Microelectromechanical gyroscope

• US 5,994,801 A
• Filed: 08/12/1998
• Issued: 11/30/1999
• Est. Priority Date: 08/12/1998
• Status: Expired due to Term

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Garcia, Ernest J.
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): MULLINS, BURTON S
• Application Number:
  US09/133,043
• Time in Patent Office: 475 Days
• Field of Search: 310/40 MM, 310/80, 74/5 R, 74/5.7, 74/5.8, 73/504.02, 73/504.08, 73/504.09, 73/504.11, 73/504.18, 300/20
• US Class Current: 310/40.0MM
• CPC Class Codes: G01C 19/02 Rotary gyroscopes
• CPC Class Codes: H02K 99/20 Motors
• CPC Class Codes: Y10T 74/12 Gyroscopes
• CPC Class Codes: Y10T 74/1282 with rotor drive
• CPC Class Codes: Y10T 74/1286 Vertical gyroscopes

Abstract

A gyroscope powered by an engine, all fabricated on a common substrate in the form of an integrated circuit. Preferably, both the gyroscope and the engine are fabricated in the micrometer domain, although in some embodiments of the present invention, the gyroscope can be fabricated in the millimeter domain. The engine disclosed herein provides torque to the gyroscope rotor for continuous rotation at varying speeds and direction. The present invention is preferably fabricated of polysilicon or other suitable materials on a single wafer using surface micromachining batch fabrication techniques or millimachining techniques that are well known in the art. Fabrication of the present invention is preferably accomplished without the need for assembly of multiple wafers which require alignment and bonding, and without piece-part assembly.

Claims

1. A gyroscope comprising:

a.) an engine formed upon a substrate and including a drive source adapted to provide a predetermined rotational torque; and

b.) a rotatable rotor/suspension assembly formed upon the substrate, the assembly mechanically coupled to the engine to receive the torque.

2. The gyroscope of claim 1 wherein the engine is a microengine.

3. The gyroscope of claim 2 further comprising means for electronic control in electrical communication with the microengine and the rotor/suspension assembly, the electronic control means being adapted to control the operation of the microengine, to measure the rotational speed of the rotor/suspension assembly, to determine a distance differential due to the angular rotation of the substrate, to determine the angular orientation of the rotor/suspension assembly with respect to the substrate and to selectively apply a preselected electrostatic force to the rotor/suspension assembly to restore the rotor/suspension assembly to its original orientation with respect to the substrate.

4. The gyroscope of claim 3 wherein the drive source further comprises a pair of linear actuators phase shifted to operate substantially 90 degrees apart in phase;

a first drive linkage; and

a second drive linkage, with each drive linkage coupled to one of the linear actuators on one end of the drive linkages, and coupled to each other at a second end of the drive linkages, the first drive linkage further being rotatably coupled to the rotor/suspension assembly to provide torque to the rotor/suspension assembly for rotation thereof.

5. The gyroscope of claim 4 wherein the rotor/suspension assembly further comprises:

a.) a shaft fabricated upon and coupled to the substrate;

b.) a rotatable anchor element suspended adjacent to the substrate by the shaft;

c.) a suspension element attached to the anchor element by a first plurality of torsional flexures; and

d.) a rotor wheel attached to the suspension element by a plurality of torsional flexures oriented sustantially orthogonally to the first plurality of torsional flexures.

6. The gyroscope of claim 5, wherein the anchor element further comprises a center pivot fabricated substantially in the center of the anchor element and rotationally coupled to the shaft, and a link pivot fabricated adjacent to the center pivot on the anchor element and rotationally coupled to the first drive linkage.

7. The gyroscope of claim 6 wherein the rotor/suspension assembly further comprises means for sensing and restoring orientation of the rotor wheel fabricated upon the substrate adjacent and in close proximity to a periphery of the rotor wheel, the means for sensing and restoring being in electronic communication with the electronic control means and adapted to obtain and communicate information about the rotor wheel'"'"'s angular speed, acceleration and orientation displacement relative to the substrate, and by direction from the electronic control means, to selectively apply a preselected electrostatic force to the rotor/suspension assembly to restore the rotor/suspension assembly to its original orientation with respect to the substrate.

8. The gyroscope of claim 7 wherein the means for sensing and restoring orientation includes at least three sense and force elements spaced substantially equally apart and partially positioned over the rotor wheel to thereby form a gap between each sense and force element and the rotor wheel.

9. The gyroscope of claim 8 wherein each sense and force element comprises a pair of cantilevered beams, one beam being a sensing element and the other beam being a forcing element, each sensing element being adapted to obtain information relating to distance variations in the gap, and each forcing element being adapted to selectively apply an attractive but controlled force to the rotor wheel as required to return the rotor/suspension assembly to its original orientation with respect to the substrate.

10. A micromachined gyroscope comprising:

a.) a rotatable rotor/suspension assembly formed upon a silicon substrate;

b.) a microengine formed upon the silicon substrate in the microdomain adjacent to the rotor/suspension assembly, the microengine including a pair of actuators operating substantially 90 degrees apart in phase;

a first drive linkage; and

a second drive linkage, the first and second drive linkages being attached to each actuator at a first end of each linkage, and a second end of each drive linkage being connected together, with the first drive linkage further being rotatably coupled to the rotor/suspension assembly; and

c.) means for electronic control in electrical communication with the microengine and the rotor/suspension assembly and operation and control thereof.

11. The gyroscope of claim 10 wherein the electronic control means is formed upon the silicon substrate in the microdomain adjacent to the rotor/suspension assembly and the microengine and is adapted to control the operation of the microengine, to measure the rotational speed of the rotor/suspension assembly, to determine a distance differential due to the angular rotation of the substrate, to determine the angular orientation of the rotor/suspension assembly with respect to the substrate and to selectively apply a preselected electrostatic force to the rotor/suspension assembly to restore the rotor/suspension assembly to its original orientation with respect to the substrate.

12. The gyroscope of claim 11 wherein the rotor/suspension assembly comprises a support shaft fabricated on the substrate, an anchor element suspended on the substrate by the shaft and having a substantially centered center pivot, a suspension element attached to and circumscribing the anchor element by a plurality of Z-axis flexures, and a rotor wheel attached to and circumscribing the suspension element by a plurality of X-axis flexures.

13. The gyroscope of claim 12 wherein the rotor/suspension assembly further comprises means for sensing and restoring orientation of the rotor wheel fabricated upon the substrate adjacent to and superposed with a periphery of the rotor wheel, the sensing and restoring orientation means being in electrical communication with the electronic control means and tailored to obtain and communicate information about the rotor wheel'"'"'s angular speed, acceleration and orientation displacement relative to the substrate, and by direction from the electronic control means, to selectively apply a preselected electrostatic force to the rotor/suspension assembly to restore the rotor/suspension assembly to its original orientation with respect to the substrate.

14. The gyroscope of claim 13 wherein the sensing and restoring orientation means includes at least three sense and force elements spaced substantially 120 degrees apart about the rotor wheel, with each sense and force element being fabricated spaced from the rotor wheel by a predetermined gap.

15. The gyroscope of claim 14 wherein each sense and force element comprises a pair of cantilevered beams, one beam being a sensing element and the other beam being a forcing element, with each sensing element being adapted to obtain information relating to distance variations in the gap, and with each forcing element being adapted to selectively apply an attractive but controlled force to the rotor wheel as required to return the rotor/suspension assembly to its original orientation with respect to the substrate.

16. A gyroscope fabricated, operated and controlled at sizes equal to or less than the millimeter domain, comprising a rotatable rotor/suspension assembly;

an engine; and

means for electronic control, all located upon a common substrate, the engine being mechanically coupled to the rotor/suspension assembly to provide a predetermined rotational torque to the rotor/suspension assembly, the engine and the rotor/suspension assembly further being in electronic communication with the electronic control means acting to control operation of the engine, to measure the rotational speed of the rotor/suspension assembly, to determine an angular orientation of the rotor/suspension assembly with respect to the substrate, and to control an electrostatic force applied to the rotor/suspension assembly to restore the rotor/suspension assembly to its original orientation with respect to the substrate.

17. The gyroscope of claim 16 wherein the engine further comprises a pair of actuators operating substantially 90 degrees apart in phase, a first drive linkage and a second drive linkage, the first and second drive linkages being attached to each actuator at a first end of the drive linkages, and the drive linkages being coupled together at a second end thereof, the first drive linkage being rotatably coupled to the rotor/suspension assembly.

18. The gyroscope of claim 17 wherein the rotor/suspension assembly further comprises a support shaft fabricated on the substrate;

an anchor element suspended over the substrate by the shaft and having a substantially centered center pivot;

a suspension element attached to and circumscribing the anchor element by a plurality of Z-axis flexures; and

a rotor wheel attached to and circumscribing the suspension element by a plurality of X-axis flexures.

19. The gyroscope of claim 18 wherein the rotor/suspension assembly further comprises means for sensing and restoring orientation of the rotor wheel fabricated upon the substrate adjacent to and superposed with a periphery of the rotor wheel, the means for sensing and restoring being in electronic communication with the electronic control means and adapted to obtain and communicate information about the rotor wheel'"'"'s angular speed, acceleration and orientation displacement relative to the substrate, and by direction from the electronic control means, to selectively apply a preselected electrostatic force to the rotor/suspension assembly to restore the rotor/suspension assembly to its original orientation with respect to the substrate.