Automated highway tracking and communication system and method

Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle

Reexamination Certificate

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Details

C180S169000, C342S450000

Reexamination Certificate

active

06219596

ABSTRACT:

FIELD OF INVENTION
The present application is directed to a system and method for determining the position of a vehicle on a highway. The system and method of the present application is further directed to a system and method for determining the location of a vehicle on the highway while simultaneously providing a communication link between a so-called intelligent transportation system and the vehicle.
BACKGROUND OF THE INVENTION
There has been an increasing recognition throughout the world that highway traffic is becoming an increasing problem, both from the standpoints of highway congestion and safety. One solution to this problem is to dramatically increase the number of highways to thereby decrease highway congestion. However, considerable expense is associated with the development of new highways and such new highways demand that an increasing percentage of land be utilized to support such highways, thereby decreasing the efficiency of a society's land utilization. Furthermore, in congested areas, there is little realistic opportunity to construct new highways, as no additional space exists. Accordingly, there is a need to make current highways more efficient.
There have been several recent proposals to develop an intelligent highway system which would allow both increased highway safety and higher highway utilization. One proposal for such an intelligent highway system is to automatically monitor and control the position of each vehicle along the highway, enabling the control of vehicle following distances and braking profiles to increase highway safety while reducing the vehicle spacing requirements otherwise necessary with individual vehicle operator control.
In such automated highway systems, it is desirable for the roadway and/or each vehicle to monitor its longitudinal position along the roadway. Further, in such systems, automated lane tracking may be considered desirable.
In such automated highway systems, it is further desirable to supply each vehicle and the operator thereof with highway originated information of various types. For example, it may be desirable to provide the operator of each vehicle with traffic jam information, regulatory information, as well as road direction and parking information.
A supplemental advantage of such an intelligent transportation system is that, through interactive control of each vehicle by the highway, less acceleration and braking inputs are necessary, reducing the amount of stop and go traffic and additionally reducing fuel requirements and according decreasing resultant pollution.
One such automated highway system which has been proposed is under development primarily by Nissan Motor Company, Limited with the support of the Japanese Ministry of Construction. Such a system determines a vehicle's lateral placement along the roadway through the use of magnetic nails imbedded down the center of the road bed and monitored by a vehicle born magnetic nail sensor which determines the relative position of the front of the vehicle with respect to the magnetic nails, and seeks to control vehicle position to center the vehicle over the magnetic nails.
In the magnetic nail lateral position measurement system, the magnetic nails have the ability of being locatable virtually anywhere. However, the ability to monitor such magnetic nails is subject to severe degradation in dependence on weather conditions. For example, a snowstorm may make such a lateral position measuring system unusable. Further, the use of such magnetic nails increases the complexity of roadway maintenance. For example, roadway resurfacing encounters significant difficulties when imbedded magnetic nails are present.
In the above-mentioned system, vehicle position longitudinally along the roadway is determined through the use of a global positioning satellite system (GPS). Each vehicle receives GPS signals and decodes them to determine the vehicle's own position. Such a GPS recorded position is integrated with velocity, acceleration, and yaw rate vehicle mounted sensors to produce a kinematic-GPS estimate of vehicle position. In such a kinematic-GPS system, while accurate longitudinal position of the vehicle may be developed, the GPS signals are not available under trees, bridges, or in tunnels, thereby limiting system useability.
The above-mentioned system further utilizes a road-to-vehicle communication system which comprises a vehicle mounted antenna communicating with a leakage coaxial cable installed along the roadway shoulder. However, this communication system must be installed separately from the above-mentioned systems, thus adding to expense.
SUMMARY OF THE INVENTION
The concepts of the present application overcome substantial disadvantages of the known automated highway systems. With respect to lateral vehicle location, the system of the present invention employs a vehicle borne transmitter which transmits a vehicle identifying signal for reflection by a roadside located reflector which, in one preferred embodiment, may function as a highway guardrail or may form part of a tunnel or highway wall or the like. The use of the highway guardrail structure as a lateral position reflector has several advantages. The guardrail is less susceptible to lateral position measurement degradation due to inclement weather such as snow, sleet, rain or the like. Precipitation is more likely to cover the roadway and the magnetic nails embedded therein than it is likely to obstruct the communication path between the guardrail and the vehicle. Accordingly, as compared to road bed mounted magnetic sensors, such a roadside located reflector is less dependent on weather.
A further advantage is obtained through the use of the vehicle transmitted interrogation signal containing a spread spectrum PRN (pseudo-random noise) code. Such spread spectrum PRN codes may be made virtually unique, effectively eliminating the risk that the transmission from a first vehicle will produce a reflection received by a second vehicle.
The system of the present invention additionally proposes to periodically mount longitudinal position transducers along the highway roadside, which transducers will be responsive to the vehicle borne interrogation signal and will produce a reply signal indicative of the vehicles position. Such a longitudinal position system has significant advantages over the known kinematic-GPS system. Firstly, such a system may include roadside sensors mounted in tunnels or in other places where GPS reception would be obscured. Secondly, the interrogations and reflections from the longitudinal position sensors may also be utilized for communication through the use of messages transmitted therewith.
Thus, the longitudinal position system of the present invention also utilizes the same roadside located infrastructure to both determine vehicle position for the benefit of both the vehicle and the roadway system, and to allow the communication of additional messages.
As explained above, the known automated highway system utilizes a leakage coaxial cable and system for such communication. However, this leakage coaxial cable system does not perform any vehicle location function. The longitudinal position detection system of the present application allows the detection of longitudinal position and the communication of imbedded messages between the vehicle and the intelligent transportation system.
It is accordingly apparent that the system of the present invention is substantially improved over the known prior art.


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