Rotational insensitivity using gravity-based adjustment

• US 7,457,719 B1
• Filed: 11/21/2006
• Issued: 11/25/2008
• Est. Priority Date: 11/21/2006
• Status: Active Grant

• Current Assignee: DP Technologies, Inc.
• Original Assignee: Fullpower Technologies Incorporated
• Inventors: Christensen, Mark Andrew, Kinsolving, Arthur, Kahn, Philippe, Lee, Brian Y
• Primary Examiner(s): Lau; Tung S
• Assistant Examiner(s): SUN, XIUQIN
• Application Number:
  US11/603,472
• Time in Patent Office: 735 Days
• Field of Search: 702/141, 318/636, 725/37
• US Class Current: 702/141
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A63F 2300/105 using inertial sensors, e.g. accelerometers, gyroscopes
• CPC Class Codes: G01C 22/006 Pedometers

Abstract

One or more rolling averages of accelerations over a sample period are created. The one or more rolling averages of accelerations are measured by an accelerometer over the sample period. A gravitational influence is identified based upon the one or more rolling averages of accelerations. A dominant axis is assigned based upon the gravitational influence.

Claims

1. A method of determining an orientation of an accelerometer, comprising:

creating one or more rolling averages of accelerations over a sample period;

identifying a gravitational influence based upon the one or more rolling averages of accelerations; and

assigning a dominant axis based upon the gravitational influence, wherein assigning the dominant axis comprises identifying an axis that has a largest average acceleration over the sample period.

2. The method of claim 1, wherein the dominant axis does not correspond to one of the actual axes of the accelerometer in its current orientation.

3. The method of claim 1, comprising:

detecting a period of a cadence of motion; and

setting the sample period such that it has at least the period of the cadence of motion.

4. The method of claim 3, comprising:

setting the sample period to a multiple of the period of the cadence of motion.

5. The method of claim 1, comprising:

utilizing acceleration along the dominant axis to detect a gesture, a periodic human motion, or a gesture and a periodic human motion.

6. The method of claim 5, comprising:

utilizing acceleration along only the dominant axis.

7. The method of claim 1, comprising:

creating a rolling average of accelerations over a sample period for each axis of the accelerometer; and

identifying a gravitational influence based upon the rolling averages of accelerations by comparing the rolling average of accelerations of each axis of the accelerometer.

8. The method of claim 1, wherein the orientation is determined to a specified degree of accuracy.

9. A method of determining an orientation of an accelerometer, comprising:

creating one or more rolling averages of accelerations over a sample period;

identifying a gravitational influence based upon the one or more rolling averages of accelerations;

comparing the gravitational influence to a lookup table; and

assigning the dominant axis based upon the gravitational influence and the lookup table.

10. The method of claim 9, wherein the lookup table includes a plurality of entries, each entry defining a probability range for a distinct orientation for the gravitational influence.

11. The method of claim 9, wherein the lookup table divides accelerations into limits that define probability ranges in which gravity is acting, each entry in the lookup table being associated with a distinct probability range.

12. The method of claim 9, wherein each entry in the lookup table includes a gravity threshold for an axis of the accelerometer, the gravity threshold identifying a percentage of a total gravity caused acceleration.

13. A device, comprising:

a rolling average logic to create one or more rolling averages of accelerations as measured by an accelerometer over a sample period;

a gravitational influence logic to identify a gravitational influence based upon the one or more rolling averages of accelerations; and

a dominant axis logic to assign a dominant axis based upon the gravitational influence, wherein the dominant axis is an axis that has a largest average acceleration over the sample period.

14. The device of claim 13, wherein the dominant axis does not correspond to one of the actual axes of the accelerometer in its current orientation.

15. The device of claim 13, comprising:

a cadence logic to detect a period of a cadence of motion; and

a sample period logic to set the sample period such that it has at least the period of the cadence of motion.

16. The device of claim 15, wherein the sample period logic sets the sample period to a multiple of the period of the cadence of motion.

17. The device of claim 13, comprising:

a motion recognition logic to utilize acceleration along the dominant axis to detect a gesture, a periodic human motion, or a gesture and a periodic human motion.

18. The device of claim 17, wherein the motion recognition logic utilizes acceleration along only the dominant axis.

19. The device of claim 13, wherein the one or more rolling average of accelerations include a different rolling average of accelerations for each axis of the accelerometer, and wherein the gravitational influence logic is configured to identify the gravitational influence by comparing the rolling average of accelerations of each axis of the accelerometer.

20. A device, comprising:

a rolling average logic to create one or more rolling averages of accelerations as measured by an accelerometer over a sample period;

a gravitational influence logic to identify a gravitational influence based upon the one or more rolling averages of accelerations;

a dominant axis logic to assign a dominant axis based upon the gravitational influence; and

a lookup table, wherein the dominant axis logic uses the lookup table to assign a dominant axis based upon the gravitational influence.

21. The device of claim 20, wherein the lookup table includes a plurality of entries, each entry defining a probability range for a distinct orientation for the gravitational influence.

22. The device of claim 20, wherein the lookup table divides accelerations into limits that define probability ranges in which gravity is acting, each entry in the lookup table being associated with a distinct probability range.

23. The device of claim 20, wherein each entry in the lookup table includes a gravity threshold for an axis of the accelerometer, the gravity threshold identifying a percentage of a total gravity caused acceleration.

24. A portable electronic device, comprising:

an accelerometer having a plurality of axes;

a rolling average logic to create a rolling average of accelerations for each of the plurality of axes as measured by the accelerometer over a sample period;

a gravitational influence logic to identify a gravitational influence based upon rolling averages of accelerations by comparing the rolling average of accelerations of each of the plurality of axes; and

a dominant axis logic to assign a dominant axis based upon the gravitational influence.

25. The portable electronic device of claim 24, comprising:

a cadence logic to detect a period of a cadence of motion; and

a sample period logic to set the sample period such that it has at least the period of the cadence of motion.

26. The portable electronic device of claim 24, comprising:

a motion recognition logic to utilize acceleration along the dominant axis to detect a gesture, a periodic human motion, or a gesture and a periodic human motion.

27. The portable electronic device of claim 26, wherein the motion recognition logic utilizes acceleration along only the dominant axis.

28. A machine-accessible medium including data that, when accessed by a machine, cause the machine to perform a method comprising:

creating one or more rolling averages of accelerations over a sample period;

identifying a gravitational influence based upon the one or more rolling averages of accelerations; and

assigning a dominant axis based upon the gravitational influence, wherein assigning a dominant axis comprises identifying an axis that has a largest average acceleration over the sample period.

29. The machine-accessible medium of claim 28, the method further comprising:

utilizing acceleration along the dominant axis to detect a gesture, a periodic human motion, or a gesture and a periodic human motion.

30. The machine-accessible medium of claim 28, the method further comprising:

detecting a period of a cadence of motion; and

setting the sample period such that it has at least the period of the cadence of motion.

31. A method of determining a device orientation comprising:

creating a rolling average of accelerations over a sample period for each axis of an accelerometer; and

determining an orientation of the accelerometer based upon the rolling average of accelerations by comparing the relative rolling average of accelerations of each axis of the accelerometer.

32. The method of claim 31, comprising:

detecting a period of a cadence of motion; and

setting sample periods for the rolling averages of accelerations such that they have at least the period of the cadence of motion.

33. The method of claim 31, comprising:

utilizing the orientation of the accelerometer to detect gestures, periodic human motions, or gestures and periodic human motions.

34. The method of claim 31, wherein the orientation of the accelerometer is determined to a specified degree of accuracy.

35. The method of claim 31, further comprising:

when a rolling average of accelerations changes, determining a new orientation of the accelerometer based upon the new rolling average of accelerations.

36. The method of claim 31, wherein determining the orientation of the accelerometer comprises:

calculating a total gravity caused acceleration based upon the rolling average of accelerations of each axis of the accelerometer;

assigning a percentage of the total gravity caused accelerations to each axis; and

calculating the orientation of the accelerometer based on the percentage of the total gravity caused acceleration assigned to each axis.

37. A method of determining a device orientation comprising:

creating at least one rolling average of accelerations;

comparing the at least one rolling average of accelerations to a lookup table; and

determining an orientation of the accelerometer based upon the at least one rolling average of accelerations and the lookup table.

38. A machine-accessible medium including data that, when accessed by a machine, cause the machine to perform a method comprising:

creating one or more rolling averages of accelerations over a sample period;

identifying a gravitational influence based upon the one or more rolling averages of accelerations;

comparing the gravitational influence to a lookup table; and

assigning the dominant axis based upon the gravitational influence and the lookup table.

39. The machine accessible medium of claim 38, wherein the lookup table includes a plurality of entries, each entry defining a probability range for a distinct orientation for the gravitational influence.

40. The machine-accessible medium of claim 38, wherein the lookup table divides accelerations into limits that define probability ranges in which gravity is acting, each entry in the lookup table being associated with a distinct probability range.

41. The machine-accessible medium of claim 38, wherein each entry in the lookup table includes a gravity threshold for an axis of the accelerometer, the gravity threshold identifying a percentage of a total gravity caused acceleration.

42. A machine-accessible medium including data that, when accessed by a machine, cause the machine to perform a method comprising:

creating a rolling average of accelerations over a sample period for each axis of an accelerometer;

identifying a gravitational influence based upon the rolling averages of accelerations by comparing the rolling average of accelerations of each axis of the accelerometer; and

assigning a dominant axis based upon the gravitational influence.

43. The machine-accessible medium of claim 42, the method further comprising:

assigning a new dominant axis based upon the rolling average of accelerations when the gravitational influence changes.