2018
Théo Perrin; Hugo Kerhervé; Charles Faure; Giammaria Cattozzo; Benoit Bideau; Richard Kulpa
Evaluation of perceived speed error during walking and running in a virtual environment Conference
European College of Sport Science, 2018.
@conference{Perrin2018,
title = {Evaluation of perceived speed error during walking and running in a virtual environment},
author = {Théo Perrin and Hugo Kerhervé and Charles Faure and Giammaria Cattozzo and Benoit Bideau and Richard Kulpa},
year = {2018},
date = {2018-01-01},
booktitle = {European College of Sport Science},
abstract = {Introduction
The development of new virtual reality (VR) devices such as Head Mounted Displays (HMD) increases opportunities for applications at the confluence of physical activity and gaming. Recently, the fields of sport and fitness have turned to VR including locomotor activities, to enhance motivation and exercise adherence. However, the relevance of such tools depend on the ability of these systems to provide realistic immersive feelings, specifically depending on depth and speed perception. The objective of this study is to estimate the error between actual and perceived locomotor speed in environment (VE).
Methods
Eleven healthy people (4 female, 7 male) with normal vision or a correction device participated in the experiment. The experiment consisted in walking and running on a motorized treadmill (h/p/Cosmos) from 3 km/h to 11 km/h with 0.5 km/h increments in a randomized order, while wearing a HMD (HTC Vive) displaying a virtual racetrack surrounded by columns placed at regular intervals. Participants were instructed to match VE with what they perceived was their actual locomotion speed (LS), using a handheld Vive controller (modifying optic flow). For each trial, we collected the speed of optic flow (OFS) adjusted by participant in 0.02 km/h increment. In order to control the effect of chance we removed best and worst trials for each participant. Correlation coefficients (r), bias, smallest detectable difference (SDD) and typical error of the estimate (TE) were calculated in the standard manner.
Results There was likely no learning effect as observation rank and error were not correlated (r=0.12). OFS slightly underestimated LS (bias: -0.04±0.24) but the two were highly correlated (r=0.82; y=0.90x+0.68) and TE (1.6±1.1 km/h) was likely not greater than SDD (0.6±1.1 km/h).
Discussion
The main result of our study was that participants were able to match OFS to actual LS. Unlike previous literature from the early 2000 using previous generation of HMD, we found that OFS was not perceived to be slower or faster, despite the relatively large standard deviation in TE. A secondary finding was that OFS estimation was not affected by locomotion speed. Therefore, modern HMD can be used to create immersive feelings of self-motion during active exercise, and further to generate new consumer experiences of training.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Introduction
The development of new virtual reality (VR) devices such as Head Mounted Displays (HMD) increases opportunities for applications at the confluence of physical activity and gaming. Recently, the fields of sport and fitness have turned to VR including locomotor activities, to enhance motivation and exercise adherence. However, the relevance of such tools depend on the ability of these systems to provide realistic immersive feelings, specifically depending on depth and speed perception. The objective of this study is to estimate the error between actual and perceived locomotor speed in environment (VE).
Methods
Eleven healthy people (4 female, 7 male) with normal vision or a correction device participated in the experiment. The experiment consisted in walking and running on a motorized treadmill (h/p/Cosmos) from 3 km/h to 11 km/h with 0.5 km/h increments in a randomized order, while wearing a HMD (HTC Vive) displaying a virtual racetrack surrounded by columns placed at regular intervals. Participants were instructed to match VE with what they perceived was their actual locomotion speed (LS), using a handheld Vive controller (modifying optic flow). For each trial, we collected the speed of optic flow (OFS) adjusted by participant in 0.02 km/h increment. In order to control the effect of chance we removed best and worst trials for each participant. Correlation coefficients (r), bias, smallest detectable difference (SDD) and typical error of the estimate (TE) were calculated in the standard manner.
Results There was likely no learning effect as observation rank and error were not correlated (r=0.12). OFS slightly underestimated LS (bias: -0.04±0.24) but the two were highly correlated (r=0.82; y=0.90x+0.68) and TE (1.6±1.1 km/h) was likely not greater than SDD (0.6±1.1 km/h).
Discussion
The main result of our study was that participants were able to match OFS to actual LS. Unlike previous literature from the early 2000 using previous generation of HMD, we found that OFS was not perceived to be slower or faster, despite the relatively large standard deviation in TE. A secondary finding was that OFS estimation was not affected by locomotion speed. Therefore, modern HMD can be used to create immersive feelings of self-motion during active exercise, and further to generate new consumer experiences of training.
The development of new virtual reality (VR) devices such as Head Mounted Displays (HMD) increases opportunities for applications at the confluence of physical activity and gaming. Recently, the fields of sport and fitness have turned to VR including locomotor activities, to enhance motivation and exercise adherence. However, the relevance of such tools depend on the ability of these systems to provide realistic immersive feelings, specifically depending on depth and speed perception. The objective of this study is to estimate the error between actual and perceived locomotor speed in environment (VE).
Methods
Eleven healthy people (4 female, 7 male) with normal vision or a correction device participated in the experiment. The experiment consisted in walking and running on a motorized treadmill (h/p/Cosmos) from 3 km/h to 11 km/h with 0.5 km/h increments in a randomized order, while wearing a HMD (HTC Vive) displaying a virtual racetrack surrounded by columns placed at regular intervals. Participants were instructed to match VE with what they perceived was their actual locomotion speed (LS), using a handheld Vive controller (modifying optic flow). For each trial, we collected the speed of optic flow (OFS) adjusted by participant in 0.02 km/h increment. In order to control the effect of chance we removed best and worst trials for each participant. Correlation coefficients (r), bias, smallest detectable difference (SDD) and typical error of the estimate (TE) were calculated in the standard manner.
Results There was likely no learning effect as observation rank and error were not correlated (r=0.12). OFS slightly underestimated LS (bias: -0.04±0.24) but the two were highly correlated (r=0.82; y=0.90x+0.68) and TE (1.6±1.1 km/h) was likely not greater than SDD (0.6±1.1 km/h).
Discussion
The main result of our study was that participants were able to match OFS to actual LS. Unlike previous literature from the early 2000 using previous generation of HMD, we found that OFS was not perceived to be slower or faster, despite the relatively large standard deviation in TE. A secondary finding was that OFS estimation was not affected by locomotion speed. Therefore, modern HMD can be used to create immersive feelings of self-motion during active exercise, and further to generate new consumer experiences of training.
Said Yacine Boulahia; Eric Anquetil; Franck Multon; Richard Kulpa
CuDi3D: Curvilinear displacement based approach for online 3D action detection Journal Article
In: Computer Vision and Image Understanding, vol. in press, 2018.
Abstract | Links/Paper | BibTeX
@article{Boulahia2018,
title = {CuDi3D: Curvilinear displacement based approach for online 3D action detection},
author = {Said Yacine Boulahia and Eric Anquetil and Franck Multon and Richard Kulpa},
doi = {https://doi.org/10.1016/j.cviu.2018.07.003},
year = {2018},
date = {2018-01-01},
journal = {Computer Vision and Image Understanding},
volume = {in press},
abstract = {Being able to interactively detect and recognize 3D actions based on skeleton data, in unsegmented streams, has become an important computer vision topic. It raises three scientific problems in relation with variability. The first one is the temporal variability that occurs when subjects perform gestures with different speeds. The second one is the inter-class spatial variability, which refers to disparities between the displacement amounts induced by different classes (i.e. long vs. short movements). The last one is the intra-class spatial variability caused by differences in style and gesture amplitude. In this paper, we design an original approach that better considers these three issues. To address temporal variability we introduce the notion of curvilinear segmentation. It consists in extracting features, not on temporally-based sliding windows, but on trajectory segments for which the cumulated displacement equals a class-based amount. Second, to tackle inter-class spatial variability, we define several competing classifiers with their dedicated curvilinear windows. Last, we address intra-class spatial variability by designing a fusion system that takes the decisions and confidence scores of every competing classifier into account. Extensive experiments on four challenging skeleton-based datasets demonstrate the relevance of the proposed approach for action recognition and online action detection.},
keywords = {},
pubstate = {published},
tppubtype = {article}
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Being able to interactively detect and recognize 3D actions based on skeleton data, in unsegmented streams, has become an important computer vision topic. It raises three scientific problems in relation with variability. The first one is the temporal variability that occurs when subjects perform gestures with different speeds. The second one is the inter-class spatial variability, which refers to disparities between the displacement amounts induced by different classes (i.e. long vs. short movements). The last one is the intra-class spatial variability caused by differences in style and gesture amplitude. In this paper, we design an original approach that better considers these three issues. To address temporal variability we introduce the notion of curvilinear segmentation. It consists in extracting features, not on temporally-based sliding windows, but on trajectory segments for which the cumulated displacement equals a class-based amount. Second, to tackle inter-class spatial variability, we define several competing classifiers with their dedicated curvilinear windows. Last, we address intra-class spatial variability by designing a fusion system that takes the decisions and confidence scores of every competing classifier into account. Extensive experiments on four challenging skeleton-based datasets demonstrate the relevance of the proposed approach for action recognition and online action detection.
Sean Lynch; Julien Pettré; Julien Bruneau; Richard Kulpa; Armel Crétual; Anne-Hélène Olivier
Effect of Virtual Human Gaze Behaviour During an Orthogonal Collision Avoidance Walking Task Conference
IEEE VR, 2018.
Abstract | Links/Paper | BibTeX
@conference{Lynch2018,
title = {Effect of Virtual Human Gaze Behaviour During an Orthogonal Collision Avoidance Walking Task},
author = {Sean Lynch and Julien Pettré and Julien Bruneau and Richard Kulpa and Armel Crétual and Anne-Hélène Olivier},
doi = {10.1109/VR.2018.8446180},
year = {2018},
date = {2018-01-01},
booktitle = {IEEE VR},
abstract = {This paper presents a study performed in virtual reality on the effect of gaze interception during collision avoidance between two walkers. In such a situation, mutual gaze can be considered as a form of nonverbal communication. Additionally, gaze is believed to detail future path intentions and to be part of the nonverbal negotiation to achieve avoidance collaboratively. We considered an avoidance task between a real subject and a virtual human character and studied the influence of the character's gaze direction on the avoidance behaviour of the participant. Virtual reality provided an accurate control of the situation: seventeen participants were immersed in a virtual environment, instructed to navigate across a virtual space using a joystick and to avoid a virtual character that would appear from either side. The character would either gaze or not towards the participant. Further, the character would either perform or not a reciprocal adaptation of its trajectory to avoid a potential collision with the participant. The findings of this paper were that during an orthogonal collision avoidance task, gaze behaviour did not influence the collision avoidance behaviour of the participants. Further, the addition of reciprocal collision avoidance with gaze did not modify the collision behaviour of participants. These results suggest that for the duration of interaction in such a task, body motion cues were sufficient for coordination and regulation. We discuss the possible exploitation of these results to improve the design of virtual characters for populated virtual environments and user interaction.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
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This paper presents a study performed in virtual reality on the effect of gaze interception during collision avoidance between two walkers. In such a situation, mutual gaze can be considered as a form of nonverbal communication. Additionally, gaze is believed to detail future path intentions and to be part of the nonverbal negotiation to achieve avoidance collaboratively. We considered an avoidance task between a real subject and a virtual human character and studied the influence of the character's gaze direction on the avoidance behaviour of the participant. Virtual reality provided an accurate control of the situation: seventeen participants were immersed in a virtual environment, instructed to navigate across a virtual space using a joystick and to avoid a virtual character that would appear from either side. The character would either gaze or not towards the participant. Further, the character would either perform or not a reciprocal adaptation of its trajectory to avoid a potential collision with the participant. The findings of this paper were that during an orthogonal collision avoidance task, gaze behaviour did not influence the collision avoidance behaviour of the participants. Further, the addition of reciprocal collision avoidance with gaze did not modify the collision behaviour of participants. These results suggest that for the duration of interaction in such a task, body motion cues were sufficient for coordination and regulation. We discuss the possible exploitation of these results to improve the design of virtual characters for populated virtual environments and user interaction.
Anne-Hélène Olivier; Julien Bruneau; Richard Kulpa; Julien Pettré
Walking with virtual people: Evaluation of locomotion interfaces in dynamic environments Journal Article
In: IEEE Transactions on Visualization and Computer Graphics, vol. 24, no. 7, pp. 2251-2263, 2018, ISSN: 1077-2626.
Abstract | Links/Paper | BibTeX
@article{Olivier2018,
title = {Walking with virtual people: Evaluation of locomotion interfaces in dynamic environments},
author = {Anne-Hélène Olivier and Julien Bruneau and Richard Kulpa and Julien Pettré},
doi = {10.1109/TVCG.2017.2714665},
issn = {1077-2626},
year = {2018},
date = {2018-01-01},
journal = {IEEE Transactions on Visualization and Computer Graphics},
volume = {24},
number = {7},
pages = {2251-2263},
abstract = {Navigating in virtual environments requires using some locomotion interfaces, especially when the dimensions of the environments exceed the ones of the Virtual Reality system. Locomotion interfaces induce some biases both in the perception of the self-motion or in the formation of virtual locomotion trajectories. These biases have been mostly evaluated in the context of static environments, and studies need to be revisited in the new context of populated environments where users interact with virtual characters. We focus on situations of collision avoidance between a real participant and a virtual character, and compared it to previous studies on real walkers. Our results show that, as in reality, the risk of future collision is accurately anticipated by participants, however with delay. We also show that collision avoidance trajectories formed in VR have common properties with real ones, with some quantitative differences in avoidance distances. More generally, our evaluation demonstrates that reliable results can be obtained for qualitative analysis of small scale interactions in VR. We discuss these results in the perspective of a VR platform for large scale interaction applications, such as in a crowd, for which real data are difficult to gather.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Navigating in virtual environments requires using some locomotion interfaces, especially when the dimensions of the environments exceed the ones of the Virtual Reality system. Locomotion interfaces induce some biases both in the perception of the self-motion or in the formation of virtual locomotion trajectories. These biases have been mostly evaluated in the context of static environments, and studies need to be revisited in the new context of populated environments where users interact with virtual characters. We focus on situations of collision avoidance between a real participant and a virtual character, and compared it to previous studies on real walkers. Our results show that, as in reality, the risk of future collision is accurately anticipated by participants, however with delay. We also show that collision avoidance trajectories formed in VR have common properties with real ones, with some quantitative differences in avoidance distances. More generally, our evaluation demonstrates that reliable results can be obtained for qualitative analysis of small scale interactions in VR. We discuss these results in the perspective of a VR platform for large scale interaction applications, such as in a crowd, for which real data are difficult to gather.
Said Yacine Boulahia; Eric Anquetil; Franck Multon; Richard Kulpa
Détection précoce dáctions squelettiques 3D dans un flot non segmenté à base de modèles curvilignes Conference
Reconnaissance des Formes, Image, Apprentissage et Perception RFIAP, 2018.
Abstract | Links/Paper | BibTeX
@conference{Boulahia2018b,
title = {Détection précoce dáctions squelettiques 3D dans un flot non segmenté à base de modèles curvilignes},
author = {Said Yacine Boulahia and Eric Anquetil and Franck Multon and Richard Kulpa},
url = {https://hal.archives-ouvertes.fr/hal-01867937},
doi = {10.1109/FG.2017.63},
year = {2018},
date = {2018-01-01},
booktitle = {Reconnaissance des Formes, Image, Apprentissage et Perception RFIAP},
pages = {1-8},
abstract = {Exergames involve using the fullbody to interact with an immersive world, which raises the challenge of capturing, processing and recognizing the action of the user even for cheap mocap systems such as the Microsoft Kinect. In fact, these recent technological advances have renewedinterest in skeleton-based action recognition. Our review of related literature reveals that the issues encountered are not the result of random processes, which could simply be studied by using statistical tools, but are instead due to the fact that the pattern to be recognized, i.e. an action, was produced by a human being. 2D hand-drawn symbols are further examples of patterns resulting from a human motion. Therefore, the main contribution of this paper is to examine the validity of transferring the expertise of hand-drawn symbol representation to better recognize actions based on skeleton data. Principally, we propose a new action representation, namely the 3DMM, as an initial case-study illustrating how such transfer could be conducted. The experimental results, obtained over two benchmarks, confirm the soundness of our approach and encourage more thorough examination of the transfer.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Exergames involve using the fullbody to interact with an immersive world, which raises the challenge of capturing, processing and recognizing the action of the user even for cheap mocap systems such as the Microsoft Kinect. In fact, these recent technological advances have renewedinterest in skeleton-based action recognition. Our review of related literature reveals that the issues encountered are not the result of random processes, which could simply be studied by using statistical tools, but are instead due to the fact that the pattern to be recognized, i.e. an action, was produced by a human being. 2D hand-drawn symbols are further examples of patterns resulting from a human motion. Therefore, the main contribution of this paper is to examine the validity of transferring the expertise of hand-drawn symbol representation to better recognize actions based on skeleton data. Principally, we propose a new action representation, namely the 3DMM, as an initial case-study illustrating how such transfer could be conducted. The experimental results, obtained over two benchmarks, confirm the soundness of our approach and encourage more thorough examination of the transfer.
Théo Perrin; Charles Faure; Kevin Nay; Giammaria Cattozzo; Anthony Sorel; Hugo Kerhervé; Benoit Bideau; Richard Kulpa
Physiological load during an active virtual reality game Proceedings Article
In: European College of Sport Science, 2018.
@inproceedings{perrin_physiological_2018,
title = {Physiological load during an active virtual reality game},
author = {Théo Perrin and Charles Faure and Kevin Nay and Giammaria Cattozzo and Anthony Sorel and Hugo Kerhervé and Benoit Bideau and Richard Kulpa},
year = {2018},
date = {2018-01-01},
booktitle = {European College of Sport Science},
abstract = {Introduction Strategies to curb the development of pathologies associated with sedentary lifestyles are usually geared toward limiting sitting time and screen use, and increasing energy expenditure (EE) through exercise. Since the early 2000’s, active games (AG) have been developed where players use upper limb or whole body motion to interact with a virtual gaming environment. AG have been documented to elicit greater oxygen consumption (VO2, +2-10 mL·min-1·kg-1) and EE (+150-250 kJ·min-1) than seated games ( 5-10 mL·min-1·kg-1 and 150 kJ·min-1, respectively). The aim of this study was to evaluate the physiological load of an AG in a portable Virtual Reality (VR) system with stereoscopic vision and head tracking, as these provide greater immersive feeling than 2D screens and might lead to greater physical engagement. Methods Nine healthy males (28±6 yr, 182±5 cm, 86±8 kg) took part in this study. After a habituation phase, participants completed three tests in a randomized order: a submaximal walking test on a treadmill at 6 km·h-1 (W6), one bout of active gaming at body weight (AGBW), and one bout of active gaming with weights amounting to approximately 2.5% of body weight worn on wrists (AGW%). The active game was a free-to-play, upper-body oriented virtual bow and arrow shooting game pre-installed with the VR system (HTC Vive). We measured VO2 and heart rate (HR) and the number of shooting actions continuously, and subsequently calculated energy expenditure based on energy equivalents for oxygen in the standard manner. Effect sizes (ES) for pairwise comparisons were calculated using Cohen’s d. Results All variables were measured when participants reached a similar level of difficulty in the game (3rd wave of opponents, lasting 15 min). VO2 in AGW% (20.6±4.5 mL·min-1·kg-1) was 22±7% and 21±19% greater than AGBW and W6, respectively. EE in AGW% (657±174 kJ·min-1) was 27±10% and 48±18% greater than AGBW and W6, respectively. Average HR in AGW% (116±7 bpm) was 16±6% greater than both AGBW and W6. The total number of shooting actions was lower in AGB% (361±81) than AGBW (-10±18%). Large ES were calculated for AGB%/AGBW and AGB%/W6 comparisons, and trivial to small ES for AGBW/W6 comparisons except for EE (large). Discussion We observed consistently higher physiological load (VO2, EE, HR) in AGW% compared to AGBW and W6, and EE was also higher in AGBW than in W6. Despite marked differences in EE, similar average HR were measured in AGBW and W6, indicating HR may not provide suitable indicators of EE during AG, which may explain some of the differences in EE we measured in this study compared to the literature. Therefore, the development of whole-body AG in VR with and without extraneous weights provides an exciting avenue to increase EE during leisure or indoor activities, and may pave the way to accompany the development of e-sports and health applications.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
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Introduction Strategies to curb the development of pathologies associated with sedentary lifestyles are usually geared toward limiting sitting time and screen use, and increasing energy expenditure (EE) through exercise. Since the early 2000’s, active games (AG) have been developed where players use upper limb or whole body motion to interact with a virtual gaming environment. AG have been documented to elicit greater oxygen consumption (VO2, +2-10 mL·min-1·kg-1) and EE (+150-250 kJ·min-1) than seated games ( 5-10 mL·min-1·kg-1 and 150 kJ·min-1, respectively). The aim of this study was to evaluate the physiological load of an AG in a portable Virtual Reality (VR) system with stereoscopic vision and head tracking, as these provide greater immersive feeling than 2D screens and might lead to greater physical engagement. Methods Nine healthy males (28±6 yr, 182±5 cm, 86±8 kg) took part in this study. After a habituation phase, participants completed three tests in a randomized order: a submaximal walking test on a treadmill at 6 km·h-1 (W6), one bout of active gaming at body weight (AGBW), and one bout of active gaming with weights amounting to approximately 2.5% of body weight worn on wrists (AGW%). The active game was a free-to-play, upper-body oriented virtual bow and arrow shooting game pre-installed with the VR system (HTC Vive). We measured VO2 and heart rate (HR) and the number of shooting actions continuously, and subsequently calculated energy expenditure based on energy equivalents for oxygen in the standard manner. Effect sizes (ES) for pairwise comparisons were calculated using Cohen’s d. Results All variables were measured when participants reached a similar level of difficulty in the game (3rd wave of opponents, lasting 15 min). VO2 in AGW% (20.6±4.5 mL·min-1·kg-1) was 22±7% and 21±19% greater than AGBW and W6, respectively. EE in AGW% (657±174 kJ·min-1) was 27±10% and 48±18% greater than AGBW and W6, respectively. Average HR in AGW% (116±7 bpm) was 16±6% greater than both AGBW and W6. The total number of shooting actions was lower in AGB% (361±81) than AGBW (-10±18%). Large ES were calculated for AGB%/AGBW and AGB%/W6 comparisons, and trivial to small ES for AGBW/W6 comparisons except for EE (large). Discussion We observed consistently higher physiological load (VO2, EE, HR) in AGW% compared to AGBW and W6, and EE was also higher in AGBW than in W6. Despite marked differences in EE, similar average HR were measured in AGBW and W6, indicating HR may not provide suitable indicators of EE during AG, which may explain some of the differences in EE we measured in this study compared to the literature. Therefore, the development of whole-body AG in VR with and without extraneous weights provides an exciting avenue to increase EE during leisure or indoor activities, and may pave the way to accompany the development of e-sports and health applications.
Marion Morel; Catherine Achard; Richard Kulpa; Séverine Dubuisson
Time-series averaging using constrained dynamic time warping with tolerance Journal Article
In: Pattern Recognition, vol. 74, pp. 77–89, 2018, ISSN: 0031-3203.
Abstract | Links/Paper | BibTeX
@article{morel2018,
title = {Time-series averaging using constrained dynamic time warping with tolerance},
author = {Marion Morel and Catherine Achard and Richard Kulpa and Séverine Dubuisson},
url = {http://www.sciencedirect.com/science/article/pii/S003132031730328X},
doi = {10.1016/j.patcog.2017.08.015},
issn = {0031-3203},
year = {2018},
date = {2018-01-01},
urldate = {2020-02-17},
journal = {Pattern Recognition},
volume = {74},
pages = {77--89},
abstract = {In this paper, we propose an innovative averaging of a set of time-series based on the Dynamic Time Warping (DTW). The DTW is widely used in data mining since it provides not only a similarity measure, but also a temporal alignment of time-series. However, its use is often restricted to the case of a pair of signals. In this paper, we propose to extend its application to a set of signals by providing an average time-series that opens a wide range of applications in data mining process. Starting with an existing well-established method called DBA (for DTW Barycenter Averaging), this paper points out its limitations and suggests an alternative based on a Constrained Dynamic Time Warping. Secondly, an innovative tolerance is added to take into account the admissible variability around the average signal. This new modeling of time-series is evaluated on a classification task applied on several datasets and results show that it outperforms state of the art methods.},
keywords = {},
pubstate = {published},
tppubtype = {article}
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In this paper, we propose an innovative averaging of a set of time-series based on the Dynamic Time Warping (DTW). The DTW is widely used in data mining since it provides not only a similarity measure, but also a temporal alignment of time-series. However, its use is often restricted to the case of a pair of signals. In this paper, we propose to extend its application to a set of signals by providing an average time-series that opens a wide range of applications in data mining process. Starting with an existing well-established method called DBA (for DTW Barycenter Averaging), this paper points out its limitations and suggests an alternative based on a Constrained Dynamic Time Warping. Secondly, an innovative tolerance is added to take into account the admissible variability around the average signal. This new modeling of time-series is evaluated on a classification task applied on several datasets and results show that it outperforms state of the art methods.
Sean Dean Lynch; Richard Kulpa; Laurentius Antonius Meerhoff; Julien Pettré; Armel Crétual; Anne-Hélène Olivier
Collision Avoidance Behavior between Walkers: Global and Local Motion Cues Journal Article
In: IEEE Transactions on Visualization and Computer Graphics, vol. 24, no. 7, pp. 2078–2088, 2018, ISSN: 2160-9306.
Abstract | Links/Paper | BibTeX
@article{lynch2018b,
title = {Collision Avoidance Behavior between Walkers: Global and Local Motion Cues},
author = {Sean Dean Lynch and Richard Kulpa and Laurentius Antonius Meerhoff and Julien Pettré and Armel Crétual and Anne-Hélène Olivier},
doi = {10.1109/TVCG.2017.2718514},
issn = {2160-9306},
year = {2018},
date = {2018-01-01},
journal = {IEEE Transactions on Visualization and Computer Graphics},
volume = {24},
number = {7},
pages = {2078--2088},
abstract = {Daily activities require agents to interact with each other, such as during collision avoidance. The nature of visual information that is used for a collision free interaction requires further understanding. We aim to manipulate the nature of visual information in two forms, global and local information appearances. Sixteen healthy participants navigated towards a target in an immersive computer-assisted virtual environment (CAVE) using a joystick. A moving passive obstacle crossed the participant's trajectory perpendicularly at various pre-defined risks of collision distances. The obstacle was presented with one of five virtual appearances, associated to global motion cues (i.e., a cylinder or a sphere), or local motion cues (i.e., only the legs or the trunk). A full body virtual walker, showing both local and global motion cues, used as a reference condition. The final crossing distance was affected by the global motion appearances, however, appearance had no qualitative effect on motion adaptations. These findings contribute towards further understanding what information people use when interacting with others.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Daily activities require agents to interact with each other, such as during collision avoidance. The nature of visual information that is used for a collision free interaction requires further understanding. We aim to manipulate the nature of visual information in two forms, global and local information appearances. Sixteen healthy participants navigated towards a target in an immersive computer-assisted virtual environment (CAVE) using a joystick. A moving passive obstacle crossed the participant's trajectory perpendicularly at various pre-defined risks of collision distances. The obstacle was presented with one of five virtual appearances, associated to global motion cues (i.e., a cylinder or a sphere), or local motion cues (i.e., only the legs or the trunk). A full body virtual walker, showing both local and global motion cues, used as a reference condition. The final crossing distance was affected by the global motion appearances, however, appearance had no qualitative effect on motion adaptations. These findings contribute towards further understanding what information people use when interacting with others.
2017
Pierre Touzard; Richard Kulpa; Benoit Bideau; Caroline Martin
Biomechanical analysis of tennis serve in young elite players: effect of the "waiter's serve" on upper limb loads Conference
Proceedings of European College of Sport Science, 2017.
@conference{Touzard2017,
title = {Biomechanical analysis of tennis serve in young elite players: effect of the "waiter's serve" on upper limb loads},
author = {Pierre Touzard and Richard Kulpa and Benoit Bideau and Caroline Martin},
year = {2017},
date = {2017-01-01},
booktitle = {Proceedings of European College of Sport Science},
abstract = {Introduction
Serve is described as the most important stroke (Johnson et al., 2006) but also the most traumatic stroke in adult elite tennis players. Joint loads must be minimized to avoid upper limb overuse injuries. A better knowledge of technical aspects of serve is essential for players and coaches. A poor serve technique increased joint loads in adult elite players and can be considered as an injury risk factor (Elliott et al., 2003; Martin et al., 2013). A particular attention must be paid to young elite players, as their bodies are developing and their serve technique is evolving. Young athletes must develop the best serve technique for limiting joint loads, avoiding overuse injuries and finally do not break a potential high-level career. The aim of this study was to analyze the effect of one technical point, the "waiter's serve position", on upper limb joint loads in young elite players.
Methods 18 young elite males (Top 10 national French ranking, age: 13.4 ± 0.8 years; height: 1.72 ± 0.08 m; weight: 59.1 ± 7.5 kg) performed 5 successful flat serves at maximum speed. Two groups were formed by experimented tennis coaches: G1 (n=10) in which players served with the « waiter's position » (racket face parallel to the ground during cocking) and G2 (n=8) in which players did not. A 16-camera Vicon MX system (200 Hz) was used for serve motion capture. Maximal upper limb joint loads were calculated with dynamic inverse method.
Results Ball speed was not different between the two groups (G1: 162.2 ± 8.9 km/h vs. G2: 164.1 ± 11.9 km/h). Shoulder internal rotation torque (G1: 0.57 ± 0.05 Nm/kg/m vs. G2: 0.51 ± 0.04 Nm/kg/m) (p=0.02), elbow varus torque (G1: 0.59 ± 0.05 Nm/kg/m vs. G2: 0.52 ± 0.01 Nm/kg/m) (p=0.003) and wrist anterior force (G1: 3.0 ± 0.2 N/kg vs. G2: 2.7 ± 0.4 N/kg) (p=0.02) were significantly higher in G1.
Discussion
In both groups, high joint loads were found. This confirms that the serve could be a traumatic stroke for upper limb joints (Dillman et al., 1995) not only in adults but also in young elite players. Moreover, the « waiter's position » induced higher upper limb joint loads, with no incidence on ball speed. Consequently, the « waiter's position » can be considered as a pathomechanical factor in young elite players, and could lead to upper limb joint injuries.
References
Dillman C, Schultheis J, Hintermeister R, Hawkins R. (1995). Tennis: Sports Medicine and Science, 6–11.
Elliott B, Fleisig G, Nicholls R, Escamilia R. (2003). J Sci Med Sport, 6(1), 76–87.
Johnson C, McHugh M, Wood T, Kibler B. (2006). Br J Sports Med, 40(8), 696–699.
Martin C, Kulpa R, Ropars M, Delamarche P. Bideau B. (2013). Med Sci Sports Exerc, 45(11), 2113-2119.
Contact pierre.touzard@hotmail.com},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Introduction
Serve is described as the most important stroke (Johnson et al., 2006) but also the most traumatic stroke in adult elite tennis players. Joint loads must be minimized to avoid upper limb overuse injuries. A better knowledge of technical aspects of serve is essential for players and coaches. A poor serve technique increased joint loads in adult elite players and can be considered as an injury risk factor (Elliott et al., 2003; Martin et al., 2013). A particular attention must be paid to young elite players, as their bodies are developing and their serve technique is evolving. Young athletes must develop the best serve technique for limiting joint loads, avoiding overuse injuries and finally do not break a potential high-level career. The aim of this study was to analyze the effect of one technical point, the "waiter's serve position", on upper limb joint loads in young elite players.
Methods 18 young elite males (Top 10 national French ranking, age: 13.4 ± 0.8 years; height: 1.72 ± 0.08 m; weight: 59.1 ± 7.5 kg) performed 5 successful flat serves at maximum speed. Two groups were formed by experimented tennis coaches: G1 (n=10) in which players served with the « waiter's position » (racket face parallel to the ground during cocking) and G2 (n=8) in which players did not. A 16-camera Vicon MX system (200 Hz) was used for serve motion capture. Maximal upper limb joint loads were calculated with dynamic inverse method.
Results Ball speed was not different between the two groups (G1: 162.2 ± 8.9 km/h vs. G2: 164.1 ± 11.9 km/h). Shoulder internal rotation torque (G1: 0.57 ± 0.05 Nm/kg/m vs. G2: 0.51 ± 0.04 Nm/kg/m) (p=0.02), elbow varus torque (G1: 0.59 ± 0.05 Nm/kg/m vs. G2: 0.52 ± 0.01 Nm/kg/m) (p=0.003) and wrist anterior force (G1: 3.0 ± 0.2 N/kg vs. G2: 2.7 ± 0.4 N/kg) (p=0.02) were significantly higher in G1.
Discussion
In both groups, high joint loads were found. This confirms that the serve could be a traumatic stroke for upper limb joints (Dillman et al., 1995) not only in adults but also in young elite players. Moreover, the « waiter's position » induced higher upper limb joint loads, with no incidence on ball speed. Consequently, the « waiter's position » can be considered as a pathomechanical factor in young elite players, and could lead to upper limb joint injuries.
References
Dillman C, Schultheis J, Hintermeister R, Hawkins R. (1995). Tennis: Sports Medicine and Science, 6–11.
Elliott B, Fleisig G, Nicholls R, Escamilia R. (2003). J Sci Med Sport, 6(1), 76–87.
Johnson C, McHugh M, Wood T, Kibler B. (2006). Br J Sports Med, 40(8), 696–699.
Martin C, Kulpa R, Ropars M, Delamarche P. Bideau B. (2013). Med Sci Sports Exerc, 45(11), 2113-2119.
Contact pierre.touzard@hotmail.com
Serve is described as the most important stroke (Johnson et al., 2006) but also the most traumatic stroke in adult elite tennis players. Joint loads must be minimized to avoid upper limb overuse injuries. A better knowledge of technical aspects of serve is essential for players and coaches. A poor serve technique increased joint loads in adult elite players and can be considered as an injury risk factor (Elliott et al., 2003; Martin et al., 2013). A particular attention must be paid to young elite players, as their bodies are developing and their serve technique is evolving. Young athletes must develop the best serve technique for limiting joint loads, avoiding overuse injuries and finally do not break a potential high-level career. The aim of this study was to analyze the effect of one technical point, the "waiter's serve position", on upper limb joint loads in young elite players.
Methods 18 young elite males (Top 10 national French ranking, age: 13.4 ± 0.8 years; height: 1.72 ± 0.08 m; weight: 59.1 ± 7.5 kg) performed 5 successful flat serves at maximum speed. Two groups were formed by experimented tennis coaches: G1 (n=10) in which players served with the « waiter's position » (racket face parallel to the ground during cocking) and G2 (n=8) in which players did not. A 16-camera Vicon MX system (200 Hz) was used for serve motion capture. Maximal upper limb joint loads were calculated with dynamic inverse method.
Results Ball speed was not different between the two groups (G1: 162.2 ± 8.9 km/h vs. G2: 164.1 ± 11.9 km/h). Shoulder internal rotation torque (G1: 0.57 ± 0.05 Nm/kg/m vs. G2: 0.51 ± 0.04 Nm/kg/m) (p=0.02), elbow varus torque (G1: 0.59 ± 0.05 Nm/kg/m vs. G2: 0.52 ± 0.01 Nm/kg/m) (p=0.003) and wrist anterior force (G1: 3.0 ± 0.2 N/kg vs. G2: 2.7 ± 0.4 N/kg) (p=0.02) were significantly higher in G1.
Discussion
In both groups, high joint loads were found. This confirms that the serve could be a traumatic stroke for upper limb joints (Dillman et al., 1995) not only in adults but also in young elite players. Moreover, the « waiter's position » induced higher upper limb joint loads, with no incidence on ball speed. Consequently, the « waiter's position » can be considered as a pathomechanical factor in young elite players, and could lead to upper limb joint injuries.
References
Dillman C, Schultheis J, Hintermeister R, Hawkins R. (1995). Tennis: Sports Medicine and Science, 6–11.
Elliott B, Fleisig G, Nicholls R, Escamilia R. (2003). J Sci Med Sport, 6(1), 76–87.
Johnson C, McHugh M, Wood T, Kibler B. (2006). Br J Sports Med, 40(8), 696–699.
Martin C, Kulpa R, Ropars M, Delamarche P. Bideau B. (2013). Med Sci Sports Exerc, 45(11), 2113-2119.
Contact pierre.touzard@hotmail.com
Anthony Sorel; Richard Kulpa; Rufin Boumpoutou; Benoit Bideau
A standardized system to evaluate reactive agility depending on anticipation time Conference
Proceedings of the World Conference on Science and Soccer, 2017.
@conference{sorel2017,
title = {A standardized system to evaluate reactive agility depending on anticipation time},
author = {Anthony Sorel and Richard Kulpa and Rufin Boumpoutou and Benoit Bideau},
year = {2017},
date = {2017-01-01},
booktitle = {Proceedings of the World Conference on Science and Soccer},
abstract = {Introduction
Reactive agility is a key factor of performance in soccer (Knoop et al. 2013). It allows the players to manage quick changes in opponents’ motions and ball trajectory. In their daily training practice, many exercises are proposed to evaluate and train this reactivity (Ricotti et al. 2013; Trecroci et al. 2016). However, no study has been proposed to objectively explore the influence of the anticipation duration, the time the player has to anticipate, on the rapidity of reaction. In this work, we propose a new evaluation system to investigate player’s reactive agility in standardized and controlled conditions, mimicking real sport situations in which the player has to run quickly toward a direction, as soon as this information is revealed.
Methods
30 elite soccer players took part of this study. They are initially standing on 2 force plates (AMTI BP600-1200) in the middle of an 8m square and have to perform a vertical jump before running toward a corner as fast as possible. A wide screen located in front of the player displays an overview of the scene and shows which target must be reached out of the 4 corners. 2 conditions are randomly proposed: either the target is already displayed before jumping, or it appears only 50ms after player’s takeoff. This second condition ensures the player only knows the direction he must run to just before landing. 3 repetitions of each condition were realized leading to a total of 24 trials per player. The evaluation method then consisted in measuring and analysing the 6 degrees of freedom of ground reaction forces applied under each foot of the player when he started to run toward the target.
Results & Discussion
Preliminary results showed an adaptation of the motor scheme depending on the condition. When target is fully defined before jumping, a rearward turn is carried out by a first support on the external foot (left foot for a backward right turn) followed by a support on the internal foot, with or without short intermediate double support. This full rearward turn is thus performed in just one stride. On the opposite, when target is shown after takeoff, the rearward turn is generally carried out with one more stride, increasing the turn-on time and distance covered. Moreover, ground reaction forces provide relevant variables carrying both temporal and dynamic information such as reaction time and amount and direction of force under each foot. These data provide an individualized evaluation of the player highlighting his strengths and weaknesses such as laterality, anticipatory skills, field position or post-traumatic recovery. A personalized training could then be considered.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Introduction
Reactive agility is a key factor of performance in soccer (Knoop et al. 2013). It allows the players to manage quick changes in opponents’ motions and ball trajectory. In their daily training practice, many exercises are proposed to evaluate and train this reactivity (Ricotti et al. 2013; Trecroci et al. 2016). However, no study has been proposed to objectively explore the influence of the anticipation duration, the time the player has to anticipate, on the rapidity of reaction. In this work, we propose a new evaluation system to investigate player’s reactive agility in standardized and controlled conditions, mimicking real sport situations in which the player has to run quickly toward a direction, as soon as this information is revealed.
Methods
30 elite soccer players took part of this study. They are initially standing on 2 force plates (AMTI BP600-1200) in the middle of an 8m square and have to perform a vertical jump before running toward a corner as fast as possible. A wide screen located in front of the player displays an overview of the scene and shows which target must be reached out of the 4 corners. 2 conditions are randomly proposed: either the target is already displayed before jumping, or it appears only 50ms after player’s takeoff. This second condition ensures the player only knows the direction he must run to just before landing. 3 repetitions of each condition were realized leading to a total of 24 trials per player. The evaluation method then consisted in measuring and analysing the 6 degrees of freedom of ground reaction forces applied under each foot of the player when he started to run toward the target.
Results & Discussion
Preliminary results showed an adaptation of the motor scheme depending on the condition. When target is fully defined before jumping, a rearward turn is carried out by a first support on the external foot (left foot for a backward right turn) followed by a support on the internal foot, with or without short intermediate double support. This full rearward turn is thus performed in just one stride. On the opposite, when target is shown after takeoff, the rearward turn is generally carried out with one more stride, increasing the turn-on time and distance covered. Moreover, ground reaction forces provide relevant variables carrying both temporal and dynamic information such as reaction time and amount and direction of force under each foot. These data provide an individualized evaluation of the player highlighting his strengths and weaknesses such as laterality, anticipatory skills, field position or post-traumatic recovery. A personalized training could then be considered.
Reactive agility is a key factor of performance in soccer (Knoop et al. 2013). It allows the players to manage quick changes in opponents’ motions and ball trajectory. In their daily training practice, many exercises are proposed to evaluate and train this reactivity (Ricotti et al. 2013; Trecroci et al. 2016). However, no study has been proposed to objectively explore the influence of the anticipation duration, the time the player has to anticipate, on the rapidity of reaction. In this work, we propose a new evaluation system to investigate player’s reactive agility in standardized and controlled conditions, mimicking real sport situations in which the player has to run quickly toward a direction, as soon as this information is revealed.
Methods
30 elite soccer players took part of this study. They are initially standing on 2 force plates (AMTI BP600-1200) in the middle of an 8m square and have to perform a vertical jump before running toward a corner as fast as possible. A wide screen located in front of the player displays an overview of the scene and shows which target must be reached out of the 4 corners. 2 conditions are randomly proposed: either the target is already displayed before jumping, or it appears only 50ms after player’s takeoff. This second condition ensures the player only knows the direction he must run to just before landing. 3 repetitions of each condition were realized leading to a total of 24 trials per player. The evaluation method then consisted in measuring and analysing the 6 degrees of freedom of ground reaction forces applied under each foot of the player when he started to run toward the target.
Results & Discussion
Preliminary results showed an adaptation of the motor scheme depending on the condition. When target is fully defined before jumping, a rearward turn is carried out by a first support on the external foot (left foot for a backward right turn) followed by a support on the internal foot, with or without short intermediate double support. This full rearward turn is thus performed in just one stride. On the opposite, when target is shown after takeoff, the rearward turn is generally carried out with one more stride, increasing the turn-on time and distance covered. Moreover, ground reaction forces provide relevant variables carrying both temporal and dynamic information such as reaction time and amount and direction of force under each foot. These data provide an individualized evaluation of the player highlighting his strengths and weaknesses such as laterality, anticipatory skills, field position or post-traumatic recovery. A personalized training could then be considered.
Camille Jeunet; Benoit Bideau; Fernando Argelaguet; Ricardo Chavarriaga; José R del Millan; Anatole Lecuyer; Richard Kulpa
Investigating neurophysiological correlates of covert attention in soccer goalkeepers Conference
Proceedings of the World Conference on Science and Soccer, 2017.
@conference{jeunet2017,
title = {Investigating neurophysiological correlates of covert attention in soccer goalkeepers},
author = {Camille Jeunet and Benoit Bideau and Fernando Argelaguet and Ricardo Chavarriaga and José R del Millan and Anatole Lecuyer and Richard Kulpa},
year = {2017},
date = {2017-01-01},
booktitle = {Proceedings of the World Conference on Science and Soccer},
abstract = {Introduction
Soccer goalkeepers must process information from their peripheral vision at the same time they look towards the ball. This ability, committing attention to a position other than the fixation point, is called Covert Visuo-Spatial Attention –CVSA– (Posner, 1980). CVSA being essential to reach high performances, it is primordial to find innovative and efficient ways of improving it. Neurofeedback, which consists in training specific brain features in order to enhance a cognitive ability, has been proven to increase attentional abilities (Fuchs et al., 2003). Also, different studies have suggested the existence of a neurophysiological marker specific to covert attention: a lateralised modulation of the alpha waves in the visual cortex (Sauseng et al., 2005; Thut et al. 2006). Moreover, it has been shown possible to compute this marker online, thus opening the door to a potential neurofeedback training procedure (Schmidt et al., 2010; Tonin et al., 2013; Trachel et al., 2015). In this view, we propose in a first instance to further investigate the relevance of this marker for soccer goalkeepers. The objective is to answer the following questions: Is this marker transferrable to goalkeepers? How stable is it across athletes? Does it depend on their expertise?
Methods
Ten soccer goalkeepers (amateurs and professionals) take part in an ElectroEncephaloGraphy (EEG) study while they perform a CVSA task. They have to look at a fixation cross and then, based on the cue displayed, commit their attention to a target located on the left or right of the screen (without overt eye movements) (Tonin et al., 2013). The protocol includes two sessions so that we can assess the stability of the marker.
Results & Discussion
An alpha wave modulation in the visual cortex should be observed contralateral to the target (e.g., in the left visual cortex when the target is on the right). Moreover, professional goalkeepers should produce a greater alpha wave modulation, reflecting a main effect of expertise. If our hypotheses are underpinned by the results, the next step will consist in proposing a new generation of EEGbased training tools for goalkeepers, with a neurofeedback training targeting this marker, and in evaluating the effect of these training tools on goalkeepers’ performance.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Introduction
Soccer goalkeepers must process information from their peripheral vision at the same time they look towards the ball. This ability, committing attention to a position other than the fixation point, is called Covert Visuo-Spatial Attention –CVSA– (Posner, 1980). CVSA being essential to reach high performances, it is primordial to find innovative and efficient ways of improving it. Neurofeedback, which consists in training specific brain features in order to enhance a cognitive ability, has been proven to increase attentional abilities (Fuchs et al., 2003). Also, different studies have suggested the existence of a neurophysiological marker specific to covert attention: a lateralised modulation of the alpha waves in the visual cortex (Sauseng et al., 2005; Thut et al. 2006). Moreover, it has been shown possible to compute this marker online, thus opening the door to a potential neurofeedback training procedure (Schmidt et al., 2010; Tonin et al., 2013; Trachel et al., 2015). In this view, we propose in a first instance to further investigate the relevance of this marker for soccer goalkeepers. The objective is to answer the following questions: Is this marker transferrable to goalkeepers? How stable is it across athletes? Does it depend on their expertise?
Methods
Ten soccer goalkeepers (amateurs and professionals) take part in an ElectroEncephaloGraphy (EEG) study while they perform a CVSA task. They have to look at a fixation cross and then, based on the cue displayed, commit their attention to a target located on the left or right of the screen (without overt eye movements) (Tonin et al., 2013). The protocol includes two sessions so that we can assess the stability of the marker.
Results & Discussion
An alpha wave modulation in the visual cortex should be observed contralateral to the target (e.g., in the left visual cortex when the target is on the right). Moreover, professional goalkeepers should produce a greater alpha wave modulation, reflecting a main effect of expertise. If our hypotheses are underpinned by the results, the next step will consist in proposing a new generation of EEGbased training tools for goalkeepers, with a neurofeedback training targeting this marker, and in evaluating the effect of these training tools on goalkeepers’ performance.
Soccer goalkeepers must process information from their peripheral vision at the same time they look towards the ball. This ability, committing attention to a position other than the fixation point, is called Covert Visuo-Spatial Attention –CVSA– (Posner, 1980). CVSA being essential to reach high performances, it is primordial to find innovative and efficient ways of improving it. Neurofeedback, which consists in training specific brain features in order to enhance a cognitive ability, has been proven to increase attentional abilities (Fuchs et al., 2003). Also, different studies have suggested the existence of a neurophysiological marker specific to covert attention: a lateralised modulation of the alpha waves in the visual cortex (Sauseng et al., 2005; Thut et al. 2006). Moreover, it has been shown possible to compute this marker online, thus opening the door to a potential neurofeedback training procedure (Schmidt et al., 2010; Tonin et al., 2013; Trachel et al., 2015). In this view, we propose in a first instance to further investigate the relevance of this marker for soccer goalkeepers. The objective is to answer the following questions: Is this marker transferrable to goalkeepers? How stable is it across athletes? Does it depend on their expertise?
Methods
Ten soccer goalkeepers (amateurs and professionals) take part in an ElectroEncephaloGraphy (EEG) study while they perform a CVSA task. They have to look at a fixation cross and then, based on the cue displayed, commit their attention to a target located on the left or right of the screen (without overt eye movements) (Tonin et al., 2013). The protocol includes two sessions so that we can assess the stability of the marker.
Results & Discussion
An alpha wave modulation in the visual cortex should be observed contralateral to the target (e.g., in the left visual cortex when the target is on the right). Moreover, professional goalkeepers should produce a greater alpha wave modulation, reflecting a main effect of expertise. If our hypotheses are underpinned by the results, the next step will consist in proposing a new generation of EEGbased training tools for goalkeepers, with a neurofeedback training targeting this marker, and in evaluating the effect of these training tools on goalkeepers’ performance.
Richard Kulpa; Charles Faure; Kevin Le Targat; Christophe Revel; Anthony Sorel; Benoit Bideau
Training of visuospatial attention of professional soccer goalkeepers with multiple-object tracking Conference
Proceedings of the World Conference on Science and Soccer, 2017.
@conference{kulpa2017,
title = {Training of visuospatial attention of professional soccer goalkeepers with multiple-object tracking},
author = {Richard Kulpa and Charles Faure and Kevin Le Targat and Christophe Revel and Anthony Sorel and Benoit Bideau},
year = {2017},
date = {2017-01-01},
booktitle = {Proceedings of the World Conference on Science and Soccer},
abstract = {Introduction
Perception is a fundamental factor in decision making and soccer goalkeepers have to concurrently process multiple moving information to make the right choice. Their ability to perceive the situation correctly is directly linked to their expertise level (Williams 2000) and is based on their Covert VisuoSpatial Attention (CVSA) (Posner 1980) as the ball and the players are continuously moving. Our goal is to assess if an individualized training protocol based on Multiple-Object Tracking (MOT), which is a complex task involving several parts of one’s visual field, can improve the CVSA of expert soccer goalkeepers.
Methods
We designed a standardized training protocol to improve the DVA, based on MOT (Pylyshyn et al. 1988). In our study, the goalkeeper had to keep visual track of red balls moving amongst a set of green moving distractor balls (“MOT” condition). An additional blue ball had to be tracked with the mouse during half of the trials ( “MOT-Tracking” condition). After 1s, all the balls became green (except the blue one when present) and the goalkeeper had to retrieve them after each 4s session. Four professional soccer goalkeepers (first national league) underwent a training period of 13 weeks. One session of 15 minutes per week was completed. Improvement in goalkeepers’ performance was ensured by an increase in training difficulty.
2 different numbers of balls to track (2 and 3) were set, with 5 to 8 distractor balls; and 3 ball speeds (18.5, 23 and 27.5.s-1). To evaluate this improvement, the same reference assessment was performed at the beginning and at the end of the training period.
Results & Discussion
Firstly, the results showed a strong ability of expert goalkeepers to track a large number of targets. Cavanagh et al. showed that up to 4 objects can be tracked depending on factors such as movement velocity (Cavanagh et al., 2005). Although we found no overall improvement for MOT condition, strong differences were observed for MOT-Tracking condition: improvement in overall performance, with increase whatever speed and number of balls to find. Indeed, initially, our subjects fully succeeded in 65±5% of the situations. At the end of the training period, they were able to retrieve balls in 81±7% of the trials. In a similar manner, improvement in performance was observed for each speed, with a stronger effect at the lowest speed (18.5.s-1), showing an improvement of 19±4% after training completion. Finally, participants showed better performance in MOT-tracking than in MOT, after period of training (difference of 15±4%), whereas no difference was observed before training period.
Conclusion
The high acuity to track multiple dynamic objects is essential for goalkeepers and a 13-week of MOT training showed improvement in this skill. Future works must include a larger set of subjects to confirm this result, and a more filed-based approach (Romeas et al., 2016).},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Introduction
Perception is a fundamental factor in decision making and soccer goalkeepers have to concurrently process multiple moving information to make the right choice. Their ability to perceive the situation correctly is directly linked to their expertise level (Williams 2000) and is based on their Covert VisuoSpatial Attention (CVSA) (Posner 1980) as the ball and the players are continuously moving. Our goal is to assess if an individualized training protocol based on Multiple-Object Tracking (MOT), which is a complex task involving several parts of one’s visual field, can improve the CVSA of expert soccer goalkeepers.
Methods
We designed a standardized training protocol to improve the DVA, based on MOT (Pylyshyn et al. 1988). In our study, the goalkeeper had to keep visual track of red balls moving amongst a set of green moving distractor balls (“MOT” condition). An additional blue ball had to be tracked with the mouse during half of the trials ( “MOT-Tracking” condition). After 1s, all the balls became green (except the blue one when present) and the goalkeeper had to retrieve them after each 4s session. Four professional soccer goalkeepers (first national league) underwent a training period of 13 weeks. One session of 15 minutes per week was completed. Improvement in goalkeepers’ performance was ensured by an increase in training difficulty.
2 different numbers of balls to track (2 and 3) were set, with 5 to 8 distractor balls; and 3 ball speeds (18.5, 23 and 27.5.s-1). To evaluate this improvement, the same reference assessment was performed at the beginning and at the end of the training period.
Results & Discussion
Firstly, the results showed a strong ability of expert goalkeepers to track a large number of targets. Cavanagh et al. showed that up to 4 objects can be tracked depending on factors such as movement velocity (Cavanagh et al., 2005). Although we found no overall improvement for MOT condition, strong differences were observed for MOT-Tracking condition: improvement in overall performance, with increase whatever speed and number of balls to find. Indeed, initially, our subjects fully succeeded in 65±5% of the situations. At the end of the training period, they were able to retrieve balls in 81±7% of the trials. In a similar manner, improvement in performance was observed for each speed, with a stronger effect at the lowest speed (18.5.s-1), showing an improvement of 19±4% after training completion. Finally, participants showed better performance in MOT-tracking than in MOT, after period of training (difference of 15±4%), whereas no difference was observed before training period.
Conclusion
The high acuity to track multiple dynamic objects is essential for goalkeepers and a 13-week of MOT training showed improvement in this skill. Future works must include a larger set of subjects to confirm this result, and a more filed-based approach (Romeas et al., 2016).
Perception is a fundamental factor in decision making and soccer goalkeepers have to concurrently process multiple moving information to make the right choice. Their ability to perceive the situation correctly is directly linked to their expertise level (Williams 2000) and is based on their Covert VisuoSpatial Attention (CVSA) (Posner 1980) as the ball and the players are continuously moving. Our goal is to assess if an individualized training protocol based on Multiple-Object Tracking (MOT), which is a complex task involving several parts of one’s visual field, can improve the CVSA of expert soccer goalkeepers.
Methods
We designed a standardized training protocol to improve the DVA, based on MOT (Pylyshyn et al. 1988). In our study, the goalkeeper had to keep visual track of red balls moving amongst a set of green moving distractor balls (“MOT” condition). An additional blue ball had to be tracked with the mouse during half of the trials ( “MOT-Tracking” condition). After 1s, all the balls became green (except the blue one when present) and the goalkeeper had to retrieve them after each 4s session. Four professional soccer goalkeepers (first national league) underwent a training period of 13 weeks. One session of 15 minutes per week was completed. Improvement in goalkeepers’ performance was ensured by an increase in training difficulty.
2 different numbers of balls to track (2 and 3) were set, with 5 to 8 distractor balls; and 3 ball speeds (18.5, 23 and 27.5.s-1). To evaluate this improvement, the same reference assessment was performed at the beginning and at the end of the training period.
Results & Discussion
Firstly, the results showed a strong ability of expert goalkeepers to track a large number of targets. Cavanagh et al. showed that up to 4 objects can be tracked depending on factors such as movement velocity (Cavanagh et al., 2005). Although we found no overall improvement for MOT condition, strong differences were observed for MOT-Tracking condition: improvement in overall performance, with increase whatever speed and number of balls to find. Indeed, initially, our subjects fully succeeded in 65±5% of the situations. At the end of the training period, they were able to retrieve balls in 81±7% of the trials. In a similar manner, improvement in performance was observed for each speed, with a stronger effect at the lowest speed (18.5.s-1), showing an improvement of 19±4% after training completion. Finally, participants showed better performance in MOT-tracking than in MOT, after period of training (difference of 15±4%), whereas no difference was observed before training period.
Conclusion
The high acuity to track multiple dynamic objects is essential for goalkeepers and a 13-week of MOT training showed improvement in this skill. Future works must include a larger set of subjects to confirm this result, and a more filed-based approach (Romeas et al., 2016).
Annabelle Limballe; Charles Faure; Pierrick Desfontaine; Benoit Bideau; Richard Kulpa
How gender affects kinematics of dribbling in soccer Conference
Proceedings of the World Conference on Science and Soccer, 2017.
@conference{limballe2017,
title = {How gender affects kinematics of dribbling in soccer},
author = {Annabelle Limballe and Charles Faure and Pierrick Desfontaine and Benoit Bideau and Richard Kulpa},
year = {2017},
date = {2017-01-01},
booktitle = {Proceedings of the World Conference on Science and Soccer},
abstract = {Introduction
Dribbling skill is a key factor of performance for soccer players (Ali, 2011). However, no study has investigated the influence of gender on these skills while there exists a disparity between men and women (Kirkendall 2007). Our goal is to evaluate this influence of gender on the kinematics of dribbling. To this end, we propose to use both the juggling test that is the reference in federal system to evaluate players’ level of expertise, and an ”8” shape task used by Zago et al. to assess dribbling skills of young players (Zago et al., 2015).
Methods
13 players (6 women and 7 men), from amateur to national level, took part in the study. They had to do a maximal number of juggles for the juggling task and to be as fast as possible for the dribbling task. They also performed reference trials in the ”8” shape slalom without ball, just running as fast as possible. Motion were captured with a Vicon system and were also filmed. We analyzed the kinematical parameters such as dribbling time, stride cadence, shoulder and hips angles, height of center of gravity relative to subject’s size.
Results and Discussion The comparison between juggling and dribbling time shows a negative correlation (p=0.0498). The dribbling test is thus coherent with the reference juggling test. It also exists a strong statistical trend between during juggling test and the level of expertise (p=0.056). No statistical difference between men and women was found for the reference condition without ball, the two groups were homogeneous in term of global running performance. However, female players adopted a lower cadence than men (p=0.033) and they had lower performance in juggling and dribbling tasks. This result show a difference of technical dribbling skills depending on gender. Otherwise, on the kinematical parameters, we did not find significant difference neither on relative height of the center of gravity, angular movement of hips or shoulders. Only a most important variability in shoulders angle was found for women, contrary to walking and running patterns but it could be explained by the specific dribbling pattern: trunk fixed and preferred leg in front to increase accuracy. Further studies should be done to have a more in depth biomechanical analysis of the dribbling pattern to confirm or not this statement. This study is currently extended to a larger population to improve statistical results.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Introduction
Dribbling skill is a key factor of performance for soccer players (Ali, 2011). However, no study has investigated the influence of gender on these skills while there exists a disparity between men and women (Kirkendall 2007). Our goal is to evaluate this influence of gender on the kinematics of dribbling. To this end, we propose to use both the juggling test that is the reference in federal system to evaluate players’ level of expertise, and an ”8” shape task used by Zago et al. to assess dribbling skills of young players (Zago et al., 2015).
Methods
13 players (6 women and 7 men), from amateur to national level, took part in the study. They had to do a maximal number of juggles for the juggling task and to be as fast as possible for the dribbling task. They also performed reference trials in the ”8” shape slalom without ball, just running as fast as possible. Motion were captured with a Vicon system and were also filmed. We analyzed the kinematical parameters such as dribbling time, stride cadence, shoulder and hips angles, height of center of gravity relative to subject’s size.
Results and Discussion The comparison between juggling and dribbling time shows a negative correlation (p=0.0498). The dribbling test is thus coherent with the reference juggling test. It also exists a strong statistical trend between during juggling test and the level of expertise (p=0.056). No statistical difference between men and women was found for the reference condition without ball, the two groups were homogeneous in term of global running performance. However, female players adopted a lower cadence than men (p=0.033) and they had lower performance in juggling and dribbling tasks. This result show a difference of technical dribbling skills depending on gender. Otherwise, on the kinematical parameters, we did not find significant difference neither on relative height of the center of gravity, angular movement of hips or shoulders. Only a most important variability in shoulders angle was found for women, contrary to walking and running patterns but it could be explained by the specific dribbling pattern: trunk fixed and preferred leg in front to increase accuracy. Further studies should be done to have a more in depth biomechanical analysis of the dribbling pattern to confirm or not this statement. This study is currently extended to a larger population to improve statistical results.
Dribbling skill is a key factor of performance for soccer players (Ali, 2011). However, no study has investigated the influence of gender on these skills while there exists a disparity between men and women (Kirkendall 2007). Our goal is to evaluate this influence of gender on the kinematics of dribbling. To this end, we propose to use both the juggling test that is the reference in federal system to evaluate players’ level of expertise, and an ”8” shape task used by Zago et al. to assess dribbling skills of young players (Zago et al., 2015).
Methods
13 players (6 women and 7 men), from amateur to national level, took part in the study. They had to do a maximal number of juggles for the juggling task and to be as fast as possible for the dribbling task. They also performed reference trials in the ”8” shape slalom without ball, just running as fast as possible. Motion were captured with a Vicon system and were also filmed. We analyzed the kinematical parameters such as dribbling time, stride cadence, shoulder and hips angles, height of center of gravity relative to subject’s size.
Results and Discussion The comparison between juggling and dribbling time shows a negative correlation (p=0.0498). The dribbling test is thus coherent with the reference juggling test. It also exists a strong statistical trend between during juggling test and the level of expertise (p=0.056). No statistical difference between men and women was found for the reference condition without ball, the two groups were homogeneous in term of global running performance. However, female players adopted a lower cadence than men (p=0.033) and they had lower performance in juggling and dribbling tasks. This result show a difference of technical dribbling skills depending on gender. Otherwise, on the kinematical parameters, we did not find significant difference neither on relative height of the center of gravity, angular movement of hips or shoulders. Only a most important variability in shoulders angle was found for women, contrary to walking and running patterns but it could be explained by the specific dribbling pattern: trunk fixed and preferred leg in front to increase accuracy. Further studies should be done to have a more in depth biomechanical analysis of the dribbling pattern to confirm or not this statement. This study is currently extended to a larger population to improve statistical results.
S D Lynch; R Kulpa; A L Meerhoff; J Pettré; A Crétual; A H Olivier
Collision avoidance behavior between walkers: global and local motion cues Journal Article
In: IEEE Transactions on Visualization and Computer Graphics, vol. PP, no. 99, pp. 1-1, 2017, ISSN: 1077-2626.
Abstract | Links/Paper | BibTeX
@article{Lynch2017,
title = {Collision avoidance behavior between walkers: global and local motion cues},
author = {S D Lynch and R Kulpa and A L Meerhoff and J Pettré and A Crétual and A H Olivier},
doi = {10.1109/TVCG.2017.2718514},
issn = {1077-2626},
year = {2017},
date = {2017-01-01},
journal = {IEEE Transactions on Visualization and Computer Graphics},
volume = {PP},
number = {99},
pages = {1-1},
abstract = {Daily activities require agents to interact with each other, such as during collision avoidance. The nature of visual information that is used for a collision free interaction requires further understanding. We aim to manipulate the nature of visual information in two forms, global and local information appearances. Sixteen healthy participants navigated towards a target in an immersive computer-assisted virtual environment (CAVE) using a joystick. A moving passive obstacle crossed the participant?s trajectory perpendicularly at various pre-defined risks of collision distances. The obstacle was presented with one of five virtual appearances, associated to global motion cues (i.e., a cylinder or a sphere), or local motion cues (i.e., only the legs or the trunk). A full body virtual walker, showing both local and global motion cues, used as a reference condition. The final crossing distance was affected by the global motion appearances, however, appearance had no qualitative effect on motion adaptations. These findings contribute towards further understanding what information people use when interacting with others.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Daily activities require agents to interact with each other, such as during collision avoidance. The nature of visual information that is used for a collision free interaction requires further understanding. We aim to manipulate the nature of visual information in two forms, global and local information appearances. Sixteen healthy participants navigated towards a target in an immersive computer-assisted virtual environment (CAVE) using a joystick. A moving passive obstacle crossed the participant?s trajectory perpendicularly at various pre-defined risks of collision distances. The obstacle was presented with one of five virtual appearances, associated to global motion cues (i.e., a cylinder or a sphere), or local motion cues (i.e., only the legs or the trunk). A full body virtual walker, showing both local and global motion cues, used as a reference condition. The final crossing distance was affected by the global motion appearances, however, appearance had no qualitative effect on motion adaptations. These findings contribute towards further understanding what information people use when interacting with others.
Marion Morel; Catherine Achard; Richard Kulpa; Séverine Dubuisson
Automatic evaluation of sports motion: A generic computation of spatial and temporal errors Journal Article
In: Image and Vision Computing, vol. 64, no. Supplement C, pp. 67 - 78, 2017, ISSN: 0262-8856.
Abstract | Links/Paper | BibTeX
@article{Morel2017,
title = {Automatic evaluation of sports motion: A generic computation of spatial and temporal errors},
author = {Marion Morel and Catherine Achard and Richard Kulpa and Séverine Dubuisson},
url = {http://www.sciencedirect.com/science/article/pii/S0262885617300951},
doi = {https://doi.org/10.1016/j.imavis.2017.05.008},
issn = {0262-8856},
year = {2017},
date = {2017-01-01},
journal = {Image and Vision Computing},
volume = {64},
number = {Supplement C},
pages = {67 - 78},
abstract = {In this paper, we propose an innovative automatic evaluation process for any sport motions. Based on a 2-level Dynamic Time Warping, the process allows the evaluation of both spatial and temporal errors of a novice motion based on an experts' motion database and without any prior knowledge on the sport. This new methodology is evaluated with regards to coaches' assessment on two different kinds of motions: tennis serves and karate tsuki.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper, we propose an innovative automatic evaluation process for any sport motions. Based on a 2-level Dynamic Time Warping, the process allows the evaluation of both spatial and temporal errors of a novice motion based on an experts' motion database and without any prior knowledge on the sport. This new methodology is evaluated with regards to coaches' assessment on two different kinds of motions: tennis serves and karate tsuki.
Said Yacine Boulahia; Eric Anquetil; Franck Multon; Richard Kulpa
Dynamic hand gesture recognition based on 3D pattern assembled trajectories Conference
7th IEEE International Conference on Image Processing Theory, Tools and Applications (IPTA 2017), 2017.
Abstract | Links/Paper | BibTeX
@conference{Boulahia2017,
title = {Dynamic hand gesture recognition based on 3D pattern assembled trajectories},
author = {Said Yacine Boulahia and Eric Anquetil and Franck Multon and Richard Kulpa},
doi = {10.1109/IPTA.2017.8310146},
year = {2017},
date = {2017-01-01},
booktitle = {7th IEEE International Conference on Image Processing Theory, Tools and Applications (IPTA 2017)},
abstract = {Over the past few years, advances in commercial 3D sensors have substantially promoted the research of dynamic hand gesture recognition. On a other side, whole body gestures recognition has also attracted increasing attention since the emergence of Kinect like sensors. One may notice that both research topics deal with human-made motions and are likely to face similar challenges. In this paper, our aim is thus to evaluate the applicability of an action recognition feature-set to model dynamic hand gestures using skeleton data. Furthermore, existing datasets are often composed of pre-segmented gestures that are performed with a single hand only. We collected therefore a more challenging dataset, which contains unsegmented streams of 13 hand gesture classes, performed with either a single hand or two hands. Our approach is first evaluated on an existing dataset, namely DHG dataset, and then using our collected dataset. Better results compared to previous approaches are reported.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Over the past few years, advances in commercial 3D sensors have substantially promoted the research of dynamic hand gesture recognition. On a other side, whole body gestures recognition has also attracted increasing attention since the emergence of Kinect like sensors. One may notice that both research topics deal with human-made motions and are likely to face similar challenges. In this paper, our aim is thus to evaluate the applicability of an action recognition feature-set to model dynamic hand gestures using skeleton data. Furthermore, existing datasets are often composed of pre-segmented gestures that are performed with a single hand only. We collected therefore a more challenging dataset, which contains unsegmented streams of 13 hand gesture classes, performed with either a single hand or two hands. Our approach is first evaluated on an existing dataset, namely DHG dataset, and then using our collected dataset. Better results compared to previous approaches are reported.
Sean Lynch; Richard Kulpa; Rens Meerhoff; Julien Pettré; Armel Crétual; Anne-Hélène Olivier
Effect of local limb cues in the prediction of global motion during collision avoidance Conference
17ème Congrès de l’Association des Chercheurs en Activités Physiques et Sportives (ACAPS), 2017.
@conference{Lynch2017c,
title = {Effect of local limb cues in the prediction of global motion during collision avoidance},
author = {Sean Lynch and Richard Kulpa and Rens Meerhoff and Julien Pettré and Armel Crétual and Anne-Hélène Olivier},
year = {2017},
date = {2017-01-01},
booktitle = {17ème Congrès de l’Association des Chercheurs en Activités Physiques et Sportives (ACAPS)},
abstract = {Navigating through a public place requires movement coordination to regulate interpersonal interactions. Behavioural responses have conflicting findings, for example, research on social interactions has shown that interactions with human avatars take place at a smaller preferred interpersonal distance compared to cylindric avatars (Lachini2014). Hackney et al. (2014) reported a larger interpersonal distance with humans as opposed to cylinders in reality. Argelaguet et al. (2015) reported no difference in clearance between a human and a similar sized box, while others suggested situational characteristics influence interaction rather than social traits (Knorr2016). Finally, distance can be regulated through geometric shapes, representing global cues, where the addition of local limb motion cues provides a temporal advantage (Meerhoff2014). The aim of our work is to determine the nature of the required visual cues conveyed by walker's body motion for collision avoidance. We designed an experiment in virtual reality to manipulate the appearance of an obstacle with global and local limb cues. Sixteen participants navigated toward a goal in a virtual environment with a joystick. A moving passive obstacle crossed the path of the participant with varying risks of collision. Obstacle appearances were a human avatar control, 2 local cue variants (legs or trunk), and 2 global cue variants (cylinder or sphere as center of mass). Analysis focused on crossing distance, number of collisions, and number of inversions in the crossing order. We also computed the Minimal Predicted Distance (MPD), linearly extrapolating the instantaneous speed and orientation to predict a future crossing point (Olivier2012). MPD reveals the adaptation performed to avoid the collision. All obstacle appearances led to qualitatively similar motion adaptation. Almost no collision and inversions of crossing order were observed. The collision avoidance behavior with respect to MPD evolution matches the one observed between two real walkers (Olivier2012): humans successfully avoided collisions independently of global or local cues. Quantitatively, global cue visual appearances (cylinder and sphere) were both significantly different from local cues (trunk and legs) and full body at final crossing distance. Evolution of MPD also showed a delayed response whilst interacting with a small sphere. These findings may suggest that not only bearing angle but also optical expansion (sphere was smaller than the other appearances) is important in the determination of future collision risk. To conclude, global motion cues provide sufficient information for successful collision avoidance, however, local motion cues reproduce repeatable responses. Our findings may be considered as guidelines for crowd simulations which should focus computational resources towards global displacement, rather than local cue specificity. Further, the consistency with local cues suggests that pairwise interactions should focus human behaviour interactions with full body avatars.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Navigating through a public place requires movement coordination to regulate interpersonal interactions. Behavioural responses have conflicting findings, for example, research on social interactions has shown that interactions with human avatars take place at a smaller preferred interpersonal distance compared to cylindric avatars (Lachini2014). Hackney et al. (2014) reported a larger interpersonal distance with humans as opposed to cylinders in reality. Argelaguet et al. (2015) reported no difference in clearance between a human and a similar sized box, while others suggested situational characteristics influence interaction rather than social traits (Knorr2016). Finally, distance can be regulated through geometric shapes, representing global cues, where the addition of local limb motion cues provides a temporal advantage (Meerhoff2014). The aim of our work is to determine the nature of the required visual cues conveyed by walker's body motion for collision avoidance. We designed an experiment in virtual reality to manipulate the appearance of an obstacle with global and local limb cues. Sixteen participants navigated toward a goal in a virtual environment with a joystick. A moving passive obstacle crossed the path of the participant with varying risks of collision. Obstacle appearances were a human avatar control, 2 local cue variants (legs or trunk), and 2 global cue variants (cylinder or sphere as center of mass). Analysis focused on crossing distance, number of collisions, and number of inversions in the crossing order. We also computed the Minimal Predicted Distance (MPD), linearly extrapolating the instantaneous speed and orientation to predict a future crossing point (Olivier2012). MPD reveals the adaptation performed to avoid the collision. All obstacle appearances led to qualitatively similar motion adaptation. Almost no collision and inversions of crossing order were observed. The collision avoidance behavior with respect to MPD evolution matches the one observed between two real walkers (Olivier2012): humans successfully avoided collisions independently of global or local cues. Quantitatively, global cue visual appearances (cylinder and sphere) were both significantly different from local cues (trunk and legs) and full body at final crossing distance. Evolution of MPD also showed a delayed response whilst interacting with a small sphere. These findings may suggest that not only bearing angle but also optical expansion (sphere was smaller than the other appearances) is important in the determination of future collision risk. To conclude, global motion cues provide sufficient information for successful collision avoidance, however, local motion cues reproduce repeatable responses. Our findings may be considered as guidelines for crowd simulations which should focus computational resources towards global displacement, rather than local cue specificity. Further, the consistency with local cues suggests that pairwise interactions should focus human behaviour interactions with full body avatars.
Sean Lynch; Julien Pettré; Julien Bruneau; Richard Kulpa; Armel Crétual; Anne-Hélène Olivier
Effect of mutual gaze on collision avoidance behavior during human walking Conference
AFRV, 2017.
@conference{Lynch2017b,
title = {Effect of mutual gaze on collision avoidance behavior during human walking},
author = {Sean Lynch and Julien Pettré and Julien Bruneau and Richard Kulpa and Armel Crétual and Anne-Hélène Olivier},
year = {2017},
date = {2017-01-01},
booktitle = {AFRV},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Said Yacine Boulahia; Eric Anquetil; Richard Kulpa; Franck Multon
12th IEEE International Conference on Automatic Face & Gesture Recognition (FG 2017), 2017.
Abstract | Links/Paper | BibTeX
@conference{Boulahia2017b,
title = {3D Multistroke Mapping (3DMM): Transfer of Hand-Drawn Pattern Representation for Skeleton-Based Gesture Recognition},
author = {Said Yacine Boulahia and Eric Anquetil and Richard Kulpa and Franck Multon},
doi = {10.1109/FG.2017.63},
year = {2017},
date = {2017-01-01},
booktitle = {12th IEEE International Conference on Automatic Face & Gesture Recognition (FG 2017)},
abstract = {Exergames involve using the fullbody to interact with an immersive world, which raises the challenge of capturing, processing and recognizing the action of the user even for cheap mocap systems such as the Microsoft Kinect. In fact, these recent technological advances have renewedinterest in skeleton-based action recognition. Our review of related literature reveals that the issues encountered are not the result of random processes, which could simply be studied by using statistical tools, but are instead due to the fact that the pattern to be recognized, i.e. an action, was produced by a human being. 2D hand-drawn symbols are further examples of patterns resulting from a human motion. Therefore, the main contribution of this paper is to examine the validity of transferring the expertise of hand-drawn symbol representation to better recognize actions based on skeleton data. Principally, we propose a new action representation, namely the 3DMM, as an initial case-study illustrating how such transfer could be conducted. The experimental results, obtained over two benchmarks, confirm the soundness of our approach and encourage more thorough examination of the transfer.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Exergames involve using the fullbody to interact with an immersive world, which raises the challenge of capturing, processing and recognizing the action of the user even for cheap mocap systems such as the Microsoft Kinect. In fact, these recent technological advances have renewedinterest in skeleton-based action recognition. Our review of related literature reveals that the issues encountered are not the result of random processes, which could simply be studied by using statistical tools, but are instead due to the fact that the pattern to be recognized, i.e. an action, was produced by a human being. 2D hand-drawn symbols are further examples of patterns resulting from a human motion. Therefore, the main contribution of this paper is to examine the validity of transferring the expertise of hand-drawn symbol representation to better recognize actions based on skeleton data. Principally, we propose a new action representation, namely the 3DMM, as an initial case-study illustrating how such transfer could be conducted. The experimental results, obtained over two benchmarks, confirm the soundness of our approach and encourage more thorough examination of the transfer.
Laurentius Meerhoff; Julien Pettré; Richard Kulpa; Sean Lynch; Armel Crétual; Anne-Hélène Olivier
Simultaneous and sequential affordances of collision avoidance between multiple pedestrians Conference
International Conference on Perception and Action, 2017.
@conference{Meerhoff2017,
title = {Simultaneous and sequential affordances of collision avoidance between multiple pedestrians},
author = {Laurentius Meerhoff and Julien Pettré and Richard Kulpa and Sean Lynch and Armel Crétual and Anne-Hélène Olivier},
year = {2017},
date = {2017-01-01},
booktitle = {International Conference on Perception and Action},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Charles Faure; Richard Kulpa; Annabelle Limballe; Benoit Bideau
Kinematic of displacement during interceptive task in an immersive virtual environment Conference
AFRV, 2017.
@conference{Faure2017,
title = {Kinematic of displacement during interceptive task in an immersive virtual environment},
author = {Charles Faure and Richard Kulpa and Annabelle Limballe and Benoit Bideau},
year = {2017},
date = {2017-01-01},
booktitle = {AFRV},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
2016
Caroline Martin; Benoit Bideau; Paul Delamarche; Richard Kulpa
Influence of a Prolonged Tennis Match Play on Serve Biomechanics Journal Article
In: PLOS ONE, vol. 11, no. 8, pp. e0159979, 2016.
Abstract | Links/Paper | BibTeX
@article{Martin2016a,
title = {Influence of a Prolonged Tennis Match Play on Serve Biomechanics},
author = {Caroline Martin and Benoit Bideau and Paul Delamarche and Richard Kulpa},
editor = {Mikhail A Lebedev},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2016_Martin_PlosOne.pdf},
doi = {10.1371/journal.pone.0159979},
year = {2016},
date = {2016-08-01},
journal = {PLOS ONE},
volume = {11},
number = {8},
pages = {e0159979},
publisher = {Public Library of Science (PLoS)},
abstract = {The aim of this study was to quantify kinematic, kinetic and performance changes that occur in the serve throughout a prolonged tennis match play. Serves of eight male advanced tennis players were recorded with a motion capture system before, at mid-match, and after a 3-hour tennis match. Before and after each match, electromyographic data of 8 upper limb muscles obtained during isometric maximal voluntary contraction were compared to determine the presence of muscular fatigue. Vertical ground reaction forces, rating of perceived exertion, ball speed, and ball impact height were measured. Kinematic and upper limb kinetic variables were computed. The results show decrease in mean power frequency values for several upper limb muscles that is an indicator of local muscular fatigue. Decreases in serve ball speed, ball impact height, maximal angular velocities and an increase in rating of perceived exertion were also observed between the beginning and the end of the match. With fatigue, the majority of the upper limb joint kinetics decreases at the end of the match. No change in timing of maximal angular velocities was observed between the beginning and the end of the match. A prolonged tennis match play may induce fatigue in upper limb muscles, which decrease performance and cause changes in serve maximal angular velocities and joint kinetics. The consistency in timing of maximal angular velocities suggests that advanced tennis players are able to maintain the temporal pattern of their serve technique, in spite of the muscular fatigue development.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of this study was to quantify kinematic, kinetic and performance changes that occur in the serve throughout a prolonged tennis match play. Serves of eight male advanced tennis players were recorded with a motion capture system before, at mid-match, and after a 3-hour tennis match. Before and after each match, electromyographic data of 8 upper limb muscles obtained during isometric maximal voluntary contraction were compared to determine the presence of muscular fatigue. Vertical ground reaction forces, rating of perceived exertion, ball speed, and ball impact height were measured. Kinematic and upper limb kinetic variables were computed. The results show decrease in mean power frequency values for several upper limb muscles that is an indicator of local muscular fatigue. Decreases in serve ball speed, ball impact height, maximal angular velocities and an increase in rating of perceived exertion were also observed between the beginning and the end of the match. With fatigue, the majority of the upper limb joint kinetics decreases at the end of the match. No change in timing of maximal angular velocities was observed between the beginning and the end of the match. A prolonged tennis match play may induce fatigue in upper limb muscles, which decrease performance and cause changes in serve maximal angular velocities and joint kinetics. The consistency in timing of maximal angular velocities suggests that advanced tennis players are able to maintain the temporal pattern of their serve technique, in spite of the muscular fatigue development.
Said Yacine Boulahia; Eric Anquetil; Richard Kulpa; Franck Multon
HIF3D: Handwriting-Inspired Features for 3D Skeleton-Based Action Recognition Conference
Proceedings of the 23rd International Conference on Pattern Recognition (ICPR 2016), 2016.
@conference{Boulahia2016,
title = {HIF3D: Handwriting-Inspired Features for 3D Skeleton-Based Action Recognition},
author = {Said Yacine Boulahia and Eric Anquetil and Richard Kulpa and Franck Multon},
year = {2016},
date = {2016-01-01},
booktitle = {Proceedings of the 23rd International Conference on Pattern Recognition (ICPR 2016)},
abstract = {Action recognition based on human skeleton structure represents nowadays a prosper research field. This is mainly due to the recent advances in terms of capture technologies and skeleton extraction algorithms. In this context, we observed that 3D skeleton-based actions share several properties with handwritten symbols since they both result from a human performance. We accordingly hypothesize that the action recognition problem can take advantage of trial and error already carried out on handwritten patterns. Therefore, inspired by one of the most efficient and compact handwriting feature-set, we propose in this paper a skeleton descriptor referred to as Handwriting-Inspired Features (HIF3D). First of all a data preprocessing is applied to joint trajectories in order to handle the variabilities among actor's morphologies. Then we extract the HIF3D features from the processed joint locations according to a time partitioning scheme so as to additionally encode the temporal information over the sequence. Finally, we selected the Support Vector Machine (SVM) to achieve the classification step. Evaluations conducted on two challenging datasets, namely HDM05 and UTKinect, testify the soundness of our approach as the obtained results outperform the state-of-the-art algorithms that rely on skeleton data.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Action recognition based on human skeleton structure represents nowadays a prosper research field. This is mainly due to the recent advances in terms of capture technologies and skeleton extraction algorithms. In this context, we observed that 3D skeleton-based actions share several properties with handwritten symbols since they both result from a human performance. We accordingly hypothesize that the action recognition problem can take advantage of trial and error already carried out on handwritten patterns. Therefore, inspired by one of the most efficient and compact handwriting feature-set, we propose in this paper a skeleton descriptor referred to as Handwriting-Inspired Features (HIF3D). First of all a data preprocessing is applied to joint trajectories in order to handle the variabilities among actor's morphologies. Then we extract the HIF3D features from the processed joint locations according to a time partitioning scheme so as to additionally encode the temporal information over the sequence. Finally, we selected the Support Vector Machine (SVM) to achieve the classification step. Evaluations conducted on two challenging datasets, namely HDM05 and UTKinect, testify the soundness of our approach as the obtained results outperform the state-of-the-art algorithms that rely on skeleton data.
Ludovic Hoyet; Anne-Helene Olivier; Richard Kulpa; Julien Pettré
Perceptual Effect of Shoulder Motions on Crowd Animations Journal Article
In: ACM Trans. Graph., vol. 35, no. 4, pp. 53:1–53:10, 2016, ISSN: 0730-0301.
Abstract | Links/Paper | BibTeX
@article{Hoyet2016,
title = {Perceptual Effect of Shoulder Motions on Crowd Animations},
author = {Ludovic Hoyet and Anne-Helene Olivier and Richard Kulpa and Julien Pettré},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2016_Hoyet_TOG.pdf},
doi = {10.1145/2897824.2925931},
issn = {0730-0301},
year = {2016},
date = {2016-01-01},
journal = {ACM Trans. Graph.},
volume = {35},
number = {4},
pages = {53:1--53:10},
publisher = {ACM},
address = {New York, NY, USA},
abstract = {A typical crowd engine pipeline animates numerous moving characters according to a two-step process: global trajectories are generated by a crowd simulator, whereas full body motions are generated by animation engines. Because interactions are only considered at the first stage, animations sometimes lead to residual collisions and/or characters walking as if they were alone, showing no sign to the influence of others. In this paper, we investigate the value of adding shoulder motions to characters passing at close distances on the perceived visual quality of crowd animations (i.e., perceived residual collisions and animation naturalness). We present two successive perceptual experiments exploring this question where we investigate first, local interactions between two isolated characters, and second, crowd scenarios. The first experiment shows that shoulder motions have a strong positive effect on both perceived residual collisions and animation naturalness. The second experiment demonstrates that the effect of shoulder motions on animation naturalness is preserved in the context of crowd scenarios, even though the complexity of the scene is largely increased. Our general conclusion is that adding secondary motions in character interactions has a significant impact on the visual quality of crowd animations, with a very light impact on the computational cost of the whole animation pipeline. Our results advance crowd animation techniques by enhancing the simulation of complex interactions between crowd characters with simple secondary motion triggering techniques.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A typical crowd engine pipeline animates numerous moving characters according to a two-step process: global trajectories are generated by a crowd simulator, whereas full body motions are generated by animation engines. Because interactions are only considered at the first stage, animations sometimes lead to residual collisions and/or characters walking as if they were alone, showing no sign to the influence of others. In this paper, we investigate the value of adding shoulder motions to characters passing at close distances on the perceived visual quality of crowd animations (i.e., perceived residual collisions and animation naturalness). We present two successive perceptual experiments exploring this question where we investigate first, local interactions between two isolated characters, and second, crowd scenarios. The first experiment shows that shoulder motions have a strong positive effect on both perceived residual collisions and animation naturalness. The second experiment demonstrates that the effect of shoulder motions on animation naturalness is preserved in the context of crowd scenarios, even though the complexity of the scene is largely increased. Our general conclusion is that adding secondary motions in character interactions has a significant impact on the visual quality of crowd animations, with a very light impact on the computational cost of the whole animation pipeline. Our results advance crowd animation techniques by enhancing the simulation of complex interactions between crowd characters with simple secondary motion triggering techniques.
Caroline Martin; Richard Kulpa; Paul Delamarche; Benoit Bideau
Influence of a prolonged tennis match play on shoulder ranges of motion. Journal Article
In: American Journal of Sports Medicine, vol. 44, no. 8, pp. 2147-51, 2016.
Abstract | Links/Paper | BibTeX
@article{Martin2016b,
title = {Influence of a prolonged tennis match play on shoulder ranges of motion.},
author = {Caroline Martin and Richard Kulpa and Paul Delamarche and Benoit Bideau},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2016_Martin_AJSM.pdf},
doi = {10.1177/0363546516645542},
year = {2016},
date = {2016-01-01},
journal = {American Journal of Sports Medicine},
volume = {44},
number = {8},
pages = {2147-51},
abstract = {BACKGROUND: Shoulder range of motion (ROM) deficits have been identified as an injury risk factor among tennis players. It is well known that shoulder internal rotation deficit increases with age and years of play, but there is a lack of knowledge regarding the influence of a prolonged tennis match on shoulder ROM.
PURPOSE: To examine changes in shoulder ROM during a prolonged tennis match.
STUDY DESIGN: Descriptive laboratory study.
METHODS: Shoulder passive internal and external rotation ROM were measured on 8 male tennis players before, every 30 minutes during, and just after a 3-hour tennis match. Total ROM was calculated as the combination of shoulder internal and external rotations. Ball velocity on the serve was measured with a radar gun before, at midmatch, and just after the match.
RESULTS: Decreases in shoulder internal rotation (-20.8°; P = .005), total ROM (-24.6°; P = .001), and serve velocity (-1.8 m/s; P = .002) were observed at the end of the match. No statistically significant difference was observed for shoulder external rotation after the match (P = .460).
CONCLUSION: Passive shoulder internal rotation and total ROM are significantly decreased during a 3-hour tennis match.
CLINICAL RELEVANCE: The results show that a prolonged tennis match play can modify values of shoulder ROM.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: Shoulder range of motion (ROM) deficits have been identified as an injury risk factor among tennis players. It is well known that shoulder internal rotation deficit increases with age and years of play, but there is a lack of knowledge regarding the influence of a prolonged tennis match on shoulder ROM.
PURPOSE: To examine changes in shoulder ROM during a prolonged tennis match.
STUDY DESIGN: Descriptive laboratory study.
METHODS: Shoulder passive internal and external rotation ROM were measured on 8 male tennis players before, every 30 minutes during, and just after a 3-hour tennis match. Total ROM was calculated as the combination of shoulder internal and external rotations. Ball velocity on the serve was measured with a radar gun before, at midmatch, and just after the match.
RESULTS: Decreases in shoulder internal rotation (-20.8°; P = .005), total ROM (-24.6°; P = .001), and serve velocity (-1.8 m/s; P = .002) were observed at the end of the match. No statistically significant difference was observed for shoulder external rotation after the match (P = .460).
CONCLUSION: Passive shoulder internal rotation and total ROM are significantly decreased during a 3-hour tennis match.
CLINICAL RELEVANCE: The results show that a prolonged tennis match play can modify values of shoulder ROM.
PURPOSE: To examine changes in shoulder ROM during a prolonged tennis match.
STUDY DESIGN: Descriptive laboratory study.
METHODS: Shoulder passive internal and external rotation ROM were measured on 8 male tennis players before, every 30 minutes during, and just after a 3-hour tennis match. Total ROM was calculated as the combination of shoulder internal and external rotations. Ball velocity on the serve was measured with a radar gun before, at midmatch, and just after the match.
RESULTS: Decreases in shoulder internal rotation (-20.8°; P = .005), total ROM (-24.6°; P = .001), and serve velocity (-1.8 m/s; P = .002) were observed at the end of the match. No statistically significant difference was observed for shoulder external rotation after the match (P = .460).
CONCLUSION: Passive shoulder internal rotation and total ROM are significantly decreased during a 3-hour tennis match.
CLINICAL RELEVANCE: The results show that a prolonged tennis match play can modify values of shoulder ROM.
Marion Morel; Richard Kulpa; Anthony Sorel; Catherine Achard; Séverine Dubuisson
Automatic and Generic Evaluation of Spatial and Temporal Errors in Sport Motions Proceedings Article
In: Proceedings of the 11th Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 3: VISAPP, pp. 542-551, Roma, Italy, 2016, ISBN: 978-989-758-175-5.
Abstract | Links/Paper | BibTeX
@inproceedings{Morel2016,
title = {Automatic and Generic Evaluation of Spatial and Temporal Errors in Sport Motions},
author = {Marion Morel and Richard Kulpa and Anthony Sorel and Catherine Achard and Séverine Dubuisson},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2016_Morel_VISAPP.pdf},
doi = {10.5220/0005778505420551},
isbn = {978-989-758-175-5},
year = {2016},
date = {2016-01-01},
booktitle = {Proceedings of the 11th Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 3: VISAPP},
pages = {542-551},
address = {Roma, Italy},
abstract = {Automatically evaluating and quantifying the performance of a player is a complex task since the important motion features to analyze depend on the type of performed action. But above all, this complexity is due to the variability of morphologies and styles of both the experts who perform the reference motions and the novices. Only based on a database of experts' motions and no additional knowledge, we propose an innovative 2-level DTW (Dynamic Time Warping) approach to temporally and spatially align the motions and extract the imperfections of the novice's performance for each joints. In this study, we applied our method on tennis serve but since it is automatic and morphology-independent, it can be applied to any individual motor performance.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Automatically evaluating and quantifying the performance of a player is a complex task since the important motion features to analyze depend on the type of performed action. But above all, this complexity is due to the variability of morphologies and styles of both the experts who perform the reference motions and the novices. Only based on a database of experts' motions and no additional knowledge, we propose an innovative 2-level DTW (Dynamic Time Warping) approach to temporally and spatially align the motions and extract the imperfections of the novice's performance for each joints. In this study, we applied our method on tennis serve but since it is automatic and morphology-independent, it can be applied to any individual motor performance.
Sean D Lynch; Richard Kulpa; Laurentius Meerhoff; Armel Crétual; Julien Pettré; Anne-Hélène Olivier
Global Motion Provides Sufficient Information for Successful Collision Avoidance During a Locomotor Task Within Virtual Reality Proceedings Article
In: AFRV, 2016.
@inproceedings{Lynch2016,
title = {Global Motion Provides Sufficient Information for Successful Collision Avoidance During a Locomotor Task Within Virtual Reality},
author = {Sean D Lynch and Richard Kulpa and Laurentius Meerhoff and Armel Crétual and Julien Pettré and Anne-Hélène Olivier},
year = {2016},
date = {2016-01-01},
booktitle = {AFRV},
abstract = {Individuals present the ability of effectively interacting with static and dynamic obstacles with considerable adaptability. Daily interactions consist of individuals crossing paths during their commute, effectively navigating through a crowd without colliding with other commuters. The aim of this work was to distinguish whether local limb motion is required to successfully avoid a single dynamic obstacle or if global motion alone provides sufficient information. Sixteen healthy subjects were immersed in a virtual environment that required navigating towards a target, whilst an obstacle crossed its path. Within the virtual environment, four occluding walls prevented the subject observing the complete environment at the initiation of movement, ensuring steady state was reached prior to obstacle interaction. The velocity and heading of the obstacle were programmed to result in a range of minimal predicted distances at the moment of crossing (MPD, varying from 0.1 to 1.2m) in front and behind the subject. The velocity and heading of the obstacle were fixed, and the subject used a joystick to control its orientation to avoid collision. Five obstacle appearances were presented in a randomized order; a full body (control condition), trunk- or legs- only (i.e., local motion only), and a cylinder or sphere representing the center of gravity (COG) (i.e., global motion only). No significant difference for obstacle appearance was found on number of collisions. However, in both global motion only conditions, subjects adopted alternative collision avoidance strategies compared to the full body control condition. Distance regulation and collision avoidance within daily activities may be principally regulated by global rather than local motion. Underlying mechanisms may differ accordingly to shape and size, however there is no impediment for successful completion of collision avoidance.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Individuals present the ability of effectively interacting with static and dynamic obstacles with considerable adaptability. Daily interactions consist of individuals crossing paths during their commute, effectively navigating through a crowd without colliding with other commuters. The aim of this work was to distinguish whether local limb motion is required to successfully avoid a single dynamic obstacle or if global motion alone provides sufficient information. Sixteen healthy subjects were immersed in a virtual environment that required navigating towards a target, whilst an obstacle crossed its path. Within the virtual environment, four occluding walls prevented the subject observing the complete environment at the initiation of movement, ensuring steady state was reached prior to obstacle interaction. The velocity and heading of the obstacle were programmed to result in a range of minimal predicted distances at the moment of crossing (MPD, varying from 0.1 to 1.2m) in front and behind the subject. The velocity and heading of the obstacle were fixed, and the subject used a joystick to control its orientation to avoid collision. Five obstacle appearances were presented in a randomized order; a full body (control condition), trunk- or legs- only (i.e., local motion only), and a cylinder or sphere representing the center of gravity (COG) (i.e., global motion only). No significant difference for obstacle appearance was found on number of collisions. However, in both global motion only conditions, subjects adopted alternative collision avoidance strategies compared to the full body control condition. Distance regulation and collision avoidance within daily activities may be principally regulated by global rather than local motion. Underlying mechanisms may differ accordingly to shape and size, however there is no impediment for successful completion of collision avoidance.
Richard Kulpa
La réalité virtuelle au service de lánalyse des interactions sportives Conference
Mathématiques et Sport, Paris, 2016.
@conference{Kulpa2016,
title = {La réalité virtuelle au service de lánalyse des interactions sportives},
author = {Richard Kulpa},
year = {2016},
date = {2016-00-01},
booktitle = {Mathématiques et Sport},
address = {Paris},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
2015
Richard Kulpa; Franck Multon; Ferran Argelaguet
Virtual Reality and Sports Proceedings Article
In: 33e International Conference of Biomechanics in Sports, ISBS, Poitiers, France, 2015, ISSN: 1999-4168.
Abstract | Links/Paper | BibTeX
@inproceedings{Kulpa2015,
title = {Virtual Reality and Sports},
author = {Richard Kulpa and Franck Multon and Ferran Argelaguet},
url = {https://ojs.ub.uni-konstanz.de/cpa/article/view/6694},
issn = {1999-4168},
year = {2015},
date = {2015-01-01},
booktitle = {33e International Conference of Biomechanics in Sports, ISBS},
address = {Poitiers, France},
abstract = {This applied session deals with the design of immersive environments for human motion performance analysis. In a first part of the session, a theoretical presentation describes the aims and scopes of such type of experiments. In a second part of the session, a review of the available immersive systems will be exposed. Finally, a practical framework will be designed in real-time with the attendees: a low-cost immersive environment based on a Microsoft Kinect, a Razer Hydra and an Oculus Rift Head Mounted Display device. We will develop an experiment to analyse perception-action coupling in soccer with simulated virtual opponents enabling to analyse the decision-making of a real goalkeeper.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
This applied session deals with the design of immersive environments for human motion performance analysis. In a first part of the session, a theoretical presentation describes the aims and scopes of such type of experiments. In a second part of the session, a review of the available immersive systems will be exposed. Finally, a practical framework will be designed in real-time with the attendees: a low-cost immersive environment based on a Microsoft Kinect, a Razer Hydra and an Oculus Rift Head Mounted Display device. We will develop an experiment to analyse perception-action coupling in soccer with simulated virtual opponents enabling to analyse the decision-making of a real goalkeeper.
Caroline Martin; Benoit Bideau; Paul Delamarche; Richard Kulpa
Influence of a prolonged tennis match play on serve biomechanics Proceedings Article
In: ISBS (International Society of Biomechanics in Sports), Poitiers, France, 2015, ISSN: 1999-4168.
Abstract | Links/Paper | BibTeX
@inproceedings{Martin2015,
title = {Influence of a prolonged tennis match play on serve biomechanics},
author = {Caroline Martin and Benoit Bideau and Paul Delamarche and Richard
Kulpa},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2015_Martin_ISBS.pdf},
issn = {1999-4168},
year = {2015},
date = {2015-01-01},
booktitle = {ISBS (International Society of Biomechanics in Sports)},
address = {Poitiers, France},
abstract = {The aim of this study was to quantify biomechanical changes that occur in the serve throughout a prolonged tennis match. Serves of tennis players were recorded with a motion capture system before (T0) during (T90), and after (T180) a 3-hour match. Before and after each match, EMG data of upper limb muscles were analyzed to determine the presence of muscular fatigue. RPE and ball velocity and biomechanical variables were analyzed. Decreases in ball velocity; maximal angular velocities and increase in RPE were observed. The majority of the upper limb joint kinetics decreases between T0 and T180. No change in timing of maximal angular velocities was observed. A prolonged tennis match induces fatigue in upper limb muscles, which decreases performance and modifies serve biomechanics.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The aim of this study was to quantify biomechanical changes that occur in the serve throughout a prolonged tennis match. Serves of tennis players were recorded with a motion capture system before (T0) during (T90), and after (T180) a 3-hour match. Before and after each match, EMG data of upper limb muscles were analyzed to determine the presence of muscular fatigue. RPE and ball velocity and biomechanical variables were analyzed. Decreases in ball velocity; maximal angular velocities and increase in RPE were observed. The majority of the upper limb joint kinetics decreases between T0 and T180. No change in timing of maximal angular velocities was observed. A prolonged tennis match induces fatigue in upper limb muscles, which decreases performance and modifies serve biomechanics.
Kristell Pothier; Nicolas Benguigui; Richard Kulpa; Chantal Chavoix
Multiple Object Tracking While Walking: Similarities and Differences Between Young, Young-Old, and Old-Old Adults Journal Article
In: The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, vol. 70, no. 6, pp. 840-849, 2015.
Abstract | Links/Paper | BibTeX
@article{Pothier2015,
title = {Multiple Object Tracking While Walking: Similarities and Differences Between Young, Young-Old, and Old-Old Adults},
author = {Kristell Pothier and Nicolas Benguigui and Richard Kulpa and Chantal Chavoix},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2015_Pothier_JG.pdf},
doi = {10.1093/geronb/gbu047},
year = {2015},
date = {2015-01-01},
journal = {The Journals of Gerontology Series B: Psychological Sciences and Social Sciences},
volume = {70},
number = {6},
pages = {840-849},
abstract = {Objective. Walking while simultaneously engaged in another activity becomes more difficult as one grows older. Here, we address the issue of changes in dual-task behavior at different stages of life, particularly in the latter stages.Methods. We developed a dual task that combined walking along an 8-m walkway with a multiple object tracking (MOT) task of increasing difficulty. This secondary cognitive task imitates visuospatial daily activities and provides reliable quantitative measurements. Our dual-task paradigm was tested on 27 young adults (23.85±2.09 years old) and two groups of older adults (18 young-old and 18 old-old adults, aged 63.89±3.32 and 80.83±3.84 years, respectively).Results. Significant decrease in tracking performance with increasing complexity of the MOT task was found in all three groups. An age-related decrease in MOT and gait performance was also found. However, young-old adults performed as well as young adults under low attentional load conditions (in the MOT task and simple walking), whereas their performance was as impaired as those of old-old adults under high attentional load conditions (in the MOT task and walking under dual-task condition).Discussion. These different profiles between the two groups of older participants could be explained in terms of compensation strategies and risk of falling.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Objective. Walking while simultaneously engaged in another activity becomes more difficult as one grows older. Here, we address the issue of changes in dual-task behavior at different stages of life, particularly in the latter stages.Methods. We developed a dual task that combined walking along an 8-m walkway with a multiple object tracking (MOT) task of increasing difficulty. This secondary cognitive task imitates visuospatial daily activities and provides reliable quantitative measurements. Our dual-task paradigm was tested on 27 young adults (23.85±2.09 years old) and two groups of older adults (18 young-old and 18 old-old adults, aged 63.89±3.32 and 80.83±3.84 years, respectively).Results. Significant decrease in tracking performance with increasing complexity of the MOT task was found in all three groups. An age-related decrease in MOT and gait performance was also found. However, young-old adults performed as well as young adults under low attentional load conditions (in the MOT task and simple walking), whereas their performance was as impaired as those of old-old adults under high attentional load conditions (in the MOT task and walking under dual-task condition).Discussion. These different profiles between the two groups of older participants could be explained in terms of compensation strategies and risk of falling.
Nicolas Vignais; Richard Kulpa; Sébastien Brault; Damien Presse; Benoit Bideau
Which technology to investigate visual perception in sport: Video vs. virtual reality Journal Article
In: Human Movement Science, vol. 39, pp. 12 - 26, 2015, ISSN: 0167-9457.
@article{Vignais2015,
title = {Which technology to investigate visual perception in sport: Video vs. virtual reality},
author = {Nicolas Vignais and Richard Kulpa and Sébastien Brault and Damien Presse and Benoit Bideau},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2015_Vignais_HMS.pdf},
doi = {http://dx.doi.org/10.1016/j.humov.2014.10.006},
issn = {0167-9457},
year = {2015},
date = {2015-01-01},
journal = {Human Movement Science},
volume = {39},
pages = {12 - 26},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sébastien Brault; Richard Kulpa; Laouen Duliscouët; Antoine Marin; Benoit Bideau
Virtual kicker vs. real goalkeeper in soccer: a way to explore goalkeeper’s performance Journal Article
In: Movement & Sport Sciences / Science & Motricité, no. 89, pp. 79-88, 2015.
Abstract | Links/Paper | BibTeX
@article{Brault2015,
title = {Virtual kicker vs. real goalkeeper in soccer: a way to explore goalkeeper’s performance},
author = {Sébastien} {Brault and Richard} {Kulpa and Laouen} {Duliscouët and Antoine} {Marin and Benoit} {Bideau},
url = {http://dx.doi.org/10.1051/sm/2015026},
doi = {10.1051/sm/2015026},
year = {2015},
date = {2015-01-01},
journal = {Movement & Sport Sciences / Science & Motricité},
number = {89},
pages = {79-88},
abstract = {The purpose of this study is to propose an original methodology to study the action of a goalkeeper facing a free kick. This methodology is based on a virtual reality setup in which a real goalkeeper is facing a virtual player and a virtual defensive wall. The setup has been improved to provide a total freedom of movement to the goalkeeper in order to have a realistic interaction between the goalkeeper and the player. The goalkeeper's movements are captured in real-time to accurately analyze his reactions. Such a methodology not only represents a valuable research tool but also provides a relevant training tool. Using this setup, this paper shows that goalkeepers are more performant during free kick with a wall composed of 5 defenders whatever its position.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The purpose of this study is to propose an original methodology to study the action of a goalkeeper facing a free kick. This methodology is based on a virtual reality setup in which a real goalkeeper is facing a virtual player and a virtual defensive wall. The setup has been improved to provide a total freedom of movement to the goalkeeper in order to have a realistic interaction between the goalkeeper and the player. The goalkeeper's movements are captured in real-time to accurately analyze his reactions. Such a methodology not only represents a valuable research tool but also provides a relevant training tool. Using this setup, this paper shows that goalkeepers are more performant during free kick with a wall composed of 5 defenders whatever its position.
Marion Morel; Benoit Bideau; Julien Lardy; Richard Kulpa
Advantages and limitations of virtual reality for balance assessment and rehabilitation Journal Article
In: Neurophysiologie Clinique/Clinical Neurophysiology, vol. 45, no. 4–5, pp. 315 - 326, 2015, ISSN: 0987-7053, (Special issue : Balance and Gait).
Abstract | Links/Paper | BibTeX
@article{Morel2015,
title = {Advantages and limitations of virtual reality for balance assessment and rehabilitation},
author = {Marion Morel and Benoit Bideau and Julien Lardy and Richard Kulpa},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2015_Morel_CN.pdf},
doi = {http://dx.doi.org/10.1016/j.neucli.2015.09.007},
issn = {0987-7053},
year = {2015},
date = {2015-01-01},
journal = {Neurophysiologie Clinique/Clinical Neurophysiology},
volume = {45},
number = {4–5},
pages = {315 - 326},
abstract = {Summary Virtual reality (VR) is now commonly used in many domains because of its ability to provide a standardized, reproducible and controllable environment. In balance assessment, it can be used to control stimuli presented to patients and thus accurately evaluate their progression or compare them to different populations in standardized situations. In balance rehabilitation, VR allows the creation of new generation tools and at the same time the means to assess the efficiency of each parameter of these tools in order to optimize them. Moreover, with the development of low-cost devices, this rehabilitation can be continued at home, making access to these tools much easier, in addition to their entertaining and thus motivating properties. Nevertheless, and even more with low-cost systems, VR has limits that can alter the results of the studies that use it: the latency of the system (the delay cumulated on each step of the process from data acquisition on the patients to multimodal outputs); and distance perception, which tends to be underestimated in VR. After having described why VR is an essential tool for balance assessment and rehabilitation and illustrated this statement with a case study, this review discusses the previous works in the domain with regards to the technological limits of VR.},
note = {Special issue : Balance and Gait},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Summary Virtual reality (VR) is now commonly used in many domains because of its ability to provide a standardized, reproducible and controllable environment. In balance assessment, it can be used to control stimuli presented to patients and thus accurately evaluate their progression or compare them to different populations in standardized situations. In balance rehabilitation, VR allows the creation of new generation tools and at the same time the means to assess the efficiency of each parameter of these tools in order to optimize them. Moreover, with the development of low-cost devices, this rehabilitation can be continued at home, making access to these tools much easier, in addition to their entertaining and thus motivating properties. Nevertheless, and even more with low-cost systems, VR has limits that can alter the results of the studies that use it: the latency of the system (the delay cumulated on each step of the process from data acquisition on the patients to multimodal outputs); and distance perception, which tends to be underestimated in VR. After having described why VR is an essential tool for balance assessment and rehabilitation and illustrated this statement with a case study, this review discusses the previous works in the domain with regards to the technological limits of VR.
2014
Caroline Martin; Benoit Bideau; Nicolas Bideau; Guillaume Nicolas; Paul Delamarche; Richard Kulpa
Energy flow during the tennis serve: comparison between injured and non-injured tennis players. Journal Article
In: American Journal of Sports Medicine, vol. 42, no. 11, pp. 2751-2760, 2014.
Abstract | Links/Paper | BibTeX
@article{Martin2014,
title = {Energy flow during the tennis serve: comparison between injured and
non-injured tennis players.},
author = {Caroline Martin and Benoit Bideau and Nicolas Bideau and Guillaume Nicolas and Paul Delamarche and Richard Kulpa},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2014_Martin_AJSM.pdf},
doi = {10.1177/0363546514547173},
year = {2014},
date = {2014-01-01},
journal = {American Journal of Sports Medicine},
volume = {42},
number = {11},
pages = {2751-2760},
abstract = {Background:Energy flow has been hypothesized to be one of the most critical biomechanical concepts related to tennis performance and overuse injuries. However, the relationships among energy flow during the tennis serve, ball velocity, and overuse injuries have not been assessed.Purpose:To investigate the relationships among the quality and magnitude of energy flow, the ball velocity, and the peaks of upper limb joint kinetics and to compare the energy flow during the serve between injured and noninjured tennis players.Study Design:Case-control study; Level of evidence, 3.Methods:The serves of expert tennis players were recorded with an optoelectronic motion capture system. The forces and torques of the upper limb joints were calculated from the motion captures by use of inverse dynamics. The amount of mechanical energy generated, absorbed, and transferred was determined by use of a joint power analysis. Then the players were followed during 2 seasons to identify upper limb overuse injuries with a questionnaire. Finally, players were classified into 2 groups according to the questionnaire results: injured or noninjured.Results:Ball velocity increased and upper limb joint kinetics decreased with the quality of energy flow from the trunk to the hand + racket segment. Injured players showed a lower quality of energy flow through the upper limb kinetic chain, a lower ball velocity, and higher rates of energy absorbed by the shoulder and elbow compared with noninjured players.Conclusion:The findings of this study imply that improper energy flow during the tennis serve can decrease ball velocity, increase upper limb joint kinetics, and thus increase overuse injuries of the upper limb joints.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Background:Energy flow has been hypothesized to be one of the most critical biomechanical concepts related to tennis performance and overuse injuries. However, the relationships among energy flow during the tennis serve, ball velocity, and overuse injuries have not been assessed.Purpose:To investigate the relationships among the quality and magnitude of energy flow, the ball velocity, and the peaks of upper limb joint kinetics and to compare the energy flow during the serve between injured and noninjured tennis players.Study Design:Case-control study; Level of evidence, 3.Methods:The serves of expert tennis players were recorded with an optoelectronic motion capture system. The forces and torques of the upper limb joints were calculated from the motion captures by use of inverse dynamics. The amount of mechanical energy generated, absorbed, and transferred was determined by use of a joint power analysis. Then the players were followed during 2 seasons to identify upper limb overuse injuries with a questionnaire. Finally, players were classified into 2 groups according to the questionnaire results: injured or noninjured.Results:Ball velocity increased and upper limb joint kinetics decreased with the quality of energy flow from the trunk to the hand + racket segment. Injured players showed a lower quality of energy flow through the upper limb kinetic chain, a lower ball velocity, and higher rates of energy absorbed by the shoulder and elbow compared with noninjured players.Conclusion:The findings of this study imply that improper energy flow during the tennis serve can decrease ball velocity, increase upper limb joint kinetics, and thus increase overuse injuries of the upper limb joints.
Caroline Martin; Benoit Bideau; Mickael Ropars; Paul Delamarche; Richard Kulpa
Upper limb joint kinetic analysis during tennis serve: Assessment of competitive level on efficiency and injury risks Journal Article
In: Scandinavian Journal of Medicine & Science in Sports, vol. 24, no. 4, pp. 700–707, 2014, ISSN: 1600-0838.
Abstract | Links/Paper | BibTeX
@article{Martin2014a,
title = {Upper limb joint kinetic analysis during tennis serve: Assessment of competitive level on efficiency and injury risks},
author = {Caroline Martin and Benoit Bideau and Mickael Ropars and Paul Delamarche and Richard Kulpa},
url = {http://dx.doi.org/10.1111/sms.12043},
doi = {10.1111/sms.12043},
issn = {1600-0838},
year = {2014},
date = {2014-01-01},
journal = {Scandinavian Journal of Medicine & Science in Sports},
volume = {24},
number = {4},
pages = {700--707},
abstract = {The aim of this work was to compare the joint kinetics and stroke production efficiency for the shoulder, elbow, and wrist during the serve between professionals and advanced tennis players and to discuss their potential relationship with given overuse injuries. Eleven professional and seven advanced tennis players were studied with an optoelectronic motion analysis system while performing serves. Normalized peak kinetic values of the shoulder, elbow, and wrist joints were calculated using inverse dynamics. To measure serve efficiency, all normalized peak kinetic values were divided by ball velocity. t-tests were used to determine significant differences between the resultant joint kinetics and efficiency values in both groups (advanced vs professional). Shoulder inferior force, shoulder anterior force, shoulder horizontal abduction torque, and elbow medial force were significantly higher in advanced players. Professional players were more efficient than advanced players, as they maximize ball velocity with lower joint kinetics. Since advanced players are subjected to higher joint kinetics, the results suggest that they appeared more susceptible to high risk of shoulder and elbow injuries than professionals, especially during the cocking and deceleration phases of the serve.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of this work was to compare the joint kinetics and stroke production efficiency for the shoulder, elbow, and wrist during the serve between professionals and advanced tennis players and to discuss their potential relationship with given overuse injuries. Eleven professional and seven advanced tennis players were studied with an optoelectronic motion analysis system while performing serves. Normalized peak kinetic values of the shoulder, elbow, and wrist joints were calculated using inverse dynamics. To measure serve efficiency, all normalized peak kinetic values were divided by ball velocity. t-tests were used to determine significant differences between the resultant joint kinetics and efficiency values in both groups (advanced vs professional). Shoulder inferior force, shoulder anterior force, shoulder horizontal abduction torque, and elbow medial force were significantly higher in advanced players. Professional players were more efficient than advanced players, as they maximize ball velocity with lower joint kinetics. Since advanced players are subjected to higher joint kinetics, the results suggest that they appeared more susceptible to high risk of shoulder and elbow injuries than professionals, especially during the cocking and deceleration phases of the serve.
Richard Kulpa
L'humain virtuel au service de la performance sportive : de l'analyse des duels sportifs vers l'entraînement en environnement virtuel Habilitation à Diriger des Recherches (HDR)
2014.
@Habilitation à Diriger des Recherches (HDR){Kulpa2014,
title = {L'humain virtuel au service de la performance sportive : de l'analyse des duels sportifs vers l'entraînement en environnement virtuel},
author = {Richard Kulpa},
year = {2014},
date = {2014-01-01},
school = {Université Rennes 2},
keywords = {},
pubstate = {published},
tppubtype = {Habilitation à Diriger des Recherches (HDR)}
}
2013
C Martin; R Kulpa; M Ropars; P Delamarche; B Bideau
Identification of Temporal Pathomechanical Factors during the Tennis Serve. Journal Article
In: Medicine & Science in Sports & Exercise, 2013.
Abstract | Links/Paper | BibTeX
@article{Martin2013,
title = {Identification of Temporal Pathomechanical Factors during the Tennis
Serve.},
author = {C Martin and R Kulpa and M Ropars and P Delamarche and B Bideau},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23657170},
doi = {10.1249/MSS.0b013e318299ae3b},
year = {2013},
date = {2013-05-01},
journal = {Medicine & Science in Sports & Exercise},
abstract = {PURPOSE:
The purposes of this study were twofold: (a) measure the effects of
temporal parameters on both ball velocity and upper limb joint kinetics
in order to identify pathomechanical factors during the tennis serve;
and (b) validate these pathomechanical factors by comparing injured
and non-injured players.
METHODS:
Serves of expert tennis players were recorded with an optoelectronic
motion capture system. These experts were then followed during 2
seasons to identify overuse upper limb injuries. Correlation coefficients
assessed the relationships between temporal parameters, ball velocity
and peaks of upper limb joint kinetics to identify pathomechanical
factors. Temporal parameters and ball velocity were compared between
injured and non-injured groups.
RESULTS:
Temporal pathomechanical factors were identified. The timings of peak
angular velocities of pelvis longitudinal rotation, upper torso longitudinal
rotation, trunk sagittal rotation, trunk transverse rotation, and
the duration between instants of shoulder horizontal adduction and
external rotation were significantly related to upper limb joint
kinetics and ball velocity. Injured players demonstrated later timings
of trunk rotations, improper differences in time between instants
of shoulder horizontal adduction and external rotation, lower ball
velocities and higher joint kinetics.
CONCLUSION:
The findings of this study imply that improper temporal mechanics
during the tennis serve can decrease ball velocity, increase upper
limb joint kinetics, and thus possibly increase injuries of overuse
upper limb.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
PURPOSE:
The purposes of this study were twofold: (a) measure the effects of
temporal parameters on both ball velocity and upper limb joint kinetics
in order to identify pathomechanical factors during the tennis serve;
and (b) validate these pathomechanical factors by comparing injured
and non-injured players.
METHODS:
Serves of expert tennis players were recorded with an optoelectronic
motion capture system. These experts were then followed during 2
seasons to identify overuse upper limb injuries. Correlation coefficients
assessed the relationships between temporal parameters, ball velocity
and peaks of upper limb joint kinetics to identify pathomechanical
factors. Temporal parameters and ball velocity were compared between
injured and non-injured groups.
RESULTS:
Temporal pathomechanical factors were identified. The timings of peak
angular velocities of pelvis longitudinal rotation, upper torso longitudinal
rotation, trunk sagittal rotation, trunk transverse rotation, and
the duration between instants of shoulder horizontal adduction and
external rotation were significantly related to upper limb joint
kinetics and ball velocity. Injured players demonstrated later timings
of trunk rotations, improper differences in time between instants
of shoulder horizontal adduction and external rotation, lower ball
velocities and higher joint kinetics.
CONCLUSION:
The findings of this study imply that improper temporal mechanics
during the tennis serve can decrease ball velocity, increase upper
limb joint kinetics, and thus possibly increase injuries of overuse
upper limb.
The purposes of this study were twofold: (a) measure the effects of
temporal parameters on both ball velocity and upper limb joint kinetics
in order to identify pathomechanical factors during the tennis serve;
and (b) validate these pathomechanical factors by comparing injured
and non-injured players.
METHODS:
Serves of expert tennis players were recorded with an optoelectronic
motion capture system. These experts were then followed during 2
seasons to identify overuse upper limb injuries. Correlation coefficients
assessed the relationships between temporal parameters, ball velocity
and peaks of upper limb joint kinetics to identify pathomechanical
factors. Temporal parameters and ball velocity were compared between
injured and non-injured groups.
RESULTS:
Temporal pathomechanical factors were identified. The timings of peak
angular velocities of pelvis longitudinal rotation, upper torso longitudinal
rotation, trunk sagittal rotation, trunk transverse rotation, and
the duration between instants of shoulder horizontal adduction and
external rotation were significantly related to upper limb joint
kinetics and ball velocity. Injured players demonstrated later timings
of trunk rotations, improper differences in time between instants
of shoulder horizontal adduction and external rotation, lower ball
velocities and higher joint kinetics.
CONCLUSION:
The findings of this study imply that improper temporal mechanics
during the tennis serve can decrease ball velocity, increase upper
limb joint kinetics, and thus possibly increase injuries of overuse
upper limb.
Annick Durny; Anne-Marie Burns; Richard Kulpa; Franck Multon
Rendre compte de léxpérience utilisateur dans un environnement virtuel pour lápprentissage de gestes de karaté. Conference
ACAPS (Association des Chercheurs en Activités Physiques et Sportives), Grenoble, France, 2013.
@conference{Durny2013,
title = {Rendre compte de léxpérience utilisateur dans un environnement virtuel
pour lápprentissage de gestes de karaté.},
author = {Annick Durny and Anne-Marie Burns and Richard Kulpa and Franck Multon},
year = {2013},
date = {2013-01-01},
booktitle = {ACAPS (Association des Chercheurs en Activités Physiques et Sportives)},
address = {Grenoble, France},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Caroline Martin; Richard Kulpa; Paul Delamarche; Benoit Bideau
Professional tennis players' serve: correlation between segmental angular momentums and ball velocity Journal Article
In: Sports Biomechanics, vol. 12, no. 1, pp. 2-14, 2013.
Abstract | Links/Paper | BibTeX
@article{Martin2013a,
title = {Professional tennis players' serve: correlation between segmental angular momentums and ball velocity},
author = {Caroline Martin and Richard Kulpa and Paul Delamarche and Benoit Bideau},
url = {http://dx.doi.org/10.1080/14763141.2012.734321},
doi = {10.1080/14763141.2012.734321},
year = {2013},
date = {2013-01-01},
journal = {Sports Biomechanics},
volume = {12},
number = {1},
pages = {2-14},
abstract = {The purpose of the study was to identify the relationships between segmental angular momentum and ball velocity between the following events: ball toss, maximal elbow flexion (MEF), racket lowest point (RLP), maximal shoulder external rotation (MER), and ball impact (BI). Ten tennis players performed serves recorded with a real-time motion capture. Mean angular momentums of the trunk, upper arm, forearm, and the hand-racket were calculated. The anteroposterior axis angular momentum of the trunk was significantly related with ball velocity during the MEF–RLP, RLP–MER, and MER–BI phases. The strongest relationships between the transverse-axis angular momentums and ball velocity followed a proximal-to-distal timing sequence that allows the transfer of angular momentum from the trunk (MEF–RLP and RLP–MER phases) to the upper arm (RLP–MER phase), forearm (RLP–MER and MER–BI phases), and the hand-racket (MER–BI phase). Since sequence is crucial for ball velocity, players should increase angular momentums of the trunk during MEF–MER, upper arm during RLP–MER, forearm during RLP–BI, and the hand-racket during MER–BI.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The purpose of the study was to identify the relationships between segmental angular momentum and ball velocity between the following events: ball toss, maximal elbow flexion (MEF), racket lowest point (RLP), maximal shoulder external rotation (MER), and ball impact (BI). Ten tennis players performed serves recorded with a real-time motion capture. Mean angular momentums of the trunk, upper arm, forearm, and the hand-racket were calculated. The anteroposterior axis angular momentum of the trunk was significantly related with ball velocity during the MEF–RLP, RLP–MER, and MER–BI phases. The strongest relationships between the transverse-axis angular momentums and ball velocity followed a proximal-to-distal timing sequence that allows the transfer of angular momentum from the trunk (MEF–RLP and RLP–MER phases) to the upper arm (RLP–MER phase), forearm (RLP–MER and MER–BI phases), and the hand-racket (MER–BI phase). Since sequence is crucial for ball velocity, players should increase angular momentums of the trunk during MEF–MER, upper arm during RLP–MER, forearm during RLP–BI, and the hand-racket during MER–BI.
Anthony Sorel; Richard Kulpa; Emmanuel Badier; Franck Multon
Dealing with variability when recognizing user's performance in natural 3D gesture interfaces Journal Article
In: International Journal of Pattern Recognition and Artificial Intelligence, vol. 27, no. 08, pp. 1350023, 2013.
Abstract | Links/Paper | BibTeX
@article{Sorel2013,
title = {Dealing with variability when recognizing user's performance in natural 3D gesture interfaces},
author = {Anthony Sorel and Richard Kulpa and Emmanuel Badier and Franck Multon},
url = {http://www.worldscientific.com/doi/abs/10.1142/S0218001413500237},
doi = {10.1142/S0218001413500237},
year = {2013},
date = {2013-01-01},
journal = {International Journal of Pattern Recognition and Artificial Intelligence},
volume = {27},
number = {08},
pages = {1350023},
abstract = {Recognition of natural gestures is a key issue in many applications including videogames and other immersive applications. Whatever is the motion capture device, the key problem is to recognize a motion that could be performed by a range of different users, at an interactive frame rate. Hidden Markov Models (HMM) that are commonly used to recognize the performance of a user however rely on a motion representation that strongly affects the overall recognition rate of the system. In this paper, we propose to use a compact motion representation based on Morphology-Independent features and we evaluate its performance compared to classical representations. When dealing with 15 very similar upper limb motions, HMM based on Morphology-Independent features yield significantly higher recognition rate (84.9%) than classical Cartesian or angular data (70.4% and 55.0%, respectively). Moreover, when the unknown motions are performed by a large number of users who have never contributed to the learning process, the recognition rate of Morphology-Independent input feature only decreases slightly (down to 68.2% for a HMM trained with the motions of only one subject) compared to other features (25.3% for Cartesian features and 17.8% for angular features in the same conditions). The method is illustrated through an interactive demo in which three virtual humans have to interactively recognize and replay the performance of the user. Each virtual human is associated with a HMM recognizer based on the three different input features.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recognition of natural gestures is a key issue in many applications including videogames and other immersive applications. Whatever is the motion capture device, the key problem is to recognize a motion that could be performed by a range of different users, at an interactive frame rate. Hidden Markov Models (HMM) that are commonly used to recognize the performance of a user however rely on a motion representation that strongly affects the overall recognition rate of the system. In this paper, we propose to use a compact motion representation based on Morphology-Independent features and we evaluate its performance compared to classical representations. When dealing with 15 very similar upper limb motions, HMM based on Morphology-Independent features yield significantly higher recognition rate (84.9%) than classical Cartesian or angular data (70.4% and 55.0%, respectively). Moreover, when the unknown motions are performed by a large number of users who have never contributed to the learning process, the recognition rate of Morphology-Independent input feature only decreases slightly (down to 68.2% for a HMM trained with the motions of only one subject) compared to other features (25.3% for Cartesian features and 17.8% for angular features in the same conditions). The method is illustrated through an interactive demo in which three virtual humans have to interactively recognize and replay the performance of the user. Each virtual human is associated with a HMM recognizer based on the three different input features.
Richard Kulpa; Benoit Bideau; Sébastien Brault
Displacements in Virtual Reality for Sports Performance Analysis Book Chapter
In: Steinicke, Frank; Visell, Yon; Campos, Jennifer; Lécuyer, Anatole (Ed.): Human Walking in Virtual Environments: Perception, Technology, and Applications, pp. 299–318, Springer New York, New York, NY, 2013, ISBN: 978-1-4419-8432-6.
Abstract | Links/Paper | BibTeX
@inbook{Kulpa2013,
title = {Displacements in Virtual Reality for Sports Performance Analysis},
author = {Richard Kulpa and Benoit Bideau and Sébastien Brault},
editor = {Frank Steinicke and Yon Visell and Jennifer Campos and Anatole Lécuyer},
url = {http://dx.doi.org/10.1007/978-1-4419-8432-6_13},
doi = {10.1007/978-1-4419-8432-6_13},
isbn = {978-1-4419-8432-6},
year = {2013},
date = {2013-01-01},
booktitle = {Human Walking in Virtual Environments: Perception, Technology, and Applications},
pages = {299--318},
publisher = {Springer New York},
address = {New York, NY},
abstract = {In real situations, analyzing the contribution of different parameters on sports performance is a difficult task. In a duel for example, an athlete needs to anticipate his opponent’s actions to win. To evaluate the relationship between perception and action in such a duel, the parameters used to anticipate the opponent’s action must then be determined. Only a fully standardized and controllable environment such as virtual reality can allow this analysis. Nevertheless, movement is inherent in sports and only a system providing a complete freedom of movements of the immersed subject (including displacements) would allow the study of the link between visual information uptake and action, that is related to performance. Two case studies are described to illustrate such use of virtual reality to better understand sports performance. Finally, we discuss how the introduction of new displacement devices can extend the range of applications in sports.},
keywords = {},
pubstate = {published},
tppubtype = {inbook}
}
In real situations, analyzing the contribution of different parameters on sports performance is a difficult task. In a duel for example, an athlete needs to anticipate his opponent’s actions to win. To evaluate the relationship between perception and action in such a duel, the parameters used to anticipate the opponent’s action must then be determined. Only a fully standardized and controllable environment such as virtual reality can allow this analysis. Nevertheless, movement is inherent in sports and only a system providing a complete freedom of movements of the immersed subject (including displacements) would allow the study of the link between visual information uptake and action, that is related to performance. Two case studies are described to illustrate such use of virtual reality to better understand sports performance. Finally, we discuss how the introduction of new displacement devices can extend the range of applications in sports.
2012
Anton Nijholt; Ronald C Arkin; Sébastien Brault; Richard Kulpa; Franck Multon; Benoit Bideau; David Traum; Hayley Hung; Eugene Santos Jr.; Deqing Li; Fei Yu; Lina Zhou; Dongsong Zhang
Trends & Controversies. Computational Deception and Noncooperation Journal Article
In: Intelligent Systems, IEEE, vol. 27, no. 6, pp. 60-75, 2012, ISSN: 1541-1672.
Abstract | Links/Paper | BibTeX
@article{Nijholt2012,
title = {Trends & Controversies. Computational Deception and Noncooperation},
author = {Anton Nijholt and Ronald C Arkin and Sébastien Brault and Richard Kulpa and Franck Multon and Benoit Bideau and David Traum and Hayley Hung and Eugene Santos Jr. and Deqing Li and Fei Yu and Lina Zhou and Dongsong Zhang},
doi = {10.1109/MIS.2012.116},
issn = {1541-1672},
year = {2012},
date = {2012-11-01},
journal = {Intelligent Systems, IEEE},
volume = {27},
number = {6},
pages = {60-75},
abstract = {Many applications require knowledge about how to deceive, including those related to safety, security, and warfare. Speech and text analysis can help detect deception, as can cameras, microphones, physiological sensors, and intelligent software. Models of deception and noncooperation can make a virtual or mixed-reality training environment more realistic, improve immersion, and thus make it more suitable for training military or security personnel. Robots might need to operate in physical and nontraining environments where they must perform military activity, including misleading the enemy. The contributions to this installment of Trends & Controversies present state-of-the-art research approaches to the analysis and generation of noncooperative and deceptive behavior in virtual humans, agents, and robots; the analysis of multiparty interaction in the context of deceptive behavior; and methods to detect misleading information in texts and computer-mediated communication. Articles include: Computational Deception and Noncooperation, by Anton Nijholt; Robots that Need to Mislead: Biologically-Inspired Machine Deception, by Ronald C. Arkin; Deception in Sports Using Immersive Environments, by Sébastien Brault, Richard Kulpa, Franck Multon, and Benoit Bideau; Non-Cooperative and Deceptive Virtual Agents, by David Traum; Deception Detection in Multiparty Contexts, by Hayley Hung; Deception Detection, Human Reasoning, and Deception Intent, by Eugene Santos Jr., Deqing Li, and Fei Yu; Automatic Deception Detection in Computer-Mediated Communication by Lina Zhou and Dongsong Zhang.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Many applications require knowledge about how to deceive, including those related to safety, security, and warfare. Speech and text analysis can help detect deception, as can cameras, microphones, physiological sensors, and intelligent software. Models of deception and noncooperation can make a virtual or mixed-reality training environment more realistic, improve immersion, and thus make it more suitable for training military or security personnel. Robots might need to operate in physical and nontraining environments where they must perform military activity, including misleading the enemy. The contributions to this installment of Trends & Controversies present state-of-the-art research approaches to the analysis and generation of noncooperative and deceptive behavior in virtual humans, agents, and robots; the analysis of multiparty interaction in the context of deceptive behavior; and methods to detect misleading information in texts and computer-mediated communication. Articles include: Computational Deception and Noncooperation, by Anton Nijholt; Robots that Need to Mislead: Biologically-Inspired Machine Deception, by Ronald C. Arkin; Deception in Sports Using Immersive Environments, by Sébastien Brault, Richard Kulpa, Franck Multon, and Benoit Bideau; Non-Cooperative and Deceptive Virtual Agents, by David Traum; Deception Detection in Multiparty Contexts, by Hayley Hung; Deception Detection, Human Reasoning, and Deception Intent, by Eugene Santos Jr., Deqing Li, and Fei Yu; Automatic Deception Detection in Computer-Mediated Communication by Lina Zhou and Dongsong Zhang.
C Martin; Richard Kulpa; Benoit Bideau; Paul Delamarche
Joint kinetic comparison of the tennis serve among various playing levels Conference
20th International Congress on Sports Sciences for Students, Budapest, 2012.
@conference{Martin2012a,
title = {Joint kinetic comparison of the tennis serve among various playing
levels},
author = {C Martin and Richard Kulpa and Benoit Bideau and Paul Delamarche},
year = {2012},
date = {2012-04-01},
booktitle = {20th International Congress on Sports Sciences for Students},
address = {Budapest},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
C Appert-Rolland; A Jelic; P Degond; J Fehrenbach; J Hua; A Cretual; R Kulpa; A Marin; A -H Olivier; S Lemercier; J Pettré
Experimental Study of the Following Dynamics of Pedestrians Journal Article
In: Pedestrian and Evacuation Dynamics 2012, pp. 305-315, 2012, ISBN: 978-3-319-02446-2.
Abstract | Links/Paper | BibTeX
@article{Appert-Rolland2012,
title = {Experimental Study of the Following Dynamics of Pedestrians},
author = {C Appert-Rolland and A Jelic and P Degond and J Fehrenbach and J Hua and A Cretual and R Kulpa and A Marin and A -H Olivier and S Lemercier and J Pettré},
url = {http://dx.doi.org/10.1007/978-3-319-02447-9_25},
doi = {10.1007/978-3-319-02447-9_25},
isbn = {978-3-319-02446-2},
year = {2012},
date = {2012-01-01},
journal = {Pedestrian and Evacuation Dynamics 2012},
pages = {305-315},
publisher = {Springer International Publishing},
abstract = {We report some experimental study of the behavior of pedestrians when they follow each other. In the frame of the PEDIGREE project, trajectories of pedestrians walking along a one-dimensional path were tracked through a high-precision motion capture. Data analysis allowed to obtain the fundamental diagram at different scales. Two unexpected transitions in the way pedestrians follow each other have been evidenced. The interest of the experiment is to capture at the same time microscopic and macroscopic characteristics of the flow. Indeed, macroscopic structures such as stop-and-go waves can also be studied from the data. Eventually, a data-based following model has been proposed. Its calibration/validation can be performed both at the microscopic or macroscopic level. It is possible to extend the model to quasi-one-dimensional flows for the modeling of pedestrian flows in corridors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report some experimental study of the behavior of pedestrians when they follow each other. In the frame of the PEDIGREE project, trajectories of pedestrians walking along a one-dimensional path were tracked through a high-precision motion capture. Data analysis allowed to obtain the fundamental diagram at different scales. Two unexpected transitions in the way pedestrians follow each other have been evidenced. The interest of the experiment is to capture at the same time microscopic and macroscopic characteristics of the flow. Indeed, macroscopic structures such as stop-and-go waves can also be studied from the data. Eventually, a data-based following model has been proposed. Its calibration/validation can be performed both at the microscopic or macroscopic level. It is possible to extend the model to quasi-one-dimensional flows for the modeling of pedestrian flows in corridors.
Sébastien Brault; Benoit Bideau; Richard Kulpa; C M Craig
Detecting Deception in Movement: The Case of the Side-Step in Rugby. Journal Article
In: PLoS One, vol. 7(6):e37494, 2012.
Abstract | Links/Paper | BibTeX
@article{Brault2012,
title = {Detecting Deception in Movement: The Case of the Side-Step in Rugby.},
author = {Sébastien Brault and Benoit Bideau and Richard Kulpa and C M Craig},
url = {http://people.rennes.inria.fr/Richard.Kulpa/papers/2012_Brault_PlosOne.pdf},
doi = {doi:10.1371/journal.pone.0037494},
year = {2012},
date = {2012-01-01},
journal = {PLoS One},
volume = {7(6):e37494},
abstract = {Although coordinated patterns of body movement can be used to communicate action intention, they can also be used to deceive. Often known as deceptive movements, these unpredictable patterns of body movement can give a competitive advantage to an attacker when trying to outwit a defender. In this particular study, we immersed novice and expert rugby players in an interactive virtual rugby environment to understand how the dynamics of deceptive body movement influence a defending player’s decisions about how and when to act. When asked to judge final running direction, expert players who were found to tune into prospective tau-based information specified in the dynamics of ‘honest’ movement signals (Centre of Mass), performed significantly better than novices who tuned into the dynamics of ‘deceptive’ movement signals (upper trunk yaw and out-foot placement) (p<.001). These findings were further corroborated in a second experiment where players were able to move as if to intercept or ‘tackle’ the virtual attacker. An analysis of action responses showed that experts waited significantly longer before initiating movement (p<.001). By waiting longer and picking up more information that would inform about future running direction these experts made significantly fewer errors (p<.05). In this paper we not only present a mathematical model that describes how deception in body-based movement is detected, but we also show how perceptual expertise is manifested in action expertise. We conclude that being able to tune into the ‘honest’ information specifying true running action intention gives a strong competitive advantage.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Although coordinated patterns of body movement can be used to communicate action intention, they can also be used to deceive. Often known as deceptive movements, these unpredictable patterns of body movement can give a competitive advantage to an attacker when trying to outwit a defender. In this particular study, we immersed novice and expert rugby players in an interactive virtual rugby environment to understand how the dynamics of deceptive body movement influence a defending player’s decisions about how and when to act. When asked to judge final running direction, expert players who were found to tune into prospective tau-based information specified in the dynamics of ‘honest’ movement signals (Centre of Mass), performed significantly better than novices who tuned into the dynamics of ‘deceptive’ movement signals (upper trunk yaw and out-foot placement) (p<.001). These findings were further corroborated in a second experiment where players were able to move as if to intercept or ‘tackle’ the virtual attacker. An analysis of action responses showed that experts waited significantly longer before initiating movement (p<.001). By waiting longer and picking up more information that would inform about future running direction these experts made significantly fewer errors (p<.05). In this paper we not only present a mathematical model that describes how deception in body-based movement is detected, but we also show how perceptual expertise is manifested in action expertise. We conclude that being able to tune into the ‘honest’ information specifying true running action intention gives a strong competitive advantage.
S Lemercier; A Jelic; R Kulpa; J Hua; J Fehrenbach; P Degond; C Appert-Rolland; S Donikian; J Pettré
Realistic following behaviors for crowd simulation Journal Article
In: Computer Graphics Forum, vol. 31, no. 2pt2, pp. 489–498, 2012, ISSN: 1467-8659.
Abstract | Links/Paper | BibTeX
@article{Lemercier2012,
title = {Realistic following behaviors for crowd simulation},
author = {S Lemercier and A Jelic and R Kulpa and J Hua and J Fehrenbach and P Degond and C Appert-Rolland and S Donikian and J Pettré},
url = {http://dx.doi.org/10.1111/j.1467-8659.2012.03028.x},
doi = {10.1111/j.1467-8659.2012.03028.x},
issn = {1467-8659},
year = {2012},
date = {2012-01-01},
journal = {Computer Graphics Forum},
volume = {31},
number = {2pt2},
pages = {489--498},
publisher = {Blackwell Publishing Ltd},
abstract = {While walking through a crowd, a pedestrian experiences a large number of interactions with his neighbors. The nature of these interactions is varied, and it has been observed that macroscopic phenomena emerge from the combination of these local interactions. Crowd models have hitherto considered collision avoidance as the unique type of interactions between individuals, few have considered walking in groups. By contrast, our paper focuses on interactions due to the following behaviors of pedestrians. Following is frequently observed when people walk in corridors or when they queue. Typical macroscopic stop-and-go waves emerge under such traffic conditions. Our contributions are, first, an experimental study on following behaviors, second, a numerical model for simulating such interactions, and third, its calibration, evaluation and applications. Through an experimental approach, we elaborate and calibrate a model from microscopic analysis of real kinematics data collected during experiments. We carefully evaluate our model both at the microscopic and the macroscopic levels. We also demonstrate our approach on applications where following interactions are prominent.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
While walking through a crowd, a pedestrian experiences a large number of interactions with his neighbors. The nature of these interactions is varied, and it has been observed that macroscopic phenomena emerge from the combination of these local interactions. Crowd models have hitherto considered collision avoidance as the unique type of interactions between individuals, few have considered walking in groups. By contrast, our paper focuses on interactions due to the following behaviors of pedestrians. Following is frequently observed when people walk in corridors or when they queue. Typical macroscopic stop-and-go waves emerge under such traffic conditions. Our contributions are, first, an experimental study on following behaviors, second, a numerical model for simulating such interactions, and third, its calibration, evaluation and applications. Through an experimental approach, we elaborate and calibrate a model from microscopic analysis of real kinematics data collected during experiments. We carefully evaluate our model both at the microscopic and the macroscopic levels. We also demonstrate our approach on applications where following interactions are prominent.
Yi Li; Marc Christie; Orianne Siret; Richard Kulpa; Julien Pettré
Cloning Crowd Motions Proceedings Article
In: Proceedings of the ACM SIGGRAPH/Eurographics Symposium on Computer Animation, pp. 201–210, Eurographics Association, Lausanne, Switzerland, 2012, ISBN: 978-3-905674-37-8.
Abstract | Links/Paper | BibTeX
@inproceedings{Li2012,
title = {Cloning Crowd Motions},
author = {Yi Li and Marc Christie and Orianne Siret and Richard Kulpa and Julien Pettré},
url = {http://dl.acm.org/citation.cfm?id=2422356.2422385},
isbn = {978-3-905674-37-8},
year = {2012},
date = {2012-01-01},
booktitle = {Proceedings of the ACM SIGGRAPH/Eurographics Symposium on Computer Animation},
pages = {201--210},
publisher = {Eurographics Association},
address = {Lausanne, Switzerland},
series = {SCA '12},
abstract = {This paper introduces a method to clone crowd motion data. Our goal is to efficiently animate large crowds from existing examples of motions of groups of characters by applying an enhanced copy and paste technique on them. Specifically, we address spatial and temporal continuity problems to enable animation of significantly larger crowds than our initial data. We animate many characters from the few examples with no limitation on duration. Moreover, our animation technique answers the needs of real-time applications through a technique of linear complexity. Therefore, it is significantly more efficient than any existing crowd simulation-based technique, and in addition, we ensure a predictable level of realism for animations. We provide virtual population designers and animators with a powerful framework which (i) enables them to clone crowd motion examples while preserving the complexity and the aspect of group motion and (ii) is able to animate large-scale crowds in real-time. Our contribution is the formulation of the cloning problem as a double search problem. Firstly, we search for almost periodic portions of crowd motion data through the available examples. Secondly, we search for almost symmetries between the conditions at the limits of these portions in order to interconnect them. The result of our searches is a set of crowd patches that contain portions of example data that can be used to compose large and endless animations. Through several examples prepared from real crowd motion data, we demonstrate the advantageous properties of our approach as well as identify its potential for future developments.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
This paper introduces a method to clone crowd motion data. Our goal is to efficiently animate large crowds from existing examples of motions of groups of characters by applying an enhanced copy and paste technique on them. Specifically, we address spatial and temporal continuity problems to enable animation of significantly larger crowds than our initial data. We animate many characters from the few examples with no limitation on duration. Moreover, our animation technique answers the needs of real-time applications through a technique of linear complexity. Therefore, it is significantly more efficient than any existing crowd simulation-based technique, and in addition, we ensure a predictable level of realism for animations. We provide virtual population designers and animators with a powerful framework which (i) enables them to clone crowd motion examples while preserving the complexity and the aspect of group motion and (ii) is able to animate large-scale crowds in real-time. Our contribution is the formulation of the cloning problem as a double search problem. Firstly, we search for almost periodic portions of crowd motion data through the available examples. Secondly, we search for almost symmetries between the conditions at the limits of these portions in order to interconnect them. The result of our searches is a set of crowd patches that contain portions of example data that can be used to compose large and endless animations. Through several examples prepared from real crowd motion data, we demonstrate the advantageous properties of our approach as well as identify its potential for future developments.
C Martin; B Bideau; G Nicolas; P Delamarche; R Kulpa
How does the tennis serve technique influence the serve-and-volley? Journal Article
In: Journal of Sports Sciences, vol. 30, no. 11, pp. 1149–1156, 2012.
Abstract | Links/Paper | BibTeX
@article{Martin2012b,
title = {How does the tennis serve technique influence the serve-and-volley?},
author = {C Martin and B Bideau and G Nicolas and P Delamarche and R Kulpa},
url = {https://www.ncbi.nlm.nih.gov/pubmed/22668422},
doi = {10.1080/02640414.2012.695079},
year = {2012},
date = {2012-01-01},
journal = {Journal of Sports Sciences},
volume = {30},
number = {11},
pages = {1149--1156},
abstract = {In tennis, a high ball velocity and a fast run toward the net are key features to successful performance of "serve-and-volley" players. For the serve, tennis players can use two techniques: the foot-up (FU) or foot-back (FB) technique. The aim of this study was to determine if the running time toward the net after the serve and the ball velocity (V(ball)) vary between these two techniques. Moreover we analysed the angular momentum values of the trunk and of the arm holding the racquet. Fifteen expert tennis players performed six successful serve-and-volleys with both techniques. Running time to the net is significantly lower for FB, whereas V(ball) is significantly higher for FU. Trunk and arm angular momentums about the transverse axis are significantly higher with FU before ball impact. A significant correlation (r = 0.81, P < 0.001) exists between changes in the maximal trunk angular momentum and in running time to the net between the two serve techniques. A significant correlation (r = 0.84, P < 0.001) also exists between changes in the maximal trunk angular momentum and in V(ball) between the two serve techniques. According to these results, FB is the best technique for moving as quickly as possible to the net because of a lower trunk angular momentum.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In tennis, a high ball velocity and a fast run toward the net are key features to successful performance of "serve-and-volley" players. For the serve, tennis players can use two techniques: the foot-up (FU) or foot-back (FB) technique. The aim of this study was to determine if the running time toward the net after the serve and the ball velocity (V(ball)) vary between these two techniques. Moreover we analysed the angular momentum values of the trunk and of the arm holding the racquet. Fifteen expert tennis players performed six successful serve-and-volleys with both techniques. Running time to the net is significantly lower for FB, whereas V(ball) is significantly higher for FU. Trunk and arm angular momentums about the transverse axis are significantly higher with FU before ball impact. A significant correlation (r = 0.81, P < 0.001) exists between changes in the maximal trunk angular momentum and in running time to the net between the two serve techniques. A significant correlation (r = 0.84, P < 0.001) also exists between changes in the maximal trunk angular momentum and in V(ball) between the two serve techniques. According to these results, FB is the best technique for moving as quickly as possible to the net because of a lower trunk angular momentum.
Kristell Pothier; Nicolas Benguigui; Anthony Dubois; Richard Kulpa; Chantal Chavoix
In: Neurophysiologie Clinique/Clinical Neurophysiology, vol. 42, no. 6, pp. 406, 2012, ISSN: 0987-7053.
@article{Pothier2012,
title = {Comparaison des interactions cognition-locomotion chez des sujets jeunes et chez des seniors jeunes et âgés : mise en évidence par la double-tâche Mar-MOT’},
author = {Kristell Pothier and Nicolas Benguigui and Anthony Dubois and Richard Kulpa and Chantal Chavoix},
url = {http://www.sciencedirect.com/science/article/pii/S0987705312003449},
doi = {10.1016/j.neucli.2012.09.063},
issn = {0987-7053},
year = {2012},
date = {2012-01-01},
journal = {Neurophysiologie Clinique/Clinical Neurophysiology},
volume = {42},
number = {6},
pages = {406},
keywords = {},
pubstate = {published},
tppubtype = {article}
}