High Q angular rate sensing gyroscope

• US 6,272,925 B1
• Filed: 09/16/1999
• Issued: 08/14/2001
• Est. Priority Date: 09/16/1999
• Status: Expired due to Term

• Current Assignee: William S. Watson
• Original Assignee: William S. Watson
• Inventors: Watson, William S.
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/397,718
• Time in Patent Office: 698 Days
• Field of Search: 735/040.2, 735/041.2, 735/041.3, 735/041.4
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams
• CPC Class Codes: G01C 19/567 using the phase shift of a vibration node or antinode
• CPC Class Codes: G01C 19/5677 of essentially two-dimensional vibrators, e.g. ring-shaped vibrators

Abstract

A structure and arrangement for improving the accuracy and efficiency of an angular rate sensing gyroscope is herein disclosed. Voltage pick-off conductors are applied to an area of the surface of a resonating element of an angular rate sensing gyroscope that is subject to substantially zero stress when the gyroscope is rotationally stationary. Actuator conductors are similarly applied to a resonating element at a location bounded by areas of the resonating element subject to substantially uniform levels of stress when the gyroscope is rotationally stationary. A method for improving the voltage response of a piezoelectric resonating element is also disclosed.

Claims

1. An oscillating gyroscope comprising:

a) a resonating element arranged and constructed to output voltage signals proportional to a level of stress induced therein;

b) means for imposing a predetermined mode of oscillation upon said resonating element;

c) a voltage pick-off conductor applied to the surface of said resonating element, said pick-off being arranged and constructed to sense stress-induced voltage signals outputted by said resonating element, said sensed voltage signals being indicative of a rate of rotation of said gyroscope, said pick-off being applied to an area of the surface of said resonating element that is subject to substantially zero stress when said gyroscope is rotationally stationary; and

d) means for processing said sensed voltage signals.

2. The gyroscope of claim 1 wherein said resonating element comprises one of a cylinder, a ring, and a bar.

3. The gyroscope of claim 1 wherein said resonating element comprises:

a) a triangular prism having three longitudinal sides, each longitudinal side having applied thereto a conductive element.

4. The gyroscope of claim 3 wherein two of said conductive elements are pick-off conductors.

5. The gyroscope of claim 1 wherein the means for imposing a predetermined mode of oscillation upon said resonating element comprises:

a) an actuator conductor applied to said resonating element at a predetermined location upon the surface of said resonating element, said actuator conductor arranged and constructed to apply a voltage signal to said resonating element at said predetermined location, said predetermined location of said resonating element being defined by boundaries that are congruent with areas of said resonating element that are subject to substantially uniform levels of stress when said gyroscope is rotationally stationary; and

b) a drive circuit constructed and arranged to apply a predetermined sequence of voltage signals to said resonating element through said actuator so as to impose a predetermined mode of oscillation upon said resonating element.

6. The oscillating gyroscope of claim 5 wherein said actuator conductor comprises two vertically symmetrical halves that are electrically isolated from one another and which are independently electrically connected to said drive circuit.

7. The gyroscope of claim 5 wherein said predetermined mode of oscillation of said resonating element is defined by a plurality of stable nodes and anti-nodes.

8. The gyroscope of claim 7 wherein said actuator is applied to the surface of said resonating element substantially at an anti-node and said pick-off is applied substantially at a node.

9. The gyroscope of claim 8 wherein said resonating element is an axi-symmetric shell and is fashioned from a piezoelectric material.

10. The gyroscope of claim 9 wherein said shell is of curvilinear shape.

11. The gyroscope of claim 1 wherein a voltage balancing conductor is applied to a predetermined area of said resonating element and in conductive communication with said pick-off conductor, said balancing conductor being arranged and constructed to zero net voltage signals sensed by said voltage pick-off conductor when said resonating element is rotationally stationary.

12. The gyroscope of claim 1 wherein the means for imposing a predetermined mode of oscillation upon said resonating element comprises:

a) an actuator conductor applied to said resonating element at a predetermined location upon the surface of said resonating element, said actuator conductor arranged and constructed to apply a voltage signal to said resonating element at said predetermined location, said predetermined location of said resonating element having a boundary defined by at least one stress gradient line that defines an area of substantially uniform stress present in said resonating element when said gyroscope is rotationally stationary; and

b) a drive circuit constructed and arranged to apply a predetermined sequence of voltage signals to said resonating element through said actuator so as to impose a predetermined mode of oscillation upon said resonating element.

13. The oscillating gyroscope of claim 12 wherein said actuator conductor comprises two vertically symmetrical halves that are electrically isolated from one another and which are independently electrically connected to said drive circuit.

14. An oscillating gyroscope comprising:

a) a resonating element arranged and constructed to output voltage signals proportional to a level of stress induced therein;

b) an actuator conductor applied to said resonating element at a predetermined location upon the surface of said resonating element for imposing a predetermined mode of oscillation upon said resonating element, said actuator conductor arranged and constructed to apply a voltage signal to said resonating element at said predetermined location, said predetermined location of said resonating element being defined by boundaries that are congruent with areas of said resonating element that are subject to substantially uniform levels of stress when said gyroscope is rotationally stationary;

c) a drive circuit constructed and arranged to apply a predetermined sequence of voltage signals to said resonating element through said actuator conductor so as to impose a predetermined mode of oscillation upon said resonating element;

d) a voltage pick-off conductor applied to the surface of said resonating element, said pick-off being arranged and constructed to sense stress-induced voltage signals outputted by said resonating element, said sensed voltage signals being indicative of a rate of rotation of said gyroscope, said pick-off being applied to an area of the surface of said resonating element that is subject to substantially zero stress when said gyroscope is rotationally stationary; and

e) means for processing said sensed voltage signals.

15. The oscillating gyroscope of claim 14 wherein said actuator conductor comprises two vertically symmetrical halves that are electrically isolated from one another and which are independently electrically connected to said drive circuit.

16. An oscillating gyroscope comprising:

a) a resonating element arranged and constructed to output voltage signals proportional to a level of stress induced therein;

b) an actuator conductor applied to said resonating element at a predetermined location upon the surface of said resonating element, said actuator conductor arranged and constructed to apply a voltage signal to said resonating element at said predetermined location, said predetermined location of said resonating element having a boundary defined by at least one stress gradient line that defines an area of substantially uniform stress present in said resonating element when said gyroscope is rotationally stationary;

c) a drive circuit constructed and arranged to apply a predetermined sequence of voltage signals to said resonating element through said actuator so as to impose a predetermined mode of oscillation upon said resonating element;

d) a voltage pick-off conductor applied to the surface of said resonating element, said pick-off being arranged and constructed to sense stress-induced voltage signals outputted by said resonating element, said sensed voltage signals being indicative of a rate of rotation of said gyroscope, said pick-off being applied to an area of the surface of said resonating element that is subject to substantially zero stress when said gyroscope is rotationally stationary; and

e) means for processing said sensed voltage signals.

17. The oscillating gyroscope of claim 16 wherein said actuator conductor comprises two vertically symmetrical halves that are electrically isolated from one another and which are independently electrically connected to said drive circuit.