Method for measuring angular velocity and a vibrating micromechanical sensor of angular velocity

• US 20080314144A1
• Filed: 05/29/2008
• Published: 12/25/2008
• Est. Priority Date: 06/01/2007
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: VTI Technologies Oy (Murata Manufacturing Co Limited)
• Inventors: Blomqvist, Anssi
• Granted Patent: US 8,474,316 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

Abstract

The invention relates to measuring devices used in measuring angular velocity, and, more precisely, to vibrating micromechanical sensors of angular velocity. In the solution for a sensor of angular velocity according to the invention, a mass is suspended by means of spring structures having non-orthogonal primary and secondary axes such, that a test activation in phase with the primary motion is induced in a detection resonator, and the angular velocity to be measured is, by means of a phase detector, detected from the phase difference between the primary motion and the secondary motion. The structure of the sensor of angular velocity according to the invention enables reliable measuring with good performance, particularly in small vibrating micromechanical solutions for a sensor of angular velocity.

Claims

1. A method for measuring angular velocity by means of a vibrating micromechanical sensor of angular velocity, which sensor of angular velocity comprises at least one seismic mass and a moving electrode associated with the mass, which mass possesses a primary motion to be activated and, in addition to the primary motion, a second degree of freedom in relation to a detection axis nearly perpendicular to the primary motion, and which mass is supported at the body of the sensor component by means of a spring structure, characterized in, that, in the method, said mass is suspended by a spring suspension having non-orthogonal primary and secondary axes such, that, in a detection resonator, a test activation is induced, in phase with the primary motion, and that the angular velocity to be measured is phase-sensitively detected, by means of a phase detector, from the phase difference between the primary motion and the secondary motion.

2. Method according to claim 1, characterized in, that one of the primary motion and secondary motion signals is phase-shifted by 90 degrees.

3. Method according to claim 1, characterized in, that at least one of the primary motion and secondary motion signals is amplified.

4. Method according to claim 1, characterized in, that the phase-sensitive detection is implemented by means of an XOR gate (49) such, that steep-edged pulse waves are made out of the primary motion and secondary motion signals by means of a comparator (48), (50), which waves are conveyed to the XOR gate (49).

5. Method according to claim 4, characterized in, that, as output of the phase-sensitive detection, a pulse-width modulated signal proportional to the phase shift between the signals is obtained.

6. Method according to claim 5, characterized in, that an analog output signal is made by low-pass filtering out of the pulse width modulated signal proportional to the phase shift between the signals, obtained as output of the phase-sensitive detection.

7. Method according to claim 1, characterized in, that the primary motion is detected directly by means of a resistive coupling.

8. An arrangement for measuring angular velocity by means of a vibrating micromechanical sensor of angular velocity, which sensor of angular velocity comprises at least one seismic mass and a moving electrode associated with the mass, which mass possesses a primary motion to be activated and, in addition to the primary motion, a second degree of freedom in relation to a detection axis nearly perpendicular to the primary motion, and which mass is supported at the body of the sensor component by means of a spring structure, characterized in, that the arrangement comprises a phase detector (11), (49) such, that, in the arrangement, said mass is suspended by means of a spring suspension having non-orthogonal primary and secondary axes such, that a test activation in phase with the primary motion is induced in a detection resonator, and the angular velocity to be measured is phase-sensitively detected by means of the phase detector from the phase difference between the primary motion and the secondary motion.

9. Arrangement according to claim 8, characterized in, that the arrangement additionally comprises a phase-shifter (13), (50) for shifting the phase of one of the primary motion or secondary motion signals by 90 degrees.

10. Arrangement according to claim 8, characterized in, that the arrangement additionally comprises an amplifier (10), (12), (48), (50) for amplifying at least one of the primary motion or secondary motion signals.

11. Arrangement according to claim 8, characterized in, that the arrangement additionally comprises an XOR gate (49) and a comparator (48), 50) such, that the phase-sensitive detection is implemented by means of an XOR gate (49) such, that the primary motion and secondary motion signals, by means of a comparator (48), (50), are made into steep-edged pulse waves, which are conveyed to the XOR gate (49).

12. Arrangement according to claim 11, characterized in, that the arrangement additionally comprises means for delivering, as output of the phase-sensitive detection, a pulse width modulated signal proportional to the phase-shift between the signals.

13. Arrangement according to claim 12, characterized in, that the arrangement additionally comprises means for low-pass filtering of the pulse-width modulated signal proportional to the phase-shift between the signals, and for delivering an analog output signal as output of the phase-sensitive detection.

14. Arrangement according to claim 8, characterized in, that the arrangement comprises means for detecting the primary motion directly by means of a resistive coupling.

15. A vibrating micromechanical sensor of angular velocity, comprising at least one seismic mass and a moving electrode associated with the mass, which mass possesses a primary motion to be activated and, in addition to the primary motion, a second degree of freedom in relation to a detection axis nearly perpendicular to the primary motion, and which mass is supported at the body of the sensor component by means of a spring structure, characterized in, that said mass is suspended by means of a spring suspension having non-orthogonal primary and secondary axes such, that a test activation in phase with the primary motion is induced in a detection resonator, and in which the angular velocity to be measured in the sensor of angular velocity is detected phase-sensitively, by means of a phase detector, from the phase difference between the primary motion and the secondary motion.

16. Sensor of angular velocity according to claim 15, characterized in, that the sensor of angular velocity comprises means for phase-shifting one of the primary motion and secondary motion signals by 90 degrees.

17. Sensor of angular velocity according to claim 15, characterized in, that the sensor of angular velocity comprises means for amplifying at least one of the primary motion and secondary motion signals.

18. Sensor of angular velocity according to claim 15, 16, or 17, characterized in, that the sensor of angular velocity further comprises an XOR gate (49) and a comparator (48), (50) such, that the phase-sensitive detection is implemented by means of the XOR gate (49) such, that, by means of the comparator (48), (50), out of the primary and secondary motion signals, steep-edged pulse waves are made, which waves are conveyed to the XOR gate (49).

19. Sensor of angular velocity according to claim 18, characterized in, that the sensor of angular velocity further comprises means for delivering, as output of the phase-sensitive detection, a pulse-width modulated signal proportional to the phase-shift between the signals.

20. Sensor of angular velocity according to claim 19, characterized in, that the sensor of angular velocity further comprises means for low-pass filtering of the pulse-width modulated signal proportional to the phase-shift between the signals, and for delivering, as output of the phase-sensitive detection, an analog output signal.

21. Sensor of angular velocity according to claim 15, characterized in, that the sensor of angular velocity comprises means for detecting the primary motion directly by means of a resistive coupling.