Inertial sensor aided heading and positioning for GNSS vehicle navigation

Patent metadata

Field	Value
Publication number	US-9803983-B2
Application number	US-201113309519-A
Country	US
Kind code	B2
Filing date	Dec 1, 2011
Priority date	Dec 3, 2010
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

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.

First claim

What is claimed is:

1. A method in a mobile device to detect if the mobile device is unmounted, the method comprising:
receiving, in the mobile device, accelerometer measurements;
determining, by the mobile device, an average of the accelerometer measurements;
computing a parameter based on the accelerometer measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring, by the mobile device, the mobile device is unmounted based on the variance being greater than the threshold.

2. The method of claim 1 , wherein the parameter comprise an angle between the accelerometer measurements and the average, and the variance comprises a variance of the angle.

3. The method of claim 1 , wherein the parameter comprise a magnitude of the accelerometer measurements, and wherein the variance comprises a variance comprising a variance of the magnitude ∥{right arrow over (a)}∥ from a magnitude of the average.

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;
determining an average of the accelerometer measurements;
computing a parameter based on the accelerometer measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring the mobile device is unmounted based on the variance being greater than the threshold.

5. The mobile device of claim 4 , wherein the parameter comprise an angle between the accelerometer measurements and the average, and the variance comprises a variance of the angle.

6. The mobile device of claim 4 , wherein the parameter comprise a magnitude of the accelerometer measurements, and wherein the variance comprises a variance comprising a variance of the magnitude from a magnitude of the average.

7. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:
means for receiving accelerometer measurements;
means for determining an average of the accelerometer measurements;
means for computing a parameter based on the accelerometer measurements and the average;
means for computing a variance of the parameter;
means for comparing the variance to a threshold; and
means for declaring the mobile device is unmounted based on the variance being greater than the threshold.

8. The mobile device of claim 7 , wherein the parameter comprise an angle between the accelerometer measurements and the average, and the variance comprises a variance of the angle.

9. The mobile device of claim 7 , wherein the parameter comprise a magnitude of the accelerometer measurements, and wherein the variance comprises a variance of the magnitude from a magnitude of the average.

10. A mobile device comprising a processor and a memory wherein the memory includes software instructions for:
receiving accelerometer measurements;
determining an average of the accelerometer measurements;
computing a parameter based on the accelerometer measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring the mobile device is unmounted based on the variance being greater than the threshold.

11. A non-transitory computer-readable storage medium including program code stored thereon, comprising program code for a mobile device for:
receiving accelerometer measurements;
determining an average of the accelerometer measurements;
computing a parameter based on the accelerometer measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring the mobile device is unmounted based on the variance being greater than the threshold.

12. A method in a mobile device to detect if the mobile device is unmounted, the method comprising:
receiving, in the mobile device, gyroscope measurements;
determining, by the mobile device, an average of the gyroscope measurements;
computing a parameter based on the gyroscope measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring, by the mobile device, the mobile device is unmounted based on the variance being greater than the threshold.

13. The method of claim 12 , wherein the parameter comprise an angle between the gyroscope measurements and the average, and the variance comprises a variance of the angle.

14. The method of claim 12 , wherein the parameter comprise a magnitude of the gyroscope measurements, and wherein the variance comprises a variance of the magnitude from a magnitude of the average.

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;
determining an average of the gyroscope measurements;
computing a parameter based on the gyroscope measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring the mobile device is unmounted based on the variance being greater than the threshold.

16. The mobile device of claim 15 , wherein the parameter comprise an angle between the gyroscope measurements and the average, and the variance comprises a variance of the angle.

17. The mobile device of claim 15 , wherein the parameter comprise a magnitude of the gyroscope measurements, and wherein the variance comprises a variance comprising a variance of the magnitude from a magnitude of the average.

18. A mobile device to detect if the mobile device is unmounted, the mobile device comprising:
means for receiving gyroscope measurements;
means for determining an average of the gyroscope measurements;
means for computing a parameter based on the gyroscope measurements and the average;
means for computing a variance of the parameter;
means for comparing the variance to a threshold; and
means for declaring the mobile device is unmounted based on the variance being greater than the threshold.

19. The mobile device of claim 18 , wherein the parameter comprise an angle between the gyroscope measurements and the average, and the variance comprises a variance of the angle.

20. The mobile device of claim 18 , wherein the parameter comprise a magnitude of the gyroscope measurements, and wherein the variance comprises a variance comprising a variance of the magnitude from a magnitude of the average.

21. A mobile device comprising a processor and a memory wherein the memory includes software instructions for:
receiving gyroscope measurements;
determining an average of the gyroscope measurements;
computing a parameter based on the gyroscope measurements and the average;
computing a variance of the parameter;
comparing the variance to a threshold; and
declaring the mobile device is unmounted based on the variance being greater than the threshold.

22. A non-transitory computer-readable storage medium including program code stored thereon, comprising program code for a mobile device for:
receiving gyroscope measurements;
determining an average of the gyroscope measurements;
computing a parameter based on the gyroscope measurements and the average;
comput

Assignees

• Czompo Joseph
• Joshi Ashutosh
• Namburi Shanta Pavan
• Ahuja Disha
• Qualcomm Inc

Inventors

• Czompo Joseph
• Joshi Ashutosh
• Namburi Shanta Pavan
• Ahuja Disha

Classifications

• G01S19/393

  Trajectory determination or predictive tracking, e.g. Kalman filtering · CPC title

• G01S19/47

  the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial · CPC title

• G01S19/52

  Determining velocity · CPC title

• G01S19/14

  specially adapted for specific applications · CPC title

• G01C25/005

  initial alignment, calibration or starting-up of inertial devices · CPC title