Gyroscopes

• US 4,489,609 A
• Filed: 12/07/1982
• Issued: 12/25/1984
• Est. Priority Date: 12/08/1981
• Status: Expired due to Term

• Current Assignee: British Technology Group Ltd. (Boston Scientific Corporation)
• Original Assignee: National Research Development Corporation
• Inventors: Burdess, James S., Maunder, Leonard
• Primary Examiner(s): Gill, James J.
• Application Number:
  US06/447,717
• Time in Patent Office: 749 Days
• Field of Search: 73/505, 310/329, 310/333, 310/366
• US Class Current: 73/504.14
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams

Abstract

A gyroscopic device comprising a beam, column or other continuous unitary structure of consistent vibratory characteristics along its full length and including piezoelectric material. The piezoelectric effect is used both excite the structure into resonant vibrations along a first axis and then, when a rate of turn is applied along a second axis at right angles to the first, to detect that rate of turn by sensing vibrations set up in the beam in a direction parallel to a third, orthogonal axis due to Coriolis forces resulting from the applied rate of turn. The beam may be held at both ends, or may be supported at one end only with the other end free. The vibrations applied to and sensed within the beam by means of the piezoelectric effect may be parallel, transverse and radial relative to the beam axis, or may be in a rotary sense around that axis. A mode of vibration in which opposite faces of the beam oscillate in parallel directions but out-of-phase is also disclosed.

Claims

1. A gyroscopic device comprising:

an elongated member of substantial length and substantially rectangular transverse section, exhibiting the piezoelectric effect and attached at at least one of its ends to supporting structure;

exciting electrodes attached to said member at a region remote from its said attachment to said fixed structure;

means using the said piezoelectric effect and said exciting electrodes to excite said region of said member into oscillations of a shearing type in which transversely-opposite faces of said member at said region oscillate in parallel directions but out-of-phase with each other, and sensing electrodes attached to said member at said region and adapted to sense electrical signals indicative of the inertia forces that are set up in said region of said member and that act along the said length of said member when a rate of turn is applied about an axis lying normal both to the said directions of said shearing oscillations and to said length of said member.

2. A gyroscopic device according to claim 1 in which said member is attached to supporting structure at both ends and said region lies substantially midway between said attached ends.

3. A gyroscopic device according to claim 1 in which said transverse section of said member is greater at said region than elsewhere.

4. A gyroscopic device according to claim 1 in which said member includes a plate held at earth potential and is of layered construction at said region, some of said layers being of material exhibiting the piezoelectric effect.