Control for vibratory gyroscope

• US 5,383,362 A
• Filed: 02/01/1993
• Issued: 01/24/1995
• Est. Priority Date: 02/01/1993
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Putty, Michael W., Eddy, David S.
• Primary Examiner(s): Goldstein, Herbert
• Assistant Examiner(s): FELBER, JOSEPH LEON
• Application Number:
  US08/011,554
• Time in Patent Office: 722 Days
• Field of Search: 73/505, 73/504
• US Class Current: 73/504.01
• CPC Class Codes: G01C 19/5677 of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
• CPC Class Codes: G01C 19/5691 of essentially three-dimensional vibrators, e.g. wine glass-type vibrators

Abstract

A control circuit for a resonating rotation sensor has a pair of closed loop controls for independently controlling component traveling waves of a resonant pattern in a ring shaped resonant member. Frequency and phase quantities of the independent traveling waves as well as time dependant quantities thereof indicate total rotation angle, rotation raze and rotation direction.

Claims

1. A control for a vibratory gyroscope having a vibratory member defining a substantially circular portion capable of supporting high-Q radial vibration in a standing wave pattern about an axis comprising, in combination:

dual oscillator means for radially displacing said circular portion along at least two radii thereof separated by a first predetermined angle to establish and maintain a pair of countercirculating resonant traveling waves;

discriminating means for establishing from the direction and magnitude of radial displacements of said circular portion along at least two radii thereof separated by a second predetermined angle a respective phase difference for each countercirculating traveling wave relative to a respective dual oscillator reference wave; and

means for controlling each respective phase difference to a third predetermined angle, whereby the frequency difference between the respective dual oscillator reference waves is a measure of the rotation rate and the phase difference therebetween is a measure of the total angle of rotation.

2. A control for a vibratory gyroscope having a vibratory member defining a substantially circular portion capable of supporting high-Q radial vibration in a standing wave pattern about an axis comprising, in combination:

dual oscillator means for radially displacing said circular portion along at least two radii thereof separated by a first predetermined angle to establish and maintain a pair of countercirculating resonant traveling waves;

discriminating means for establishing from the direction and magnitude of radial displacements of said circular portion along at least two radii thereof separated by a second predetermined angle a respective phase difference for each countercirculating traveling wave relative to a respective dual oscillator reference wave; and

a pair of phase locked loops for closed loop controlling the phase difference between each countercirculating traveling wave and its respective dual oscillator reference wave, whereby the frequency difference between the respective dual oscillator reference waves is a measure of the rotation rate and the phase difference therebetween is a measure of the total angle of rotation.

3. A control as claimed in claim 2 wherein each of said countercirculating resonant traveling waves comprises a fundamental resonant traveling wave.

4. A control as claimed in claim 2 wherein said dual oscillator means comprises a plurality of capacitive forcers, each of the forcers being positioned adjacent said circular portion along one of said radii.

5. A control as claimed in claim 2 wherein said discriminating means comprises a plurality of capacitive pickoffs, each of the pickoffs being positioned adjacent said circular portion along one of said radii.

6. A control as claimed in claim 2 wherein the predetermined angles separating the radii correspond to one-quarter wavelength of the traveling wave.

7. A control for a vibratory gyroscope having a vibratory member defining a substantially circular waveguide capable of supporting high-Q radial vibration in a standing wave pattern about an axis comprising, in combination:

a unidirectional driver for generating a reference signal effective to excite a resonant traveling wave in said circular waveguide;

a unidirectional receiver responsive to the traveling wave and effective to produce a pair of resonant traveling wave phase components;

means responsive to said resonant traveling wave phase components and said reference signal phase components for producing a phase error signal; and

a phase locked loop responsive to said phase error signal for regulating said reference signal by forcing said phase error signal to zero to thereby keep the phase of the reference signal locked to the phase of the resonant traveling wave.

8. A control for a vibratory gyroscope having a vibratory member defining a substantially circular portion capable of supporting high-Q radial vibration in a standing wave pattern about an axis comprising, in combination:

pick-off means responsive to radial motion at two positions adjacent said circular portion separated by a predetermined angle for producing first and second pick-off signals equal to the summation of equal wavelength clockwise and counterclockwise resonant traveling waves at each respective pick-off means;

means for generating first and second reference signals;

clockwise separating means responsive to said first and second pick-off signals and phase relatives of said first reference signal for producing a clockwise error signal proportional to the phase difference between the clockwise resonant traveling wave and said first reference signal;

counterclockwise separating means responsive to said first and second pick-off signals and phase relatives of said second reference signal for producing a counterclockwise error signal proportional to the phase difference between the counterclockwise resonant traveling wave and said second reference signal;

a phase locked loop responsive to said clockwise error signal for locking the phase of the first reference signal to the phase of the clockwise resonant traveling wave; and

a phase locked loop responsive to said counterclockwise error signal for locking the phase of the second reference signal to the phase of the counterclockwise resonant traveling wave.

9. A control for a vibratory gyroscope having a vibratory member defining a substantially circular portion capable of supporting high-Q radial vibration in a standing wave pattern about an axis comprising, in combination:

an electro-mechanical clockwise traveling wave loop for

a) launching a clockwise resonant traveling wave in said circular portion, said wave having a wavelength of one-half the circumference of said circular portion and a unit amplitude,

b) maintaining the unit amplitude of the clockwise resonant traveling wave with a predetermined phase relative of a clockwise reference signal,

c) tracking the frequency of the clockwise resonant traveling wave,

d) tracking the phase of the clockwise resonant traveling wave relative to a predetermined phase relative of the reference signal;

an electro-mechanical counterclockwise traveling wave loop for

a) launching a counterclockwise resonant traveling wave in said circular portion, said wave having a wavelength of one-half the circumference of said circular portion and the unit amplitude,

b) maintaining the unit amplitude of the counterclockwise resonant traveling wave with a predetermined phase relative of a counterclockwise reference signal,

c) tracking the frequency of the counterclockwise resonant traveling wave,

d) tracking the phase of the counterclockwise resonant traveling wave relative to a predetermined phase relative of the counterclockwise reference signal,

whereby the frequency difference between the respective reference signals is a measure of the rotation rate and the phase difference between the respective reference signals is a measure of the total angle of rotation.

10. A method for controlling a vibratory gyroscope having a vibratory member defining a substantially circular portion capable of supporting high-Q radial vibration in a standing wave pattern about an axis comprising the steps of:

a) launching a clockwise resonant traveling wave in said circular portion, said wave having a wavelength of one-half the circumference of said circular portion and a unit amplitude;

b) maintaining the unit amplitude of the clockwise resonant traveling wave with a predetermined phase relative of a clockwise reference signal;

c) tracking the frequency of the clockwise resonant traveling wave;

d) tracking the phase of the clockwise resonant traveling wave relative to a predetermined phase relative of the reference signal;

e) launching a counterclockwise resonant traveling wave in said circular portion, said wave having a wavelength of one-half the circumference of said circular portion and the unit amplitude;

f) maintaining the unit amplitude of the counterclockwise resonant traveling wave with a predetermined phase relative of a counterclockwise reference signal;

g) tracking the frequency of the counterclockwise resonant traveling wave; and

h) tracking the phase of the counterclockwise resonant traveling wave relative to a predetermined phase relative of the counterclockwise reference signal.