INERTIAL SENSOR AIDED HEADING AND POSITIONING FOR GNSS VEHICLE NAVIGATION

• US 20120173142A1
• 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, OPSHAUG, Guttorm Ringstad, CHHOKRA, Kumar Gaurav, BIACS, Zoltan Fenene, RILEY, Wyatt T.
• Granted Patent: US 9,816,818 B2
• Time in Patent Office: Days
• US Class Current: 701/501
• 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 for providing an improved heading, the method comprising:

receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

receiving a GNSS heading (H_GNSS) from a GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)}); and

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form the improved heading.

2. The method of claim 1, wherein computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) from a projection of the gyroscope measurement ({right arrow over (ω

)}) to the gravity vector ({right arrow over (g)}).

3. The method of claim 1, wherein combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) using a weighting factor.

4. A mobile device to provide an improved heading, the mobile device comprising:

an inertial measurement unit comprising an accelerometer and a gyroscope;

a Global Navigation Satellite Systems receiver (GNSS receiver);

a processor coupled to the inertial measurement unit and the GNSS receiver; and

memory coupled to the processor, comprising code for;

receiving an accelerometer measurement ({right arrow over (a)}) from the accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from the gyroscope;

receiving a GNSS heading (H_GNSS) from the GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)}); and

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form the improved heading.

5. The mobile device of claim 4, wherein computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) from a projection of the gyroscope measurement ({right arrow over (ω

)}) to the gravity vector ({right arrow over (g)}).

6. The mobile device of claim 4, wherein combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) using a weighting factor.

7. A mobile device to provide an improved heading, the mobile device comprising:

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

means for receiving a gyroscope measurement ({right arrow over (ω

)});

means for receiving a GNSS heading (H_GNSS);

means for computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

means for computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based a projection of the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)}); and

means for combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate

8. The mobile device of claim 7, wherein the means for computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises means for computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) from a projection of the gyroscope measurement ({right arrow over (ω

)}) to the gravity vector ({right arrow over (g)}).

9. The mobile device of claim 7, wherein the means for combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises means for combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) using a weighting factor.

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

receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

receiving a GNSS heading (H_GNSS) from a GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on a projection of the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)}); and

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form the improved heading.

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

receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

receiving a GNSS heading (H_GNSS) from a GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)}); and

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form the improved heading.

12. A method in a mobile device for providing an improved velocity, the method comprising:

receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

receiving a GNSS velocity ({right arrow over (V)}_GNSS) comprising a GNSS heading ({right arrow over (H)}_GNSS) from a GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on a projection of the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)});

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form an improved heading (Ĥ

); and

computing the improved velocity from the improved heading (Ĥ

).

13. The method of claim 12, wherein computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) comprises computing the virtual gyroscope heading rate ({dot over (H)}_Gyro) from a projection of the gyroscope measurement ({right arrow over (ω

)}) to the gravity vector ({right arrow over (g)}).

14. The method of claim 12, wherein combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form an improved heading (Ĥ

) comprises combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) using weighting factors.

15. The method of claim 12, further comprising:

computing a velocity ({right arrow over (V)}_GNSS-based) based on the GNSS velocity ({right arrow over (V)}_GNSS); and

projecting the velocity ({right arrow over (V)}_GNSS-based) on the improved heading (Ĥ

).

16. The method of claim 12, further comprising:

computing a GNSS velocity ({right arrow over (V)}_GNSS-KF) from the GNSS velocity ({right arrow over (V)}_GNSS) using a Kalman filter, wherein the velocity ({right arrow over (V)}_GNSS-based) is the GNSS velocity ({right arrow over (V)}_GNSS-KF); and

projecting the Kalman-filtered GNSS velocity ({right arrow over (V)}_GNSS-KF) on the improved heading (Ĥ

).

17. The method of claim 12, further comprising:

feeding an error signal, based a difference between the Kalman-filtered GNSS velocity ({right arrow over (V)}_GNSS-KF) and the GNSS velocity ({right arrow over (V)}_GNSS) to the Kalman filter as a correction signal.

18. A mobile device to provide an improved velocity, the mobile device comprising:

an inertial measurement unit comprising an accelerometer and a gyroscope;

a Global Navigation Satellite Systems receiver (GNSS receiver);

a processor coupled to the inertial measurement unit and the GNSS receiver; and

memory coupled to the processor, comprising code for;

receiving an accelerometer measurement ({right arrow over (a)}) from the accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from the gyroscope;

receiving a GNSS velocity ({right arrow over (V)}GNSS) comprising a GNSS heading ({right arrow over (H)}_GNSS) from the GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)});

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form an improved heading (Ĥ

); and

computing the improved velocity from the improved heading (Ĥ

).

19. A mobile device to provide an improved velocity, the mobile device comprising:

means for receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

means for receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

means for receiving a GNSS velocity ({right arrow over (V)}_GNSS) comprising a GNSS heading ({right arrow over (H)}_GNSS) from a GNSS receiver;

means for computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

means for computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)});

means for combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form an improved heading (Ĥ

); and

means for computing the improved velocity from the improved heading (Ĥ

).

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

receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

receiving a GNSS velocity ({right arrow over (V)}_GNSS) comprising a GNSS heading ({right arrow over (H)}_GNSS) from a GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)});

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form an improved heading (Ĥ

); and

computing an improved velocity from the improved heading (Ĥ

).

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

receiving an accelerometer measurement ({right arrow over (a)}) from an accelerometer;

receiving a gyroscope measurement ({right arrow over (ω

)}) from a gyroscope;

receiving a GNSS velocity ({right arrow over (V)}_GNSS) comprising a GNSS heading ({right arrow over (H)}_GNSS) from a GNSS receiver;

computing a gravity vector ({right arrow over (g)}) based on the accelerometer measurement ({right arrow over (a)});

computing a virtual gyroscope heading rate ({dot over (H)}_Gyro) based on the gyroscope measurement ({right arrow over (ω

)}) and the gravity vector ({right arrow over (g)});

combining the GNSS heading (H_GNSS) and virtual gyroscope heading rate ({dot over (H)}_Gyro) to form an improved heading (Ĥ

); and

computing an improved velocity from the improved heading (Ĥ

).