The Influence of Fog on Motion Discrimination Thresholds in Car Following

A possible explanation for close following in fog is that it would allow drivers to control headway more precisely by reducing motion perception thresholds. The purpose of our experiments was to determine the motion discrimination thresholds for closing and receding under normal and foggy conditions. An experiment and a pilot study were conducted on a driving simulator in which subjects were presented with a car following situation. Subjects had to press a button as soon as they detected that the lead vehicle was closing or receding, and their choice response time was recorded. Several visibility conditions were tested corresponding to different contrasts between the lead vehicle outline and the background, ranging from clear weather conditions to foggy conditions in which the vehicle could only be seen by its rear lights. Initial headway and lead vehicle acceleration were also varied. As expected, response times were longest with small accelerations and long headways. There was also an effect of visibility conditions with longer response times when the contrast between the vehicle outline and the background was 5% or less. Moreover, the reduction of response time corresponding to a reduction of headway was greater in fog than in clear conditions, at least in the given range of distances. This suggests that driving closer in fog may have a perceptual-control benefit in terms of a reduction in response times that partially offsets the reduction in timeheadway. Driving closer may also benefit lateral trajectory control because the lead vehicle is less likely to be lost in fog

Towards the development of a User Interface to model scenarios on driving Simulators

International audienceScenario Modeling on driving simulator requires careful consideration and controlled environment (depending on the research objectives) to achieve the desired goal of the experiment. It is one of the critical steps while designing and implementing an experiment on a driving simulator. It specifies where and what happens in the simulator by specifying, where to place the virtual objects and what those objects will be doing during the experimental trials. But complex and technical nature of driving simulator makes it difficult for the end-users (behavioral researchers/trainers) to design and execute and experimental protocol

Gaze Behavior During Simulated Driving: Elements for a Visual Driving Aid

Analyses of optic flow due to observer self-motion and analyses ofthe driver’s gazing behavior during curve driving have suggested that the driverhas a tendency to look at a location close to the tangent point on the inside edge ofthe road. Psychophysical experiments have further demonstrated that this visualstrategy can be partly explained as an optimization of information pick-up. Themain objective of the present study was to investigate, in an interactive simulationcontext, if this perceptual strategy might be used to define a visual aid for curvedriving. In the framework of the French ARCOS project (Research action forsecure driving; www.arcos2004.com), we used a mini-simulator developed byINRETS (MSIS-CIR group) in collaboration with FAROS company, with twomain original characteristics: (1) during curve driving, the tangent point can becalculated and inserted in the visual scene in real-time and (2) a real-time eyerecordingsystem (EYELINK,® SMI) allows us to evaluate the relationshipsbetween driving performance, gaze direction and the on-line presentation of thetangent point

Prevention of wrong way accidents on highways: a human factors approach

TRA2014 - Transport Research Arena, PARIS, FRANCE, 14-/04/2014 - 17/04/2014Every year, on highways, drivers taking wrong way cause accidents. This paper focuses on a behavioral evaluation of two static road signs to prevent wrong way driving. The devices are a light barrier and the standard wrong way signal (B1) on a yellow background (B1Y). Currently, the design or selection process of road signs does not take into any systematic Human Factors criteria. One of the objectives of the research is to identify a design methodology of road signs. Two questions are asked : 1) how an 'impaired driver' reacts when facing signs designed to prevent a wrong way, 2) to define the impact of this type of road sign on attention and behavior of drivers. Dynamic tests are used to evaluate the robustness of both road signs against different risk factors and more specifically, age. The results of tests give a complete evaluation (qualitative and quantitative) of the wrong way road signs and the implication for road sign design and human factors evaluation.Chaque année sur les routes à chaussées séparées des conducteurs s'engageant en contresens provoque des accidents. Ce document traite de l'évaluation comportementale de deux dispositifs statiques pour empêcher les prises à contresens. Les dispositifs sont une barrière de plots lumineux et le panneau sens interdit classique (B1) sur fond jaune (B1J). Actuellement, le processus de conception ou l'évaluation de signalisations ne prend pas en compte les critères des facteurs humains. L'un des objectifs de la recherche est d'identifier une méthodologie de conception de la signalisation routière. Deux questions sont posées : 1) comment une 'conduite diminué' réagit face à une signalisation anti-contresens, 2) Définir l'impact de cette signalisation sur l'attention et le comportement des conducteurs. Les tests dynamiques ont été réalisés pour évaluer la robustesse des nouvelles signalisations routières par rapport à différents facteurs de risque et de la perception du danger. Les résultats des tests donnent une évaluation complète (qualitative et quantitative) des signalisations anti-contresens et les implications pour la conception de signalisation routière ainsi que l'évaluation des facteurs humains

A detailed description of a user-centered interface to model scenarios on driving simulator

International audienceModeling scenarios on driving simulators is a complex and difficult task for end-users because most of them usually don’t have the skills required to program the scenarios. In this paper, we present a User-centered solution in which we split the scenario modeling interface into 3 subinterfaces (Template Builder, Experiment Builder, Experiment Interface) based on user skills.We have developed a prototype of the interface, which is explained in detail

Filling the user skill gap using HCI techniques to implement experimental protocol on driving simulators

Programming activities are performed not only by programmers but also by end-users in order to support their primary goals in different domains and applications. End-users do not have formal training in programming, so interaction environment and systems are needed, which could account for user skills. The objective of our work is to fill the gap between the user skills and the goals they want to achieve using driving simulators. This paper presents the results of a research in which we have proposed a solution for the primary users of the driving simulator to design and implement experimental protocol. We have used the user-centered design (UCD) technique, conducted a user survey, and proposed a solution, in which we have categorized the Interface of the driving simulator into three sub-interfaces based on the skills of the users. These interfaces are Experiment Builder (Nontechnical persons), Template builder (for technical persons) and Experiment Interface (for any user to run as experiment). A prototype based on this concept is developed and some feedback were collected from end-users. Our results indicate that, users can implement an experimental protocol without having programming skills using our proposed design

Filling the user skill gap using HCI techniques to implement experimental protocol on driving simulators

Abstract-Programming activities are performed not only by programmers but also by end-users in order to support their primary goals in different domains and applications. End-users do not have formal training in programming, so interaction environment and systems are needed, which could account for user skills. The objective of our work is to fill the gap between the user skills and the goals they want to achieve using driving simulators. This paper presents the results of a research in which, we have proposed a solution for the primary users of the driving simulator to design and implement experimental protocol. We have used user-centered design (UCD) technique, conducted a user survey, and proposed a solution, in which we have categorized the Interface of the driving simulator into three sub-interfaces based on the skills of the users. These interfaces are Experiment Builder (Nontechnical persons), Template builder (for technical persons) and Experiment Interface (for any user to execute experiment). A prototype based on this concept is developed and evaluated. Our results indicate that, users can implement an experimental protocol without having programming skills using our proposed design

Low prevalence of colonoscopic surveillance of inflammatory bowel disease patients with longstanding extensive colitis: a clinical practice survey nested in the CESAME cohort

International audienceBackground: Surveillance colonoscopy is recommended for inflammatory bowel disease (IBD) patients with longstanding extensive colitis (LEC). Aims: To assess modalities and results of colonoscopic surveillance in a subset of CESAME cohort patients at high risk of colorectal cancer (CRC) and followed in university French hospitals. Methods: Among 910 eligible patients with more than a 7-year history of extensive colitis at CESAME enrolment, 685 patients completed a questionnaire on surveillance colonoscopy and 102 were excluded because of prior proctocolectomy. Finally, 583 patients provided information spanning a median period of 41 months (IQR 38-43) between cohort enrolment and the end of follow-up. Details of the colonoscopic procedures and histological findings were obtained for 440 colonoscopies in 270 patients. Results: Only 53.5% (n=312) of the patients with LEC had at least one surveillance colonoscopy during the study period, with marked variations across the 9 participating centres (27.3% to 70.0%, p= < 0.0001). Surveillance rate was significantly lower in Crohn's colitis than in ulcerative colitis (UC) (47.6% vs 68.5%, p=< 0.0001). Independent predictors of colonoscopic surveillance were male sex, UC IBD subtype, longer disease duration, previous history of CRC, and disease management in a centre with large IBD population. Random biopsies, targeted biopsies and chromoendoscopy were performed during respectively 70.7%, 26.6 and 30.0% of surveillance colonoscopies. Two cases of high-grade dysplasia were detected in patients undergoing colonoscopic surveillance. Two advanced-stage CRC were diagnosed in patients who did not have colonosocopic surveillance. Conclusions: Colonoscopic surveillance rate is low in IBD patients with longstanding extensive colitis

Body movement strategies to initiate the crossing of a street in front of traditional and self-driving cars in young and older adults

International audienceBACKGROUND AND AIM: The safety of elderlies is a key societal issue, especially when considering that 48% of pedestrian fatalities involve people aged 65 or more (Sécurité Routière 2017-France). Aging affects street crossing behavior, with a decrease of walking speed or more risky decisions because elderly people have difficulties to estimate the approaching speed of vehicles, especially in complex situations. In young adults, recent work focused on body movement performed to initiate the crossing, showing a top down sequence of advancement along the antero-posterior axis: the head initiates the crossing movement, followed by the shoulders, elbows, wrists, hips, knees and ankles. Identifying such motion invariants can be particularly useful in the context of self-driving vehicles which aim at predicting the intent of crossing. In this study, we aim at investigating body movement strategies performed before crossing in older adults in complex mixed traffic. METHODS: 30 young adults (YA, 21-39yo) and 30 older adults (OA, 68-81yo) were asked to cross (or not) a virtual two-way street by walking in a simulator. Participants performed a total of 120 trials where we manipulated: the type of vehicles (Conventional and/or Self driving car, the latest always stopping to let the pedestrian cross the street), their speed (30 or 50km/h), their position on the lane (far/near lane), as well as the temporal gap available to cross the street (1,2,3,4 or 5s). After computing temporal body segment motion and orientations, we analyzed the delays in initiating the crossing movement for the head, shoulders and hips with respect to the feet. We also performed hierarchical clustering to identify specific groups of behavior. RESULTS: Preliminary results show a top-down sequence of forward body motion, starting from the head to the feet, whatever the traffic condition and the group. In OA, the head initiates the motion sooner than YA wrt their feet. Moreover, while the horizontal angle profile of the head, shoulders and hips does not allow to identify invariants due to the large variety of behaviors before crossing, the trunk tilt angle profile appears to be a relevant marker for predicting the intent to cross the street. CONCLUSIONS: While aging was shown to affect street crossing decisions, our results highlight consistent behavior between YA and OA regarding trunk tilt profile when initiating the crossing. In line with previous work on YA, we also show a top down sequence of advancement of body segments. Future work is needed to use our results to predict the intent of crossing on a new database. Beside the choice to cross the street, future work is also needed to understand body segment motion and walking speed profile while crossing

Le mouvement de caméra 3D : projet d'interface tangible d'animation de caméra virtuelle

Edgar Morin disait : « Plus généralement encore, c’est parce que le mouvement restitue la vie à qui en a qu’il donne la vie à qui n’en a pas. Il peut donner du corps à l’incorporel, de la réalité à l’irréalité, de la vie à l’inanimé. Mentir, illusionner! Tel est le résultat premier de la prodigieuse vérité du mouvement. […] De même que le mouvement peut donner du corps à ce qui en est dépourvu, il peut insuffler de l’âme à ce qu’il anime » (MORIN, 1956). Les caméras, dans un logiciel d’animation 3D, ne peuvent pas être directement manipulées avec nos mains comme le ferait un opérateur de caméra sur un plateau de tournage. Leurs mouvements sont plutôt générés par ordinateur à la suite de plusieurs manipulations sur les coordonnées spatiales de l’objet de caméra dans le logiciel. Ce sont des interventions très mathématiques. Lorsque j’anime une caméra, je visualise son déplacement en l’imaginant, grâce aux mouvements de mes mains. Je souhaiterais transférer ce mouvement de prévisualisation de façon intuitive et en temps réel sur l’objet-caméra de l’espace de travail 3D. Dans ce cas, comment concevoir un système de captation et d’interaction plus intuitif, plus près de l'humain et quel en serait le design? Comment réaliser une interface permettant de produire un mouvement de caméra virtuelle fluide et réaliste? Est-ce que le mouvement généré par ce système ne devient pas un mouvement autonome pouvant servir à de multiples usages? C’est sur cette dimension que porte cette recherche, sur ce mensonge, cette illusion de l’intangibilité du mouvement. En fait, au-delà de l'outil et des technologies, l'axe principal de cette recherche réside dans l'exploration des différents moyens permettant d’insuffler de l'âme au mouvement, par conséquent humaniser la caméra virtuelle. Je souhaiterais tout de même aboutir par le biais de cette recherche à un outil assez convaincant pour pouvoir l’utiliser dans mon milieu de travail