ANGULAR RATE SENSOR HAVING A SENSE ELEMENT CONSTRAINED TO MOTION ABOUT A SINGLE AXIS AND FLEXIBLY ATTACHED TO A ROTARY DRIVE MASS

• US 20020189351A1
• Filed: 06/14/2001
• Published: 12/19/2002
• Est. Priority Date: 06/14/2001
• Status: Abandoned Application

• Current Assignee: Irvine Sensors Corp.
• Original Assignee: Irvine Sensors Corp.
• Inventors: Reeds, John W., Hsu, Ying W.
• Application Number:
  US09/882,807
• Publication Number:
  US 20020189351A1
• Time in Patent Office: Days
• US Class Current: 73/504.04
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

Disclosed is a micro-gyro and method of driving a micro-gyro. The method and structure are embodied in a micro-gyro of the type where first flexures extend from an anchor connect to a sense plate, where second flexures extend from the sense plate connect to a drive ring, where the drive ring is driven to oscillate about a drive axis, and where the first flexures constrain the sense plate from moving about the drive axis but permit the sense plate and the attached drive ring to rock about a sense axis. The sense plate, drive ring and flexures form a plate-ring-flexure system that is tuned such that the system rocks about the sense axis in a first or fundamental mode where the plate and ring move substantially in phase at the lowest resonant frequency.

Claims

1. A method of driving a micro-gyro comprised of a substrate, an anchor extending upward from the substrate, a sense plate supported from the anchor and above the substrate by first flexures that constrain its motion to a single-degree-of-freedom rocking motion about a sense axis, and a drive ring supported from the sense plate by second flexures that permit the drive ring to angularly oscillate about a drive axis that is substantially perpendicular to the sense axis and permits the drive ring to move in a rocking motion about the sense axis;

the sense plate, the drive ring and the first and second flexures forming a plate-ring-flexure system that has a first resonant mode associated with a first natural frequency where the plate and ring rock substantially in phase about the sense axis and a higher resonant mode associated with a higher natural frequency where the plate and ring rock substantially in opposite phase about the sense axis, the method comprising the step of;

providing a drive means for angularly oscillating the drive ring about the drive axis such that a rotational rate of the micro-gyro about a rate axis that is substantially perpendicular to both the sense axis and the drive axis creates an oscillatory coriolis force that causes the plate-ring-flexure system to angularly oscillate about the sense axis; and

oscillating the drive ring with the drive means at a drive frequency that is near the first natural frequency of the first resonant mode of the plate-ring-flexure system such that the plate and ring rock substantially in phase about the sense axis.

2. A micro-gyro of substantially planar construction that senses rotational rate about a rate axis that is substantially parallel to a plane of the micro-gyro comprising:

a substrate;

an anchor extending upward from the substrate;

first inner flexures connected to the anchor and extending from the anchor above and substantially parallel to the plane of the micro-gyro;

a sense plate that is flexibly connected to the anchor via the first flexures and constrained to a single-degree-of-freedom rocking motion about a sense axis that is substantially parallel to the plane of the micro-gyro and substantially perpendicular to the rate axis;

second outer flexures connected to the sense plate and extending from the sense plate substantially parallel to the plane of the micro-gyro;

a drive ring that is flexibly connected to the sense plate via the second flexures, the second flexures and the drive ring designed to cause the drive ring alone to angularly oscillate at a natural frequency around the sense plate and about a drive axis that is substantially perpendicular to the plane of the micro-gyro and to the sense and rate axes, the drive ring driven about the drive axis at a drive frequency; and

the first flexures, the sense plate, the second flexures and the drive ring forming a plate-ring-flexure system wherein an angular motion of the system about the rate axis and the angular oscillation of the ring about the drive axis result in an angular response of the plate-ring-flexure system wherein the plate and ring oscillate substantially in-phase and substantially at the drive frequency, close to a first mode frequency that constitutes a lowest natural resonant frequency of the plate-ring-flexure system about the sense axis.

3. A micro-gyro of substantially planar construction that senses rotational rate about a rate axis that is substantially parallel to a plane of the micro-gyro comprising:

a sense plate that is connected to the substrate via first flexures that substantially constrain the sense plate to a rocking motion about a sense axis that is substantially parallel to the plane of the micro-gyro and substantially perpendicular to the rate axis;

a drive ring that is flexibly connected to the sense plate via second flexures that substantially permit the drive ring to oscillate about the drive axis at a drive frequency while the sense plate remains stationary about the drive axis,

the first flexures, the sense plate, the second flexures and the drive ring forming a plate-ring-flexure system wherein the plate and ring oscillate substantially in-phase at the drive frequency and close to a first mode frequency that constitutes a lowest natural resonant frequency of the plate-ring-flexure system about the sense axis.