Systems and methods for space-time radar imaging

• US 7,994,967 B2
• Filed: 04/13/2010
• Issued: 08/09/2011
• Est. Priority Date: 10/19/2007
• Status: Expired due to Fees

• Current Assignee: Technology Service Corporation
• Original Assignee: Technology Service Corporation
• Inventors: Mountcastle, Paul D.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Barker; Matthew M
• Application Number:
  US12/759,334
• Publication Number:
  US 20100265124A1
• Time in Patent Office: 483 Days
• Field of Search: 342/180
• US Class Current: 342/180
• CPC Class Codes: G01S 13/89 for mapping or imaging
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

A method of imaging a moving object, including the steps of acquiring radar data reflected by the moving object, determining a motion state of the moving object; and generating a three-dimensional representation of the moving object based on the determined motion state, is disclosed. The motion state may be a complete solution of translational and rotational motion determined based on at least one of the inertia tensor components of the moving object, or solutions of Euler'"'"'s torque-free equations of motions. The three-dimensional representation may be generated by reconstructing static patterns of the moving object based on estimated initial translational and rotational conditions of the object. A system for imaging the moving object according to this method is also disclosed.

Claims

1. A system for imaging an object moving in torque-free motion, the system comprising:

a receiver configured to acquire radar data reflected by an object moving in torque-free motion;

a memory configured to store instructions for processing the acquired radar data; and

a processor configured to determine a motion state of the moving object and generate a three-dimensional representation of the moving object, based on the determined motion state.

2. The system of claim 1, wherein the processor is configured to determine a motion state of the moving object by solving for complete solutions of the translational and rotational motion states of the moving object.

3. The system of claim 2, wherein the rotational motion state is based on solutions of Euler'"'"'s torque-free equations of motions.

4. The system of claim 1, wherein the processor is configured to generate the three-dimensional representation of the moving object by associating radar pulse times with orientation estimates of the moving object.

5. The system of claim 1, further comprising a display unit that is configured to display the three-dimensional representation and the determined motion state simultaneously.

6. A computer-implemented method of imaging an object moving in torque-free motion, the method comprising the steps of:

acquiring radar data reflected by the moving object;

defining an intensity of the radar data as a function of generalized coordinates of motion;

defining estimated initial conditions for the generalized coordinates of motion;

integrating the intensity of the defined radar data across at least a portion of the moving object;

redefining the estimated initial conditions until the integrated intensity of the radar data has been optimized; and

generating a three-dimensional representation of the moving object by reconstructing static patterns of the moving object as a function of the estimated initial conditions that optimize the integrated intensity of the radar data.

7. The method of claim 6, wherein the static patterns are reconstructed by propagating the estimated initial conditions across radar pulse times based on at least one model of the generalized coordinates of motion.

8. The method of claim 6, the method further comprising the step of:

displaying a three-dimensional representation of the moving object based on the estimated initial conditions that optimize the integrated intensity of the radar data.

9. The method of claim 6, wherein the generalized coordinates of motion include models of the moving object that include at least one of:

inertia tensor components;

Euler angles;

Euler rates;

spin precession rates; and

cone angle.

10. A computer-implemented method of imaging an object moving in torque-free motion, the method comprising:

acquiring radar data reflected by the moving object;

determining a complete motion state of the moving object; and

generating a three-dimensional representation of the moving object based on the determined complete motion state, by associating radar pulse times with orientation estimates of the moving object.

11. The method of claim 10, wherein the complete motion state of the moving object is determined by solving for the translational and rotational motion states of the moving object.

12. The method of claim 11, wherein the rotational motion state is based on at least one of:

a model of the inertia tensor components of the moving object, and solutions of Euler'"'"'s torque-free equations of motions.

13. The method of claim 11, wherein the translational and rotational motion states include six invariant parameters of rotational motion and six invariant parameters of orbital motion.

14. The method of claim 10, wherein the step of determining includes:

estimating initial translational and rotational conditions for the moving object;

reconstructing static patterns of the moving object based on the estimated initial translational and rotational conditions; and

defining an energy functional of the moving object as a function of the reconstructed static patterns;

wherein the estimated initial translational and rotational conditions are iterated until the energy functional has been maximized.

15. The method of claim 14 wherein the estimated initial conditions include generalized models of the moving object that include at least one of:

inertia tensor components;

Euler angles;

Euler rates;

spin precession rates; and

cone angle.

16. The method of claim 14, wherein three-dimensional representation of the moving object is generated by reconstructing static patterns of the moving object as a function of the estimated initial conditions that maximize the energy functional.

17. The method of claim 14, wherein the three-dimensional representation of the moving object is generated by associating radar pulse times with the reconstructed static patterns.

18. The method of claim 14, the method further comprising the step of:

displaying the three-dimensional representation that expresses the estimated initial conditions corresponding to the maximized energy functional.

19. A computer-readable medium that stores a set of executable instructions, which when read by a processor perform steps in a method of imaging an object moving in torque-free motion, the steps comprising:

acquiring radar data reflected by the moving object;

determining a motion state of the moving object; and

generating a three-dimensional representation of the moving object based on the determined motion state.

20. The computer-readable medium of claim 19, wherein the motion state of the moving object is determined by solving for complete solutions of the translational and rotational motion states of the moving object.

21. The computer-readable medium of claim 20, wherein the rotational motion state is based on a model of the inertia tensor components of the moving object.

22. The computer-readable medium of claim 20, wherein the rotational motion state is based on solutions of Euler'"'"'s torque-free equations of motions.

23. The computer-readable medium of claim 19, wherein the three-dimensional representation of the moving object is generated by associating radar pulse times with orientation estimates of the moving object.

24. The computer-readable medium of claim 19, wherein:

the step of determining includes;

defining an intensity of the radar data as a function of generalized coordinates of motion;

defining estimated initial conditions for the generalized coordinates of motion;

integrating the intensity of the defined radar data across at least a portion of the moving object; and

redefining the estimated initial conditions until the integrated intensity of the radar data has been optimized.

25. A computer-implemented method of imaging an object moving in torque-free motion, the method comprising the steps of:

acquiring radar data reflected by the moving object;

defining a metric of the radar data as a function of generalized coordinates of motion;

defining estimated initial conditions for the generalized coordinates of motion;

integrating the metric of the radar data across at least a portion of the moving object;

redefining the estimated initial conditions until the integrated metric of the radar data has been optimized; and

generating a three-dimensional representation of the moving object by reconstructing static patterns of the moving object as a function of the estimated initial conditions that optimize the integrated metric of the radar data.

26. A system for imaging an object moving in torque-free motion, the system comprising:

a receiver configured to acquire radar data reflected by the moving object;

a memory configured to store instructions for processing the acquired radar data; and

a processor configured to determine a motion state of the moving object and generate a three-dimensional representation of the moving object, based on the determined motion state;

wherein the motion state is determined based on a model of the inertia tensor components of the moving object.