REDUCING POWER CONSUMPTION OR ERROR OF DIGITAL COMPASS

• US 20130006573A1
• Filed: 06/30/2011
• Published: 01/03/2013
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Brunner, Christopher, Kulik, Victor
• Granted Patent: US 9,541,393 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G06F 1/1694 the I/O peripheral being a single or a set of motion sensors for pointer control or gesture input obtained by sensing movements of the portable computer
• CPC Class Codes: G06F 1/325 Power saving in peripheral device
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry

Abstract

Example methods, apparatuses, or articles of manufacture are disclosed herein that may be utilized, in whole or in part, to facilitate or support one or more operations or techniques for reducing power consumption or error of a digital compass.

Claims

1. A method comprising, at a mobile device:

suspending a process to calibrate a magnetometer in response to a determination that said mobile device is in a stationary state.

2. The method of claim 1, and further comprising determining that said mobile device is in said stationary state based, at least in part, on measurements obtained from at least one accelerometer.

3. The method of claim 1, and further comprising determining that said mobile device is in said stationary state based, at least in part, on measurements obtained from at least one gyroscope.

4. The method of claim 1, and further comprising determining that said mobile device is in said stationary state based, at least in part, on measurements obtained from said magnetometer.

5. The method of claim 4, wherein said determining that said mobile device is in said stationary state is based, at least in part, on a variance of a sliding window of said measurements obtained from said magnetometer.

6. The method of claim 1, and further comprising:

detecting an interval of motion of said mobile device; and

suspending calibration of said magnetometer before and after said interval.

7. A method comprising, at a mobile device:

detecting at least one condition; and

changing a rate at which a process of calibrating a magnetometer is to be executed based, at least in part, on said detected at least one condition.

8. The method of claim 7, wherein said rate is based, at least in part, on a sampling rate of said magnetometer.

9. The method of claim 8, wherein said sampling rate is determined, at least in part, in connection with at least one of:

a user rotating said mobile device;

a host application requesting at least one magnetometer sample;

or any combination thereof.

10. The method of claim 7, wherein said detected at least one condition comprises an estimated turn rate of an orientation of said mobile device.

11. The method of claim 10, wherein said turn rate is estimated based, at least in part, on at least one measurement received from a gyroscope.

12. The method of claim 10, wherein said turn rate is estimated based, at least in part, on a variation in magnetometer measurements.

13. The method of claim 10, wherein said turn rate is estimated based, at least in part, on at least one measurement received from an accelerometer.

14. The method of claim 7, wherein said detected at least one condition comprises a measure of fitness of at least one calibration parameter.

15. The method of claim 14, wherein said measure of fitness is determined based, at least in part, on an ellipse/ellipsoid fitting-type process via magnetometer samples.

16. The method of claim 14, wherein said measure of fitness is determined based, at least in part, on a turn angle computed via measurements received from at least one of:

said magnetometer;

an accelerometer;

a gyroscope;

or any combination thereof.

17. An apparatus comprising:

a mobile device comprising a magnetometer and at least one processor to;

suspend a process to calibrate said magnetometer in response to a determination that said mobile device is in a stationary state.

18. The apparatus of claim 17, wherein said at least one processor further to:

determine that said mobile device is in said stationary state based, at least in part, on measurements obtained from at least one accelerometer.

19. The apparatus of claim 17, wherein said at least one processor further to:

determine that said mobile device is in said stationary state based, at least in part, on measurements obtained from at least one gyroscope.

20. The apparatus of claim 17, wherein said at least one processor further to:

determine that said mobile device is in said stationary state based, at least in part, on measurements obtained from said magnetometer.

21. The apparatus of claim 20, wherein said processor is further to determine that said mobile device is in said stationary state based, at least in part, on a variance of a sliding window of said measurements obtained from said magnetometer.

22. The apparatus of claim 17, wherein said at least one processor further to:

detect an interval of motion of said mobile device; and

suspend calibration of said magnetometer before and after said interval.

23. An apparatus comprising:

means for detecting at least one condition; and

means for changing a rate at which a process of calibrating a magnetometer is to be executed based, at least in part, on said detected at least one condition.

24. The apparatus of claim 23, wherein said detected at least one condition comprises an estimated turn rate of an orientation of a mobile device.

25. The apparatus of claim 24, wherein said estimated turn rate is estimated based, at least in part, on at least one measurement received from a gyroscope.

26. The apparatus of claim 24, wherein said estimated turn rate is estimated based, at least in part, on a variation in magnetometer measurements.

27. The apparatus of claim 24, wherein said estimated turn rate is estimated based, at least in part, on at least one measurement received from an accelerometer.

28. The apparatus of claim 23, wherein said detected at least one condition comprises a measure of fitness of at least one calibration parameter.

29. The apparatus of claim 28, wherein said measure of fitness is determined based, at least in part, on an ellipse/ellipsoid fitting-type process via magnetometer samples.

30. The apparatus of claim 28, wherein said measure of fitness is determined based, at least in part, on a turn angle computed via measurements received from at least one of said magnetometer;

an accelerometer;

a gyroscope;

or any combination thereof.

31. An article comprising:

a non-transitory storage medium having instructions stored thereon executable by a special purpose computing platform to;

suspend, at a mobile device, a process to calibrate a magnetometer in response to a determination that said mobile device is in a stationary state.

32. The article of claim 31, wherein said non-transitory storage medium further includes instructions to:

determine that said mobile device is in said stationary state based, at least in part, on measurements obtained from at least one accelerometer.

33. The article of claim 31, wherein said non-transitory storage medium further includes instructions to:

determine that said mobile device is in said stationary state based, at least in part, on measurements obtained from at least one gyroscope.

34. The article of claim 31, wherein said non-transitory storage medium further includes instructions to:

detect an interval of motion of said mobile device; and

suspend calibration of said magnetometer before and after said interval.