Vibrating beam gyroscopic measuring apparatus

• US 5,597,955 A
• Filed: 01/11/1996
• Issued: 01/28/1997
• Est. Priority Date: 06/11/1992
• Status: Expired due to Term

• Current Assignee: Societe D'Applications Generales D'Electricite et de Mecanique Sagem
• Original Assignee: Societe D'Applications Generales D'Electricite et de Mecanique Sagem
• Inventors: Leger, Pierre, Marchais, Olivier, Bienaime, Francis
• Primary Examiner(s): Oda, Christine K.
• Application Number:
  US08/583,942
• Time in Patent Office: 383 Days
• Field of Search: 310/333, 310/321, 310/329, 338/2, 338/5, 73/504.16, 73/504.15, 73/504.14, 73/504.12, 73/504.04
• US Class Current: 73/504.16
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/5614 Signal processing

Abstract

A rate gyro or a gyroscope includes a resonator having four mutually parallel identical beams integral with a common square base and projecting from the base at corners of a virtual square. The beams have a same resonant frequency in two directions parallel to the two sides of the square base. It further has first transducers for vibrating each beam in a first direction orthogonal to the beams, connected to a driving circuit and second transducers for detecting an amplitude of vibration of the beams in a second direction each orthogonal to a respective first direction.

Claims

1. Vibrating beam gyroscopic measuring apparatus, having:

a resonator comprising four identical beams having central axes which are mutually parallel, a common base having a square surface, said four beams being integral with said base at said square surface and projecting in a same direction from said square surface of said base at all four corners formed by said square surface, said beams being constructed to have a same resonant frequency in two directions parallel to two adjacent sides of said square base,

first transducers for vibrating each of said beams in a first direction orthogonal to said beams, connected to a driving circuit, and

second transducers for detecting an amplitude of vibration of said beams in second directions each orthogonal to a respective said first direction and connected to a measurement circuit.

2. Apparatus according to claim 1, wherein said first and second transducers are piezo-electric elements.

3. Apparatus according to claim 1, wherein only some of the beams are provided with said first transducers.

4. Apparatus according to claim 1, wherein all said four beams carry said second transducers connected to deliver signals to said measurement circuit.

5. Apparatus according to claim 1, wherein said measurement circuit is in closed loop and delivers Coriolis force balancing circuits to compensating said second transducers carried by all said four beams.

6. Apparatus according to claim 1, wherein said first transducers are arranged in a cicumferential row and said second transducers are disposed in another row spaced from the first row along the resonator.

7. Apparatus according to claim 1, wherein said first transducers and said driving circuit are arranged and connected to vibrate all said beams in mutually parallel directions.

8. Apparatus according to claim 1, wherein said first and second transducers are electrostatic transducers comprising stationary elements which constitute capacitors with said beams of conducting metal.

9. Apparatus according to claim 8, further comprising means for applying a bias DC voltage to said resonator and wherein said second transducers are connected by pairs to respective charge amplifiers which are applied to plus and minus inputs of an algebraic summer.

10. Apparatus according to claim 8, wherein said first transducers are connected to constitute two pairs and connected to a DC voltage generator which deliver voltages +V and -V in phase opposition on said two pairs.

11. Apparatus according to claim 8, wherein said electrostatic transducers comprise electrodes confronting said beams, said electrostatic transducers being carried by electrically insulating cross-plates located between said beams.

12. Vibrating beam gyroscopic measuring apparatus, having:

a resonator comprising four mutually parallel identical beams integral with a common square base and projecting from said base at all corners of a virtual rectangle, said beams being constructed to have a same resonant frequency in two directions parallel to the two sides of said square base,

first transducers for vibrating each of said beams in a first direction orthogonal to said beams, connected to a driving circuit, and

second transducers for detecting an amplitude of vibration or said beams in second directions each orthogonal to a respective said first direction and connected to a measurement circuit,

wherein said first transducers and said driving circuit are arranged for vibrating two of said beams in a first direction parallel to two sides of said rectangle and the other two of said beams in a direction parallel to the other two sides of said rectangle.

13. Vibrating beam gyroscopic measuring apparatus, having:

a resonator comprising four mutually parallel identical beams integral with a common square base and projecting from said base at all corners of a virtual rectangle, said beams being constructed to have a same resonant frequency in two directions parallel to the two directions of two mutually adjacent sides of said square base,

first transducers for vibrating each of said beams in a first direction orthogonal to said beams, connected to a driving circuit, and

second transducers for detecting an amplitude of vibration of said beams in second directions each orthogonal to a respective said first direction and connected to a measurement circuit, wherein said driving circuit is a closed loop circuit for maintaining an amplitude of vibration in an input mode at a constant value, is connected to receive input signals from some of said first transducers associated with two said beams and delivers a driving signal to others of said first transducers associated by the other two beams.

14. Apparatus according to claim 13, wherein said first transducers and said driving circuit are arranged and connected to vibrate all said beams in mutually parallel directions.

15. Apparatus according to claim 13, wherein said first transducers and said driving circuit are arranged for vibrating said beams one of radially or tangentially.

16. Apparatus according to claim 13, wherein the driving circuit (20) comprises an amplifier (32) which drives a multiplier (34) through a pass band filter controlled by a phase regulation loop and wherein said multiplier (34) has a gain controlled by the amplitude regulation closed loop (38) which receives the output signal of amplifier (32) and a reference signal.

17. Apparatus according to claim 13, wherein said transducers are electrostatic transducers comprising stationary elements which constitute capacitors with said beams of conducting metal.

18. Apparatus according to claim 17, further comprising means for applying a bias DC voltage to said resonator and wherein said second transducers are connected by pairs to respective charge amplifiers which are applied to plus and minus inputs of an algebric summer.

19. Apparatus according to claim 17, wherein said first transducers are connected to constitute two pairs and connected to an DC voltage generator which deliver voltages +V and -V in phase opposition on said two pairs.

20. Apparatus according to claim 17, wherein said electrostatic transducers comprise electrodes confronting said beams said electrostatic transducer being carried by electrically insulating cross-plates located between said beams.

21. Vibrating beam gyroscopic measuring apparatus for measuring an amount of rotation, having:

a resonator comprising four mutually parallel identical beams integral with a common square base and projecting from said base at all corners of a virtual square, each of said beams being constructed to have a same resonant frequency in two directions parallel to the two directions of two adjacent sides of said square base,

first transducers for vibrating and detecting an amount of vibration of each of said beams in a first direction orthogonal to said beams,

second transducers for vibrating and detecting an amount of vibration of each of said beams in a second direction orthogonal to a respective said first direction, and

a driving and measurement circuit having;

two loss compensation channels each of said channels for compensating losses along one of said first direction and said second direction, each of said channels comprising a first multiplier for multiplying an input signal received from one of said first and second transducers by a sine or cosine of an estimated angle of said resonator around a direction parallel to the beams and a second multiplier for multiplying said input signal with a sum of the output signals delivered by the first multipliers of the two channels, said second multiplier having an output communicating to a respective one of said first transducers and second transducers for compensating losses along one of said directions, and

an angular encoding circuit providing said estimated angle, having subtracting means with two inputs, one of the inputs being connected to receive the product of a first one of said inputs and the sine of the estimated angle and the other of which is connected to receive the product of the cosine of said estimated angle and the other input and an output delivering an analog signal representative of said estimated angle.

22. Vibrating beam gyroscopic measuring apparatus, having:

a resonator comprising four mutually parallel identical beams integral with a common square base and projecting from said base at all corners of a virtual rectangle, said beams being constructed to have a same resonant frequency in two directions parallel to the two directions of the sides of said square base,

first transducers for vibrating each of said beams in a first direction orthogonal to said beams, connected to a driving circuit,

second transducers for detecting an amplitude of vibration of said beams in second directions each orthogonal to a respective said first direction, and

a measurement circuit connected to receive signals from said second transducers, comprising an input amplifier followed with a synchronous demodulator which receives a reference signal consisting of an output signal of said driving circuit and which delivers an output signal representing the rate of turn of the resonator and further comprising a servo loop consisting of a connection between an output of the input amplifier and said first transducers used for compensation of losses.