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Doumiati M.,Ecole Polytechnique - Palaiseau | Doumiati M.,Compiegne University of Technology | Victorino A.C.,Compiegne University of Technology | Charara A.,Compiegne 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. Source

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 - Montbeliard
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. Source

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. Source

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). Source

Faure B.,French National Institute for Transport and Safety Research | Chiello O.,French National Institute for Transport and Safety Research | Pallas M.-A.,French National Institute for Transport and Safety Research | Serviere C.,CNRS GIPSA Laboratory
17th International Congress on Sound and Vibration 2010, ICSV 2010 | Year: 2010

Rolling noise is the main contribution to railway noise for speeds up to 300 km/h. A part of this noise is radiated by the rail excited by the wheel/rail roughness at each contact patch. The general purpose of this study is to use microphone array measurements to characterize the acoustic field radiated by the rail in order to determine its contribution to rolling noise. This noise component results from the propagation of several vibration waves along the rail, such as lateral or vertical bending waves. Classical array processing methods based on beamforming are not appropriate to this extended source. Using a model of a continuously supported Timoshenko beam, the vibration field in the rail may be expressed as a superposition of two flexural waves: one propagating wave and one near-field wave. At high frequencies, propagating waves have a low decay rate and then ac-tually propagate over long distances. At low frequencies, both waves are strongly attenuated, and the rail behaves rather like a point source. The resulting acoustic field has heterogeneous properties depending on frequency, excitation amplitudes and the vibration characteristics of the rail on its support (wave numbers, decay rates). In this paper, the model used to determine the acoustic field is based on the superposition of el-ementary fields corresponding to the different vibration waves propagating along the rail. The objective is to determine whether and how these fields may be identified, separated and char-acterized (amplitudes, wave numbers and decay rates) at a given frequency using microphone array measurements. This is performed by using algorithms based on the minimization of the error between measured and model-predicted spectral density matrices. The effects of errors on model parameters and random noise added on measured signals are taken into account. Simulation results are presented and the robustness of the method is discussed. Source

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