Data processing: vehicles – navigation – and relative location – Relative location – Collision avoidance
Reexamination Certificate
2001-07-09
2003-05-13
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Relative location
Collision avoidance
C701S120000, C701S122000, C701S300000, C340S945000, C340S961000, C340S963000, C342S029000, C342S032000
Reexamination Certificate
active
06564149
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to collision avoidance systems and, more particularly, to a method, system, and computer software program product for determining conflicting paths between mobile airborne vehicles.
BACKGROUND OF THE INVENTION
Air traffic is ever increasing as the number of aircraft in service continues to grow. Travel demands and movement of air cargo also contribute to the number of aircraft taking to the skies. Accordingly, the avoidance of mid-air collisions between aircraft has become a significant concern as keeping track of heavy air traffic becomes an increasingly difficult process. The speed and size of modern aircraft are factors contributing to the difficulty of the tracking process, especially when multiple aircraft are involved. Approximations may no longer be acceptable as air space becomes limited and as time and separation distances decrease. Also, proposals to replace the present air traffic control system with a “free flight” system will require reliable collision warnings based on aircraft-to-aircraft communications.
In some instances, the devices used to determine the aircraft position relative to the earth may be subject to inaccuracies. Global Navigation Satellite Systems (“GNSS”) such as, for example, Global Positioning System (“GPS”) devices, are well known in the art and are commonly used for the determination of the geodetic longitude and latitude coordinates of mobile vehicles employing such a device. For simplicity, a GPS device will be discussed herein as an example of a GNSS, wherein the term “GNSS” and “GPS” may be used interchangeably. However, it will be understood by one skilled in the art that the present invention is not restricted to a GPS device and may be applicable to other GNSS-type devices according to the spirit and scope of the present invention.
With a GPS device, information signals transmitted from a plurality of satellites to a GPS receiver are analyzed using known trilateration techniques in order to determine the geodetic coordinates of the receiver, wherein the geodetic coordinates are typically provided in latitude and longitude. The geodetic coordinates (latitude and longitude), however, may vary in accuracy due to, for example, atmospheric conditions, selective satellite availability, and the relevant positions of the satellites with respect to the line-of-sight view of the satellites. Often associated with this variance in GPS accuracy is an integrity determination, which produces a warning if it is determined that the GPS accuracy is insufficient to be relied upon for navigational purposes. Accordingly, where a GPS integrity system is provided, a maximum horizontal position error, otherwise referred to as a “horizontal protection level” (“HPL”) may be determined and compared to an allowable radial error, otherwise referred to as a “horizontal alarm limit” (“HAL”). If the HPL is found to exceed the HAL, then a warning is issued that the geodetic coordinates should not be relied upon for accuracy.
In other instances, the GPS device may be interfaced with other navigational equipment, wherein the GPS device may also be relied upon to provide location coordinates as well as position accuracy and/or integrity information. For example, the GPS device may be interfaced with a Mode S transponder, via a processing unit, with the transponder configured to receive either position integrity or position accuracy information from the GPS device, as is known in the art. The position accuracy or integrity information is converted into a corresponding code in a data stream which is then transmitted by the transponder. The data thus transmitted by the transponder indicates the position of the vehicle carrying the GPS device, as well as the level of integrity and/or accuracy of that position information.
Other factors may also contribute to inaccuracies in an aircraft collision avoidance system. For example, horizontal separation distances are often calculated based upon a flat earth model. Such a flat earth model may generate only a small amount of error for short ranges near the equator. However, since the earth is shaped more as a spheroid, the magnitude of error increases as the latitude shifts away from the equator. Thus, at or near the poles, the flat earth model will be subject to inaccuracies and generally cannot be used to calculate horizontal separation distances or ranges thereof.
Thus, there exists a need for a technology capable of determining conflicting flight paths between aircraft or other airborne vehicles that is able to account for sources of inaccuracies in determining horizontal separation distances, such as in navigational devices used by the airborne vehicles and in the modeling of the earth, so as to obtain a collision avoidance system that is effective regardless of geodetic latitude and longitude and that is configured to facilitate navigational efficiency and user-friendliness.
SUMMARY OF THE INVENTION
The above and other needs are met by the present invention which, in one embodiment, provides a method of determining conflicting flight paths between a first airborne vehicle and a second airborne vehicle. First, a position and a velocity vector are determined for each of the first airborne vehicle and the second airborne vehicle. A cylindrical volume is then defined about the first airborne vehicle such that the first airborne vehicle is centrally disposed therein. A separation distance is then determined between the first airborne vehicle and the second airborne vehicle, at least partially from the position and the velocity vector of each vehicle, at a selected time and using a great circle earth model. An accuracy factor is thereafter determined for the position of each vehicle. The determined separation distance is then modified by the accuracy factor. A determination is then made as to whether the modified separation distance is within the cylindrical volume about the first airborne vehicle during a time range so as to determine whether conflicting flight paths exist between the vehicles.
Another advantageous aspect of the present invention comprises a system for determining conflicting paths between a first airborne vehicle and a second airborne vehicle. The system comprises a computer device housed by the first airborne vehicle. The computer device further comprises a processing portion for determining a position and a velocity vector for each of the first airborne vehicle and second airborne vehicle. Another processing portion defines a cylindrical volume about the first airborne vehicle, wherein the first airborne vehicle is centrally disposed therein. A further processing portion determines a separation distance between the first airborne vehicle and the second airborne vehicle at a selected time and using a great circle earth model. Another processing portion determines an accuracy factor for the position of each vehicle. Still another processing portion modifies the determined separation distance by the accuracy factor. Still a further processing portion then determines whether the modified separation distance is within the cylindrical volume about the first airborne vehicle during a time range so as to determine whether conflicting flight paths exist between the vehicles.
Still another advantageous aspect of the present invention comprises a computer software program product capable of being executed by a computer device so as to determine conflicting flight paths between a first airborne vehicle and a second airborne vehicle. The computer software program product comprises an executable portion capable of determining a position and a velocity vector for each of the first and the second airborne vehicles. Another executable portion is capable of defining a cylindrical volume about the first airborne vehicle such that the first airborne vehicle is centrally disposed therein. Still another executable portion is capable of determining a separation distance between the first vehicle and the second vehicle at a selected time and using a great circle earth model. Yet ano
Alston & Bird LLP
Louis-Jacques Jacques H.
United Parcel Service of America Inc.
LandOfFree
Method for determining conflicting paths between mobile... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for determining conflicting paths between mobile..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for determining conflicting paths between mobile... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3027061