Method for tracking a target having substantially constrained movement

• US 6,260,759 B1
• Filed: 08/11/1998
• Issued: 07/17/2001
• Est. Priority Date: 08/11/1998
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Landau, Herbert, Nguyen, Quan Bach
• Primary Examiner(s): Lee, Michael G.
• Assistant Examiner(s): Lee, Diane I.
• Application Number:
  US09/132,274
• Time in Patent Office: 1,071 Days
• Field of Search: 235/411, 235/412, 235/413, 235/417, 235/404, 342/95, 342/96, 342/97, 342/90, 342/114, 342/115
• US Class Current: 235/411
• CPC Class Codes: G01S 13/5242 with means for platform motion or scan motion compensation, e.g. airborne MTI
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 7/066 with means for showing the history of the radar trails, e.g. artificial remanence
• CPC Class Codes: G01S 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

A method for tracking a target having substantially constrained movement utilizes the steps of determining constrains for movement of the target, obtaining information on movement of the target, and predicting that the target will continue to move upon a route segment after the target has begun to move thereupon. The constraints are made up of a plurality of separate alternate route segments. Predicting that the target will continue to move upon the route segment upon which it is previously moving facilitates targeting, intercept and intelligence with a substantial degree of reliability, particularly when continuing information, such as radar returns, is not available.

Claims

1. A method for predicting target location and movement through an environment utilizing location data for physical constraints disposed within the environment and determining restrictions on target movement within the environment in response to the location data, the method comprising the steps of:

(a) obtaining a location for each of the respective physical constraints;

(b) acquiring a target position and a target direction of movement;

(c) determining whether one or more of the physical constraints restrict target movement along the target direction of movement within the environment;

(d) predicting constrained route segments for the target in response to a determination that target movement along the target direction of movement is restricted by one or more of the physical constraints; and

(e) predicting unconstrained route segments for the target in response to a determination that target movement along the target direction of movement is not restricted by the physical constraints.

2. The method of claim 1 wherein step (d) further comprises predicting the constrained route segments based on the target position, target direction of movement, and the respective locations of extermal constraints restricting target movement.

3. The method of claim 1 wherein step (e) further comprises predicting the unconstrained route segments based on the target position and target direction of movement.

4. The method of claim 1 wherein step (d) further comprises predicting constrained route segments based upon a known destination for the targets.

5. The method of claim 1 wherein step (e) further comprises predicting unconstrained route segments based upon a known destination for the target.

6. The method of claim 1 wherein step (b) further comprises obtaining the target position at least twice, measuring elapsed time between each acquisition of the position, and calculating a target directional velocity based on change in target position and the elapsed time between each acquisition of the target position.

7. The method of claim 1 wherein target movement is restricted to ground travel.

8. The method of claim 7 wherein target position and target direction of movement is obtained by radar detection.

9. The method of claim 8 wherein step (d) further comprises attempting to obtain a subsequent target position after predicting constrained route segments.

10. The method of claim 9 wherein step (d) further comprises obtaining terrain information for a land area along the constrained route segments, determining whether the terrain will shield the target from radar signals along the constrained route segments, and then classifying the target as screened when the subsequent target position cannot be obtained and when it is determined that the terrain shields the target from radar signals along the constrained route segments.

11. The method of claim 9 wherein step (d) further comprises predicting locations of radar blind regions, determining whether the radar blind regions are located along the constrained route segments, and classifying the target as screened when the subsequent target position cannot be obtained and when it is determined that the radar blind regions are located along the constrained route segments.

12. The method of claim 9 wherein step (d) further comprises returning to step (c) if the subsequent target position is obtained.

13. The method of claim 12 wherein step (c) further comprises comparing the constrained route segments with the subsequent target position and then classifying the constrained route segments in a low confidence category when the subsequent target position does not correspond with the constrained route segments.

14. The method of claim 12 wherein step (c) further comprises comparing the constrained route segments with the subsequent target position and then classifying the constrained route segments in a high confidence category when the subsequent target position corresponds with the constrained route segments.

15. The method of claim 1 wherein target movement is restricted to water travel.

16. The method of claim 1 wherein target movement is restricted to ground travel and air travel.

17. The method of claim 1 wherein the target movement includes water and air travel.

18. The method of claim 1 wherein the target movement includes water and ground travel.

19. A method for predicting movement of a plurality of targets through an environment utilizing location data for physical constraints disposed within the environment and determining restrictions on target movement within the environment in response to the location data, the method comprising steps of:

(a) obtaining a location for each of the respective physical constraints;

(b) acquiring a target position and a target direction of movement for each of the targets;

(c) determining whether each target movement along each respective target direction of movement within the environment is restricted by one or more of the physical constraints;

(d) predicting constrained route segments for any respective target in response to a determination that the respective target movement along the respective target direction of movement is restricted by one or more of the physical constraints; and

(e) predicting unconstrained route segments for any respective target in response to a determination that the respective target movement along the respective target direction of movement is not restricted by the physical constraints.

20. The method of claim 19 wherein step (d) further comprises grouping individual targets into a single composite target when the targets are predicted to move along the same constrained route segments in unison.

21. The method of claim 19 wherein step (e) further comprises grouping individual targets into a single composite target when the targets are predicted to move along the same unconstrained route segments in unison.

22. A method for predicting target location and movement for a target restricted to ground travel through an environment containing physical constraints, the method comprising steps of:

(a) obtaining a location for each of the respective constraints;

(b) acquiring a target position and a target direction of movement by radar detection;

(c) determining whether any constraints restrict target movement along the target direction of movement;

(d) predicting constrained route segments for the target in response to a determination that target movement along the target direction of movement is restricted by one or more of the constraints, comparing the constrained route segments with a subsequent target position, and classifying the constrained route segments in a low confidence category when the subsequent target position does not correspond with the constrained route segments within a threshold association;

(e) predicting unconstrained route segments for the target in response to a determination that target movement along the target direction of movement is not restricted by the constraints.

23. A method for predicting target location and movement for a target restricted to ground travel through an environment containing physical constraints, the method comprising steps of:

(a) obtaining a location for each of the respective constraints;

(b) acquiring a target position and a target direction of movement by radar detection;

(c) determining whether any constraints restrict target movement along the target direction of movement;

(d) predicting constrained route segments for the target in response to a determination that target movement along the target direction of movement is restricted by one or more of the constraints, comparing the constrained route segments with a subsequent target position, and classifying the constrained route segments in a high confidence category when the subsequent target position corresponds with the constrained route segments within a threshold association;

(e) predicting unconstrained route segments for the target in response to a determination that target movement along the target direction of movement is not restricted by the constraints.