Gyroscopic devices

• US 4,655,081 A
• Filed: 02/20/1985
• Issued: 04/07/1987
• Est. Priority Date: 02/22/1984
• Status: Expired due to Term

• Current Assignee: British Technology Group Ltd. (Boston Scientific Corporation)
• Original Assignee: National Research Development Corporation
• Inventors: Burdess, James S.
• Primary Examiner(s): Tokar, Michael J.
• Assistant Examiner(s): Chapman, Jr., John E.
• Application Number:
  US06/703,538
• Time in Patent Office: 776 Days
• Field of Search: 73/505, 310/329, 310/366, 310/369
• US Class Current: 73/504.13
• CPC Class Codes: G01C 19/567 using the phase shift of a vibration node or antinode

Abstract

A gyroscopic device comprising a resonator in the form of a disc, cylinder or like structure of circular outline, of a composition containing piezo-electric material and preferably made of a an integral mass of such material. The resonator is excited into dilatation-type vibration by electric currents applied to exciting electrodes electro-deposited in a regular pattern around the circumference of the structure, and these vibrations are sensed by detecting electrodes similarly deposited around the wall in a similar but angularly displaced pattern. A measure of any rate of turn which the structure is undergoing about its axis can be derived from the resulting phase shift of the electrical output from the detecting electrodes.

Claims

1. A gyroscopic device comprising:

a circular disc having first and second oppositely facing faces, and axis, and comprising an intergral mass of material having piezo-electric properties, said disc being adapted to be rotated about its axis at a rate of turn, said second face having an electrode;

a plurality of first electrodes mounted in an axisymmetric formation on said disc first face;

means for providing an AC voltage between said plurality of first electrodes and said electrode on said second face for causing, in conjunction with the piezo-electric properties of said disc, a pattern of strain to be generated within said disc, said pattern varying cyclically around said disc in a circumferential direction;

a plurality of second electrodes axisymmetrically mounted on said disc first face and angularly displaced with respect to said plurality of first electrodes, said second electrodes emitting electrical signals which are generated by an interaction between said pattern of strain and the piezo-electric properties of said disc, said electrical signals varying when said disc is rotated about its axis due to an angular displacement of the cyclically varying strain pattern; and

means for measuring said rate of turn from the variation of said electrical signals.

2. A gyroscopic device according to claim 1 in which said disc is anchored to ground by means of a support connecting said ground to a center of said disc.

3. A gyroscopic device according to claim 2 in which areas of ground lie adjacent to both faces of said disc, and in which separate supports extending away from said disc in opposite axial directions connect said disc to both of said areas of ground.

4. A device according to claim 1 wherein said second electrodes are mounted at locations coinciding, in the absence of any said rate of turn, with nodes of said pattern of strain generated by said first electrodes.

5. A device according to claim 1 wherein said electrodes are electro-deposited on said disc first face.

6. A gyroscopic device, comprising:

a radially polarized hollow cylinder having an axis and comprising an intergral mass of material having piezo-electric properties, said cylinder having an inner wall, and outer wall, and a uniform cross-section along the entire length of said cylinder, said cylinder being adapted to be rotated about its axis at a rate of turn;

a plurality of first electrodes mounted in an axisymmetric formation on one of said walls, and an electrode mounted on the other of said walls;

means for providing an AC voltage between said plurality of first electrodes and said electrode on said other wall for causing, in conjunction with the piezo-electric properties of said cylinder, a pattern of strain to be generated within said cylinder, said pattern varying cyclically around said cylinder in a circumferential direction;

a plurality of second electrodes axisymmetrically mounted on said one wall and angularly displaced with respect to said plurality of first electrodes, for emitting electrical signals which are generated by an interaction between said pattern of strain and the piezo-electric properties of said cylinder and which vary when said cylinder is rotated about its axis due to an angular displacement of the cyclically varying strain pattern; and

means for measuring said rate of turn from the variation of said electrical signals.

7. A gyroscopic device according to claim 6 in which said second electrodes are mounted at locations coinciding, in the absence of any said rate of turn, with nodes of said pattern of cyclical strain generated by said first electrodes.

8. A gyroscopic device according to claim 6 in which areas of ground lie adjacent to both axial ends of said cylinder, and in which each said axial end of said cylinder is anchored to a respective adjacent area of ground.

9. A gyroscopic device according to claim 6 in which said electrodes are mounted on said cylinder by electro-deposition.