Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1998-12-23
2001-02-06
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C073S38200R, C702S092000, C702S152000, C701S220000
Reexamination Certificate
active
06185502
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system for providing an accurate geographic position of a vehicle.
BACKGROUND OF THE INVENTION
In the past, gyros and accelerometers have been used in a combination, in order to provide inputs to a gyro navigation system. These inputs have been used by the gyro navigation system in order to provide a geographic position of a vehicle on which the system is placed.
However, with the passage of time, sensor axes of the gyros becomes less accurate, due to drift of spin axes of the rotors of the gyros. The provided geographic position of the vehicle becomes less accurate with time, due to such drift of the spin axes of the rotors of the gyros.
The passive position fix system of the present invention uses gyros and accelerometers of a gyro navigation system on a vehicle to find a gyro position of a vehicle on which the passive position fix system has been placed. The passive position fix system compares stored a gravity gradient and gravity anomaly map-set, for each of several geographic positions in a region around the gyro position of the vehicle, with measurements from gravity gradient sensors and a gravity anomaly sensor. The passive position fix system finds a best estimate of the position difference between the gyro position and the geographic position of the vehicle. The gyro navigation system is updated with this best estimate of position difference. The passive position fix system thus provides an updated gyro position of the vehicle.
The gyro navigation system, gravity gradient and gravity anomaly map-sets, and a gravity gradient and gravity anomaly sensor system are central parts of the passive position fix system.
The gravity gradient and gravity anomaly sensor system and the gravity gradient and gravity anomaly map-sets are used in a map matching technique in the passive position fix system. The gravity gradient and gravity anomaly sensor system and the gravity gradient and gravity anomaly map-sets can be used to periodically update the gyro position provided by the gyro navigation system.
The gravity gradient and gravity anomaly sensor system and gravity gradient and gravity anomaly map-sets could be used independently to provide geographic locations of a vehicle.
The passive position fix system has a gravity gradient and gravity anomaly sensor system. The gravity gradient and gravity anomaly sensor system firstly measures six gravity related parameters. The six measured parameters are five gravity gradients and one gravity anomaly.
These six measured parameters are then successively compared to each of several stored map-sets for geographic positions in the region of the gyro position as provided by the gyro navigation system. A stored map-set is a set of stored map parameters for a corresponding geographic position. A set of stored map parameters consists of five predetermined gravity gradients and one predetermined gravity anomaly of a corresponding geographic position.
Information derived from comparisons of the map-sets with the six measured gravity related parameters is used by a real-time filtering algorithm to compute a displacement vector between the gyro position as provided by the gyro navigation system and the geographic position whose map-set provides a match. The displacement vector is used to update the gyro position of the gyro navigation system of the passive position fix system.
An objective of the passive position fix system (PPFS) is to allow an operator on a vehicle to accurately determine the geographic position of the vehicle, in real-time, without exposure or radiation of energy, in a completely passive manner.
The objectives of the PPFS are:
a) passivity
b) accuracy
c) manual/automatic fix site selection and course guidance from site to site
SUMMARY OF THE INVENTION
A passive position fix system on a vehicle, the vehicle having a geographic position over the earth comprising gyro means for providing a first gyro position of the vehicle, map storage means for receiving the first gyro position and in response providing map-sets associated with geographic positions in the vicinity of the first gyro position provided by the gyro means, each map-set comprising a stored set of gravity gradients and a gravity anomaly at an associated geographic position on the earth, gravity sensor means for providing a GSS-set, the GSS-set comprising a sensed set of gravity gradients values and a gravity anomaly value at the geographic position of the vehicle, comparator means for receiving the GSS-set and for sequencially receiving the map-sets and for determining when there is a match between the GSS-set and a map-set and for providing a displacement vector based on which map-set matches the GSS-set, and processor means for placing a second gyro position in the gyro means based on the first gyro position and on the displacement vector.
REFERENCES:
patent: 3731537 (1973-05-01), Trageser
patent: 4173784 (1979-11-01), Heath et al.
patent: 4399694 (1983-08-01), Mayer
patent: 4783742 (1988-11-01), Peters
patent: 5339684 (1994-08-01), Jircitano et al.
Chew Sung Leong
Dmytrasz Joseph N.
Gatta Joseph
Mauser Lorraine M.
Sumner Donald L.
Cuchlinski Jr. William A.
Pipala Edward
Tarlano John
The United States of America as represented by the Secretary of
LandOfFree
Passive position fix system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Passive position fix system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Passive position fix system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2600324