Automated Ground Transportation Research Articles

Towards functional requirements for automated ground transport vehicles operating under harsh weather conditions

An automated vehicle (AV) needs to translate all human driver capabilities into specific functionalities by using a large number of systems. An AV also depends on external systems which are capable of communicating with it. In the AWARD project, the concept of System of Systems (SoS) is used to denote a set of four interoperable systems belonging to the Automated Ground goods Transport System (AGTS). This paper proposes a new methodology for defining the Functional Requirements (FR) needed for the AGTS setup. This methodology defines FR concerning Operational Design Domain (ODD)- and AGTS-elements. We first provide a study about the most commonly used sensor systems in AVs. Then, we describe the SoS and an example of the ODD definition. Finally, we illustrate how a list of FR is obtained from the relationship between an ODD and the different elements of the SoS.

A lane changing time point and path tracking framework for autonomous ground vehicle

Performing stable and safe lane changes can avoid collisions and improve traffic safety. In recent years, most of the research in automated ground transportation was focused on path planning and path tracking. However, this work emphasizes the importance of lane changing time point. Based on traditional safety distance, a novel concept, that is the synthesized safety distance for lane changing (SSDLC), is proposed to study lane changing time point. It consists of the reference safety distance and lane changing safety distance, and the weight coefficient between them is obtained by fuzzy logic control algorithm. Additionally, the joint model predictive control (JMPC) is proposed to follow the reference trajectory. This newly established algorithm not only considers the physical saturation of actuators but the yaw stability characteristics. To overcome the calculation difficulty to obtain the optimal results in the prescribed time, the algorithm adds a relaxation factor in the objective function. Finally, the lane changing time point and path tracking framework is modeled and simulated on a CarSim-Simulink platform. Four scenarios are carried out to illustrate the feasibility of the proposed framework.

Design evaluation of an interface between passengers and an automated ground transportation system : Bateman, R.P. In: Compass for Technology, Proceedings of the 23rd Annual Meeting of the Human Factors Society, Boston, Massachusetts, Oct 29–Nov 1 1979, Edited by C.K. Bensel, pp 119–123

Design evaluation of an interface between passengers and an automated ground transportation system : Bateman, R.P. In: Compass for Technology, Proceedings of the 23rd Annual Meeting of the Human Factors Society, Boston, Massachusetts, Oct 29–Nov 1 1979, Edited by C.K. Bensel, pp 119–123

Design Evaluation of an Interface between Passengers and an Automated Ground Transportation System

In an automated airport ground transportation system, passengers who are not familiar with the system nor oriented with respect to the airport, are faced with the problem of selecting a vehicle and destination to change between airlines. The design of an interface between an untrained human user and an automated system requires skillful application of basic human factors principles. An existing system was studied to determine its effectiveness. Passengers were interviewed to identify specific problems. An operational sequence diagram was used to analyze the interface problem. A simplified sequence is proposed in a design modification which can be implemented at minimum cost. A redesign of the complete interface, using the power of the computer which controls the system, and applying human factors principles, results in a greatly simplified operational sequence diagram and is recommended for future systems.

The experimental evaluation of flat periodic transmission lines for use as an information source in automated transportation systems

A brief summary of some past studies of the use of transmission lines as an information source for automated ground transportation systems is presented. One method, which involves the use of helically wound transmission lines, was found to be promising [6] but such lines are difficult to implement. Here the geometry-dependent properties of the magnetic-field distribution of flat periodic transmission lines is developed. It is found that such lines should be usable as a replacement for helically wound lines. The results of an experimental evaluation of several flat lines are presented with emphasis on triangular-shaped lines. It is found that the performance characteristics are even better than those of the helically wound line.

A continuous longitudinal control signal for automated transportation systems via the low-frequency excitation of helical transmission lines

A method of generating continuous position information for use in the longitudinal control of automated ground transport systems is presented. The technique utilizes two specially excited four-wire helically wound transmission lines. The method of excitation, the signal detection, and processing schemes necessary to obtain the control signal, and the results of laboratory tests are presented. The technique should provide accurate, easily implementable, and environmentally impervious means of generating information for longitudinal control.

On Distributed Control in Automated Ground Transport

The achievement of safe and efficient longitudinal control is probably the most significant technical problem associated with individual- vehicle, automated ground transport systems such as automated guideway transit and the automatic highway. Here a hierarchical approach to such control which includes a central computer for supervising an area-wide network, a regional computer for control of operations in each reqion of that network, a sector computer for vehicle control in each sector of a region, and individual vehicle control, is described. In addition, recent advances pertaining to the design, development and testing of a sector-level control facility for the evaluation of high-speed (to 30 m/sec), small time-headway (1-2 sec) operations will be presented.

Wire-reference configurations in vehicle lateral control

Lateral control is an essential function for all forms of individual automated ground transport. Here two aspects of such control--the magnetic field distributions associated with a guideway-based, wire-reference configuration, and the associated vehicle-based sensors--are reviewed. Two wire-reference schemes have thus far been suggested. In the first, the amplitude characteristics of the magnetic field are employed to obtain the lateral control signal. In this paper, a theoretical analysis and detailed field measurements are used to define both ideal characteristics and those which would be encountered in a realistic operating environment. The resulting problems, which involve amplitude distortions of the field due to the proximity of steel-reinforcing materials, are defined, and their effects on vehicle control--poor tracking and passenger discomfort--are discussed. In the second approach, the lateral control signal is primarily dependent on the phase characteristics of the magnetic field. A theoretical analysis and a corresponding experimental field study, which are discussed herein, indicated that the problems associated with the first approach were largely overcome, as evidenced by successful full-scale tests of an automatically steered vehicle.

Automated Ground Transportation System Stations with Multiple Loading Positions

This paper presents analytical results for multiple loading positions that are arranged in series, parallel, or some series-parallel combination. Vehicles approach the station at a constant velocity before decelerating at a constant level to reach their designated loading positions. After remaining in the station for a specified period of time they accelerate at a constant level until resuming their initial velocity. Expressions for maximum station throughput are derived upon taking emergency stopping distance and the braking system response time as alternative bases for the minimum spacing between successive vehicles. It is noted for several illustrations that much of the high station throughput associated with response time intervehicle spacings may be alternatively achieved by adhering to the simpler control strategy involving stopping distance spacings and by employing an emergency braking rate which is approximately twice the level for operational deceleration.

Synchronous longitudinal reference signal generation—An experimental study of its use in automatic vehicle control

A method of obtaining a continuous reference signal for use in the synchronous longitudinal control of automated ground transport systems is presented and evaluated in preliminary full-scale tests. The results of the latter, which were obtained using a reference signal in conjunction with an instrumented vehicle at speeds from 0 to 46 ft/s over 1600 ft of roadway, are presented. Successful operation was achieved with both steady-state and time-varying velocity command signals. A significant finding, with respect to implementation of the method, was that the roadway environment introduces signal attenuation (2 dB/100 ft) that must be circumvented before practical long-distance operation can be achieved. However, with system refinement, the technique holds great promise for future implementation.

On the operation of automated ground transportation systems, part I: Urban problems and perspectives

Several approaches to the operation of automated ground transport systems for urban use are presented and evaluated. Such systems have been suggested principally in response to the problems of urban traffic congestian and are often proposed as solutions to such problems. Thus this paper, the first of a series of three, discusses the problems of urban transportation and their origins, identifying as the principal elements the institutional structure, urban geography, and design of facilities for urban automotive transport. Importantly, the origins of a significant portion of "the urban transportation problem" lie outside the transport sector. Six potential applications for automated transport systems are suggested, ranging from specialized single-link "horizontal elevators" to general-purpose wide-area networks.

Safety criteria for automated ground transportation systems

Safety criteria for automated ground transportation systems

Comments on "Design and control considerations for automated ground transportation systems"

Comments on "Design and control considerations for automated ground transportation systems"

Design and control considerations for automated ground transportation systems

Fundamental system and control problems associated with proposed automated ground transportation concepts are discussed. The problem formulation provides a systematic approach toward the synthesis and techinical evaluation of a large class and future systems employing automatically controlled single-mode or dual-mode vehicles on intracity guideway networks. Important system engineerig problems--common to some degree to all proposed concepts--are defined and the associated control requirements are discussed. Basic performance criteria, the weighted average travel time and relative safety of travel, are formulated. Tradeoffs between important system parameters are identified and their relations to performance and cost are discussed. Analysis of system operation is based upon idealized models in which perfect information and control are assumed. Upper bounds on performance are thus obtained, and the main constraints are identified. The degradation of system performance resulting from random arrivals and departures is thereafter analyzed quantitatively. Finally, control problems arising from the use of short headways are discussed. The objective of the paper is to help develop a systematic approach to the design of automated transportation systems using digital computers and modern electronic communications. It concentrates on the functional system problems of relatively simple networks, which lend themselves to direct analytical approaches and which constitute a point of departure for more complex networks.