System and method for determining orientation based on solar positioning

• US 7,315,781 B2
• Filed: 06/20/2006
• Issued: 01/01/2008
• Est. Priority Date: 08/18/2003
• Status: Expired due to Term

• Current Assignee: Textron Systems Corporation (Textron Inc)
• Original Assignee: Textron Systems Corporation (Textron Inc)
• Inventors: Litchfield, Mark H., McCormack, Joseph, Delude, David
• Primary Examiner(s): Camby; Richard M.
• Application Number:
  US11/471,325
• Publication Number:
  US 20070145252A1
• Time in Patent Office: 560 Days
• Field of Search: 701/1, 701/3, 701/4, 701/13, 701/222, 701200-217, 244/158.R, 244/164
• US Class Current: 701/207
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

Determination of the orientation of a unit is based on solar positioning. An actual measurement of the position of the sun is taken and compared to a theoretical determination of the position of the sun. By comparing the actual and theoretical positions, the orientation of the unit is determined in an accurate, reliable, and economical manner.

Claims

1. A system for determining the orientation of an object relative to a source of electromagnetic radiation comprising:

a two-dimensional array of sensors, each of the sensors producing a corresponding output signal when placed in the path of electromagnetic radiation emitted by the source;

a radiation director that directs the electromagnetic radiation from the source onto the two-dimensional array of sensors; and

a controller that receives the output signals of the sensors, and that determines the orientation of the object relative to the source based on the output signals of the sensors.

2. The system of claim 1 wherein the two-dimensional array of sensors comprises a charge-coupled device (CCD) array.

3. The system of claim 1 wherein the two-dimensional array of sensors comprises a bolometer array.

4. The system of claim 1 wherein the source of the electromagnetic radiation is the sun.

5. The system of claim 1 wherein the electromagnetic radiation is of a type selected from the group consisting of visible radiation, infrared radiation, and ultraviolet radiation.

6. The system of claim 1 wherein the sensors are optical sensors.

7. The system of claim 6 wherein the optical sensors comprise photodiodes.

8. The system of claim 7 wherein the output signals are derived from the intensity of light radiation received at the photodiodes.

9. The system of claim 1 wherein the output signals of the sensors are binary signals that indicate those sensor elements of the two-dimensional sensor array that are activated in response to receiving the electromagnetic energy at a level above a predetermined threshold.

10. The system of claim 9 wherein the controller determines the orientation of the object based on multiple samples of the output signals of the sensors taken at predetermined time intervals.

11. The system of claim 9 wherein the controller further:

tracks elements of the sensor array that are activated at each sample interval;

fits a polynomial to the activated sensor elements over time;

determines the orientation of the object based on the polynomial.

12. The system of claim 1 wherein the controller determines the orientation of the object further based on a known factor of a type selected from the types consisting of:

time, latitude, longitude, and altitude.

13. The system of claim 1 wherein the radiation director comprises a pinhole in a housing body containing the two-dimensional array of sensors.

14. The system of claim 1 wherein the radiation director comprises a lens attached to a housing body containing the two-dimensional array of sensors.

15. The system of claim 1 wherein the radiation director comprises an optical element attached to a housing body containing the two-dimensional array of sensors.

16. The system of claim 1 wherein the controller determines the orientation of the object further based on a theoretical determination of the electromagnetic radiation source position.

17. The system of claim 16 wherein the controller further determines the orientation of the object by comparing the theoretical determination of the electromagnetic radiation source position to an actual determination of the position based on the output signals of the sensors.

18. A system for determining the orientation of an object relative to a source of electromagnetic radiation comprising:

a housing constructed and arranged to be positioned at a stationary, earth-based location;

a two-dimensional array of sensors positioned in the housing, each of the sensors producing a corresponding output signal when placed in the path of electromagnetic radiation emitted by the source;

a radiation director on the housing that directs the electromagnetic radiation from the source onto the two-dimensional array of sensors; and

a controller that receives the output signals of the sensors, and that determines the orientation of the object including the housing relative to the source based on the output signals of the sensors.

19. The system of claim 18 wherein the two-dimensional array of sensors comprises a charge-coupled device (CCD) array.

20. The system of claim 19 wherein the two-dimensional array of sensors comprises a bolometer array.

21. The system of claim 18 wherein the radiation director comprises a pinhole in the housing.

22. The system of claim 18 wherein the radiation director comprises a lens.

23. The system of claim 18 wherein the radiation director comprises an optical element.

24. The system of claim 18 wherein the controller determines the orientation of the object further based on a theoretical determination of the electromagnetic radiation source position.

25. The system of claim 24 wherein the controller further determines the orientation of the object by comparing the theoretical determination of the electromagnetic radiation source position to an actual determination of the position based on the output signals of the sensors.

26. The system of claim 18 wherein the source of the electromagnetic radiation is the sun.

27. The system of claim 18 wherein the electromagnetic radiation is of a type selected from the group consisting of visible radiation, infrared radiation, and ultraviolet radiation.

28. The system of claim 18 wherein the sensors are optical sensors.

29. The system of claim 28 wherein the optical sensors comprise photodiodes.

30. The system of claim 29 wherein the output signals are derived from the intensity of light radiation received at the photodiodes.

31. The system of claim 18 wherein the output signals of the sensors are binary signals that indicate those sensor elements of the two-dimensional sensor array that are activated in response to receiving the electromagnetic energy at a level above a predetermined threshold.

32. The system of claim 31 wherein the controller determines the orientation of the object based on multiple samples of the output signals of the sensors taken at predetermined time intervals.

33. The system of claim 31 wherein the controller further:

tracks elements of the sensor array that are activated at each sample interval;

fits a polynomial to the activated sensor elements over time;

determines the orientation of the object based on the polynomial.

34. The system of claim 18 wherein the controller determines the orientation of the object further based on a known factor of a type selected from the types consisting of:

time, latitude, longitude, and altitude.

35. A method for determining the orientation of an object relative to a source of electromagnetic radiation comprising:

positioning the object at a stationary, earth-based location;

directing electromagnetic radiation emitted by the source through a radiation director onto a two-dimensional array of sensors contained in the object, each of the sensors producing a corresponding output signal when placed in the path of electromagnetic radiation emitted by the source;

determining the orientation of the object relative to the source based on the sensor output signals.

36. The method of claim 35 wherein the two-dimensional array of sensors comprises one of a charge-coupled device (CCD) array and a bolometer array.

37. The method of claim 36 wherein the CCD array comprises a plurality of pixels, and wherein the movement of the orientation of the object relative to the source of electromagnetic radiation is mapped onto the pixels of the CCD array.

38. The method of claim 35 wherein the output signals of the sensors are binary signals that indicate those sensor elements of the two-dimensional sensor array that are activated in response to receiving the electromagnetic energy at a level above a predetermined threshold.

39. The method of claim 38 further comprising determining the orientation of the object based on multiple samples of the output signals of the sensors taken at predetermined time intervals.

40. The method of claim 39 further comprising:

tracking elements of the sensor array that are activated at each sample interval;

fitting a polynomial to the activated sensor elements over time;

determining the orientation of the object based on the polynomial.

41. The method of claim 40 wherein the orientation of the object is determined based on a known factor of a type selected from the types consisting of:

time, latitude, longitude, and altitude.