Vibrating inertial rate sensor utilizing skewed drive or sense elements

• US 20070240508A1
• Filed: 12/18/2006
• Published: 10/18/2007
• Est. Priority Date: 04/18/2006
• Status: Active Grant

• Current Assignee: Watson Industries, Inc.
• Original Assignee: Watson Industries, Inc.
• Inventors: Watson, William
• Granted Patent: US 7,526,957 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5691 of essentially three-dimensional vibrators, e.g. wine glass-type vibrators

Abstract

A vibrating inertial rate sensor has sense elements that operate on axes that are rotationally skewed from a node reference axis, enabling both a rate sense and a drive sense determination. Alternatively, the skew may be applied to rotationally offset the drive elements from antinode reference axes to affect active torquing of the gyroscope. The skewed sensing scheme may be applied to vibratory systems having one or more node axes. The skewed drive scheme may be applied to vibratory systems having two or more node axes to affect active torquing.

Claims

1. An inertial sensor for sensing a rate of angular rotation, comprising:

a vibratory resonator comprising an axisymmetric body having a central axis;

means for generating an oscillation pattern on said vibratory resonator, said oscillation pattern having a plurality of diametrically opposed nodes and diametrically opposed antinodes that define a plurality of reference axes;

a plurality of operational element pairs operatively coupled to said axisymmetric body, each of said operational element pairs being centered in diametric opposition to define an operational element axis corresponding to the respective operational element pair such that a first skewed operational element axis is characterized by a first rotational offset relative to a first of said plurality of reference axes, said first skewed operational element axis not being coincident with any of said plurality of reference axes, and a second skewed operational element axis is characterized by a second rotational offset from a second of said plurality of reference axes, said second rotational offset being of substantially equal magnitude with and in a direction opposite from said first rotational offset.

2. The inertial sensor of claim 1 wherein said plurality of operational element pairs are in physical contact with a surface of said axisymmetric body.

3. The inertial sensor of claim 2 wherein said physical contact comprises a bonding or gluing.

4. The inertial sensor of claim 1 wherein said first skewed operational element pair and said second skewed operational element pair are sense elements.

5. The inertial sensor of claim 1 wherein said plurality of reference axes define a substantially uniform angular displacement between adjacent reference axes of said plurality of reference axes and said first rotational offset is less than half of said substantially uniform angular displacement.

6-8. -8. (canceled)

9. An inertial sensor for sensing a rate of angular rotation, comprising:

a first vibrating member driven into oscillation along a first drive vector;

a first sense element operatively coupled to said first vibrating member and sensing a first response vector;

said first response vector having a first drive component proportional to said first drive vector and a first rotation rate component proportional to said rate of angular rotation;

a second vibrating member driven into oscillation along a second drive vector;

said second drive vector being substantially parallel with said first drive vector; and

a second sense element operatively coupled to said second vibrating member and sensing a second response vector,

said second response vector having a second drive component proportional to said second drive vector and a second rotation rate component proportional to said rate of angular rotation,

said second drive component having a magnitude substantially equal to said first drive component,

said second drive component having a direction substantially opposite to said first drive component.

10. The inertial sensor of claim 9 wherein said first drive vector and said second drive vector act substantially along a common axis.

11. An inertial sensor for sensing a rate of angular rotation, comprising:

a resonant body having a centerline; and

a plurality of drive element pairs that drive an oscillation pattern on said resonant body, said drive elements being rotationally offset with respect to a uniform angular distribution about said centerline, said drive elements operable to torque said oscillation pattern about said centerline.

12. A method of measuring the drive oscillation and the rotation rate of a vibrating gyroscope comprising:

selecting a vibrating gyroscope comprising;

a first sensing element configured to sense a first vibration vector having a first drive oscillation component and a first rotational rate component;

a second sensing element configured to sense a second vibration vector having a second drive oscillation component and a second rotational rate component,

said second drive oscillation component being of substantially equal magnitude with and in a direction opposite to said first drive oscillation component;

obtaining a first signal from said first sensing element and a second signal from said second sensing element;

subtracting said second signal from said first signal to determine a rotation rate of said vibrating gyroscope; and

adding said first signal to said second signal to determine the magnitude of a drive oscillation.

13. A method of rotating a drive oscillation pattern on an axisymmetric resonant body comprising:

selecting a vibrating gyroscope comprising;

an resonant body axisymmetric about a central axis;

a first drive element pair in diametric opposition about said central axis and configured to drive a first vibration pattern on said resonant body, said first vibration pattern capable of being driven by a first input signal;

a second drive element pair in diametric opposition about said central axis and configured to drive a second vibration pattern on said resonant body, said second vibration pattern capable of being driven by a second input signal, wherein said second nodal distribution is rotationally offset from said first nodal distribution; and

applying said first input signal to said first drive element pair and a second input signal to said second drive element pair to produce a combined vibration pattern having a third nodal distribution.

14. The method of claim 13 further comprising:

inferring an orientation of said third nodal distribution;

adjusting either of said first signal and said second signal to rotate said third nodal distribution.

15. The method of claim 13 further comprising:

determining a gain ratio of said first signal to said second signal;

adjusting said gain ratio to rotate said third nodal distribution.