Terrain correlation system

• US 6,218,980 B1
• Filed: 05/05/1987
• Issued: 04/17/2001
• Est. Priority Date: 09/13/1982
• Status: Expired due to Term

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Goebel, Robert H., Torretta, David C., Panagos, Philip, Heffern, Patrick A., Fogle, Dale A.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US07/047,540
• Time in Patent Office: 5,096 Days
• Field of Search: 342/64, 364/453, 364/456, 364/457
• US Class Current: 342/64
• CPC Class Codes: G01C 21/1652 with ranging devices, e.g. LIDAR or RADAR
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01S 13/935 for terrain-avoidance

Abstract

A terrain correlation system for use in conjunction with an inertial navigation system of a vehicle is provided which can update position information and which is both independent of altitude and compatible with varying course paths. In the preferred embodiment, reference terrain altitude maps are converted to reference map transformation values. The reference map transformation values are used in conjunction with a terrain correlation process to establish vehicle position. The system also is able to select reference map scenes to the left, right, front or rear of present vehicle position so that curved travel paths can be updated in a manner similar to more conventional straight line vehicle paths.

Claims

1. In a navigation system for a vehicle including a navigation computer for generating a predetermined course, means for determining the distance of the vehicle from the terrain of which it is traversing, said distance determining means comprising radar means for directing radiation toward the terrain and for receiving a radar return back from the terrain, and means for storing at least one reference map in data form corresponding to the terrain over which the predetermined course is to traverse, the improvement comprising means for transforming the reference map data to simulated data based on at least a known distance of the vehicle from the terrain over which the vehicle is traveling and on simulated radar returns from the terrain at said known distance, means for comparing the simulated data to data representative of the actual distance from said terrain, and means for determining the position of said vehicle with respect to said map based on said comparison.

2. The improvement of claim 1 wherein said vehicle is a missile, and said means for determining the position of said vehicle with respect to said map based on said comparison further includes means for generating an error signal based on said position for use by said navigation computer.

3. A navigation system for a vehicle comprising:

a navigational computer for generating a course command signal for said vehicle;

means for determining the distance of the vehicle from the terrain over which it is traveling;

means for storing at least one reference map in data form corresponding to the course over which the vehicle is traveling;

said storing means including means for storing at least reference maps portions that are to the right, to the left, or straight with respect to a previous reference map;

means for determining the present position of the vehicle with respect to said reference map;

means for determining whether the present position of the vehicle is one left, right or straight with respect to the immediately preceding position; and

means for electronically selecting map data based on said determination to be used in determining the next position of the vehicle.

4. The navigation system of claim 3, wherein the distance determining means comprises radar means for directing radiation toward the terrain and for receiving radar returns back from the terrain, and said means for determining the present position further includes means for transforming the reference map data to simulated data based on at least a known distance of the vehicle from the terrain over which the vehicle is traveling and on simulated radar returns from the terrain at said known distance.

5. The navigation system of claim 4 wherein said means for determining the present position further includes means for comparing the simulated data to data representing the actual distance from the terrain over which said vehicle is traversing.

6. The navigation system of claim 5 wherein said vehicle is a missile, and said means for determining the position of said vehicle with respect to said map based on said comparison further includes means for generating an error signal based on said position for use by said navigational computer.

7. A navigation system for a vehicle, comprising:

a navigational computer for generating a course command signal for said vehicle;

means for determining the distance of the vehicle from the terrain over which it is traveling, comprising radar means for directing radiation toward the terrain and receiving radar returns back from the terrain;

means for storing at least one reference map in data form corresponding to the terrain over which the vehicle is to traverse;

means for transforming the reference map data to simulated map data based on at least a known distance of the vehicle from the terrain over which the vehicle is traveling and on simulated radar returns from the terrain at said known distance; and

comparing and determining means for comparing the simulated data to data representing the actual distance from said terrain.

8. The navigation system of claim 7 further including means for determining whether the present position of said vehicle is one to the left, right or inline with respect to the immediately preceding position;

and

means for selecting map data based on said last mentioned determination to be used in determining the next position of the vehicle.

9. The navigation system of claim 8 wherein said vehicle is a missile, and said comparing and determining means further includes means for generating an error signal based on the determined position for use by said navigational computer.

10. A control system comprising:

a navigational computer for generating a course command;

means for storing a reference map in data form corresponding to the course over which the navigational computer is monitoring, including means for storing reference map data that is left, right or in line with respect to the present monitored position;

means for determining whether the present monitored position is one left, right or inline with respect to the immediately preceding monitored position; and

means for selecting a succeeding map, the next map data reference being based on said determination.

11. The control system of claim 10 adapted for use in vehicle guidance, further including means for determining the distance of the vehicle from the terrain over which the vehicle is traversing, said distance determining means comprising radar means for directing radiation toward the terrain and for receiving radar returns back from the terrain;

and

said means for determining the position being monitored comprising means for transforming the reference map data to simulated data based on at least a known mean distance of the vehicle from the terrain over which the vehicle is traveling and on simulated radar returns from the terrain at said known mean distance, said means for determining the position of said vehicle based on said comparison comprising means for comparing the simulated data to data representing the actual distance of said vehicle from said terrain.

12. The improvement of claim 11 wherein said vehicle is a missile, and said means for determining the position of said vehicle with respect to said map based on said comparison further includes means for generating an error signal based on said determined position for use by said navigational computer.

13. A navigational system for a vehicle, comprising:

a navigational computer for generating a course signal for said vehicle;

means for determining the distance of the vehicle from the terrain over which it is traveling, comprising radar means for directing radiation toward the terrain and for receiving radar returns back from the terrain;

means for storing a reference map in data form corresponding to the course over which the vehicle is traveling;

means for transforming the selected reference map data to simulated data based on at least a known distance of the vehicle from the terrain over which the vehicle is traveling and on simulated radar returns from the terrain at said known distance;

means for comparing the simulated data to data representing the actual distance from said terrain;

means for determining the present position of said vehicle with respect to said map based on said comparison;

means for determining whether the present position of the vehicle is one left, right or inline with respect to the immediately preceding position; and

means for selecting map data based on said last mentioned determination to be used in determining the next position of the vehicle.

14. The control system of claim 13 wherein said vehicle is a missile, and said means for determining the position of said vehicle with respect to said map based on said comparison further includes means for generating an error signal based on said position for use by said navigational computer.