INERTIAL UNIT HAVING VIBRATING GYROS MOUNTED ON A CAROUSEL, AND AN ANGLE-MEASUREMENT METHOD

• US 20130312518A1
• Filed: 05/23/2013
• Published: 11/28/2013
• Est. Priority Date: 05/24/2012
• Status: Active Grant

• Current Assignee: Safran Electronics & Defense
• Original Assignee: Sagem Defense Securite SA (Safran SA)
• Inventors: RENAULT, Alain, LIGNON, Christian, BRUNSTEIN, Etienne
• Granted Patent: US 9,279,682 B2
• Time in Patent Office: Days
• US Class Current: 73/504.08
• CPC Class Codes: G01C 19/04 Details
• CPC Class Codes: G01C 19/5691 of essentially three-dimensional vibrators, e.g. wine glass-type vibrators
• CPC Class Codes: G01P 1/02 Housings

Abstract

An inertial unit comprising an inertial core (3) that is connected to a control unit. (50) and that includes three gyros (9, 10, 11) that are mounted relative to one another so as to have sensing axes (X, Y, Z) that are substantially perpendicular to one another, the gyros being vibrating axisymmetric gyros with hemispherical resonators, the unit being characterized in that the core is mounted on a carousel (2) arranged to drive the inertial core in rotation about an axis of rotation (4) at at least one frequency that corresponds to a minimum for spectral error density of the gyros. An angle-measurement method making use of the unit.

Claims

1. An inertial unit comprising an inertial core (3) that is connected to a control unit (50) and that includes three gyros (9, 10, 11) that are mounted relative to one another so as to have sensing axes (X, Y, Z) that are substantially perpendicular to one another, the gyros being vibrating axisymmetric gyros with hemispherical resonators, the unit being characterized in that the core is mounted on a carousel (2) arranged to drive the inertial core in rotation about an axis of rotation (4) at at least one predetermined frequency of rotation.

2. An inertial unit according to claim 1, wherein the axis of rotation (4) coincides with a trisector of the sensing axes (X, Y, Z).

3. An inertial unit accorddng to claim 1, wherein the axis of rotation (4) is distinct from a trisector of the sensing axes (X, Y, Z).

4. An inertial unit according to claim 3, wherein the axis of rotation is such that the gyros (9, 10, 11) have errors that appear at frequencies that are not identical, and the frequencies at which gyro errors appear are not harmonics of one another.

5. An inertial unit according to claim 1, wherein the carousel (2) is arranged to cause the inertial core to perform continuous rotary motion.

6. An inertial unit according to claim 1, wherein the carousel (2) is arranged to cause the inertial core to perform alternating rotary motion.

7. An inertial unit according to claim 1, wherein the carousel (2) is positioned so that the axis of rotation (4) is vertical.

8. An inertial unit according to claim 1, wherein the carousel (2) is positioned so that the axis of rotation (4) is horizontal.

9. An angle-measurement method making use of an inertial unit in accordance with any preceding claim, the method comprising the steps of:

causing the carousel (2) to rotate about the axis of rotation (4); and

taking measurements with each gyro (9, 10, 11) during rotation of the carousel.

10. A method according to claim 9, wherein a measurement operation is performed continuously during rotation.

11. A method according to claim 9, wherein the axis of rotation (4) is such that the gyros (9, 10, 11) have errors that appear at frequencies that are not identical and the frequencies at which the gyro errors appear are not harmonics of one another, and wherein a step is performed of allocating errors to the gyros as a function of the frequencies at which the errors appear.