High bandwidth coriolis vibratory gyroscope (cvg) with in-situ bias self-calibration

Patent metadata

Field	Value
Publication number	US-2016202060-A1
Application number	US-201514594978-A
Country	US
Kind code	A1
Filing date	Jan 12, 2015
Priority date	Jan 12, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

Provided herein is a method for determining a bias-compensated inertial rotation rate of a Coriolis vibratory gyroscope (“CVG”). The method comprises determining an initial mode that the CVG is operating; obtaining average uncompensated inertial rotation rate measurements from a previous mode transition period; obtaining average uncompensated bias measurements from the previous mode transition period; determining a first transition between a AGC mode and a FTR mode of a given axis; calculating a first estimate of bias of the CVG based on the first transition that was determined and the average uncompensated bias measurements from the previous mode transition period; and calculating, by a processor, a first bias-compensated inertial rotation rate of the CVG based on the first bias that was calculated and the average uncompensated inertial rotation rate measurements from a previous mode transition period.

First claim

What is claimed is:

1 . A method for determining a bias-compensated inertial rotation rate of a Coriolis vibratory gyroscope (“CVG”), the method comprising:
determining an initial mode that the CVG is operating;
obtaining average uncompensated inertial rotation rate measurements from a previous mode transition period;
obtaining average uncompensated bias measurements from the previous mode transition period;
determining a first transition between an automatic gain control mode and a force-to-rebalance mode of a given axis;
calculating a first estimate of bias of the CVG based on the first transition that was determined and the average uncompensated bias measurements from the previous mode transition period; and
calculating, by a processor, a first bias-compensated inertial rotation rate of the CVG based on the first bias that was calculated and the average uncompensated inertial rotation rate measurements from a previous mode transition period.

2 . The method of claim 1 , further comprising:
determining a second transition between the automatic gain control mode and the force-to-rebalance mode of a given axis; calculating a second estimate of bias of the CVG based on the second transition that was determined and the average uncompensated bias measurements from the previous mode transition period; and calculating a second bias-compensated inertial rotation rate of the CVG based on the second bias that was calculated and the average uncompensated inertial rotation rate measurements from a previous mode transition period.

3 . The method of claim 1 , further comprising providing a signal to control transitions between the automatic gain control mode and the force-to-rebalance mode of a given axis.

4 . The method of claim 3 , wherein the signal is operable to switch a first actuator control signal and a second actuator control signal.

5 . The method of claim 1 , wherein the first bias is calculated based on one or more force-to-rebalance measurements from force-to-rebalance mode operating on a drive axis and on a sense axis.

6 . The method of claim 1 , wherein a result of the determining the first transition is a transition from the automatic gain control mode to the force-to-rebalance mode of a given axis, the method further comprises determining an updated estimate of bias by subtracting a new average bias from a last calculated average bias.

7 . The method of claim 1 , wherein a result of the determining the first transition is a transition from the force-to-rebalance mode to the automatic gain control mode of a given axis, the method further comprises determining an updated estimate of bias by subtracting a last calculated average bias from a new average bias.

8 . The method of claim 1 , wherein the determining an updated bias-compensated inertial rotation rate further comprises subtracting a biased inertial rotation rate from the first estimate of bias that was calculated for the automatic gain control mode.

9 . The method of claim 1 , wherein the determining an updated bias-compensated inertial rotation rate further comprises adding a biased inertial rotation rate to the first estimate of bias that was calculated for the force-to-rebalance mode.

10 . A Coriolis vibratory gyroscope (“CVG”) comprising:
a vibratory member;
a controller;
a first actuator electrically coupled to the vibratory member and arranged about a drive axis of the CVG and operable to obtain a control signal from the controller and provide a voltage sufficient to cause and maintain the vibratory member to vibrate in a first mode of oscillation;
a second actuator electrically coupled to the vibratory member and arranged about a sense axis of the CVG and operable to detect a voltage based on a second mode of oscillation of the vibratory member caused by a rotation of the CVG about an axis of rotation and to provide a counter-balancing signal sufficient to null the voltage based on the second mode of oscillation, wherein the sense axis is orthogonal to the drive axis in a modal reference frame,
wherein the controller is operable to perform a method comprising:
determining an initial mode that the CVG is operating;
obtaining average uncompensated inertial rotation rate measurements from a previous mode transition period;
obtaining average bias measurements from the previous mode transition period;
determining a first transition between an automatic gain control mode and a force-to-rebalance mode;
calculating a first estimate of bias of the CVG based on the first transition that was determined and the average bias measurements from the previous mode transition period; and
calculating, by a processor, a first bias-compensated inertial rotation rate of the CVG based on the first bias that was calculated and the average uncompensated inertial rotation rate measurements from a previous mode transition period.

11 . The CVG of claim 10 , wherein the controller is further operable to perform the method comprising:
determining a second transition between the automatic gain control mode and the force-to-rebalance mode of a given axis; calculating a second estimate of bias of the CVG based on the second transition that was determined and an average uncompensated bias measurements from the previous mode transition period; and calculating a second bias-compensated inertial rotation rate of the CVG based on the second bias that was calculated and the average uncompensated inertial rotation rate measurements from a previous mode transition period.

12 . The CVG of claim 10 , wherein the controller is further operable to perform the method, further comprising providing a signal to control transitions between the automatic gain control mode and the force-to-rebalance mode of a given axis.

13 . The CVG of claim 12 , wherein the signal is operable to switch the signal to control the transitions between the automatic gain control mode and the force-to-rebalance mode.

14 . The CVG of claim 10 , wherein the first bias is calculated based on one or more force-to-rebalance measurements from the force-to-rebalance mode operating on the drive axis and on the sense axis.

15 . The CVG of claim 10 , wherein a result of the determining the first transition is a transition from the automatic gain control mode to the force-to-rebalance mode of a given axis, the method further comprises determining an updated estimate of bias by subtracting a new average bias from a last calculated average bias.

16 . The CVG of claim 10 , wherein a result of the determining the first transition is a transition from the force-to-rebalance mode to the automatic gain control mode of a given axis, the method further comprises determining an updated estimate of bias by subtracting a last calculated average bias from a new average bias.

17 . The CVG of claim 10 , wherein the determining an updated bias-compensated inertial rotation rate further comprises subtracting a biased inertial rotation rate from the first estimate of bias that was calculated for the automatic gain control mode.

18 . The CVG of claim 10 , wherein the determining an updated bias-compensated inertial rotation rate further comprises adding a biased inertial rotation rate to the first estimate of bias that was calculated for the force-to-rebalance mode.

Assignees

• Boeing Co

Inventors

• Liu John Y

Classifications

• G01C19/5719

  using planar vibrating masses driven in a translation vibration along an axis · CPC title

• G01C19/5726

  Signal processing · CPC title

• G01C19/5776 Primary

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title

• G01C25/005

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

• G01C19/5705 Primary

  using masses driven in reciprocating rotary motion about an axis · CPC title