 kicks (roundhouse and frontal kicks) performed by 15 adult participants on a master level in taekwon-do. The kinematic target effect comparison includes two targets – a training shield and a table tennis ball hanging from the ceiling. Markers were placed on the lower extremities of participants. Spatial-temporal variables were registered for both kicking legs, techniques, and target types. Results: Both roundhouse and frontal kicks revealed target and marker dependent differences during its execution. The kinematic target effect coefficient values differ for the specific marker and kick type. Conclusion: The wireless motion capture systems could be helpful in the training process and an athlete’s evaluation before sports competitions.

3

Application of artificial neural networks in fall prediction

84%

Walczak T. , Sopa M. , Pogorzała A. M.

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tom Vol. 32, nr 2

art. no. 2021210

EN

The problem of fall is still unsolved even though it is a serious problem, especially in group of elderly. Also, another difficulty is to analyse falls that occur in day-to-day life. Those events are hard to observe by specialists and so it is hard to analyse them. Following work contains a description of experimental process for external force-caused fall observation with the use of motion capture system and dynamometric platforms. Data collected according to this protocol were later used for time series neural networks. Obtained results of analysis were compared to popular model of human stability. Conducted inquiry proves that it is possible to detect fall even before it occurs and while it is external force-caused fall the loss of stability develops earlier than it was assumed.

4

Suryey on physically-based animation techniques

84%

Lebek K. , Stępień J.

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tom Vol. 32, nr 4A

43-55

EN

Physically-based animation, thanks to the growing computing power of currently used computer hardware, has a chance to become a leading trend in the computer-aided animation of virtual characters. While synthesized motion may offer lower quality than recorded with motion-capture techniąues, results are very promising.

PL

Animacja oparta ns symulacji fizycznej, dzięki rosnącej mocy obliczeniowej obecnie używanego sprzętu komputerowego, ma szansę zostać wiodącym trendem w komputerowo wspomaganej animacji postaci wirtualnych. Mimo niewiele gorszej jakości ruchu syntetyzowanego w stosunku do technik motion-capture wyniki są bardzo obiecujące.

5

Which of the five classical ballet positions is the most demanding for the dancer’s body? An electromyography-based study to determine muscular activity

67%

Gorwa J. , Kabaciński J. , Murawa M. , Fryzowicz A.

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tom Vol. 22, no. 4

3--14

EN

The study aimed to determine which of the five classical ballet positions is the most demanding regarding muscular activity, values of external rotation in the hip joints, angular values of foot progression as well as the inclination (tilt) of the pelvis in the sagittal plane. Methods: In this cross-sectional study, 14 female pre-professional ballet dancers (aged 11–16) participated. Participants were tasked with the sequential adoption of five classical ballet positions (CP1–CP5). The electromyographic activity of the muscles of the trunk and the lower limb was recorded with surface electrodes. Kinematic data including hip and knee external rotation, foot progression angle and pelvic tilt were collected using a motion capture system. Results: Symmetric positions CP1 and CP2 were not as demanding as asymmetric CP3–CP5. Higher values of hip and foot external rotation without greater muscular effort in CP2 than CP1 was noticed. Considering asymmetric positions, CP3 did not trigger a greater activity of hip or foot muscular groups than CP4 and CP5. CP4 was characterised by the greatest pelvic anterior tilt and the lowest activity of GM in the forward lower limb. In CP5, forward lower limb entailed a higher activity of muscles supporting the foot than in the remaining positions. Conclusion: In terms of biomechanics, the most demanding classical ballet position in pre-professional dancers is CP4, followed by CP5, CP3, CP1 and CP2. This finding can be applied in educational methodology of dancers, figure skaters, synchronized swimmers, acrobatic gymnasts, rhythmic gymnasts or cheerleaders.

6

On the feasible regions delimiting natural human postures in a novel skeletal representation

67%

Hengeveld S. B. , Mucherino A.

Annals of Computer Science and Information Systems

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2022

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tom Vol. 30

175--179

EN

The de facto standard for storing human motion data on a computer involves a representation based on Euler angles. This representation, while effective, has several short- comings. Triplets of Euler angles are not unique, and the same posture may be expressed using different combinations of angles. Furthermore, many possible Euler angle triplets correspond to unnatural positions for human joints. This means that, in general, a large part of the representational space remains unused. In this paper, we investigate a recently proposed representation inspired by molecular representations. It uses only two (instead of three) degrees of freedom per joint: a vector and a torsion angle. Using the two key ingredients of this new representation, we present a complete analysis of the Graphics Lab Motion Capture Database. The data found in this analysis provide us with some powerful insights about natural and unnatural human postures in human motions. These insights can potentially lead to possible constraints on human motions which may be used to more effectively solve open problems in the computer graphics community, most notably the problem of (human) motion adaptation.