SPATIAL ALIGNMENT DETERMINATION FOR AN INERTIAL MEASUREMENT UNIT (IMU)

• US 20110125404A1
• Filed: 11/20/2009
• Published: 05/26/2011
• Est. Priority Date: 11/20/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Czompo, Joseph
• Granted Patent: US 8,781,737 B2
• Time in Patent Office: Days
• US Class Current: 701/216
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

The subject matter disclosed herein relates to a system and method for determining a spatial alignment of an inertial measurement unit (IMU). By way of example, a method is described in which a first vehicle-based direction is identified, and the first vehicle-based direction is associated with a first direction that is transformable to an earth-based coordinate frame. A spatial alignment of the IMU is determined based at least partially on the first direction.

Claims

1. A method comprising:

identifying a first vehicle-based direction based, at least in part, on one or more correlation operations that relate to first vehicle-related movement data and at least one of a first acceleration or a second acceleration, said first acceleration and said second acceleration corresponding to one or more accelerations measured using an inertial measurement unit (IMU);

associating said first vehicle-based direction with a first direction that is transformable to an earth-based coordinate frame; and

determining a spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said first direction.

2. The method of claim 1, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system.

3. The method of claim 2, wherein said identifying a first vehicle-based direction comprises:

ascertaining at least one first correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said first acceleration;

ascertaining at least one second correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said second acceleration; and

selecting a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

4. The method of claim 1, wherein said first vehicle-based direction comprises a right-left direction, said first direction comprises a right direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises rotational data.

5. The method of claim 4, wherein said identifying a first vehicle-based direction comprises:

ascertaining at least one first correlative indication between and/or among said rotational data and said first acceleration;

ascertaining at least one second correlative indication between and/or among said rotational data and said second acceleration; and

selecting a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

6. The method of claim 1, further comprising:

identifying a second vehicle-based direction based, at least in part, on one or more correlation operations that relate to second vehicle-related movement data and at least one of said first acceleration or said second acceleration; and

associating said second vehicle-based direction with a second direction that is transformable to the earth-based coordinate frame,

wherein said determining comprises determining said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said second direction.

7. The method of claim 6, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system;

and wherein said second vehicle-based direction comprises a right-left direction, said second direction comprises a right direction that is transformable to the earth-based coordinate frame, and said second vehicle-related movement data comprises rotational data.

8. The method of claim 7, wherein said determining further comprises:

transforming said right-left direction and said course-over-ground direction into directions in a cardinal-direction-based coordinate frame; and

transforming said directions in the cardinal-direction-based coordinate frame into directions in the earth-based coordinate frame.

9. The method of claim 1, further comprising:

identifying an up-down direction based, at least in part, on one or more comparative operations that relate to said first acceleration, said second acceleration, and a third acceleration;

said third acceleration corresponding to at least one acceleration measured using the IMU; and

associating said up-down direction with an up direction that is transformable to the earth-based coordinate frame, said up direction at least substantially parallel to a direction of gravity,

wherein said determining a spatial alignment of the IMU comprises determining said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said up direction.

10. The method of claim 9, wherein said identifying an up-down direction comprises comparing said first acceleration, said second acceleration, and said third acceleration to select a strongest acceleration;

and wherein said up-down direction corresponds to a direction associated with said strongest acceleration.

11. The method of claim 1, wherein at least one of said first acceleration or said second acceleration is produced using an eigenvector.

12. The method of claim 1, wherein at least one of said first acceleration or said second acceleration comprises an acceleration that is projected onto a horizontal plane, the horizontal plane at least substantially orthogonal to an up direction.

13. The method of claim 1, further comprising:

transmitting said spatial alignment of the IMU to another device.

14. The method of claim 1, further comprising:

applying said spatial alignment of the IMU to navigation performed by a satellite positioning system-inertial navigation system.

15. A device comprising:

at least one memory configured to store instructions; and

one or more processors to execute said instructions and render the device a special purpose computing device to;

identify a first vehicle-based direction based, at least in part, on one or more correlation operations that relate to first vehicle-related movement data and at least one of a first acceleration or a second acceleration, said first acceleration and said second acceleration corresponding to one or more accelerations measured using an inertial measurement unit (IMU);

associate said first vehicle-based direction with a first direction that is transformable to an earth-based coordinate frame; and

determine a spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said first direction.

16. The device of claim 15, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system.

17. The device of claim 16, wherein to identify a first vehicle-based direction said one or more processors are further to execute said instructions to:

ascertain at least one first correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said first acceleration;

ascertain at least one second correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said second acceleration; and

select a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

18. The device of claim 15, wherein said first vehicle-based direction comprises a right-left direction, said first direction comprises a right direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises rotational data.

19. The device of claim 18, wherein to identify a first vehicle-based direction said one or more processors are further to execute said instructions to:

ascertain at least one first correlative indication between and/or among said rotational data and said first acceleration;

ascertain at least one second correlative indication between and/or among said rotational data and said second acceleration; and

select a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

20. The device of claim 15, wherein said one or more processors are further to execute said instructions and render the device a special purpose computing device to:

identify a second vehicle-based direction based, at least in part, on one or more correlation operations that relate to second vehicle-related movement data and at least one of said first acceleration or said second acceleration; and

associate said second vehicle-based direction with a second direction that is transformable to the earth-based coordinate frame,

wherein to determine a spatial alignment of the IMU said one or more processors are further to execute said instructions to determine said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said second direction.

21. The device of claim 20, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system;

and wherein said second vehicle-based direction comprises a right-left direction, said second direction comprises a right direction that is transformable to the earth-based coordinate frame, and said second vehicle-related movement data comprises rotational data.

22. The device of claim 21, wherein to determine a spatial alignment of the IMU said one or more processors are further to execute said instructions to:

transform said right-left direction and said course-over-ground direction into directions in a cardinal-direction-based coordinate frame; and

transform said directions in the cardinal-direction-based coordinate frame into directions in the earth-based coordinate frame.

23. The device of claim 15, wherein said one or more processors are further to execute said instructions and render the device a special purpose computing device to:

identify an up-down direction based, at least in part, on one or more comparative operations that relate to said first acceleration, said second acceleration, and a third acceleration;

said third acceleration corresponding to at least one acceleration measured using the IMU; and

associate said up-down direction with an up direction that is transformable to the earth-based coordinate frame, said up direction at least substantially parallel to a direction of gravity,

wherein to determine a spatial alignment of the IMU said one or more processors are further to determine said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said up direction.

24. The device of claim 23, wherein to identify an up-down direction said one or more processors are further to compare said first acceleration, said second acceleration, and said third acceleration to select a strongest acceleration;

and wherein said up-down direction corresponds to a direction associated with said strongest acceleration.

25. The device of claim 15, wherein at least one of said first acceleration or said second acceleration is produced using an eigenvector.

26. The device of claim 15, wherein at least one of said first acceleration or said second acceleration comprises an acceleration that is projected onto a horizontal plane, the horizontal plane at least substantially orthogonal to an up direction.

27. The device of claim 15, wherein said one or more processors are further to execute said instructions and render the device a special purpose computing device to:

transmit said spatial alignment of the IMU to another device.

28. The device of claim 15, wherein said one or more processors are further to execute said instructions and render the device a special purpose computing device to:

apply said spatial alignment of the IMU to navigation performed by a satellite positioning system-inertial navigation system.

29. An apparatus comprising:

means for identifying a first vehicle-based direction based, at least in part, on one or more correlation operations that relate to first vehicle-related movement data and at least one of a first acceleration or a second acceleration, said first acceleration and said second acceleration corresponding to one or more accelerations measured using an inertial measurement unit (IMU);

means for associating said first vehicle-based direction with a first direction that is transformable to an earth-based coordinate frame; and

means for determining a spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said first direction.

30. The apparatus of claim 29, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system.

31. The apparatus of claim 30, wherein said means for identifying a first vehicle-based direction comprises:

means for ascertaining at least one first correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said first acceleration;

means for ascertaining at least one second correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said second acceleration; and

means for selecting a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

32. The apparatus of claim 29, wherein said first vehicle-based direction comprises a right-left direction, said first direction comprises a right direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises rotational data.

33. The apparatus of claim 32, wherein said means for identifying a first vehicle-based direction comprises:

means for ascertaining at least one first correlative indication between and/or among said rotational data and said first acceleration;

means for ascertaining at least one second correlative indication between and/or among said rotational data and said second acceleration; and

means for selecting a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

34. The apparatus of claim 29, further comprising:

means for identifying a second vehicle-based direction based, at least in part, on one or more correlation operations that relate to second vehicle-related movement data and at least one of said first acceleration or said second acceleration; and

means for associating said second vehicle-based direction with a second direction that is transformable to the earth-based coordinate frame,

wherein said means for determining comprises means for determining said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said second direction.

35. The apparatus of claim 34, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system;

and wherein said second vehicle-based direction comprises a right-left direction, said second direction comprises a right direction that is transformable to the earth-based coordinate frame, and said second vehicle-related movement data comprises rotational data.

36. The apparatus of claim 35, wherein said means for determining further comprises:

means for transforming said right-left direction and said course-over-ground direction into directions in a cardinal-direction-based coordinate frame; and

means for transforming said directions in the cardinal-direction-based coordinate frame into directions in the earth-based coordinate frame.

37. The apparatus of claim 29, further comprising:

means for identifying an up-down direction based, at least in part, on one or more comparative operations that relate to said first acceleration, said second acceleration, and a third acceleration;

said third acceleration corresponding to at least one acceleration measured using the IMU; and

means for associating said up-down direction with an up direction that is transformable to the earth-based coordinate frame, said up direction at least substantially parallel to a direction of gravity,

wherein said means for determining a spatial alignment of the IMU comprises means for determining said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said up direction.

38. The apparatus of claim 37, wherein said means for identifying an up-down direction comprises means for comparing said first acceleration, said second acceleration, and said third acceleration to select a strongest acceleration;

and wherein said up-down direction corresponds to a direction associated with said strongest acceleration.

39. The apparatus of claim 29, wherein at least one of said first acceleration or said second acceleration is produced using an eigenvector.

40. The apparatus of claim 29, wherein at least one of said first acceleration or said second acceleration comprises an acceleration that is projected onto a horizontal plane, the horizontal plane at least substantially orthogonal to an up direction.

41. The apparatus of claim 29, further comprising:

means for transmitting said spatial alignment of the IMU to another device.

42. The apparatus of claim 29, further comprising:

means for applying said spatial alignment of the IMU to navigation performed by a satellite positioning system-inertial navigation system.

43. An article comprising:

at least one storage medium having stored thereon instructions executable by one or more processors to;

identify a first vehicle-based direction based, at least in part, on one or more correlation operations that relate to first vehicle-related movement data and at least one of a first acceleration or a second acceleration, said first acceleration and said second acceleration corresponding to one or more accelerations measured using an inertial measurement unit (IMU);

associate said first vehicle-based direction with a first direction that is transformable to an earth-based coordinate frame; and

determine a spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said first direction.

44. The article of claim 43, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system.

45. The article of claim 44, wherein to identify a first vehicle-based direction said at least one storage medium has stored thereon further instructions executable by one or more processors to:

ascertain at least one first correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said first acceleration;

ascertain at least one second correlative indication between and/or among said acceleration data that is derived from data provided by a satellite positioning system and said second acceleration; and

select a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

46. The article of claim 43, wherein said first vehicle-based direction comprises a right-left direction, said first direction comprises a right direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises rotational data.

47. The article of claim 46, wherein to identify a first vehicle-based direction said at least one storage medium has stored thereon further instructions executable by one or more processors to:

ascertain at least one first correlative indication between and/or among said rotational data and said first acceleration;

ascertain at least one second correlative indication between and/or among said rotational data and said second acceleration; and

select a direction that is associated with said first acceleration or said second acceleration as said first vehicle-based direction based on said at least one first correlative indication and/or said at least one second correlative indication.

48. The article of claim 43, wherein said at least one storage medium has stored thereon further instructions executable by one or more processors to:

identify a second vehicle-based direction based, at least in part, on one or more correlation operations that relate to second vehicle-related movement data and at least one of said first acceleration or said second acceleration; and

associate said second vehicle-based direction with a second direction that is transformable to the earth-based coordinate frame,

wherein to determine a spatial alignment of the IMU said at least one storage medium has stored thereon further instructions executable by one or more processors to determine said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said second direction.

49. The article of claim 48, wherein said first vehicle-based direction comprises a forward-backward direction, said first direction comprises a course-over-ground direction that is transformable to the earth-based coordinate frame, and said first vehicle-related movement data comprises acceleration data that is derived from data provided by a satellite positioning system;

and wherein said second vehicle-based direction comprises a right-left direction, said second direction comprises a right direction that is transformable to the earth-based coordinate frame, and said second vehicle-related movement data comprises rotational data.

50. The article of claim 49, wherein to determine a spatial alignment of the IMU said at least one storage medium has stored thereon further instructions executable by one or more processors to:

transform said right-left direction and said course-over-ground direction into directions in a cardinal-direction-based coordinate frame; and

transform said directions in the cardinal-direction-based coordinate frame into directions in the earth-based coordinate frame.

51. The article of claim 43, wherein said at least one storage medium has stored thereon further instructions executable by one or more processors to:

identify an up-down direction based, at least in part, on one or more comparative operations that relate to said first acceleration, said second acceleration, and a third acceleration;

said third acceleration corresponding to at least one acceleration measured using the IMU; and

associate said up-down direction with an up direction that is transformable to the earth-based coordinate frame, said up direction at least substantially parallel to a direction of gravity,

wherein to determine a spatial alignment of the IMU said at least one storage medium has stored thereon further instructions executable by one or more processors to determine said spatial alignment of the IMU with respect to the earth-based coordinate frame based at least partially on said up direction.

52. The article of claim 51, wherein to identify an up-down direction said at least one storage medium has stored thereon further instructions executable by one or more processors to compare said first acceleration, said second acceleration, and said third acceleration to select a strongest acceleration;

and wherein said up-down direction corresponds to a direction associated with said strongest acceleration.

53. The article of claim 43, wherein at least one of said first acceleration or said second acceleration is produced using an eigenvector.

54. The article of claim 43, wherein at least one of said first acceleration or said second acceleration comprises an acceleration that is projected onto a horizontal plane, the horizontal plane at least substantially orthogonal to an up direction.

55. The article of claim 43, wherein said at least one storage medium has stored thereon further instructions executable by one or more processors to:

transmit said spatial alignment of the IMU to another device.

56. The article of claim 43, wherein said at least one storage medium has stored thereon further instructions executable by one or more processors to:

apply said spatial alignment of the IMU to navigation performed by a satellite positioning system-inertial navigation system.