INERTIAL SENSOR AIDED HEADING AND POSITIONING FOR GNSS VEHICLE NAVIGATION

• US 20120173190A1
• Filed: 12/01/2011
• Published: 07/05/2012
• Est. Priority Date: 12/03/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: CZOMPO, Joseph, JOSHI, Ashutosh, NAMBURI, Shanta Pavan, AHUJA, Disha
• Granted Patent: US 9,803,983 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/393 Trajectory determination or predictive tracking, e.g. Kalman filtering
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

An apparatus and method for providing an improved heading estimate of a mobile device in a vehicle is presented. First, the mobile device determines if it is mounted in a cradle attached to the vehicle; if so, inertia sensor data may be valid. While in a mounted stated, the mobile device determines whether it has been rotated in the cradle; if so, inertia sensor data may no longer be reliable and a recalibration to determine a new relative orientation between the vehicle and the mobile device is needed. If the mobile device is mounted and not recently rotated, heading data from multiple sensors (e.g., GPS, gyroscope, accelerometer) may be computed and combined to form the improved heading estimate. This improved heading estimate may be used to form an improved velocity estimate. The improved heading estimate may also be used to compute a bias to correct a gyroscope.

Claims

1. A method in a mobile device to detect if the mobile device is unmounted, the method comprising:

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing a parameter p based on the accelerometer measurements {right arrow over (a)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

2. The method of claim 1, wherein the parameter p comprise an angle θ

between the accelerometer measurements {right arrow over (a)} and the average {right arrow over (a)}_AVG, and the variance σ

_p² comprises a variance σ

_θ

² of the angle θ

.

3. The method of claim 1, wherein the parameter p comprise a magnitude ∥

{right arrow over (a)}∥

of the accelerometer measurements {right arrow over (a)}, and wherein the variance σ

_p² comprises a variance σ

<sub>∥

a∥</sub>

² comprising a variance of the magnitude ∥

{right arrow over (a)}∥

from a magnitude ∥

{right arrow over (a)}_AVG∥

of the average {right arrow over (a)}_AVG.

4. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

an inertial measurement unit comprising an accelerometer;

a processor coupled to the inertial measurement unit; and

memory coupled to the processor, comprising code for;

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing a parameter p based on the accelerometer measurements {right arrow over (a)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

5. The mobile device of claim 4, wherein the parameter p comprise an angle θ

between the accelerometer measurements {right arrow over (a)} and the average {right arrow over (a)}_AVG, and the variance σ

_p² comprises a variance σ

_θ

² of the angle θ

.

6. The mobile device of claim 4, wherein the parameter p comprise a magnitude ∥

{right arrow over (a)}∥

of the accelerometer measurements {right arrow over (a)}, and wherein the variance σ

_p² comprises a variance σ

<sub>∥

a∥</sub>

² comprising a variance of the magnitude ∥

{right arrow over (a)}∥

from a magnitude ∥

{right arrow over (a)}_AVG∥

of the average {right arrow over (a)}_AVG.

7. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

means for receiving accelerometer measurements {right arrow over (a)};

means for determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

means for computing a parameter p based on the accelerometer measurements {right arrow over (a)};

means for computing a variance σ

_p² of the parameter;

means for comparing the variance σ

_p² to a threshold; and

means for declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

8. The mobile device of claim 7, wherein the parameter p comprise an angle θ

between the accelerometer measurements {right arrow over (a)} and the average {right arrow over (a)}_AVG, and the variance σ

_p² comprises a variance σ

_θ

² of the angle θ

.

9. The mobile device of claim 7, wherein the parameter p comprise a magnitude ∥

{right arrow over (a)}∥

of the accelerometer measurements {right arrow over (a)}, and wherein the variance σ

_p² comprises a variance σ

<sub>∥

a∥</sub>

² comprising a variance of the magnitude ∥

{right arrow over (a)}∥

from a magnitude ∥

{right arrow over (a)}_AVG∥

of the average {right arrow over (a)}_AVG.

10. A device comprising a processor and a memory wherein the memory includes software instructions for:

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing a parameter p based on the accelerometer measurements {right arrow over (a)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

11. A non-volatile computer-readable storage medium including program code stored thereon, comprising program code for:

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing a parameter p based on the accelerometer measurements {right arrow over (a)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

12. A method in a mobile device to detect if the mobile device is unmounted, the method comprising:

receiving gyroscope measurements {right arrow over (ω

)};

determining an average {right arrow over (ω

)}_AVG of the gyroscope measurements {right arrow over (ω

)};

computing a parameter p based on the gyroscope measurement {right arrow over (ω

)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

13. The method of claim 12, wherein the parameter p comprise an angle θ

between the gyroscope measurement {right arrow over (a)} and the average {right arrow over (ω

)}_AVG and the variance σ

_p² comprises a variance σ

_θ

² of the angle θ

.

14. The method of claim 12, wherein the parameter p comprise a magnitude ∥

{right arrow over (ω

)}∥

of the gyroscope measurement {right arrow over (ω

)}, and wherein the variance σ

_p² a variance σ

<sub>∥

{right arrow over (ω

)}∥</sub>

² of the magnitude ∥

{right arrow over (ω

)}∥

from a magnitude ∥

{right arrow over (ω

)}_AVG∥

of the average {right arrow over (ω

)}_AVG.

15. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

an inertial measurement unit comprising a gyroscope;

a processor coupled to the inertial measurement unit; and

memory coupled to the processor, comprising code for;

receiving gyroscope measurements {right arrow over (ω

)};

determining an average {right arrow over (ω

)}_AVG of the gyroscope measurements {right arrow over (ω

)};

computing a parameter p based on the gyroscope measurement {right arrow over (ω

)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

16. The mobile device of claim 15, wherein the parameter p comprise an angle θ

between the gyroscope measurements {right arrow over (ω

)} and the average {right arrow over (ω

)}_AVG, and the variance σ

_p² comprises a variance is σ

_ω

² of the angle θ

.

17. The mobile device of claim 15, wherein the parameter p comprise a magnitude ∥

{right arrow over (ω

)}∥

of the gyroscope measurements {right arrow over (ω

)}, and wherein the variance σ

_p² comprises a variance σ

<sub>∥

ω

∥</sub>

² comprising a variance of the magnitude ∥

{right arrow over (ω

)}∥

from a magnitude ∥

{right arrow over (ω

)}_AVG∥

of the average {right arrow over (ω

)}_AVG.

18. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

means for receiving gyroscope measurements {right arrow over (ω

)};

means for determining an average {right arrow over (ω

)}_AVG of the gyroscope measurements {right arrow over (ω

)};

means for computing a parameter p based on the gyroscope measurement {right arrow over (ω

)};

means for computing a variance σ

_p² of the parameter;

means for comparing the variance σ

_p² to a threshold; and

means for declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

19. The mobile device of claim 18, wherein the parameter p comprise an angle θ

between the gyroscope measurements {right arrow over (ω

)} and the average {right arrow over (ω

)}_AVG, and the variance σ

_p² comprises a variance is σ

_ω

² of the angle θ

.

20. The mobile device of claim 18, wherein the parameter p comprise a magnitude ∥

{right arrow over (ω

)}∥

of the gyroscope measurements {right arrow over (ω

)}, and wherein the variance σ

_p² comprises a variance σ

<sub>∥

ω

∥</sub>

² comprising a variance of the magnitude ∥

{right arrow over (ω

)}∥

from a magnitude ∥

{right arrow over (ω

)}_AVG∥

of the average {right arrow over (ω

)}_AVG.

21. A device comprising a processor and a memory wherein the memory includes software instructions for:

receiving gyroscope measurements {right arrow over (ω

)};

determining an average {right arrow over (ω

)}_AVG of the gyroscope measurements {right arrow over (ω

)};

computing a parameter p based on the gyroscope measurement {right arrow over (ω

)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

22. A non-volatile computer-readable storage medium including program code stored thereon, comprising program code for:

receiving gyroscope measurements {right arrow over (ω

)};

determining an average {right arrow over (ω

)}_AVG of the gyroscope measurements {right arrow over (ω

)};

computing a parameter p based on the gyroscope measurement {right arrow over (ω

)};

computing a variance σ

_p² of the parameter;

comparing the variance σ

_p² to a threshold; and

declaring the mobile device is unmounted based on the variance σ

_p² being greater than the threshold.

23. A method in a mobile device to detect if the mobile device is unmounted, the method comprising:

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing an angle θ

between the average {right arrow over (a)}_AVG and an axis perpendicular to a viewable display on the mobile device;

comparing the angle θ

to 90 degrees; and

declaring the mobile device is unmounted based on the angle θ

being less than a threshold from 90 degrees.

24. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

an inertial measurement unit comprising an accelerometer;

a processor coupled to the inertial measurement unit; and

memory coupled to the processor, comprising code for;

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing an angle θ

between the average {right arrow over (a)}_AVG and an axis perpendicular to a viewable display on the mobile device;

comparing the angle θ

to 90 degrees; and

declaring the mobile device is unmounted based on the angle θ

being less than a threshold from 90 degrees.

25. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

means for receiving accelerometer measurements {right arrow over (a)};

means for determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

means for computing an angle θ

between the average {right arrow over (a)}_AVG and an axis perpendicular to a viewable display on the mobile device;

means for comparing the angle θ

to 90 degrees; and

means for declaring the mobile device is unmounted based on the angle θ

being less than a threshold from 90 degrees.

26. A device comprising a processor and a memory wherein the memory includes software instructions for:

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing an angle θ

between the average {right arrow over (a)}_AVG and an axis perpendicular to a viewable display on the mobile device;

comparing the angle θ

to 90 degrees; and

declaring the mobile device is unmounted based on the angle θ

being less than a threshold from 90 degrees.

27. A non-volatile computer-readable storage medium including program code stored thereon, comprising program code for:

receiving accelerometer measurements {right arrow over (a)};

determining an average {right arrow over (a)}_AVG of the accelerometer measurements {right arrow over (a)};

computing an angle θ

between the average {right arrow over (a)}_AVG and an axis perpendicular to a viewable display on the mobile device;

comparing the angle θ

to 90 degrees; and

declaring the mobile device is unmounted based on the angle θ

being less than a threshold from 90 degrees.

28. A method in a mobile device to detect if the mobile device is unmounted, the method comprising:

computing variance values σ

_p² for at least one of;

(a) a sequence of accelerometer measurements ({right arrow over (a)});

(b) a sequence of averages ({right arrow over (a)}_AVG) of accelerometer measurements;

(c) a sequence of gyroscope measurements ({right arrow over (ω

)});

(d) three sequences of scalar channelized gyroscope measurements (ω

_X, ω

_Y, ω

_Z); and

(e) a virtual gyroscope heading rate ({dot over ( H);

setting a flag if any of the variance values σ

_p² exceed a respective threshold; and

declaring the mobile device is not in a mounted state based on the flag.

29. The method of claim 28, wherein setting and declaring comprise:

counting a number of times any of the variance values over a window of time exceed a respective threshold; and

declaring the mobile device is not in a mounted state based on the number being greater than a threshold.

30. The method of claim 28, wherein computing the variance values for at least one of (a)-(e) comprises computing the variance values for at least two of (a)-(e).

31. The method of claim 28, wherein computing the variance values for at least one of (a)-(e) comprises computing the variance values for at least three of (a)-(e).

32. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

an inertial measurement unit comprising an accelerometer;

a processor coupled to the inertial measurement unit; and

memory coupled to the processor, comprising code for;

computing variance values σ

_p² for at least one of;

(a) a sequence of accelerometer measurements ({right arrow over (a)});

(b) a sequence of averages ({right arrow over (a)}_AVG) of accelerometer measurements;

(c) a sequence of gyroscope measurements ({right arrow over (ω

)});

(d) three sequences of scalar channelized gyroscope measurements (ω

_X, ω

_Y, ω

_Z); and

(e) a virtual gyroscope heading rate ({dot over ( H);

setting a flag if any of the variance values σ

_p² exceed a respective threshold; and

declaring the mobile device is not in a mounted state based on the flag.

33. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:

means for computing variance values σ

_p² for at least one of;

(a) a sequence of accelerometer measurements ({right arrow over (a)});

(b) a sequence of averages ({right arrow over (a)}_AVG) of accelerometer measurements;

(c) a sequence of gyroscope measurements ({right arrow over (ω

)});

(d) three sequences of scalar channelized gyroscope measurements (ω

_X, ω

_Y, ω

_Z); and

(e) a virtual gyroscope heading rate ({dot over ( H);

means for setting a flag if any of the variance values σ

_p² exceed a respective threshold; and

means for declaring the mobile device is not in a mounted state based on the flag.

34. A device comprising a processor and a memory wherein the memory includes software instructions for:

computing variance values σ

_p² for at least one of;

(a) a sequence of accelerometer measurements ({right arrow over (a)});

(b) a sequence of averages ({right arrow over (a)}_AVG) of accelerometer measurements;

(c) a sequence of gyroscope measurements ({right arrow over (ω

)});

(d) three sequences of scalar channelized gyroscope measurements (ω

_X, ω

_Y, ω

_Z); and

(e) a virtual gyroscope heading rate ({dot over ( H);

setting a flag if any of the variance values σ

_p² exceed a respective threshold; and

declaring the mobile device is not in a mounted state based on the flag.

35. A non-volatile computer-readable storage medium including program code stored thereon, comprising program code for:

computing variance values σ

_p² for at least one of;

(a) a sequence of accelerometer measurements ({right arrow over (a)});

(b) a sequence of averages ({right arrow over (a)}_AVG) of accelerometer measurements;

(c) a sequence of gyroscope measurements ({right arrow over (ω

)});

(d) three sequences of scalar channelized gyroscope measurements (ω

_X, ω

_Y, ω

_Z); and

(e) a virtual gyroscope heading rate ({dot over ( H);

setting a flag if any of the variance values σ

_p² exceed a respective threshold; and

declaring the mobile device is not in a mounted state based on the flag.