Method for calibrating gyro sensor on basis of vehicle speed

Patent metadata

Field	Value
Publication number	US-11454515-B2
Application number	US-201716626848-A
Country	US
Kind code	B2
Filing date	Dec 26, 2017
Priority date	Jun 30, 2017
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

The present disclosure relates to a gyro sensor calibration method based on vehicle velocity, which can extract a weighting factor in consideration of vehicle velocity, apply the extracted weighting factor to an extended Kalman filter, and accurately calibrate a gyro sensor in real time, in order to prevent accumulation of scale factor calibration errors, which may occurs as a turning radius is changed depending on vehicle velocity in a turning section, when a GNSS-based dead reckoning (DR) system calibrates a scale factor of the gyro sensor through the extended Kalman filter using GNSS information received in the turning section.

First claim

What is claimed is:

1. A gyro sensor calibration method based on vehicle velocity, the method comprising:
an initial calibration step in which control logic of a dead reckoning (DR) system performs initial calibration;
a weighting factor extraction step in which the control logic extracts a weighting factor based on a relationship between turning velocity of a vehicle and scale factors, wherein the scale factors are stored in a database;
a scale factor update step in which the control logic updates a gyro sensor scale factor of a gyro sensor among the scale factors, using the weighting factor, when the turning velocity of the vehicle is equal to or more than a first threshold value; and
a gyro sensor calibration step in which the control logic calibrates the gyro sensor using the updated gyro sensor scale factor of the gyro sensor,
wherein when the turning velocity of the vehicle is less than the first threshold value, the control logic calibrates the gyro sensor using a previously stored gyro sensor scale factor.

2. The gyro sensor calibration method of claim 1 , further comprising a weight value application step in which the control logic applies the extracted weighting factor to an extended Kalman filter,
wherein in the scale factor update step, the control logic updates the gyro sensor scale factor of the gyro sensor using the weighting factor applied to the extended Kalman filter.

3. The gyro sensor calibration method of claim 1 , wherein in the initial calibration step, the control logic calculates an average value of gyro sensor scale factors, and stores a relationship between the gyro sensor scale factors and the turning velocity of the vehicle in a database.

4. The gyro sensor calibration method of claim 3 , wherein the initial calibration step comprises:
determining whether Global Navigation Satellite System (GNSS) reliability, the turning velocity of the vehicle and a turning angle are equal to or more than a second threshold value, respectively;
calculating and storing the gyro sensor scale factor when the GNSS reliability, the turning velocity of the vehicle and the turning angle are equal to or more than the second threshold values, respectively;
determining whether a number of the stored scale factors is equal to or more than a predetermined value; and
calculating the average value of the gyro sensor scale factors when the number of the stored scale factors is equal to or more than the predetermined value.

5. The gyro sensor calibration method of claim 4 , wherein the initial calibration step further comprises changing the second threshold value of the turning velocity of the vehicle to repeat calibration, when the number of the stored scale factors is less than the predetermined value.

6. The gyro sensor calibration method of claim 4 , wherein the GNSS reliability is determined through National Marine Electronics Association (NMEA) protocol information including a number of satellites, a signal-to-noise ratio of a satellite signal, a horizontal/vertical/position precision reduction rate, and a horizontal position error.

7. The gyro sensor calibration method of claim 4 , wherein when extracting the weighting factor, the control logic calculates an increase ratio between the gyro sensor scale factors corresponding to a maximum value and a minimum value of the turning velocity of the vehicle based on the relationship between the scale factors and the turning velocity of the vehicle, and extracts the weighting factor corresponding to the turning velocity of the vehicle based on the increase ratio.

8. The gyro sensor calibration method of claim 4 , wherein when the number of the stored scale factors is less than the predetermined value, the control logic changes the first threshold value of the turning velocity of the vehicle to repeat calibration.

9. The gyro sensor calibration method of claim 2 , wherein the extended Kalman filter calibrates the position information of the vehicle and the gyro sensor using Global Navigation Satellite System (GNSS) reliability information, a gyro sensor output value and weighting factor information.

10. The gyro sensor calibration method of claim 7 , wherein the control logic calibrates gyro sensor scale factors of the gyro sensor by applying a weighting factor obtained by subtracting the first threshold value from the turning velocity of the vehicle, as the weighting factor calculated through the gyro sensor scale factor corresponding to a minimum value of the turning velocity of the vehicle and the gyro sensor scale factor corresponding to a maximum value of the turning velocity of the vehicle.

11. A dead reckoning (DR) system comprising:
a gyro sensor; and
control logic configured to calibrate the gyro sensor based on velocity of a vehicle,
wherein the control logic performs initial calibration, extracts a weighting factor based on a relationship between turning velocity of the vehicle and scale factors, the scale factors being stored in a database, updates a gyro sensor scale factor of the gyro sensor, among the scale factors, using the weighting factor when the turning velocity of the vehicle is equal to or more than a first threshold value, and calibrates the gyro sensor using the updated gyro sensor scale factor of the gyro sensor,
wherein when the turning velocity of the vehicle is less than the first threshold value, the control logic calibrates the gyro sensor using a previously stored gyro sensor scale factor.

12. The DR system of claim 11 , wherein the control logic applies the extracted weighting factor to an extended Kalman filter, and updates the gyro sensor scale factor of the gyro sensor using the weighting factor applied to the extended Kalman filter.

13. The DR system of claim 11 , wherein when performing the initial calibration, the control logic calculates an average value of gyro sensor scale factors, and stores a relationship between gyro sensor scale factors and the turning velocity of the vehicle in a database.

14. The DR system of claim 13 , wherein when performing the initial calibration, the control logic calculates and stores the gyro sensor scale factor when Global Navigation Satellite System (GNSS) reliability, the turning velocity of the vehicle and a turning angle are equal to or more than a second threshold value, respectively, determines whether a number of the stored scale factors is equal to or more than a predetermined value, and calculates an average value of the gyro sensor scale factors when the number of the stored scale factors is equal to or more than the predetermined value.

15. The DR system of claim 14 , wherein the GNSS reliability is determined through National Marine Electronics Association (NMEA) protocol information including a number of satellites, a signal-to-noise ratio of a satellite signal, a horizontal/vertical/position precision reduction rate, and a horizontal position error.

16. The DR system of claim 14 , wherein when extracting the weighting factor, the control logic calculates an increase ratio between the gyro sensor scale factors corresponding to a maximum value and a minimum value of the turning velocity of the vehicle based on the relationship between the scale factors and the turning velocity of the vehicle, and extracts the weighting factor corresponding to the turning velocity of the vehicle based on the increase ratio.

17. The DR system of claim 14 , wherein when the number of the stored scale factors is less than the predetermined value, the control logic changes the second threshold value of the turning velocity of the vehicle to repeat calibration.

Assignees

• Hyundai Autoever Corp

Inventors

• Seo Myung Hwan
• Min Jeong Dong

Classifications

• G01C25/005 Primary

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

• G01S19/01

  Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO · CPC title

• G01C19/00

  Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects · CPC title

• G01S19/396

  Determining accuracy or reliability of position or pseudorange measurements · CPC title

• G01C21/188

  for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems · CPC title