Showing papers in "IEEE Transactions on Intelligent Transportation Systems in 2001"

Basic study on traffic information system using LED traffic lights

Abstract: The vehicle information and communication system (VICS) is starting to become practicable. The infrared system of a VICS detects vehicles on the road by using optical beacons to control traffic and to supply real-time traffic information. But it needs an enormous budget because the optical beacons must be located on every lane of the road throughout the country. We propose a traffic information system using existing LED traffic lights, and focus on its visible rays and power used for traffic control, the number and location of the traffic lights, and the movement toward LED traffic lights. We design the best service area not to interfere with other service areas and analyze its basic performance such as the suitable modulation, required SNR and the amount of receivable information.

Safety verification of conflict resolution manoeuvres

Abstract: We address the problem of generating provably-safe conflict resolution maneuvers for aircraft in uncertain environments. We assume that a maneuver is composed of a sequence of flight modes, which are segments of constant heading, of constant bank angle, or of constant airspeed. Each of these flight modes has associated to it the kinematics of the aircraft, and hence the maneuver is a hybrid system. While the flight modes are defined ahead of time, their sequencing and parameter values do not necessarily have to be. We present an algorithm for generating provably safe maneuvers, which is based on a general procedure for designing controllers for hybrid systems. The result is a maneuver, proven to be safe within the limits of the models used, which is a familiar sequence of commands easily executable by the flight management systems. The maneuvers may be viewed as protocols, or "rules of the road", and are well-defined for each conflict scenario. We present results for two example maneuvers.

Content-based event retrieval using semantic scene interpretation for automated traffic surveillance

Abstract: This paper proposes an object segmentation and tracking algorithm for visual surveillance applications. In order to detect moving objects from a dynamic background scene which may have temporal clutters such as swaying plants, we devised an adaptive background update method and a motion classification rule. A two-dimensional token-based tracking system using a Kalman filter is designed to track individual objects under occlusion conditions. We propose a new occlusion reasoning approach where we consider two different types of occlusion: explicit occlusion and implicit occlusion. By tracking individual objects with segmented data, we can generate motion trajectories and set a motion model using polynomial curve fitting. The trajectory model is used as an indexing key for accessing the individual object in the semantic level. We also propose an efficient way of indexing and searching based on object-specific features at different semantic levels. The proposed searching scheme supports various queries including query by example, query by sketch, and query on weighting parameters for event-based retrieval. When retrieving an interested video clip, the system returns the best matching event in the similarity order. In addition, we implement a temporal event graph for direct accessing and browsing of a specific event in the video sequence.

Discrimination of the road condition toward understanding of vehicle driving environments

Abstract: The detection of vehicle driving environments is necessary to secure transport facilities safe from accidents and to keep the performance smooth. The road condition is one of the most important factors toward detection of vehicle driving environments. Conventional discrimination methods for road conditions involved the use of optical or ultrasonic sensors. However, since these sensors can only provide spot information, detected results do not always reflect the spacious condition. To deal with this problem, a new algorithm that employs image analysis technology for discrimination of road conditions is proposed in this paper. In this algorithm, for discrimination of road conditions, we focused on features related to water and snow on the road, and we extracted these features by image analysis. Features related to water were extracted by the ratio of horizontal polarization image intensity to vertical polarization image intensity for each pixel. Features related to snow were extracted by texture analysis using the co-occurrence matrix. We employ a multivariate analysis to discriminate five kinds of the road conditions: "Dry," "Wet," "Slushy," "Icy" and "Snowy," on the basis of these features extracted from the road images as well as temperature. Furthermore, we conducted field tests to verify the accuracy of this algorithm and obtained favorable discrimination accuracy rate of 92.3% on the average.

A study of aircraft taxi performance for enhancing airport surface traffic control

Abstract: In view of the ever-increasing air traffic, much attention in air traffic management research has been given to improving arrival and departure efficiency. As air traffic begins and ends at the airport, the issues of taxi delays and ground incursions are becoming more evident. The paper considers the surface-traffic problem at major airports and envisions a collaborative traffic and aircraft control environment where a surface traffic automation system will help coordinate surface traffic movements. Specifically, the paper studies the performance potential of high-precision taxi toward the realization of such an environment. A state-of-the-art nonlinear control system based on feedback linearization is designed for a detailed B-737 aircraft taxi model. The simulation model with the nonlinear control system is evaluated extensively in a scenario representing the demanding situation of an arrival aircraft crossing an adjacent active runway immediately following its own landing. The evaluation establishes the potential of an automated system to achieve high-precision taxi control, including the ability to comply with taxi clearances with tight time margins. Such a high-precision taxi capability reduces the time margin required for clearing taxiing aircraft to cross active runways, thus increasing the opportunity for issuing such clearances, which in turn reduces the need for aircraft to hold short at the runways to wait for the opportunity for crossing. The results from the analyses provide insight into future aircraft operational capabilities toward the design of the envisioned surface traffic automation system. Moreover, the nonlinear control design serves as a preliminary study for future auto-taxi functional development.

Stability and performance of intersecting aircraft flows under decentralized conflict avoidance rules

Abstract: This paper considers the problem of two intersecting aircraft flows under decentralized conflict resolution rules. Considering aircraft flowing through a fixed control volume, new air traffic control models and scenarios are defined that enable the study of long-term aircraft flow stability. For a class of two intersecting aircraft flows, this paper considers conflict scenarios involving arbitrary encounter angles. It is shown that aircraft flow stability, defined both in terms of safety and performance, is preserved under the decentralized conflict resolution algorithm considered. It is shown that the lateral deviations experienced by aircraft in each flow are bounded.

Real-time high density people counter using morphological tools

Abstract: Deals with an application of image sequence analysis. In particular, it addresses the problem of determining the number of people who get into and out of a train carriage when it is crowded, and background and/or illumination changes. The proposed system analyzes image sequences and processes them using an algorithm based on the use of several morphological tools, which are presented in detail in the paper.

A radio-on-fiber based millimeter-wave road-vehicle communication system by a code division multiplexing radio transmission scheme

Abstract: A radio-on-fiber (ROF) based road-vehicle communication system is described in which several radio base stations (RBSs) communicate with a control station (CS) over ROF connections. The RBSs use the same millimeter-wave frequency band to communicate with mobile stations (MSs). The result is one large virtual cellular zone encompassing several RBSs controlled by one CS. However, in one virtual cellular zone, interference arises at the bound between adjacent cellular zones because the RBSs in each zone transmit their signals using the same frequency band. To minimize this interference, code division multiplexing is used to modulate the signals sent between the MSs and RBSs. Testing using an experimental course demonstrated that by using this system, we can achieve an error-free continuous communication system with a maximum transmission rate of 4.608 Mbps.

LED location beacon system based on processing of digital images

Abstract: This paper is in the field of vehicle positioning technology for the intelligent transportation systems. The ideas of an innovative light-emitting diode (LED)-based location beacon system are developed and verified. The system developed is a combination of several latest technologies which include a CMOS vision sensor, high brightness LED, and digital image processing techniques. It belongs to a new kind of simplex communication link. A digital camera is used to capture images contained in the LED beacon signal. The captured digital images are processed by the algorithms developed and a location code is extracted. The location code can be used for calibration of a vehicle positioning system which may consist of a GPS, inertial navigation system (INS) and other sensors. The issues examined include the structure of the transmitter and the receiver, the signaling method, the transmission protocol of the LED panel, the relationship between the camera capturing rate and the LED pattern update rate, the digital camera exposure technology, and the efficiency of the image processing algorithms. Experiments using a prototype transmitter and a receiver were performed. The experimental results provide a good demonstration of the viability of the ideas and methodologies developed.

A methodology for studying cognitive groupings in a target-tracking task

Abstract: In the present research, a special form of cluster analysis was successful in revealing cognitive groupings having appreciable influence on task performance in a target-tracking task designed to resemble ATC. The method of cluster analysis was derived from the "virtual associative network" model of memory organization and applied to the record of eye fixations in the course of task performance. Results using inexperienced subjects showed fixation clustering consistent with Gestalt factors. Task objectives did not seem to affect grouping as much. The subjects' recall was generally poor, except where direct manipulation of targets occurred. We conclude that: 1) cognitive grouping influences performance; 2) recall techniques may not be able to elicit subjects' cognitive groupings; and 3) such groupings can be determined via analysis of eye fixations. These findings have implications for studying workload assessment and information structuring in complex visual scanning tasks.

Recognizing vehicles in infrared images using IMAP parallel vision board

Abstract: Describes a method for vehicle recognition, in particular for recognizing make and model. Our system takes into account the fact that vehicles of the same make and model number come in different colors; it employs infrared (IR) images, thereby eliminating color differences. The use of IR images also enables us to use the same algorithm both day and night. This ability is particularly important because the algorithm must be able to locate many feature points, especially at night. Our algorithm is based on a configuration of local features. For the algorithm, our system first makes a compressed database of local features of a target vehicle from training images given in advance; the system then matches a set of local features in the input image with those in the training images for recognition. This method has the following three advantages: (1) it can detect even if part of the target vehicle is occluded; (2) it can detect even if the target vehicle is translated due to running out of the lanes; and (3) it does not require us to segment a vehicle part from input images. We have two implementations of the algorithm. One is referred to as the eigenwindow method, while the other is called the vector-quantization method. The former method is good at recognition, but is not very fast. The latter method is not very good at recognition but it is suitable for an IMAP parallel image-processing board; hence, it can be fast. In both implementations, the above-mentioned advantages have been confirmed by performing outdoor experiments.

Feasibility analysis of steering control as a driver-assistance function in collision situations

Abstract: This paper addresses the feasibility of post-impact maneuvers that aim to mitigate accident sequences. In particular, the discussions emphasize the possibility of applying steering control to stabilize the trajectories of vehicles involved in a collision. The problem of interest is defined with descriptions of accident scenarios, limitations of applicability, and performance requirements. A model of vehicle dynamics is constructed to facilitate the design of steering controllers. Various collision scenarios are simulated to demonstrate the effectiveness of a generic feedback controller. The analysis provided herein shows steering control is promising as a driver-assistance function in emergency situations.

The use of computer vision in monitoring weaving sections

Abstract: This paper presents algorithms for vision-based monitoring of weaving sections. These algorithms have been developed for the Minnesota Department of Transportation in order to acquire data for several weaving sections in the Twin Cities area. Unlike commercially available systems, the proposed algorithms can track and count vehicles as they change lanes. Furthermore, they provide the velocity and the direction of each vehicle in the weaving section. Experimental results from various weaving sections under various weather conditions are presented. The proposed methods are based on the establishment of correspondences among blobs and vehicles as the vehicles move through the weaving section. The blob tracking problem is formulated as a bipartite graph optimization problem.

Problem resolution support for free flight operations

Abstract: The MITRE Corporation's Center for Advanced Aviation System Development (CAASD) has been conducting research into new automation capabilities to support free flight operations. One of these capabilities is a problem resolution function to assist the en route sector controller team in handling the more complex traffic patterns that can result from a less structured free flight environment. This function is termed problem analysis, resolution and ranking (PARR). PARR is envisaged as an enhancement to the user request evaluation tool (URET) free flight phase 1 (FFP1) capability, and has been designated as priority research for the follow-on free flight phase 2 (FFP2) effort. PARR is being developed as a series of incremental enhancements, with the first step focusing on the resolution of aircraft-to-aircraft and aircraft-to-airspace problems. Follow-on enhancements include resolutions for metering and other traffic flow management (TFM) flow initiatives, resolutions for the avoidance of severe weather areas, and the integration into a common en route sector team CHI. A research management plan has been prepared by the Federal Aviation Administration and MITRE/CAASD to support this development process. The paper describes the initial PARR capabilities, along with an extension to incorporate assigned metering time constraints.

Inter-vehicle spread spectrum communication and ranging system with concatenated EOE sequence

Abstract: Proposes a method for designing spread sequences for a spread spectrum (SS) communication and ranging system. The proposed sequence is composed by concatenated equivalently odd and even (EOE) inner-sequences and an M outer sequence. We have previously proposed EOE sequences that have equivalently good properties of both even and odd correlation, what are important features for acquisition and demodulation in SS communications. Usually, simple concatenation of pseudonoise-sequences results in sequences with bad autocorrelation properties. Unlike the latter, concatenation of EOE inner sequences result in sequences with good correlation properties, exhibiting low sidelobe peaks, what is useful for achieving stable acquisition. The proposed sequences have long period. Therefore, the single concatenated EOE sequence is suitable for a spread spectrum system with both communication and ranging functions.

Ultrasonic vehicle detector for side-fire implementation and extensive results including harsh conditions

Abstract: Concerns vehicle detectors, which collect passing vehicle information and traffic condition in real time. This paper develops an ultrasonic vehicle detector (UVD) system that can be implemented in a side-fire configuration. Conventionally, UVD systems are installed in overhead configurations. If these sensors can be mounted from the side of a road, the installation cost can be reduced. In addition, the aesthetic integrity of roadways will not be affected very much. However, this side-fire configuration has not been used, because of the fact that vehicles generally do not have sufficiently large oblique-angled surfaces to reflect the emitted ultrasonic wave back to the sensor for detection. This paper reports on the feasibility of a side-fire UVD system. A new low-cost instrumentation and control system for side-fire implementation was developed, and comprehensive experiments were performed at highway and downtown test sites. Experimental conditions included various traffic conditions as well as various weather conditions, including daylight, dusk, night, heavy rain, and heavy snow. Traffic data were generated for every five minutes. For the highway location, the vehicle counting error was less than 1%. For the downtown location, the error was approximately 3% during normal weather conditions and approximately 5% during a snow storm. The larger error in downtown is mainly attributed to vehicles changing lane. We believe that these side-fire implementation results are adequate for implementing advanced traveler information systems (ATIS).

Investigation for a global AVL system

Abstract: Real-time reporting systems are now becoming widely available, in order to aid emergency dispatch assistance and traffic control management as being an important part of intelligent transportation systems (ITS). Based on the fact that the global system mobile (GSM) standard is widely accepted as being the most comprehensively deployed of all the various second generation digital cellular telephony standards, studies have been focused on using it as a communication link for real-time application reporting. This paper introduces a study made on an integrated system incorporating a global positioning system (GPS) receiver, a control area network (CAN) and the short message service (SMS) of GSM as the transmission media. The goal of the research study conducted, is to measure the end to end delays experienced, and consequently its practicality, when using a CAN bus and the GSM-SMS bearer service for position reporting for use in an ITS environment. The paper initially presents the previous research that has been carried out relevant to this study. Following it outlines the system architecture of the integrated system studied together with its functionality in an ITS environment. The results obtained from the various simulation scenarios are presented as well as an estimation algorithm that aims to diminish the positioning error incorporated from the transmission delays occurred. Concluding this paper discusses the advantages of using this integrated system as a solution for position reporting in ITS as well as proposing further research to be conducted.

Validating a future operational concept for en route air traffic control

Abstract: In an effort to accommodate the predicted growth in air traffic, the Federal Aviation Administration (FAA) and the aviation community have developed a concept of operations for the National Airspace System (NAS) called Free Flight. This operational concept has been developed for the midterm time frame (nominally a period of time that centers around 2005). The Center for Advanced Aviation System Development (CAASD) at The MITRE Corporation developed the concept and has conducted laboratory exercises to validate the portion of the concept that applies to the en route domain. The paper describes CAASD's laboratory efforts to begin validating the en route portion of the concept by examining the operational issues associated with the concept and the functional issues related to its evolution to the midterm. The laboratory validation exercises described examine the functionality of possible capability enhancements, but do not address associated detailed human factors issues. Favorable results from CAASD's initial qualitative validation efforts support the need for further quantitative validation activities that include more detailed analyses, further development of operational procedures and computer-human interfaces, and more rigorous exercises involving FAA field controllers.

The rate control index for traffic flow

Abstract: The objective of air traffic flow management is to maintain safe and efficient use of airspace and airports by regulating the flow of traffic. We introduce a single-valued metric for post-operatively rating the performance of achieved traffic flow against targeted traffic flow. We provide variations on the metric, one of which factors out stochastic conditions upon which a plan is formulated, and show how these improve on current traffic control analysis techniques. The core of the metric is intuitive and simple, yet leads to an interesting optimization problem that can be efficiently solved via dynamic programming. Numerical results of the metric are given as well as a sample of the type of analysis that should follow a low rating by the metric. Although this metric was originally developed to rate the performance of ground delay programs, it is equally applicable to any setting in which the flow of discrete objects such as vehicles is controlled and later evaluated.

Performance of COFDM-based transmitter diversity in a road-to-vehicle communication system

Abstract: Proposes a coded orthogonal frequency-division multiplexing (COFDM) based road-to-vehicle communication system. The proposed system makes efficient use of COFDM in order to get the implicit transmitter diversity effect. The paper then evaluates the received signal power and bit error rate performance in two diversity models. In one model, two antennas are vertically set up on top of a base station (BS) post. The other model uses two BS and the same signal is simultaneously transmitted from both BS. Computer simulation results show that the proposed scheme is capable of obtaining the transmitter diversity effect in both models.

An experimental approach to measuring the effects of a controller conflict probe in a free routing environment

Abstract: The unstructured traffic environment that is gradually evolving in the National Airspace System may necessitate decision aiding tools to help controllers manage aircraft traffic efficiently and within acceptable safety and workload levels. An experiment was designed to assess the effect of conflict detection and trial planning resolution aids and traffic conditions on the performance of controllers and the efficiency of flight. Twelve controllers participated in a high-fidelity simulation study in the Indianapolis Center dynamic simulation facility using the user request evaluation tool (URET). Study results indicated that URET clearly improves the acceptability of operations and may enhance safety, particularly in the unstructured environment. In addition, the study findings strongly support a shift toward more strategic air traffic control with conflict probe as well as a significant increase in the contribution of the D controller to the primary sector tasks. Because of study limitations, it was not possible to associate any quantitative estimates of airspace user benefits with the potentially more efficient resolution strategies. The results and experimental approach are discussed in terms of their contribution to measurement methods and issues in the evolutionary progression toward a free flight-based air traffic system.