VIBRATORY GYROSCOPE

• US 20140000365A1
• Filed: 06/26/2013
• 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: AALTONEN, Lasse
• Granted Patent: US 10,365,105 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5726 Signal processing
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Abstract

An improved sensing device comprising micromechanical gyroscope and a feed-back loop with a controller for creating a damp control signal. A frequency generator generates a drive signal for drive mode vibration and a reference signal that is in quadrature-phase in relation to the drive mode vibration. The quadrature reference signal is summed with the damp control signal of the controller. The resulting transducer control signal is fed to the second mechanical resonator. Stable cancellation of the actual mechanical quadrature motion is achieved already at the sensing element level, before the detection of the Coriolis signal.

Claims

1. A sensing device comprising 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 rotation of the sensing device; and

the sensing device further comprises

a feed-back loop comprising a controller for creating a feed-back signal and an electromechanical transducer, the transducer being configured to oppose sense mode vibration of the second mechanical resonator according to an input control signal;

a frequency generator for generating a drive signal for drive mode vibration and a reference signal that is in quadrature-phase in relation to the drive mode vibration;

a summing element configured to sum the quadrature reference signal with a output signal of the controller to be fed as feedback signal to the second mechanical resonator.

2. A sensing device according to claim 1, wherein the summing element is a weighted summing element.

3. A sensing device according to claim 2, wherein weights of the summed signals have been adjusted during manufacturing of the sensing device.

4. A sensing device according to claim 1, wherein the sensing device further comprises a detection unit and a quadrature signal amplitude controller;

the detection unit is configured to input a sensed signal, and the reference signal;

the detection unit is configured to generate a detected quadrature signal from the sensed signal and the reference signal;

the quadrature signal amplitude controller is configured to apply the detected quadrature signal to control the level of the reference signal before feeding it to the summing element.

5. A sensing device according to claim 1, wherein the sending device further comprises a detection unit and a bias controller;

the detection unit is configured to input a sensed signal, and the reference signal;

the detection unit is configured to generate a detected quadrature signal from the sensed signal and the reference signal;

the bias controller is configured to input the detected quadrature signal and input to the summing element a bias control signal corresponding to the detected quadrature signal.

6. A sensing device according to claim 1, wherein the response function of the control element is a frequency response function that has a resonant frequency characteristic that essentially coincides with a resonant frequency of the second mechanical resonator.

7. A sensing device according to claim 1, wherein the control element is a signal processing filter.

8. A control element according to claim 7, wherein the quality factor of the signal processing filter is above 1.

9. A control element according to claim 7, wherein the quality factor of the signal processing filter is in the range 3 to 10.

10. A method for sensing rotation of a sensing device comprising a micromechanical gyroscope with 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 rotation of the sensor device;

creating a feed-back signal in a feed-back loop comprising a controller and an electromechanical transducer, the transducer being configured to damp sense mode vibration of the second mechanical resonator according to an input signal;

generating in a frequency generator a drive signal for drive mode vibration and a reference signal that is in quadrature-phase in relation to the drive mode vibration;

summing the quadrature reference signal with an output signal of the controller to create an input signal for the second mechanical resonator.

11. A method according to claim 10, wherein the sensing device further comprises a detection unit and a quadrature signal amplitude controller;

the method comprising

feeding a sensed signal, and the reference signal to the detection unit;

generating from the sensed signal and the reference signal in the detection unit a detected quadrature signal;

using the detected quadrature signal in the quadrature signal amplitude controller to control the level of the reference signal before feeding it to the summing element.

12. A method according to claim 10, wherein the sensing device further comprises a detection unit and a bias controller;

the method comprising;

feeding a sensed signal, and the reference signal to the detection unit;

generating from the sensed signal and the reference signal in the detection unit a detected quadrature signal;

using the detected quadrature signal in the bias controller to create a bias voltage control signal corresponding to the detected quadrature signal;

summing the quadrature reference signal, the bias voltage control signal and the output signal of the controller to create an input signal for the second mechanical resonator.