Electronic Bias Compensation for a Gyroscope

• US 20130179105A1
• Filed: 01/11/2012
• Published: 07/11/2013
• Est. Priority Date: 01/11/2012
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Liu, Yong, Challoner, Anthony Dorian
• Granted Patent: US 9,417,066 B2
• Time in Patent Office: Days
• US Class Current: 702/87
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

A method for compensating for bias of a gyroscope. In one embodiment, bias measurements for a plurality of drive angles are generated using the gyroscope. A set of equations for the bias of the gyroscope is identified using a model for motion of the gyroscope. The set of equations includes a set of parameters for the bias of the gyroscope. A set of values for the set of parameters is identified using the bias measurements and the set of equations.

Claims

1. A method for compensating for bias of a gyroscope, the method comprising:

generating bias measurements for a plurality of drive angles using the gyroscope;

identifying a set of equations for the bias of the gyroscope using a model for motion of the gyroscope in which the set of equations includes a set of parameters for the bias of the gyroscope; and

identifying a set of values for the set of parameters using the bias measurements and the set of equations.

2. The method of claim 1, wherein the step of identifying the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope comprises:

identifying the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope and an assumption that an inertial rate for the gyroscope is substantially zero.

3. The method of claim 1 further comprising:

estimating the bias of the gyroscope at a selected drive angle using the set of equations with the set of values for the set of parameters to form an estimated bias.

4. The method of claim 3 further comprising:

subtracting the estimated bias from a measurement generated by the gyroscope for the selected drive angle to substantially compensate for the bias of the gyroscope.

5. The method of claim 2, wherein the step of identifying the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero comprises:

identifying the model for the motion of the gyroscope;

modifying the model for the motion of the gyroscope based on the assumption that the inertial rate for the gyroscope is substantially zero to form a modified model; and

identifying the set of equations for the bias of the gyroscope using the modified model for the motion of the gyroscope.

6. The method of claim 2, wherein the step of identifying the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero comprises:

identifying a first equation in the set of equations for an in-phase bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero; and

identifying a second equation in the set of equations for an in-quadrature bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero.

7. The method of claim 6 further comprising:

identifying a drive angle that reduces the in-quadrature bias of the gyroscope to substantially zero using the set of equations; and

operating the gyroscope at the drive angle identified.

8. The method of claim 1, wherein the step of generating the bias measurements for the plurality of drive angles using the gyroscope comprises:

generating the bias measurements for the plurality of drive angles using the gyroscope, wherein the plurality of drive angles includes angles selected from a range between about 0 degrees and about 360 degrees with respect to a first axis.

9. The method of claim 1, wherein the step of identifying the set of values for the set of parameters using the bias measurements and the set of equations comprises:

identifying the set of values for the set of parameters using the bias measurements, the set of equations, and an iterative algorithm, wherein the set of parameters includes at least one of a drive axis misalignment angle, a sense axis misalignment angle, a damping azimuth angle, a damping asymmetry term, a difference between natural frequencies of a drive axis for the gyroscope and a sense axis for the gyroscope, and an azimuth angle of the drive axis with respect to a first axis.

10. The method of claim 1, wherein the gyroscope is a Coriolis vibratory gyroscope.

11. An apparatus comprising:

a compensation system configured to;

receive bias measurements for a plurality of drive angles from a gyroscope;

identify a set of equations for the bias of the gyroscope using a model for motion of the gyroscope in which the set of equations includes a set of parameters for the bias of the gyroscope; and

identify a set of values for the set of parameters using the bias measurements and the set of equations.

12. The apparatus of claim 11, wherein in being configured to identify the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope, the compensation system is configured to identify the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope and an assumption that an inertial rate for the gyroscope is substantially zero.

13. The apparatus of claim 11, wherein the compensation system is further configured to estimate the bias of the gyroscope at a selected drive angle using the set of equations with the set of values for the set of parameters to form an estimated bias.

14. The apparatus of claim 13, wherein the compensation system is further configured to subtract the estimated bias from a measurement generated by the gyroscope for the selected drive angle to substantially compensate for the bias of the gyroscope.

15. The apparatus of claim 12, wherein in being configured to identify the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero, the compensation system is configured to:

identify the model for the motion of the gyroscope;

modify the model for the motion of the gyroscope based on the assumption that the inertial rate for the gyroscope is substantially zero to form a modified model; and

identify the set of equations for the bias of the gyroscope using the modified model for the motion of the gyroscope.

16. The apparatus of claim 12, wherein in being configured to identify the set of equations for the bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero, the compensation system is configured to:

identify a first equation in the set of equations for an in-phase bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero; and

identify a second equation in the set of equations for an in-quadrature bias of the gyroscope using the model for the motion of the gyroscope and the assumption that the inertial rate for the gyroscope is substantially zero.

17. The apparatus of claim 11, wherein in being configured to receive the bias measurements for the plurality of drive angles from the gyroscope, the compensation system is configured to receive the bias measurements for the plurality of drive angles from the gyroscope, wherein the plurality of drive angles includes angles selected from a range between about 0 degrees and about 360 degrees with respect to a first axis.

18. The apparatus of claim 11, wherein in being configured to identify the set of values for the set of parameters using the bias measurements and the set of equations, the compensation system is configured to identify the set of values for the set of parameters using the bias measurements, the set of equations, and an iterative algorithm.

19. A method for electronically compensating for bias of a gyroscope, the method comprising:

generating bias measurements for a plurality of drive angles using the gyroscope;

identifying a set of equations for the bias of the gyroscope using a model for motion of the gyroscope and an assumption that an inertial rate for the gyroscope is substantially zero in which the set of equations includes a set of parameters for the bias of the gyroscope;

identifying a set of values for the set of parameters using the bias measurements and the set of equations;

estimating the bias of the gyroscope at a selected drive angle using the set of equations with the set of values for the set of parameters to form an estimated bias; and

subtracting the estimated bias from a measurement generated by the gyroscope for the selected drive angle to substantially compensate for the bias of the gyroscope.

20. The method of claim 19, wherein the gyroscope is a Coriolis vibratory gyroscope.