Vibratory gyroscope

• US 9,958,270 B2
• Filed: 06/27/2013
• Issued: 05/01/2018
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Blomqvist, Anssi
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): Campbell, Irving A
• Application Number:
  US13/928,879
• Publication Number:
  US 20140000366A1
• Time in Patent Office: 1,769 Days
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5726 Signal processing
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A sensing device comprising a micromechanical gyroscope, the gyroscope comprising an improved sensing device with a micromechanical gyroscope, where the resonance frequency of the first mechanical resonator and the resonance frequency of the second mechanical resonator are adjusted to essentially coincide. The device comprises a feed-back loop connected to the second mechanical resonator, the quality factor of the combination of the feed-back loop and the second mechanical resonator being less than 10. More accurate sensing is achieved without essentially adding complexity to the sensor device configuration.

Claims

1. A sensing device comprising a micromechanical gyroscope, the gyroscope comprising:

a first mechanical resonator for drive mode vibration;

a second mechanical resonator coupled to the first mechanical resonator for sense mode vibration corresponding to an angular velocity, wherein a resonance frequency of the first mechanical resonator and a resonance frequency of the second mechanical resonator are initially set to essentially coincide; and

a damping feed-back loop connected to the second mechanical resonator for damping the sense mode vibration of the second mechanical resonator, the damping feed-back loop comprising a signal processing filter that has a resonant frequency characteristic that coincides with the resonance frequency of the second mechanical resonator, wherein a sign of the signal processing filter is selected such that a phase shift of the damping feed-back loop is either 0 or −

π

, and an electrical Q value, which is an electrical quality factor, of the signal processing filter is in a range between 3 to 10.

2. A sensing device according to claim 1, wherein the initial frequency separation between the resonance frequency of the first mechanical resonator and the resonance frequency of the second mechanical resonator is in the range of 0 to 0.05.

3. A sensing device according to claim 1, wherein the resonance frequencies of the first and second mechanical resonators are designed to behave similarly over changes in environment.

4. A sensing device according to claim 1, wherein the second mechanical resonator comprises a first transducer and a second transducer, wherein the first transducer and the second transducer are area modulated type of capacitive or electric transducers.

5. A sensing device according to claim 4, wherein deviation of the resonant frequency characteristic from the resonance frequency of the first mechanical resonator is less than 50%.

6. A sensing device according to claim 1, wherein the second mechanical resonator comprises a first transducer and a second transducer, wherein the first transducer and the second transducer are piezoelectric transducers.

7. A sensing device according to claim 1, wherein a loop gain of the damping feed-back loop for frequencies below the resonant frequency of the first mechanical resonator is in the range 0.1 to 0.3.

8. A method of manufacturing a sensing device comprising a micromechanical gyroscope, the gyroscope comprising a first mechanical resonator for drive mode vibration and a second mechanical resonator coupled to the first mechanical resonator for sense mode vibration corresponding to an angular velocity, the method comprising:

initially setting a resonance frequency of the first mechanical resonator and a resonance frequency of the second mechanical resonator to essentially coincide; and

connecting a damping feed-back loop to the second mechanical resonator, the damping feed-back loop comprising a signal processing filter that has a resonant frequency characteristic at the resonance frequency of the second mechanical resonator, wherein a sign of the signal processing filter is selected such that a phase shift of the damping feed-back loop is either 0 or −

π

, and an electrical Q value, which is an electrical quality factor, of the signal processing filter is in a range between 3 to 10.