MECHANICAL OSCILLATOR CONTROL ELECTRONICS

• US 20060238260A1
• Filed: 04/26/2005
• Published: 10/26/2006
• Est. Priority Date: 04/26/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Demma, Nick Anthony
• Granted Patent: US 7,443,257 B2
• Time in Patent Office: Days
• US Class Current: 331/10
• 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: Y10T 74/1229 Gyroscope control

Abstract

A control system for a mechanical oscillator having a sinusoidal drive signal with a frequency that is a fractional multiple of a frequency of a signal of the mechanical oscillator. The drive signal may be in phase and in registration with the signal from the mechanical oscillator. A sense signal may be picked off from the oscillator and be demodulated to obtain a parameter sensed by the oscillator. The drive signal to the oscillator may be selected or blanked out while receiving and demodulating the sense signal.

Claims

1. A mechanical oscillator control system comprising:

a first phase locked loop connected to a mechanical oscillator pick off; and

a second phase locked loop connected to an output of the first phase locked loop; and

wherein the second phase locked loop may output a sinusoidal wave signal having a fractional multiple frequency of a signal from the mechanical oscillator motor pick off.

2. The system of claim 1, wherein the sinusoidal wave signal and the signal from the mechanical oscillator pick off are registered relative to each other.

3. The system of claim 2, wherein an edge or cross-over point of the sinusoidal wave signal coincides with an edge or cross-point of the signal from the mechanical oscillator pick off.

4. The system of claim 1, further comprising:

a demodulator connected to a mechanical oscillator sense pick off; and

a switch connected to an output of the second phase locked loop and to a drive input of the mechanical oscillator.

5. The system of claim 4, further comprising:

a controller connected to the demodulator and to the switch; and

wherein;

the switch is closed so that the second phase locked loop may provide the sinusoidal wave signal to the drive input of the mechanical oscillator; and

the switch may be opened so that the demodulator can read a signal from the mechanical oscillator sense pick off.

6. The system of claim 5, wherein an output signal of the first phase locked loop has an edge that coincides with an edge of a signal from the mechanical oscillator pick off.

7. The system of claim 6, further comprising:

a plurality of switches; and

wherein the switches are actuated at an edge or cross-over point of the sinusoidal wave signal.

8. The system of claim 7, wherein instructions of the controller may cycle at an edge or cross-over point of the sinusoidal wave signal.

9. A method for sinusoidal mechanical oscillator control comprising:

picking off a first signal having a first frequency from a mechanical oscillator;

providing a second signal having a second frequency that is a fraction of the first frequency, and is phase locked to the first signal;

providing sinusoidal wave signal that is phase locked to the second signal; and

providing the sinusoidal wave signal to a drive input of the mechanical oscillator.

10. The method of claim 9, further comprising assuring that the sinusoidal wave signal is in registration with the first signal in that an edge or cross-over point of the sinusoidal wave signal is aligned in time with an edge or cross-over point of the first signal.

11. The method of claim 10, further comprising:

picking off a sense signal from the mechanical oscillator; and

demodulating the sense signal to obtain a sensed parameter.

12. The method of claim 11, further comprising switching off the sinusoidal signal to the drive input of the mechanical oscillator when demodulating the sense signal.

13. The method of claim 12, wherein the mechanical oscillator is a vibratory mass gyroscope.

14. The method of claim 12, wherein the mechanical oscillator is fabricated with MEMS technology.

15. A gyroscope control system comprising:

a first phase locked loop connected to a first output of the gyroscope;

a second phase locked loop connected to an output of the first phase locked loop; and

a signal selector connected to an output of the second phase locked loop and to an input of the gyroscope.

16. The system of claim 15, wherein:

the output of the gyroscope is a pick off signal having a frequency f;

the output of the first phase locked loop is a signal at a frequency f/2 which is phase locked to the pick off signal; and

the output of the second phase locked loop is a sine wave at a frequency f/2 phase locked to the signal at the output of the first phase locked loop.

17. The system of claim 16, further comprising:

a demodulator connected to a second output of the gyroscope; and

wherein;

the demodulator occasionally reads a gyroscope rotation rate from a signal from the second output of the gyroscope; and

the signal selector prevents a signal from the output of the second phase locked loop from going to the input of the gyroscope when the demodulator reads a gyroscope rotation rate from a signal of the second output of the gyroscope.

18. The system of claim 17, wherein:

the first output of the gyroscope may provide a pick off signal; and

the input of the gyroscope may receive a driver signal for the gyroscope.

19. The system of claim 18, wherein:

the first phase locked loop comprises;

a phase detector connected to the first output of the gyroscope;

a loop filter connected to the phase detector; and

a voltage controlled oscillator connected to the loop filter and to the second phase locked loop; and

the second phase locked loop comprises;

a phase detector connected to an output of the voltage controlled oscillator;

a loop filter connected to the phase detector; and

a sinusoidal voltage controlled oscillator connected to the loop filter and to the signal selector.

20. The system of claim 19, wherein:

the output of the first phase locked loop may provide first and second signals locked to signals of the first output of the gyroscope;

the first signal has a frequency of f; and

the second frequency has a frequency of f/2.

21. The system of claim 20, wherein:

the first signal is a first switch signal;

the second signal is a second switch signal; and

each of the first and second switch signals has an edge that coincides with an edge of the gyroscope pick off signal.

22. The system of claim 21, wherein the sine wave has a cross-over point that coincides with the edge of the gyroscope pick off signal.

23. The system of claim 22, further comprising:

a controller connected to the demodulator and the signal selector; and

wherein the controller provides a signal to the signal selector to blank out the output of the second phase locked loop going to the input of the gyroscope when the demodulator reads a gyroscope rotation rate from the signal of the second output of the gyroscope.

24. A mechanical oscillator control system comprising:

an analog-to-digital converter having a mechanical oscillator pickoff input;

a digital signal processor connected to an output of the analog-to-digital converter; and

a digital-to-analog converter connected to an output of the digital signal processor, and having a mechanical oscillator drive output; and

wherein;

the digital signal processor is for providing a mechanical oscillator drive signal having a synthetically generated waveform, and for receiving a mechanical oscillator pickoff signal;

the mechanical oscillator drive signal has a fractional multiple frequency of the mechanical oscillator pickoff signal; and

the mechanical oscillator drive signal is in synch with the mechanical oscillator pickoff signal.

25. The system of claim 24, wherein:

the mechanical oscillator drive signal is synchronously in registration with the mechanical oscillator pickoff signal;

the mechanical oscillator is a vibratory gyroscope;

the mechanical oscillator drive signal is a motor drive signal; and

the mechanical oscillator pickoff signal is a motor pickoff signal.

26. The system of claim 24, wherein the digital signal processor comprises:

a numerically controlled fractional multiple frequency sine wave oscillator; and

a phase compensator connected to an output of the numerically controlled fractional multiple frequency sine wave oscillator and connected to an input of the digital-to-analog converter.

27. The system of claim 26, wherein the digital signal processor further comprises:

a first multiplier connected to the output of the analog-to-digital converter;

a numerically controlled cosine wave oscillator having an output connected to the first multiplier;

a first finite impulse filter connected to an output of the first multiplier;

a difference amplifier connected to an output of the first finite impulse filter;

an integrator connected to an output of the difference amplifier; and

a variable gain amplifier connected in between an output of the phase compensator and the input of the digital-to-analog converter, and connected to an output of the integrator.

28. The system of claim 27, wherein the digital signal processor further comprises:

a second multiplier connected to the output of the analog-to-digital converter;

a numerically controlled sine wave oscillator having an output connected to the second multiplier;

a loop filter connected to an output of the second multiplier; and

a second finite impulse filter connected to an output of the loop filter, and connected to an input of the numerically controlled sine wave oscillator and to an input of the numerically controlled cosine wave oscillator.