Navigation by ocean surface topography

Patent metadata

Field	Value
Publication number	US-9653003-B2
Application number	US-201514636419-A
Country	US
Kind code	B2
Filing date	Mar 3, 2015
Priority date	Mar 21, 2014
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

Methods and apparatus ascertain a geographic position based on topographic contours of ocean surfaces. Observed ocean topographic contours are matched to predicted ocean topography and/or ocean topographic information stored in a database. Such systems and methods do not necessarily require INS, GPS, RF beacons, optical beacons or celestial sightings. These systems and methods may be used as references to correct INS. These systems and methods may be used to ascertain a geographic location of an aircraft, spacecraft, watercraft, landcraft (vehicle), person or the like. Similarly, these systems and methods may be used as part of a guidance system for guiding a craft to a destination. These systems and methods may be used in tandem with, or as backups for, other types of navigation or guidance systems or as one input to a navigation filter.

First claim

What is claimed is:

1. A geographic positioning system useful above the surface of earth, comprising:
an ocean topography prediction model providing predicted topographical information about predicted contours of a surface of at least a portion of a body of water on the earth, the predicted topographical information about the predicted contours comprising one or more of: (a) predicted surface height gradient information, (b) predicted surface temperature gradient information, (c) predicted surface color gradient information or (d) a combination thereof, the predicted topographical information correlating the predicted contours with geographic locations on the earth, the ocean topography prediction model being configured to predict the predicted topographical information based at least in part on one or more of: (a) historical ocean surface height information, (b) historical ocean temperature information, (c) historical ocean color information or (d) a combination thereof;
a sensor configured to detect a contour of a portion of the surface of the body of water beneath the sensor by imaging the portion of the body of water from above; and
a contour matching engine coupled to the ocean topography prediction model and to the sensor and configured to automatically match the detected contour to a predicted contour provided by the ocean topography prediction model and automatically provide a geographic location of the detected contour.

2. A geographic positioning system according to claim 1 , further comprising a navigation filter coupled to receive:
the geographic location provided by the contour matching engine; and
at least one other geographic location provided by a corresponding at least one other geographic positioning system.

3. A geographic positioning system according to claim 2 , wherein the at least one other geographic positioning system comprises an inertial navigation system.

4. A geographic positioning system according to claim 1 , wherein the ocean topography prediction model is configured to predict the predicted topographical information based at least in part on at least one of:
a time at which the sensor detects the contour;
a weather prediction;
information about a prevailing wind; and
information about a current in the body of water.

5. A geographic positioning system according to claim 1 , wherein the ocean topography prediction model comprises a database storing the topographical information about the surface of the at least a portion of the body of water.

6. A geographic positioning system according to claim 5 , wherein the topographical information stored in the database includes topographical information about contours of a portion of the surface of the earth not covered by the body of water.

7. A geographic positioning system according to claim 1 , wherein the predicted topographical information provided by the ocean topography prediction model includes topographical information about contours of a portion of the surface of the earth not covered by the body of water.

8. A geographic positioning system according to claim 1 , wherein the sensor comprises at least one of:
a radar;
a radio altimeter;
a 3-dimensional imaging camera;
a stereo camera;
a laser altimeter;
a LIDAR;
a surface temperature sensor; and
a surface color sensor.

9. A method for ascertaining a geographic position above the surface of earth, the method comprising:
generating topographical information about contours of a surface of at least a portion of a body of water on the earth, the topographical information correlating the contours with geographic locations on the earth, wherein generating the topographical information comprises executing on a processor the steps of:
(a) receiving historical contour information about the body of water on the surface of the earth;
(b) automatically generating a mathematical model of a state of the body of water corresponding to a start time, based at least in part on the historical contour information;
(c) setting an index time equal to the start time;
(d) automatically estimating rates of change of respective portions of the modeled state of the body of water;
(e) incrementing the index time;
(f) automatically estimating a new state of the body of water corresponding to the index time, based on the estimated rates of change and a previous modeled state of the body of water, thereby automatically generating a new mathematical model of the state of the body of water;
(g) automatically replacing the previous mathematical model with the new mathematical model of the state of the body of water;
(h) repeating at least (f) until the index time reaches a predetermined value; and
(i) outputting predicted surface contour information about the body of water, including one or more of (1) surface height contour information about the body of water, (2) surface temperature contour information about the body of water, (3) surface color contour information about the body of water or (4) a combination thereof, based on the new mathematical model of the state of the body of water;

using a sensor, automatically detecting a contour of a portion of the surface of the body of water beneath the sensor by imaging the portion of the body of water from above;
automatically matching the detected contour to a contour in the generated topographical information; and
automatically providing a geographic location of the detected contour.

10. The method of claim 9 , further comprising:
providing the geographic location to a navigation filter;
providing at least one other geographic location from a corresponding at least one other geographic positioning system to the navigation filter; and
automatically calculating a solution geographic location by the navigation filter, based on the geographic location and the at least one other geographic location.

11. The method of claim 9 , wherein generating the topographical information comprises predicting the topographical information based at least in part on historical ocean topographical information.

12. The method of claim 11 , wherein receiving generating the topographical information further comprises predicting the topographical information based at least in part on at least one of:
a time at which the sensor detects the contour of the portion of the surface of the earth;
a weather prediction;
information about a prevailing wind; and
information about a current in the body of water.

13. The method of claim 9 , wherein generating the topographical information comprises retrieving, from a database, topographical information about contours of a portion of the surface of the earth not covered by the body of water.

14. The method of claim 9 , wherein detecting the contour of the portion of the surface of the earth comprises imaging at least one of:
the portion of the surface of the earth with a radar;
the portion of the surface of the earth with a radio altimeter;
the portion of the surface of the earth with a 3-dimensional imaging camera;
the portion of the surface of the earth with a stereo camera;
the portion of the surface of the earth with a laser altimeter;
the portion of the surface of the earth with a LIDAR;
the portion of the surface of the earth from an aircraft;
the portion of the surface of the earth from a spacecraft;
the portion of the surface of the earth from a lighter-than-air craft; and
the portion of the surface of the earth from a watercraft.

15. A computer program product for ascertaining a geographic position from above the surface of earth, the computer program product comprising a non-transit

Assignees

• Charles Stark Draper Laboratory Inc

Inventors

• Laine Juha-Pekka J
• Blasche Gregory P
• Bohn Paul
• Dawson Robin Mark Adrian
• Foley Walter
• Lane Benjamin F
• Mcclain Sean
• Waldron Erik L
• Smith Stephen P

Classifications

• G06F17/10

  Complex mathematical operations {(function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544)} · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• G09B29/10 Primary

  Map spot or coordinate position indicators; Map reading aids (optical projection apparatus per se G03B) · CPC title

• G01C21/20

  Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence) · CPC title

• G01C21/005

  with correlation of navigation data from several sources, e.g. map or contour matching (G01C21/30 takes precedence) · CPC title