METHODS FOR ADJUSTING A RELATIVE NAVIGATION SYSTEM

• US 20130107219A1
• Filed: 11/01/2011
• Published: 05/02/2013
• Est. Priority Date: 11/01/2011
• Status: Active Grant

• Current Assignee: GE Aviation Systems LLC (GE Aerospace)
• Original Assignee: GE Aviation Systems LLC (GE Aerospace)
• Inventors: Feldmann, Michael Steven, Saggio, Frank III, Washburn, John Robert
• Granted Patent: US 8,872,081 B2
• Time in Patent Office: Days
• US Class Current: 353/11
• CPC Class Codes: B64F 1/20 Arrangement of optical beacons
• CPC Class Codes: G01C 21/24 specially adapted for cosmonautical navigation
• CPC Class Codes: G01S 1/70 using electromagnetic waves other than radio waves
• CPC Class Codes: G05D 1/0684 on a moving platform, e.g. aircraft carrier
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

A relative navigation system projects a grid into space from a grid generator and an object, such as an unmanned aerial vehicle, may use the projected grid to aid in the landing of the object. Methods of adjusting the projected grid including stabilizing the projected grid and orienting the grid generator relative to the earth.

Claims

1. A method of stabilizing a grid projected from a grid generator of a relative navigation system, with the grid generator defining a reference frame, the method comprising:

repeatedly projecting into space from the grid generator a plurality of lines defining a grid, with the lines encoded with grid data configured to identify predetermined points on the grid;

between a prior grid projection and a subsequent grid projection of the repeated grid projections, determining a change in a reference frame of the grid generator relative to the prior grid projection; and

based on the determined change, altering the grid data of the subsequent grid projection such that the subsequent grid projection appears stabilized relative to the prior grid projection.

2. The method of claim 1 wherein the altering of the grid data comprises the grid data of the subsequent grid projection indicating that the data is the same as a spatially closest grid point of the prior grid projection.

3. The method of claim 1 wherein the determining the change comprises determining angular changes in roll, pitch, and yaw of the reference frame, and the altering the grid data comprises converting the angular changes of roll, pitch, and yaw into grid line adjustments.

4. The method of claim 1 wherein one of the points is a reference point about which the grid may be stabilized.

5. The method of claim 4 wherein the reference point is a center of the grid.

6. The method of claim 4 wherein the determining a change comprises determining a change in the reference frame relative to the reference point.

7. The method of claim 6 wherein the determining the change comprises determining a vector from the reference frame to the reference point for the prior grid projection, determining angular changes in roll, pitch, and yaw of the reference frame, rotating the vector through the roll, pitch, and yaw, determining a new position of the reference frame from the rotation of the vector, determining a second vector from the new position of the reference frame to the reference point for the prior grid projection, and converting the angular changes in roll, pitch, and yaw into grid line adjustments.

8. The method of claim 7 wherein the determining the change further comprises determining a change between the reference frame and a center of gravity of an object on which the grid generator is mounted.

9. The method of claim 8 wherein the determining the change between the reference frame and the center of gravity comprises determining a vector from the center of gravity to the reference frame for the prior projection, determining angular changes in roll, pitch, and yaw of the reference frame, rotating the vector through the roll, pitch, and yaw, determining a new position of the reference frame from the rotation of the vector, determining a second vector from the new position of the reference frame to the center of gravity for the prior projection, and converting the angular changes in roll, pitch, and yaw into grid line adjustment.

10. The method of claim 1, further comprising determining a frequency of the change in the reference frame and altering the grid data when the frequency of the change is between 1 Hz and 5 Hz.

11. A method of orienting relative to earth a grid generator for a relative navigation system, the method comprising:

leveling the grid generator;

determining a heading of the grid generator relative to a reference direction; and

projecting from the grid generator a plurality of lines defining a grid along a predetermined heading.

12. The method of claim 11 wherein the leveling comprises conducting an approximate leveling.

13. The method of claim 12 wherein the leveling is at least horizontal leveling.

14. The method of claim 11 wherein the determining the heading of the grid generator relative to the reference direction comprises determining true north.

15. The method of claim 11 wherein the determining the heading of the grid generator relative to the reference direction comprises determining an azimuth of the grid generator.