SYSTEM AND METHOD FOR DETERMINING GEO LOCATION OF A TARGET USING A CONE COORDINATE SYSTEM

• US 20160061932A1
• Filed: 10/23/2013
• Published: 03/03/2016
• Est. Priority Date: 09/24/2013
• Status: Active Grant

• Current Assignee: Raytheon Applied Signal Technology Incorporated (Rtx Corporation)
• Original Assignee: Raytheon Applied Signal Technology Incorporated (Rtx Corporation)
• Inventors: May, William D.
• Granted Patent: US 9,759,802 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 2205/03 Airborne
• CPC Class Codes: G01S 5/0249 Determining position using measurements made by a non-stationary device other than the device whose position is being determined
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: G01S 5/0269 Inferred or constrained positioning, e.g. employing knowledge of the physical or electromagnetic environment, state of motion or other contextual information to infer or constrain a position
• CPC Class Codes: G01S 5/02695 Constraining the position to lie on a curve or surface
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

A method for determining geo-position of a target by an aircraft includes: receiving navigation data related to the aircraft including aircraft attitude information; receiving multilateration information related to the target including an angle to the target; calculating an axis for a cone fixed to the aircraft, based on the received aircraft attitude information; calculating a central angle for the cone from the received angle to the target; generating two vectors orthogonal to the cone axis; calculating a cone model from the axis, the central angle and the two vectors; and intersecting the cone model with an earth model to obtain a LEP curve, wherein the LEP curve is used to determine the geo position of the target.

Claims

1. A method performed by one or more processors for determining geo-position of a target by an aircraft, the method comprising:

receiving navigation data related to the aircraft including aircraft attitude information;

receiving multilateration information related to the target including an angle to the target;

calculating an axis for a cone fixed to the aircraft, based on the received aircraft attitude information;

calculating a central angle for the cone from the received angle to the target;

generating two vectors orthogonal to the cone axis;

calculating a cone model from the axis, the central angle and the two vectors; and

intersecting the cone model with an earth model to obtain a locus of emitter positions (LEP) curve, wherein the LEP curve is used to determine the geo position of the target.

2. The method of claim 1, further comprising:

repeating the method of claim 1;

accumulating, in a computer storage medium, the plurality of LEP curves; and

determining a position that is closest to all the accumulated LEP curves to establish a position of the target.

3. The method of claim 1, wherein the model of the earth is digital elevation data.

4. The method of claim 3, wherein the digital elevation data is a rectangular grid of measurement points, each associated with an elevation relative to an ellipsoidal earth model.

5. The method of claim 1, wherein the model of the earth is a sphere.

6. The method of claim 1, wherein the navigation data includes position, heading, pitch and roll data.

7. A system for determining geo position of a target by an aircraft comprising:

a receiver for receiving navigation data related to the aircraft and multilateration information related to the target, wherein the navigation data includes aircraft attitude information and the multilateration information includes an angle to the target;

one or more processors for calculating an axis for a cone fixed to the aircraft, based on the received aircraft attitude information, calculating a central angle for the cone from the received angle to the target, generating two vectors orthogonal to the cone axis, calculating a cone model from the axis, the central angle and the two vectors, and intersecting the cone model with an earth model to obtain a locus of emitter positions (LEP) curve, wherein the LEP curve is used to determine the geo position of the target.

8. The system of claim 7, wherein said one or more processors are further configured to:

repeating receiving navigation data, calculating the axis and the central angle, generating the two vectors, and intersecting the cone model with an earth model to obtain a plurality of LEP curves;

accumulating, in a computer storage medium, the plurality of LEP curves; and

determining a position that is closest to all the accumulated LEP curves to establish a position of the target.

9. The system of claim 7, wherein the model of the earth is digital elevation data.

10. The system of claim 8, wherein the digital elevation data is a rectangular grid of measurement points, each associated with an elevation relative to an ellipsoidal earth model.

11. The system of claim 7, wherein the model of the earth is a sphere.

12. The system of claim 7, wherein the navigation data includes position, heading, pitch and roll data.

13. A method performed by one or more processors for determining geo position of a target by an aircraft, the method comprising:

(a). receiving navigation data related to the aircraft and multilateration information related to the target;

(b). calculating a locus of emitter positions (LEP) curve from the received navigation data and multilateration information using a cone model fixed to the aircraft longitudinal axis and intersecting the cone model with a three-dimensional geometric model of the earth;

(c). repeating steps (a) and (b);

(d). accumulating, in a computer storage medium, the calculated LEP curves; and

(e). electronically determining a position that is closest to all the accumulated LEP curves to establish a position of the target.

14. The method of claim 13, wherein the model of the earth is digital elevation data.

15. The method of claim 14, wherein the digital elevation data is a rectangular grid of measurement points, each associated with an elevation relative to an ellipsoidal earth model.

16. The method of claim 13, wherein the model of the earth is a sphere.

17. The method of claim 13, wherein the navigation data includes position, heading, pitch and roll data.