Familiarization with a Forward Collision Warning on driving simulator: cost and benefit on driversystem interactions and trust

International audienceIntroducing Advanced Driver Assistance Systems (ADAS) into the vehicle could improve drivers’ comfort and reduce road crashes. However, suitable methods are required to study driver/system interactions. In fact, ADAS generate critical use cases, i.e. situations where alarms, or absence of alarms, can be negative for safety. The present study aimed at evaluating the impact of getting familiar, by means of a driving simulator, with critical situations when using the Forward Collision Warning system (FCW). We hypothesized that experiencing the system’s function in critical situations would improve drivers’ performance and their trust in the FCW. We compared judgments and driving performance of three independent groups: a “control group” where drivers did not use the FCW, an “unfamiliarized group” where drivers used the FCW without having been familiarized with the system, and a “familiarized group” where drivers used the FCW after having been familiarized. Results showed that familiarization made driver/system interactions more effective and safer. Moreover, familiarized drivers rated the system more positively than unfamiliarized drivers. However, familiarization decreased drivers’ self-confidence and did not prevent from haste when overtaking slow vehicles. We discussed the relevance of using a driving simulator in FCW’s studies and the possibility to transfer skills and knowledge to field operational tests. Finally, we proposed possible improvements to make the familiarization with the system still more effective.Introduire des systèmes avancés d’aide au conducteur dans le véhicule pourrait augmenter le confort des conducteurs et réduire le nombre d’accidents. Toutefois, des méthodes d’évaluations adaptées sont nécessaires à l’étude des interactions conducteur/système. Les systèmes d’aide génèrent effectivement des cas d’usage critiques, i.e. des situations ou les alertes, ou l’absence d’alertes, peuvent être négatives pour la sécurité. L’objectif de la recherche était d’évaluer l’impact de la familiarisation avec les cas critiques d’usage du Forward Collision Warning (FCW) sur simulateur de conduite. Nous avons testé l’hypothèse selon laquelle l’expérience du fonctionnement du FCW dans des situations critiques d’usage augmente la performance de conduite et la confiance des conducteurs dans le système. Nous avons comparé les jugements et la performance de conduite de trois groupes expérimentaux : un groupe contrôle où les conducteurs n’utilisaient pas le FCW, un groupe « non familiarisé » où les conducteurs utilisaient le système sans avoir été familiarisés et un groupe « familiarisé » où les conducteurs utilisaient le système après avoir été familiarisés. Les résultats montrent que la familiarisation rend les interactions conducteur/système plus efficaces et plus sûres. Par ailleurs, les conducteurs familiarisés ont des opinions plus positives sur le FCW comparé aux non familiarisés. Néanmoins, la familiarisation diminue la confiance des participants dans leur capacité de conduite. De plus, elle ne permet pas d’éviter que les conducteurs dépassent de façon trop précipitée les véhicules lents. Nous discutons la pertinence du simulateur pour l’étude du FCW et la possibilité de transfert des connaissances à la conduite sur route réelle. Finalement, nous proposons des améliorations pour rendre la familiarisation avec le système plus efficace

Familiarization with a Forward Collision Warning on driving simulator: cost and benefit on driversystem interactions and trust

Introducing Advanced Driver Assistance Systems (ADAS) into the vehicle could improve drivers’ comfort and reduce road crashes. However, suitable methods are required to study driver/system interactions. In fact, ADAS generate critical use cases, i.e. situations where alarms, or absence of alarms, can be negative for safety. The present study aimed at evaluating the impact of getting familiar, by means of a driving simulator, with critical situations when using the Forward Collision Warning system (FCW). We hypothesized that experiencing the system’s function in critical situations would improve drivers’ performance and their trust in the FCW. We compared judgments and driving performance of three independent groups: a “control group” where drivers did not use the FCW, an “unfamiliarized group” where drivers used the FCW without having been familiarized with the system, and a “familiarized group” where drivers used the FCW after having been familiarized. Results showed that familiarization made driver/system interactions more effective and safer. Moreover, familiarized drivers rated the system more positively than unfamiliarized drivers. However, familiarization decreased drivers’ self-confidence and did not prevent from haste when overtaking slow vehicles. We discussed the relevance of using a driving simulator in FCW’s studies and the possibility to transfer skills and knowledge to field operational tests. Finally, we proposed possible improvements to make the familiarization with the system still more effective.Introduire des systèmes avancés d’aide au conducteur dans le véhicule pourrait augmenter le confort des conducteurs et réduire le nombre d’accidents. Toutefois, des méthodes d’évaluations adaptées sont nécessaires à l’étude des interactions conducteur/système. Les systèmes d’aide génèrent effectivement des cas d’usage critiques, i.e. des situations ou les alertes, ou l’absence d’alertes, peuvent être négatives pour la sécurité. L’objectif de la recherche était d’évaluer l’impact de la familiarisation avec les cas critiques d’usage du Forward Collision Warning (FCW) sur simulateur de conduite. Nous avons testé l’hypothèse selon laquelle l’expérience du fonctionnement du FCW dans des situations critiques d’usage augmente la performance de conduite et la confiance des conducteurs dans le système. Nous avons comparé les jugements et la performance de conduite de trois groupes expérimentaux : un groupe contrôle où les conducteurs n’utilisaient pas le FCW, un groupe « non familiarisé » où les conducteurs utilisaient le système sans avoir été familiarisés et un groupe « familiarisé » où les conducteurs utilisaient le système après avoir été familiarisés. Les résultats montrent que la familiarisation rend les interactions conducteur/système plus efficaces et plus sûres. Par ailleurs, les conducteurs familiarisés ont des opinions plus positives sur le FCW comparé aux non familiarisés. Néanmoins, la familiarisation diminue la confiance des participants dans leur capacité de conduite. De plus, elle ne permet pas d’éviter que les conducteurs dépassent de façon trop précipitée les véhicules lents. Nous discutons la pertinence du simulateur pour l’étude du FCW et la possibilité de transfert des connaissances à la conduite sur route réelle. Finalement, nous proposons des améliorations pour rendre la familiarisation avec le système plus efficace

When drivers' training-courses are shared by different trainers

International audienceThis paper aims to analyze the consequences of a specific organization of work in driving schools: in France, in some driving schools, several trainers may successively train a single trainee. Consequences on training duration and on trainer activity are analyzed based on data collected in the course of three studies. We show that the duration of driver training increases in the case of multiple trainer switches during a training course. Trainer switches during the course also have consequences on the activity of trainers, since they must, as a result, engage in asynchronous cooperation. We analyzed this cooperation from two points of view: one focused the use of a collective tool, the Trainee Record Form (TRF) designed as a tool for communication between trainers of the same trainee, as well as with the trainee; and one focused on the characteristics of trainer diagnosis at the beginning of a lesson, when he trains someone for the first time. We observe various uses of the TRF, ambiguous written comments that may be read by the future trainer or a lack of collective use. Our data also suggests difficulties in elaborating a diagnosis: with a new trainee, trainers systematically delayed their decisions regarding didactical objectives: to carry these out, they needed to watch the trainee drive. The results of these three studies are discussed in terms of their consequences for training organization and training of driving trainers

Couplage d'un réservoir d'hydrure de magnésium avec une source externe de chaleur

L'objectif de la thèse était d'étudier la faisabilité d'un couplage thermique entre un réservoir d'hydrure métallique et une source externe de chaleur. L'évolution des propriétés de composites à base d'hydrure de magnésium (MgH2) a été étudiée en fonction du nombre de cycles d'hydruration. On observe une très bonne stabilité de la capacité massique d'absorption sur le long terme (600 cycles réalisés). Les premiers cycles sont néanmoins marqués par une évolution importante de la microstructure qui dépend de la proportion et/ou de la nature de l'additif utilisé lors de la mécano-synthèse des poudre d'hydrure. Cette évolution est associée à une augmentation de la conductivité thermique, mais également à une légère dégradation des cinétiques intrinsèques de réaction ainsi qu'à une expansion volumique des composites. Nos mesures montrent que l'amplitude des contraintes mécaniques engendrées sur les parois d'un réservoir se stabilisent après une cinquantaine de cycles. Un réservoir contenant 10 kg de MgH2, et capable de stocker 6500 Nl d'hydrogène en 35 minutes a ensuite été développé au laboratoire. L'énergie des réactions d'absorption et de désorption est échangée avec une source externe de chaleur via un fluide caloporteur. Ce système permet de représenter l'intégration thermique d'un réservoir d'hydrure dans un système de cogénération. Un modèle numérique a été développé afin de mieux appréhender le comportement de ce réservoir. Des essais de couplage entre un réservoir de taille plus modeste et une pile à combustible haute température (SOFC) développant une puissance électrique de 1 kW ont également été réalisés au Politecnico di Torino.The main target of the thesis was to study the thermal integration of a magnesium hydride (MgH2) tank with an external heat source. At first, the evolution of material properties upon cycling were investigated. A large microstructural evolution was observed during the first cycles which impacts on kinetics of reaction and thermal conductivity. An expansion of the composites is also observed. Quantity and/or nature of the additives used during material preparation was identified as an important parameter controlling this phenomenon. Our measures show that mechanical strains on the tank wall due to this expension are stable after 40 hydrogenation cycles. A large number of cycles was applied to these composites which exhibits a very high stability upon cycling. A large scale magnesium hydride tank (10 kg MgH2) storing 6500 Nl of hydrogen in 35 minutes was developed and tested. The energy of reaction is exchanged with an external heat source by a heat transfer fluid. This installation allows to simulate the integration of a magnesium hydride tank into a co-generation system. A numerical model was developed in order to better understand and predict the behavior of this tank. A thermal integration test of the MgH2 with a high temperature fuel cell (SOFC) was performed at Politecnico di Torino.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Proposal and validation of a questionnaire to investigate risk behavior of drivers from Brazil and Portugal

Traffic accidents are among the leading causes of death around the world. The causes of its occurrence largely correspond to the human factor. With this, many studies are carried out to examine the main determinants underlying human behavior in traffic and more specifically, risk behaviors. The use of questionnaires to relate personality traits and other characteristics are widely used to investigate this type of behavior. This paper aims to present the steps performed during the development of a questionnaire to investigate risk behaviors, including qualitative and quantitative analyzes. Through pilot tests, it was possible to evaluate the comprehension of the questions as well as the reliability of the scale with the Cronbach's alpha test. At the end of all steps, the questionnaire reached satisfactory results that made it suitable for application to the final sample.Os acidentes de trânsito estão entre as principais causas de morte em todo o mundo. As causas de sua ocorrência correspondem na sua maior parte ao fator humano. Com isso, muitos estudos são realizados a título de compreender o comportamento humano no trânsito e mais especificamente, comportamentos de risco. Questionários relacionando traços de personalidade e outras características são amplamente utilizados a fim de investigar esse tipo de comportamento. Esse trabalho tem por objetivo apresentar as etapas realizadas durante o desenvolvimento de um questionário para investigação de comportamentos de risco, contemplando análises qualitativas e quantitativas. Através de testes pilotos, foi possível avaliar a compreensão das perguntas, bem como a confiabilidade da escala com o teste do alfa de Cronbach. Ao final de todas as etapas, o questionário atingiu resultados satisfatórios indicando que está adequado para aplicação à amostra final.info:eu-repo/semantics/publishedVersio

Driving Behaviors 2–3 Years After Traumatic Brain Injury Rehabilitation: A Multicenter Case-Control Study

Introduction: Driving an automobile is an important activity for the social participation of individuals with traumatic brain injury (TBI). Return to safe driving is usually addressed during rehabilitation, but we know little about driving behaviors in the years following TBI rehabilitation.Objective: To explore self-reported and objective (official driving records) post-rehabilitation driving behaviors and offenses in individuals with TBI: (a) having passed a driving evaluation, (b) who did not undergo a driving evaluation, and (c) non-injured controls.Methods: Cross-sectional design with 162 adults: (a) 48 participants with mild, moderate, or severe TBI whose drivers' license was suspended and reinstated following a driving evaluation during rehabilitation (TBI-DE; M = 42.2 years of age, SD = 11.5); (b) 24 participants with TBI who maintained their driving privileges without undergoing a driving evaluation (TBI-NE; M = 36.5 years of age, SD = 9.9); (c) 90 non-injured controls (M = 43.8 years of age, SD = 11.4). Participants with TBI were recruited from seven rehabilitation centers, 2–3 years after the end of rehabilitation in the province of Quebec, Canada. During a telephone interview, data were obtained regarding self-reported driving: (a) habits; (b) self-efficacy; (c) anger expression; (d) sensation-seeking; (e) violations/errors; (f) accidents, driving offenses, and demerit points for the two-year interval predating the study. Objective data for driving offenses, accidents, and demerit points were obtained from the automobile regulatory body for the same period and for the two-year interval before the injury for the TBI groups.Results: Compared to non-injured controls, the TBI-DE group reported significantly lower scores for self-reported verbal aggressive expression of anger and driving violations/errors. Conversely, their official driving records showed significantly more demerit points for the last 2 years, and a significantly higher frequency of serious post-rehabilitation accidents (10), compared to the TBI-NE group (one) and the control group (none). Compared to pre-injury levels, individuals with TBI had significantly more demerit points post-rehabilitation.Conclusions: Individuals with TBI may underestimate risky driving behaviors even if they have been deemed fit to drive. Reduced self-awareness, memory, and dysexecutive problems following TBI could influence self-report of driving behaviors and explain discrepancies between self-reported and objective driving-related behaviors. Recommendations for research and practice are provided

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data