VIBRATORY GYROSCOPE

• US 20140000366A1
• Filed: 06/27/2013
• Published: 01/02/2014
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Electronics OY (Murata Manufacturing Co Limited)
• Inventors: BLOMQVIST, Anssi
• Granted Patent: US 9,958,270 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• 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 the angular velocity, wherein the resonance frequency of the first mechanical resonator and the resonance frequency of the second mechanical resonator are initially adjusted to essentially coincide;

a damping 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.

2. A sensing device according to claim 1, wherein

the feed-back loop comprises a transducer element and a controlling element;

the transducer element comprises a first transducer and a second transducer;

the first transducer is configured to output a first electrical signal that corresponds to the sense mode vibration;

the control element is configured to receive from the first transducer the first electrical signal and generate a second electrical signal according to a specific response function, the response function defining correspondence between values of the first electrical signal and the second electrical signal;

the control element is configured to feed the second electrical signal to the second transducer;

the second transducer is configured to exert to the mass an opposing force that corresponds to the second electrical signal;

the control element is a signal processing filter, response function of the signal processing filter having a resonant frequency characteristic that essentially coincides with the first resonant frequency.

3. 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.

4. 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.

5. A sensing device according to claim 1, wherein first transducer and the second transducer of the second resonator are area modulated type of capacitive/electrostatic transducers.

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

7. A sensing device according to claim 1, wherein the structure of the first mechanical resonator or the second mechanical resonator is designed to keep the ratio of mechanical and electrostatic contributions to the spring essentially constant.

8. A sensing device according to claim 2, wherein the control element is a signal processing filter.

9. A sensing device according to claim 8, wherein the quality factor of the signal processing filter is above 1.

10. A sensing device according to claim 8, wherein the quality factor of the signal processing filter is in the range 3 to 10.

11. A sensing device according to claim 8, wherein the loop gain of the closed feed-back loop for frequencies below the first resonant frequency is in the range 0.1 to 0.3.

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

13. 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 the angular velocity, the method comprising:

adjusting the resonance frequency of the first mechanical resonator and the resonance frequency of the second mechanical resonator to essentially coincide;

connecting to the second mechanical resonator a feed-back loop connected, the quality factor of the combination of the feed-back loop and the second mechanical resonator being less than 10.