Vibrating inertial rate sensor utilizing skewed drive or sense elements

• US 7,526,957 B2
• Filed: 12/18/2006
• Issued: 05/05/2009
• Est. Priority Date: 04/18/2006
• Status: Expired due to Fees

• Current Assignee: Watson Industries, Inc.
• Original Assignee: Watson Industries, Inc.
• Inventors: Watson, William S.
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US11/640,823
• Publication Number:
  US 20070240508A1
• Time in Patent Office: 869 Days
• Field of Search: 735/040.4, 735/041.2, 735/041.3, 735/041.4, 735/041.5, 735/041.6, 735/040.2, 73/13.7, 73/13.8
• US Class Current: 73/504.13
• 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 a plurality of operational element axes, each corresponding to a respective one of said operational element pairs such that a first of said plurality of operational element axes is characterized by a first rotational offset relative to a first of said plurality of reference axes, said first of said operational element axes not being in rotational alignment about said central axis with any of said plurality of reference axes, and such that a second of said plurality operational element axes is characterized by a second rotational offset relative to a second of said plurality of reference axes, said second of said plurality of operational element axes not being in rotational alignment about said central axis with any of said plurality of reference axes, said second rotational offset being of substantially equal magnitude with and in a rotational 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 a first of said plurality of operational element pairs and a second of said plurality of operational element pairs 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 wherein said first rotational offset is less than half of said substantially uniform angular displacement.

6. 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 to sense a first response vector;

said first response vector having a first drive component and a first rotation rate component, said first sense element being oriented to sense said first drive component and said first rotation rate component of said first response vector, said first drive component being of a first fixed proportion to said first drive vector for resolution of said first drive vector, said first rotation rate component being 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 to sense a second response vector, said second response vector having a second drive component and a second rotation rate component, said second sense element being oriented to sense said second drive component and said second rotation rate component of said second response vector, said second drive component being of a second fixed proportion to said second drive vector for resolution of said second drive vector, said second rotation rate component being proportional to said rate of angular rotation, said second drive component having a direction substantially opposite to said first drive component.

7. The inertial sensor of claim 6 wherein said first drive vector and said second drive vector act substantially along a common axis.

13. The inertial sensor of claim 6, wherein said first fixed proportion and said second fixed proportion are substantially equal.

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

a resonant body having a centerline; and

a plurality of drive element pairs for generation of an oscillation pattern on said resonant body, each of said plurality of drive element pairs being centered in diametric opposition about said centerline, said plurality of drive element pairs being non-uniformly distributed about said centerline, said drive element pairs being operable to torque said oscillation pattern about said centerline.

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

providing the vibrating gyroscope comprising

a first sensing element oriented at a first fixed skew angle relative to a first node reference axis to sense a first vibration vector having a first drive oscillation component and a first rotational rate component, and

a second sensing element oriented at a second fixed skew angle relative to a second node reference axis to sense a second vibration vector having a second drive oscillation component and a second rotational rate component, said second drive oscillation component being in a direction substantially opposite 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.

14. The method of claim 9 wherein said vibrating gyroscope provided in said step of providing is a tuning fork type gyroscope.

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

providing a vibrating gyroscope comprising;

a 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 having a first nodal distribution 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 having a second nodal distribution 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 at a fixed angle relative to said first nodal distribution; and

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

11. The method of claim 10 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.

12. The method of claim 10 further comprising:

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

adjusting said gain ratio to rotate said third nodal distribution.