ACCELEROMETER-AIDED GYROSCOPE

• US 20120158296A1
• Filed: 02/09/2011
• Published: 06/21/2012
• Est. Priority Date: 02/15/2010
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: WATERS, Deric W., PANDE, Tarkesh
• Granted Patent: US 8,612,146 B2
• Time in Patent Office: Days
• US Class Current: 701/509
• CPC Class Codes: G01C 19/04 Details
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: Y10T 74/1229 Gyroscope control

Abstract

A system comprises a gyroscope configured to produce a gyroscope signal, an accelerometer configured to produce an accelerometer signal, and a filter unit coupled to the gyroscope and having a configurable bandwidth. The filter unit configured to filter the gyroscope signal. The system also comprises control logic that is configured to alter the bandwidth of the filter unit based on the accelerometer signal.

Claims

1. A system, comprising:

a gyroscope configured to produce a gyroscope signal;

an accelerometer configured to produce an accelerometer signal;

a filter unit coupled to said gyroscope and having a configurable bandwidth, said filter unit configured to filter the gyroscope signal; and

control logic coupled to said accelerometer and to said filter unit and configured to alter the bandwidth of the filter unit based on the accelerometer signal.

2. The system of claim 1 wherein the gyroscope comprises a multi-axis gyroscope and said gyroscope signal comprises a separate, single axis gyroscope signal corresponding to each axis of the gyroscope, and said filter unit comprises a separate filter corresponding to each single axis gyroscope signal, each of said separate filters having a bandwidth configurable by the control logic based on the accelerometer signal.

3. The system of claim 2 wherein the accelerometer comprises a multi-axis accelerometer and said accelerometer signal comprises a separate, single axis accelerometer signal corresponding to each axis of the accelerometer.

4. The system of claim 3 further comprising a transformation computation unit that transforms the single axis accelerometer signals to a different reference frame and wherein said control logic processes only a subset of the single axis accelerometer signals, after the transformation, and configures the bandwidth of the separate filters based on said subset.

5. The system of claim 1 wherein, based on the accelerometer signal, said control logic is configured to assert a signal to said gyroscope to cause the gyroscope to transition to a low power, off, or sleep mode.

6. The system of claim 1 wherein, the control logic alters the bandwidth of the filter unit for a first bandwidth based on the accelerometer signal being above a threshold and alters the bandwidth of the filter unit for a second bandwidth based on the accelerometer signal being below the threshold.

7. The system of claim 1 wherein, the control logic alters the bandwidth of the filter unit for a first bandwidth based on the accelerometer signal being above a first threshold and alters the bandwidth of the filter unit for a second bandwidth based on the accelerometer signal being below the first threshold but above a second threshold, and the control logic asserts a disable signal to the gyroscope based on the accelerometer signal being below the second threshold, said disable signal causing the gyroscope to power off or transition to a low power or sleep mode.

8. The system of claim 1 further comprising a buffer into which the gyroscope signal is stored and said filter unit retrieves and then filters the gyroscope signal from the buffer.

9. The system of claim 1 wherein said filter unit comprises a plurality of filters.

10. A method, comprising:

setting a bandwidth of a gyroscope filter based on an accelerometer signal; and

filtering, by said gyroscope filter, a signal from a gyroscope.

11. The method of claim 10 wherein setting the bandwidth of the gyroscope filter comprises determining whether the accelerometer signal is less than or greater than threshold.

12. The method of claim 11 wherein setting bandwidth of the gyroscope filter comprises setting the bandwidth to a lower bandwidth based on the accelerometer signal being less than the threshold and to a higher bandwidth based on the accelerometer signal being greater than the threshold.

13. The method of claim 10 wherein setting the bandwidth of the gyroscope filter comprises comparing the accelerometer signal to lower and upper thresholds.

14. The method of claim 13 further comprising transitioning the gyroscope to a low power state including at least one of an off state and a sleep mode based on the accelerometer signal being less than the lower threshold.

15. The method of claim 13 wherein setting the bandwidth of the gyroscope filter comprises setting the bandwidth to a lower bandwidth based on the accelerometer signal being between the lower and upper thresholds and to a higher bandwidth based on the accelerometer signal being greater than the upper threshold.

16. The method of claim 10 further comprising computing a metric based on the accelerometer signal and setting the bandwidth of the gyroscope signal based on the computed metric.

17. The method of claim 16 wherein computing the metric comprises computing at least one of variances of the accelerometer signal, standard deviations of the accelerometer signal, and the square root of a value based on the acceleration signal less a gravitational constant.

18. A system, comprising:

a gyroscope configured to produce a gyroscope signal;

a filter unit coupled to said gyroscope and having a configurable bandwidth, said filter unit configured to filter the gyroscope signal; and

control logic coupled to said filter unit and configured to alter the bandwidth of the filter unit based on an accelerometer signal.

19. The system of claim 18 wherein the gyroscope comprises a multi-axis gyroscope and said gyroscope signal comprises a separate, single axis gyroscope signal corresponding to each axis of the gyroscope, and said filter unit comprises a separate filter corresponding to each single axis gyroscope signal, each of said separate filters having a bandwidth configurable by the control logic based on the accelerometer signal.

20. The system of claim 18 wherein said control logic is configured to assert a signal, based on the accelerometer signal, to said gyroscope to cause the gyroscope to transition to a low power state comprising at least one of an off state and a sleep mode.

21. The system of claim 18 wherein, the control logic alters the bandwidth of the filter unit for a first bandwidth based on the accelerometer signal being above a first threshold and alters the bandwidth of the filter unit for a second bandwidth based on the accelerometer signal being below the first threshold but above a second threshold, and the control logic asserts a disable signal to the gyroscope based on the accelerometer signal being below the second threshold, said disable signal causing the gyroscope to power off or transition to a low power or sleep mode.

22. The system of claim 18 further comprising a buffer into which the gyroscope signal is stored and said filter unit retrieves and then filters the gyroscope signal from the buffer.

23. The system of claim 18 wherein said filter unit comprises a plurality of filters.