Tracking of a moving object

• US 7,394,046 B2
• Filed: 05/20/2005
• Issued: 07/01/2008
• Est. Priority Date: 05/28/2004
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Olsson, Hakan, Axelsson, Leif, Wallenberg, Jan
• Primary Examiner(s): Gregory; Bernarr E
• Application Number:
  US10/908,644
• Publication Number:
  US 20080128546A1
• Time in Patent Office: 1,138 Days
• Field of Search: 244 31- 33, 342 61- 65, 342/89, 342/90, 342/175, 342/195, 342 73- 81, 333/166, 89/11.1, 701/1, 701/3, 701/200
• US Class Current: 244/3.1
• CPC Class Codes: G01S 11/04 using angle measurements

Abstract

A system for determination of kinematics of a moving object comprising: a sensor producing angular data for the object at a number of observation times, a state initialization unit, receiving angular data from the sensor and on basis thereof determining a first kinematic state of the object, and a tracking filter having a prediction unit, arranged to determine a predicted kinematics state of the object on bases of a kinematic model of the object, wherein the kinematic model comprises a guidance law locked on a known position, and at least one previously determined kinematic state of the object, and a state updating unit, receiving angular data from the sensor and the predicted kinematic state of the object, and on basis thereof determining an updated kinematic state of the object.

Claims

1. A method for determination of kinematics of a moving object, the method comprising:

receiving angular data for the moving object at a plurality of observation times;

determining a first kinematic state of the moving object based on the angular data at a first observation time;

determining a predicted kinematic state of the moving object based on a kinematic model of the moving object and at least one previously determined kinematic state of the moving object;

determining a subsequent kinematic state of the moving object at a subsequent observation time based on the predicted kinematic state of the moving object and the angular data for the moving object, wherein the kinematic model comprises an assumption that the moving object follows a guidance law navigating the moving object to a known position;

determining whether the moving object is moving toward the known position; and

generating a warning that the moving object is moving toward the known position if it is determined that the moving object is moving toward the known position.

2. The method according to claim 1, wherein the known position is on a moving target, the method further comprising:

receiving kinematic data for the moving target; and

determining the predicted kinematic state of the moving object based on the received kinematic data for the moving target.

3. The method according to claim 2, further comprising:

receiving navigation data for the moving target; and

determining the predicted kinematics state of the moving object based on the moving target navigation data.

4. The method according to claim 3, wherein the moving target navigation data comprises a position of the moving target, a velocity of the moving target and an acceleration of the moving target.

5. The method according to claim 1, wherein the guidance law is locked on a moving target, the method further comprising:

receiving kinematic data for the moving target; and

determining the predicted kinematic state of the moving object based on the received kinematic data for the moving target.

6. The method according to claim 1, further comprising:

storing more than one guidance law;

assuming that the moving object uses one of the stored guidance laws;

determining an assumed guidance law based on the stored guidance laws and the received angular data; and

determining the subsequent predicted kinematics state of the moving object based on the assumed guidance law.

7. The method according to claim 6, further comprising:

storing a plurality of object types;

associating each object type with one of the stored guidance laws;

determining an object type of the moving object from the plurality of object types based on said received angular data; and

determining the assumed guidance law in dependence of the determined type of the moving object.

8. The method according to claim 6, further comprising:

determining more than one predicted kinematics state of the moving object, each predicted state being determined based on one of the stored guidance laws;

estimating an error component for the predicted kinematic states based on the received angular data; and

determining the assumed guidance law based on the estimated error components.

9. The method according to claim 8, wherein the error component comprises an error covariance matrix for the predicted kinematic state.

10. The method according to claim 8, further comprising:

storing information about a plurality of object types and which guidance law a specific object type preferably uses; and

identifying the object type of the moving object based on the stored information and the assumed guidance law.

11. The method according to claim 6, further comprising:

determining whether the moving object uses the assumed guidance law with a certain degree of reliability; and

producing an approach warning if the assumed guidance law of the moving object follows the known position with a certain degree of reliability.

12. The method according to claim 11, further comprising:

estimating an error component for the predicted kinematic state based on the received angular data; and

determining whether the moving object uses the assumed guidance law with a certain degree of reliability based on the estimated error component.

13. The method according to claim 1, wherein the determination of predicted kinematic state of the moving object comprises determining a position of the moving object relative to the known position, and determining a closing velocity of the moving object, and wherein the predicted kinematic state comprises information about position and velocity of the moving object.

14. The method according to claim 1, wherein said angular data comprises at least a horizontal bearing.

15. The method according to claim 1, further comprising:

calculating an acceleration of the moving object based on the kinematic model; and

determining the predicted kinematic state of the moving object based on the calculated acceleration.

16. A computer program product, comprising:

a computer readable medium; and

computer program instructions recorded on the computer readable medium and executable by a processor for carrying out a method comprising

receiving angular data for the moving object at a plurality of observation times;

determining a first kinematic state of the moving object based on the angular data at a first observation time;

determining a predicted kinematic state of the moving object based on a kinematic model of the moving object and at least one previously determined kinematic state of the moving object;

determining a subsequent kinematic state of the moving object at a subsequent observation time based on the predicted kinematic state of the moving object and the angular data for the moving object, wherein the kinematic model comprises an assumption that the moving object follows a guidance law navigating the moving object to a known position;

determining whether the moving object is moving toward the known position; and

generating a warning that the moving object is moving toward the known position if it is determined that the moving object is moving toward the known position.

17. A system for determining kinematics of a moving object, the system comprising:

a sensor configured to produce angular data for the moving object at a plurality of observation times;

a state initialization unit configured to receive the angular data from the sensor and on basis thereof determining a first kinematic state of the moving object; and

a tracking filter comprising a prediction unit and configured to determine a predicted kinematic state of the moving object based on a kinematic model of the moving object and at least one previously determined kinematic state of the moving object, and comprising a state updating unit configured to receive angular data from the sensor and the predicted kinematic state of the object, and on a basis thereof determining an updated kinematic state of the object,

wherein the kinematic model comprises a guidance law navigating the moving object to a known position.

18. The system according to claim 17, wherein the guidance law assumes that the moving object follows a moving target and the prediction unit is configured to receive kinematic data for the moving target and on a basis thereof determine the predicted kinematic state of the moving object.

19. The system according to claim 18, wherein the prediction unit is configured to receive navigation data from the moving target and on a basis thereof determine the predicted kinematic state of the moving object.

20. The system according to claim 17, further comprising:

a library configured to store a plurality of guidance laws; and

a guidance law selecting unit configured to determine an assumed guidance law based on the stored guidance laws and the received angular data,

wherein the prediction unit configured to determine the predicted kinematic state of the moving object based on the assumed guidance law.

21. The system according to claim 20, wherein the library is configured to store a plurality of object types, each object type being associated with one of the stored guidance laws, and wherein the guidance law selecting unit is configured to receive the angular data and on a basis thereof determine the type of object, and to determine the assumed guidance law depending on the determined type of the moving object.

22. The system according to claim 20, wherein said tracking filter is configured to determine more than one predicted kinematic state of the moving object based on the stored guidance laws, and to estimate an error component for the predicted kinematic states based on the angular data, and wherein the system is configured to determine the assumed guidance law based on the estimated error components.

23. The system according to claim 22, wherein the error component comprises an error covariance matrix for the predicted kinematic state.

24. The system according to claim 22, wherein the library is configured to store information about a plurality of object types and which guidance law a specific object type preferably uses, the system further comprising:

an identification module arranged to identify the type of object based on the stored information and the assumed guidance law.

25. The system according to claim 20, further comprising:

an approach-warning unit configured to determine whether the moving object uses the assumed guidance law with a certain degree of reliability, and to produce an approach warning if the assumed guidance law of the object follows the known position with a certain degree of reliability.

26. The system according to claim 25, wherein the tracking filter is configured to receive the angular data and on a basis thereof estimate an error component for the predicted kinematic state, and wherein the approach-warning unit is configured to determine whether the moving object uses the assumed guidance law with a certain degree of reliability based on the estimated error component.

27. The system according to claim 17, wherein the determination of kinematics of the moving object comprises determining a position of the moving object relative to the known position, and determining a closing velocity of the moving object, and wherein the kinematic state comprises information about the position and velocity of the moving object.

28. A system according to claim 17, wherein the angular data comprises a horizontal bearing.

29. The system according to claim 17, wherein the prediction unit is configured to calculate an acceleration of the moving object based on the kinematic model, and to determine the predicted kinematic state of the moving object based on the calculated acceleration.

30. A system for determining kinematics of a moving object in an aircraft for passive determination of the kinematics of a missile, the system comprising:

a sensor configured to produce angular data for the object at a number of observation times;

a state initialization unit configured to receive angular data from the sensor and on a basis thereof determine a first kinematic state of the moving object; and

a tracking filter comprising a prediction unit and configured to determine a predicted kinematic state of the moving object based on a kinematic model of the moving object and at least one previously determined kinematic state of the moving object, and comprising a state updating unit configured to receive angular data from the sensor and the predicted kinematic state of the object, and on a basis thereof determining an updated kinematic state of the object,

wherein the kinematic model comprises a guidance law navigating the moving object to a known position.