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Doumiati M.,Ecole Polytechnique - Palaiseau | Doumiati M.,Compiègne University of Technology | Victorino A.C.,Compiègne University of Technology | Charara A.,Compiègne University of Technology | Lechner D.,French National Institute for Transport and Safety Research
IEEE/ASME Transactions on Mechatronics | Year: 2011

The principal concerns in driving safety with standard vehicles or cybercars are understanding and preventing risky situations. A close examination of accident data reveals that losing control of the vehicle is the main reason for most car accidents. To help to prevent such accidents, vehicle-control systems may be used, which require certain input data concerning vehicle-dynamic parameters and vehicle-road interaction. Unfortunately, some fundamental parameters, like tire-road forces and sideslip angle are difficult to measure in a car, for both technical and economic reasons. Therefore, this study presents a dynamic modeling and observation method to estimate these variables. One of the major contributions of this study, with respect to our previous work and to the largest literature in the field of the lateral dynamic estimation, is the fact that lateral tire force at each wheel is discussed in details. To address system nonlinearities and unmodeled dynamics, two observers derived from extended and unscented Kalman filtering techniques are proposed and compared. The estimation process method is based on the dynamic response of a vehicle instrumented with available and potentially integrable sensors. Performances are tested using an experimental car. Experimental results demonstrate the ability of this approach to provide accurate estimations, and show its practical potential as a low-cost solution for calculating lateral tire forces and sideslip angle. © 2010 IEEE.

Houacine M.,French National Institute for Transport and Safety Research | Houacine M.,University Claude Bernard Lyon 1 | Khardi S.,French National Institute for Transport and Safety Research | Khardi S.,University Claude Bernard Lyon 1
Journal of Aircraft | Year: 2010

Gauss pseudospectral method employed for less noise and fuel consumption from aircraft operations is presented. The assumptions include that the motion of the point mass aircraft is described in an inertial frame attached to the Earth and the wind effects are not taken into account. The flight simulation must start from a feasible fixed initial state X(t0) and finish at another feasible endpoint X(tf). Assume that θ is the function translating these conditions and it takes its values in the interval (θmin, θmax). The refraction corrections are not considered, since no spectral composition is used. The aircraft airspeed is greater than that obtained when noise is included, and the aircraft therefore takes less time to reach the touchdown point when the fuel is optimized. The airspeed increase is mostly obtained by a decrease in the flight-path angle and leads to a higher noise impact.

Peng Y.,Hunan University | Peng Y.,University of Strasbourg | Deck C.,University of Strasbourg | Yang J.,Hunan University | And 3 more authors.
2011 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury | Year: 2011

This study investigates head impact conditions for different vehicle types for both adult and child pedestrians in terms of head impact point (Wrap Around Distance: WAD), head relative velocity and impact angle. A simulation matrix is established using four parameters: vehicle model, pedestrian size, pedestrian gait and collision speed. A total of five vehicle types Super Mini Car (SMC), Small Family Car (SFC), Large Family Car (LFC), Multi Purpose Vehicle (MPV) and Sport Utility Vehicle (SUV) are selected to consider different shapes and sizes of vehicles. Two mathematical models of the pedestrian, first a 50th male pedestrian and second a 6 year old child pedestrian, are used in the MADYMO environment. Seven pedestrian gaits (0%, 20%, 40%, 60%, 80%, front and rear) are determined based on typical pedestrian accidents. In order to simulate a large range of impact conditions, four impact speeds (30km/h, 40km/h, 50km/h and 60km/h) are considered for each pedestrian position and vehicle type. The results indicate that the head impact velocity, impact angle and head impact point is influenced by vehicle front geometry. It is obvious that pedestrian position and vehicle travel speed strongly influence head impact conditions as well. The results of this study suggest that head impact conditions should be considered in regulation test procedures involving the front of different passenger vehicles.

Boccara V.,French National Institute for Transport and Safety Research | Boccara V.,INRETS | Delhomme P.,French National Institute for Transport and Safety Research | Vidal-Gomel C.,Paris 8 University | Rogalski J.,Paris 8 University
Accident Analysis and Prevention | Year: 2011

Promoting self-assessment accuracy among student drivers could help improve road safety for young novice drivers (Minimum Requirement for Driving Instructor Training, 2005). It is crucial to investigate the development of this ability in student drivers, although few studies have been conducted on this issue to our knowledge. The present study was aimed at examining the development of accuracy in student drivers' self-assessments. Students' self-ratings of their skills were compared to instructors' ratings based on the students' progression through the four steps of the French driver training course. The ratings were collected from two versions of an ad hoc questionnaire about students' ability to turn right, overtake another vehicle, and turn left in driving situations. The questionnaire included a three-part assessment scale (six driving subtasks required to perform the maneuver, the number of driving subtasks managed simultaneously, and the student's autonomy), demographic data, and the students' progress in the training program. The participants were 149 student drivers (58 men and 91 women) with a mean age of 22.2 years, and 38 professional driving instructors (36 men and 2 women) from 13 driving schools in Paris. The psychometric quality of the scale was satisfactory (αs > .9) concerning the self-ratings as well as the instructors' ratings in the three parts of the scale. As a whole and as expected, the self-ratings and the instructors' ratings became increasingly positive as the training progressed, on each part of the assessment scale. The students' and the instructors' ratings did not differ significantly between the three driving situations tested, nor between male and female students in each training step. Furthermore, students' overestimation of their driving skills was mainly observed on step 1, less on steps 2 and 3, but never on step 4. Thus, the students became rather aware of their current driving skills as the driver training course progressed. The results on the development of the self-assessment accuracy in driver training are discussed. © 2011 Elsevier Ltd.

Truong Cong D.-N.,French National Institute for Transport and Safety Research | Khoudour L.,French National Institute for Transport and Safety Research | Achard C.,CNRS Institute of Robotics and Intelligent Systems | Douadi L.,French National Institute for Transport and Safety Research
IEICE Transactions on Information and Systems | Year: 2010

This paper presents an automatic system for detecting and re-identifying people moving in different sites with non-overlapping views. We first propose an automatic process for silhouette extraction based on the combination of an adaptive background subtraction algorithm and a motion detection module. Such a combination takes advantage of both approaches and is able to tackle the problem of particular environments. The silhouette extraction results are then clustered based on their spatial belonging and colorimetric characteristics in order to preserve only the key regions that effectively represent the appearance of a person. The next important step consists in characterizing the extracted silhouettes by the appearance-based signatures. Our proposed descriptor, which includes both color and spatial feature of objects, leads to satisfying results compared to other descriptors in the literature. Since the passage of a person needs to be characterized by multiple frames, a large quantity of data has to be processed. Thus, a graphbased algorithm is used to realize the comparison of passages of people in front of cameras and to make the final decision of re-identification. The global system is tested on two real and difficult data sets recorded in very different environments. The experimental results show that our proposed system leads to very satisfactory results. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.

Yahiaoui T.,Lille University of Science and Technology | Khoudour L.,French National Institute for Transport and Safety Research | Meurie C.,University of Technology of Belfort - Montbéliard
Journal of Electronic Imaging | Year: 2010

We are interested particularly in the estimation of passenger flows entering or exiting from buses. To achieve this measurement, we propose a counting system based on stereo vision. To extract three-dimensional information in a reliable way, we use a dense stereo-matching procedure in which the winner-takes-all technique minimizes a correlation score. This score is an improved version of the sum of absolute differences, including several similarity criteria determined on pixels or regions to be matched. After calculating disparity maps for each image, morphological operations and a binarization with multiple thresholds are used to localize the heads of people passing under the sensor. The markers describing the heads of the passengers getting on or off the bus are then tracked during the image sequence to reconstitute their trajectories. Finally, people are counted from these reconstituted trajectories. The technique suggested was validated by several realistic experiments. We showed that it is possible to obtain counting accuracy of 99% and 97% on two large realistic data sets of image sequences showing realistic scenarios. © 2010 SPIE and IS&T.

Carnis L.,French National Institute for Transport and Safety Research
European Transport Research Review | Year: 2010

Purpose: From the economic literature, the automated speed enforcement schemes can be interpreted as a specific institution, which works to the reduction of the social cost and enables a better use of road infrastructures. It also represents a particular technology for producing traffic safety. Method: Analyzing the ASE schemes through an economic approach stresses crucial characteristics to investigate. Our analysis proposes to follow the economic approach guidelines to identify and to analyze an ASE program (resources, goals and appraisal). Results and Conclusion: This framework also enables a systematic analysis of the ASE schemes by emphasizing on the important characteristics. It makes also possible to establish comparisons between different systems and to be able to identify a specific risk regulation regime. An application is done for the French system (Contrôle Automatisé or CA) and the British program (Safety Camera Programme or SCP). © 2010 The Author(s).

Guilbault M.,French National Institute for Transport and Safety Research | Gouvernal E.,French National Institute for Transport and Safety Research
Transportation Research Record | Year: 2010

Freight transport is closely linked to industrial and commercial activities and can be seen as a fully integrated element of the production process. Shipper production and logistic constraints play an important role in the choice of transport solutions. However, there are few statistics on which to base an analysis of the relationship between transport and its production- and logistics-related determinants. Two large national surveys were undertaken in France to provide new empirical data. The methodological aspects of these surveys-the 1988 shipper survey and the 2004 survey by the European Community Humanitarian Office-are presented. The use of the shipment as the measurement unit instead of the usual tonne or tonne-kilometer approach is one of the major innovations of these surveys that provide new statistical insight. Another particularity is the tracking of the shipment and the identification of each transport leg and operator involved in the shipment. The entire transport Chain, physical and organizational, is described. A selection of results, indicators, and trends is presented with a focus on the main changes in recent years, on the basis of a comparison between the two data sets. Special attention is paid to the relationship between transport choices and the production characteristics of sites and the increasing spatial and temporal fragmentation of shipments, which makes the choice of modes other than the road increasingly difficult.

PubMed | French National Institute for Transport and Safety Research
Type: Journal Article | Journal: Perceptual and motor skills | Year: 2010

This exploratory study was carried out during a postlicense training program for senior drivers. The aim was to study driving-ability assessments made by 37 older drivers and by instructors, according to age (< 72 yr.; > 72 yr.) and sex. After an open-road test course, both the older drivers self-assessments and the instructors assessments were collected on an ad hoc questionnaire that considered both general and specific aspects of driving ability. The seniors ratings of their own driving ability were consistent with the instructors ratings, at both levels considered. For general driving ability, men were evaluated more positively than were women, both by themselves and by the instructors. For specific aspects of driving, men got higher ratings than did women for driving on roundabouts. Concerning driving on four-lane roads, men in the younger senior group (< 72 yr.) were assessed more positively than were women in that group, whereas no significant gender-related difference was found among the older seniors. Concerning visual skills, the younger participants assessed their own visual skills more positively than did the older participants. In contrast, the instructors assessments of the younger and older seniors were not significantly different. The results are discussed in terms of possible ways of improving training programs for licensed senior drivers.

PubMed | French National Institute for Transport and Safety Research
Type: Journal Article | Journal: Psychopharmacology | Year: 2010

The effects of hypnotic drugs on driving performance are most often evaluated on young healthy subjects by using a monotonous motorway driving test. The effects of drugs in urban driving situations have not yet been evaluated in any age group. Our objectives were to assess residual effects of the most prescribed hypnotics, zolpidem and zopiclone, on older middle-age drivers capacities in an urban situation.Sixteen healthy subjects aged 55 to 65 years underwent this double-blind, balanced, cross-over study. Zopiclone (7.5 mg), zolpidem (10 mg), and flunitrazepam (1 mg; used as positive control) or a placebo were administered at each subjects home at 11:00 PM: under the supervision of an investigator. The next morning, the subjects had to drive in a simulated urban environment where accident scenarios were introduced. Accident scenarios were implemented using data from real accident cases.Hypnotics did not significantly increase the number of collisions. However, significantly higher speeds were found with zopiclone and flunitrazepam; moreover, zolpidem and zopiclone induced modifications of the lateral position of the car on the road.This study did not reveal any major residual effects of the hypnotics studied on driving performance in aging drivers. However, the urban driving situations used here for the first time in the evaluation of drugs revealed some modifications in driving habits which could lead to risky behavior. It thus appears that urban driving simulations are useful for gaining knowledge about the effects of drugs on driving behavior.

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