Vibratory gyroscope

Patent metadata

Field	Value
Publication number	US-9958270-B2
Application number	US-201313928879-A
Country	US
Kind code	B2
Filing date	Jun 27, 2013
Priority date	Jun 29, 2012
Publication date	May 1, 2018
Grant date	May 1, 2018

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.

First claim

The invention claimed is:

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.

Assignees

• Murata Electronics Oy
• Murata Manufacturing Co

Inventors

• Blomqvist Anssi

Classifications

• G01C19/5726 Primary

  Signal processing · CPC title

• G01C19/5776

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title

• B81B7/008

  MEMS characterised by an electronic circuit specially adapted for controlling or driving the same (B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00) · CPC title

• G01C19/5762 Primary

  the sensing mass being connected to a driving mass, e.g. driving frames · CPC title

• Y10T29/49002

  Electrical device making · CPC title