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International Journal of ITS Research
| HOME Vol., 2, No. 1 Abstracts |
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| Abstracts |
Regular Papers 02-03 In Japan, more users have been able to make use of traffic information service in real time as VICS (Vehicle Information and Communication System) and navigation systems have been deployed. However, navigation systems can not always guide drivers on appropriate routes using only travel time data as they are because of the problems of accuracy and quantity. Therefore, this paper proposes estimation methods of statistical traffic data for an appropriate route search in navigation system. It includes several ideas for making the statistical traffic data more accurate. This paper describes and evaluates the algorithms for the estimation. Keywords: Travel time, Traffic congestion, Statistics, Estimation, Navigation system, Route search
02-05 This study evaluates a method of providing pre-trip information that predicts congestion and travel time by matching past accumulated traffic data with traffic data on the day of the trip while taking into account the time required to reach the Metropolitan Expressway. Since pre-trip information is available at the time of access to the information media, it is highly likely that the congestion conditions have changed by the time people actually drive on the Metropolitan Expressway. Predicted future travel time is also very useful for drivers to decide their trip departure times. Therefore, it is necessary to provide pre-trip information while predicting traffic fluctuations. The proposed method is verified using observed traffic data on two major radial routes and it is concluded that estimated travel time is accurate enough for the practical use. Keywords: Traffic information, Travel time prediction, Forecast method, pre-trip
02-06 Recently the analysis on road traffic conditions with the use of probe-cars has been paid increasing attention. Probe-cars enable us to obtain the spacious data. However, since probe-cars generally provide the coordinates as vehicle's location point, analysts have to identify the vehicle's cruising route. It is difficult to identify the route at the section where elevated urban expressways are allocated parallel with the other roads. This study develops the method of identifying the vehicle's cruising route even where there are elevated urban expressways. It also develops the travel time prediction method using accumulated probe-car data. Keywords: probe-car, route identification, travel time prediction
02-11 This paper presents the Probabilistic Vehicle Routing and scheduling Problem with Time Windows (VRPTW-P) model which takes into account the uncertainty of travel times. Probe vehicle data of travel times were obtained from actual operation of pickup-delivery truck in Osaka-Kobe area. The optimal solution of VRPTW-P resulted in considerably reducing total cost, travel times and CO2, NOx and SPM emissions compared with expected average case based on the real operation. This is attributed to better routing of VRPTW-P to choose more reliable roads. Therefore, VRPTW-P can contribute to establish efficient an environmentally friendly delivery systems in urban area. Keywords: Freight transport, Vehicle routing and scheduling, Travel time, Intelligent transport systems, Optimisation
02-10 A fiber optical magnetometer, SmartLIM (Laser Interferometric Magnetometer), has been developed. The SmartLIM adopts the Mach-Zehnder interferometer to detect the local disturbance of the geomagnetic field produced by a car driven nearby. Its high sensitivity enables us to install the detector at the a depth of 0.5m from under the road surface, or beneath the bottom side underside of an elevated road. . The SmartLIM was tested for over four seasons at under an elevated road after following our factory site test. The results have confirmed its excellent detection capability and usefulness as a traffic counter. Keywords: Magnetometers, traffic counter, field test results
02-13 In this study, a system was developed for successive observations of trajectories of vehicles with images of plural video cameras installed adjacently along roads through the use of techniques such as image processing and geometry transformation. This system can more highly equilibrate the observation precision and the observation range than the use of images of a single video camera. In addition, it can exclude the influence of occlusion where a vehicle is shadowed by another in video images. Furthermore, an observation equation was derived in combination of equations of triangles that approximate road surfaces with equations of a 3D projective transform. The measurement accuracy of this method was evaluated in comparison with results of a precision survey of trajectories of a 1/22 scale vehicle model. Keywords: vehicle tracking, vehicle behavior, image processing, Kalman smoother
02-14 Sensor fusion of millimeter-wave (MMW) radar and a camera is beneficial for advanced driver assistance functions such as obstacle avoidance and Stop&Go. In this paper, we propose a method for detecting a moving obstacle using MMW radar and CCD camera, along with a calibration method for two sensors. Our method is designed for detecting moving obstacles, such as cars, motorcycles, pedestrians, bicycles, and so on in urban areas, observed by a camera mounted on a vehicle. In the proposed method, we detect a moving obstacle by estimating image boundaries which enclose a group of feature points exactly on the obstacle. In order to determine the group, feature points in a whole image are detected at every image frame and tracked over several consecutive frames, and then we apply a motion segmentation technique, so-called subspace factorization, developed in the computer vision domain. For robustness in boundary estimation, we use MMW radar so as to detect the obstacle's rough position which results in an image region where an obstacle would exist; the motion segmentation technique is applied toward the tracks that drop in the region. Note that an obstacle's position detected by MMW radar is remarkably rough because MMW radar has low directional resolution. Nevertheless, the position contributes to rapid and robust estimation for satisfactory image boundaries. We demonstrate the validity of the proposed method through experiments using sensors that are mounted on a vehicle. Keywords: millimeter-wave radar, sensor fusion, moving obstacle detection, motion segmentation
02-09 This paper proposes a novel notion of spatio-temporal range image and an efficient way to construct 3D geometric model of urban scene with the use of this range image. We mount vertical and horizontal line-scanning laser range finders on our vehicle. The vertical one is for acquiring the scene geometry itself, and the horizontal one is for self-positioning of the vehicle. Laminating horizontal-scanning data along time axis, we can get a spatio-temporal range image which simultaneously represents spatial feature and temporal continuity of the scene geometry. Analyzing this range image, we can estimate the velocity or the self-position of our vehicle without using any external devices as GPS or INS. With this information, we can align the position of the vertical scanning lines and construct a proper 3D model of urban scene. Keywords: City scanning, 3D geometry model, Range image, EPI, Self positioning, Alignment
02-15 In Japan, anti-icing chemicals are used to secure the safety and smoothness of vehicular traffic in the winter season. Especially since the use of spike tires on roads was prohibited, the consumption of such chemicals has been increasing year after year. On the other hand, the desire to reduce the amount of such chemicals to be salted has been mounting in recent years for cost reduction as well as for our concern for the road environment. In turn, the Japan Highway Public Corporation (JH) developed a salinity measurement sensor which can be mounted in a patrol car or a pre-wetted salt spreader to measure salinity in real time and control the amount of chemicals to be salted, and confirmed the measurement accuracy through verification testing in the field. The JH also conducted verification testing on a new method of salinity measurement to optimize the salting amount of chemicals even when the roadway surface is not adequately wet and confirmed that measurement by this method could be achieved. Keywords: Salinity measurement sensor, On-vehicle, Real time measurement
02-01 A fault tolerant steer-by-wire (SBW) system requires an operation procedure to cope with partial system degradations. This paper presents a reliability quantification method that converts the operation procedure into an augmented Markov transition diagram where each state represents either a normal SBW, or a partially degraded or a completely failed SBW. The system reliability is quantified in terms of the state probabilities calculated from a numerical integration of the Markov diagram specified by component failure rates. A structural design was already proposed and an example of operation procedure was derived in our previous study for a SBW system consisting of a principal SBW, a standby SBW and a mechanical backup hopefully with a power assist feature. The proposed method is demonstrated by an application to this SBW design. It turns out that the SBW system demonstrates a considerably high reliability through the introduction of mechanical backup. The power assist, however, is rarely available during the mechanical backup mode. This lack of power assist can be reduced by increasing reliability of ECU (Electronic Control Unit). Keywords: steer-by-wire, reliability, fault tolerance, partial system degradation, Markov diagram
Technical note 01-02 In establishing themes for the Phase 2 promotion Activities of the ASV (ASV-2) proposed by the Japanese Ministry of Land, Infrastructure, and Transport, we again analyzed traffic accident data as we did during phase one. More than half of all traffic deaths occur among those who are more vulnerable in traffic accidents, namely pedestrians, motorcycle riders and bicyclists, with most of these deaths resulting from being struck by automobiles. While a number of technologies have been developed and put into practical application in the areas of accident-avoidance assistance and injury risk reduction for automobile drivers, we also recognized the need to develop advanced technologies to help reduce accidents and injuries involving these more vulnerable parties. Accordingly, we defined the main theme of this phase as gprotecting parties more vulnerable in traffic accidents.h Additionally, we established greducing automobile driver workload and fatigueh as a secondary theme, since reduced workload and fatigue allows automobile drivers to remain more attentive to surroundings and to interpret situations, make judgements, and/or perform control maneuvers more correctly, thereby contributing to the prevention of traffic accidents. Keywords: Driver assistance, Vision enhancement, ACC, Lane keep, Inter-vehicle communication, Night vision |
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