High Q angular rate sensing gyroscope

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.

Description

RELATED APPLICATIONS[0001]This application claims priority from Patent Cooperation Treaty application no. PCT / US00 / 25318, filed on Sep. 14, 2000, which is itself a Continuation-in-Part of U.S. patent application Ser. No. 09 / 397,718 filed Sep. 16, 1999. In addition, U.S. patent application Ser. No. 09 / 880,433 filed on 13 Jun. 2001 is a divisional application of U.S. patent application Ser. No. 09 / 397,718.FIELD OF THE INVENTION[0002]The present invention is drawn to an angular rate sensor of the type utilizing an oscillating resonating element. More specifically, the present invention is drawn to the shape and placement of actuators and pick-offs upon resonating elements of angular rate gyroscopes.BACKGROUND OF THE INVENTION[0003]Rate gyroscopes operate on the principle of inertia. Standing waves are excited in a resonating element to produce a desired mode of oscillation having a predetermined number of nodes. The oscillations have an amplitude, a frequency, and an inherent oscillato...

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Benefits of technology

[0012]Therefore, it is an objective of the present invention to provide a uniformly polarized piezoelectric resonator. It is another object of the present invention to improve the accuracy and Q value of the resonator by providing a plurality of actuators that are contoured to conform to areas of substantially uniform stress in the walls of the resonator and which are located on the resonator so as to maximize the flexure of the resonator wall per unit volt applied to the resonator. Similarly, it is yet another object of the invention to suppress unwanted modes of oscillation through the proper arrangement of actuators and pick-offs on

Problems solved by technology

These undesirable bending forces create voltage signals that may degrade the signal to noise ratio of the voltage output of the sensing elements and may indicate falsely that the angular rate sensor is being rotated about its sensitive axis.

Problems with angular rate sensors of the type patented by Varnham include a relatively low Q value, low sensitivity, and low accuracy.

In addition, the application of actuators and pick-offs across a range of stresses, in combination with non-uniform voltage responses in the piezoelectric materials, make it more difficult to force the resonator to oscillate in its desired mode.

Piezoelectric materials are not uniform in their voltage response and therefore it is frequently the case that a pick-off having a large surface area will sense net voltages skewed by an uneven voltage response of the piezoelectric material.

And because the actual voltages sensed by the pick-offs are quite small, voltage signal components due to uneven voltage responses frequently alter the signal to noise ratio of the sensed voltages to an extent that makes it difficult to determine accurately the rate and magnitude of rotation of the gyroscope.

Furthermore, because it is also frequently the case that the voltage response of respective areas of the piezoelectric materials that make up a resonator may vary independently with changes in the ambient temperature of the operating environment of the gyroscope, the noise to signal ratio of the sensed v

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