Angular rate producer with microelectromechanical system technology

• US 6,311,555 B1
• Filed: 11/17/1999
• Issued: 11/06/2001
• Est. Priority Date: 11/17/1999
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: McCall, Hiram, Lin, Ching-Fang
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/442,596
• Time in Patent Office: 720 Days
• Field of Search: 734/88, 735/040.2, 735/041.2, 735/041.6, 700/1, 700/73, 700/302, 700/303, 700/304, 701/1
• US Class Current: 73/488
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

An angular rate producer is provided for measuring vehicle angular rate, wherein high performance dither drive signal generation and angular sensing signal extracting means are provided for hands-on vibrating type angular rate detecting units, including tuning forks and vibrating strings to obtain highly accurate angular rate signals. The angular rate producer includes an vibrating type angular rate detecting unit for detecting angular rate via Corilois Effect; an interfacing circuitry for converting angular motion-induced signals from the vibrating type angular rate detecting unit into angular rate signals and converting inertial element dither motion signals from the vibrating type angular rate detecting unit into processible inertial element dither motion signals; and a digital processing system for locking the high-quality factor frequency and amplitude of the vibrating inertial elements in the vibrating type angular rate detecting unit by means of providing an electronic energy including dither drive signal for the vibrating type angular rate detecting unit using the processible inertial element dither motion signals.

Claims

1. An angular rate producer with microelectromechanical system technology for measuring a vehicle angular rate, comprising:

an angular rate detecting unit receiving dither drive signal to maintain an oscillation of at least one set of inertial element with constant momentum and producing angular motion-induced signals with respect to said vehicle angular rate and inertial element dither motion signals;

an interfacing means for converting said angular motion-induced signals from said angular rate detecting unit into consistent and repeatable angular rate signals that are proportional to said vehicle angular rate, and converting said inertial element dither motion signals from said angular rate detecting unit into digital element displacement signals with predetermined phase; and

a digital processing system for inputting said digital element displacement signals for producing said dither drive signal for locking high-quality factor frequency and amplitude of said oscillating inertial element in said angular rate detecting unit.

2. The angular rate producer, as recited in claim 1, wherein said angular rate detecting unit is a vibrating type angular rate detecting unit for detecting vehicle angular motions and outputting said angular motion-induced signals which are voltages proportional to angular rate and torque signals.

3. The angular rate producer, as recited in claim 1, wherein said angular rate detecting unit is a vibrating type angular rate detecting unit for detecting angular rate through Corilois Effect.

4. The angular rate producer, as recited in claim 3, wherein said vibrating type angular rate detecting unit receives dither drive signal to keep said inertial elements oscillating;

carrier reference oscillation signals, including capacitive pickoff excitation signals; and

displacement restoring signals, including electrostatic torque signals to maintain said inertial elements without offset to obtain improved sensing performance.

5. The angular rate producer, as recited in claim 4, wherein said vibrating type angular rate detecting unit detects angular motion of a vehicle in accordance with dynamic theory, that is Coriolis Effect, and outputs said angular motion-induced signals, including rate displacement signals which may be modulated carrier reference oscillation signals, and said inertial element dither motion signals, including dither displacement signals.

6. The angular rate producer, as recited in claim 3, wherein said angular rate detecting unit further includes an additional self-torque loops to maintain said inertial elements without offset to obtain improved sensing performance and receives said dither drive signal to keep said inertial elements oscillating, and said carrier reference oscillation signals, including capacitive pickoff excitation signals.

7. The angular rate producer, as recited in claim 6, wherein said vibrating type angular rate detecting unit detects angular motions of a vehicle in accordance with a dynamic theory, that is Coriolis Effect, and outputs torque signals, and said inertial element dither motion signals, including dither displacement signals.

8. The angular rate producer, as recited in claim 1, 2 or 3, wherein said digital processing system receives said digital inertial element displacement signals with known phase from said interfacing circuitry for finding frequencies which have highest Quality Factor (Q) Values, locking said frequencies, and locking an amplitude to produce said dither drive signal, including high frequency sinusoidal signals with a precise amplitude, to said angular rate detecting unit to keep said inertial elements oscillating at a predetermined resonant frequency.

9. The angular rate producer, as recited in claim 1, 2 or 3, wherein said interfacing means comprises an interfacing circuitry which comprises:

an oscillator for providing reference pickoff signals;

a dither motion control circuitry for receiving said inertial element dither motion signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator, and producing said digital inertial element displacement signals with known phase; and

an angle signal loop circuitry for receiving said angular motion-induced signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator, and transforming said angular motion-induced signals into said angular rate signals.

10. The angular rate producer, as recited in claim 8, wherein said interfacing means comprises an interfacing circuitry which comprises:

an oscillator for providing reference pickoff signals;

a dither motion control circuitry for receiving said inertial element dither motion signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator, and producing said digital inertial element displacement signals with known phase; and

an angle signal loop circuitry for receiving said angular motion-induced signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator, and transforming said angular motion-induced signals into said angular rate signals.

11. The angular rate producer, as recited in claim 9, wherein said angle rate signal loop circuitry comprises:

a high pass filter circuit, which is connected to said vibrating type angular rate detecting unit, for receiving said angular motion-induced signals and removing low frequency noise of said angular motion-induced signals, which are AC voltage signals output from vibrating type angular rate detecting unit, to form filtered angular motion-induced signals;

a voltage amplifier circuit for amplifying said filtered angular motion-induced signals to an extent of at least 100 milivolts to form amplified angular motion-induced signals;

an amplifier and summer circuit for subtracting a difference between said angle rates of said amplified angular motion-induced signals to produce a differential angle rate signal;

a demodulator, which is connected to said amplifier and summer circuit, for extracting an amplitude of said in-phase differential angle rate signal from said differential angle rate signal and said capacitive pickoff excitation signals from said oscillator; and

a low-pass filter, which connected to said demodulator, for removing a high frequency noise of said amplitude signal of said in-phase differential angle rate signal to form said angular rate signal output.

12. The angular rate producer, as recited in claim 10, wherein said angle rate signal loop circuitry comprises:

a high pass filter circuit, which is connected to said vibrating type angular rate detecting unit, for receiving said angular motion-induced signals and removing low frequency noise of said angular motion-induced signals, which are AC voltage signals output from vibrating type angular rate detecting unit, to form filtered angular motion-induced signals;

a voltage amplifier circuit for amplifying said filtered angular motion-induced signals to an extent of at least 100 milivolts to form amplified angular motion-induced signals;

an amplifier and summer circuit for subtracting a difference between said angle rates of said amplified angular motion-induced signals to produce a differential angle rate signal;

a demodulator, which is connected to said amplifier and summer circuit, for extracting an amplitude of said in-phase differential angle rate signal from said differential angle rate signal and said capacitive pickoff excitation signals from said oscillator; and

a low-pass filter, which connected to said demodulator, for removing a high frequency noise of said amplitude signal of said in-phase differential angle rate signal to form said angular rate signal output.

13. The angular rate producer, as recited in claim 11, wherein said angle rate signal loop circuitry further comprises an integrator connected with said low-pass filter for integrating said angular rate signal to form a displacement restoring signal, and a driver amplifier connected to said integrator for amplifying said displacement restoring signal to form a driving signal, including a re-torque signal, to said vibrating type angular rate detecting unit to maintain said inertial elements of said vibrating type angular rate detecting unit without offset.

14. The angular rate producer, as recited in claim 12, wherein said angle rate signal loop circuitry further comprises an integrator connected with said low-pass filter for integrating said angular rate signal to form a displacement restoring signal, and a driver amplifier connected to said integrator for amplifying said displacement restoring signal to form a driving signal, including a re-torque signal, to said vibrating type angular rate detecting unit to maintain said inertial elements of said vibrating type angular rate detecting unit without offset.

15. The angular rate producer, as recited in claim 9, wherein said dither motion control circuitry further comprises:

a trans impedance amplifier circuit, which is connected to said vibrating type angular rate detecting unit, for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

an amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal; and

an analog/digital converter, which is connected to said low-pass filter, for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

16. The angular rate producer, as recited in claim 10, wherein said dither motion control circuitry further comprises:

a trans impedance amplifier circuit, which is connected to said vibrating type angular rate detecting unit, for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

an amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal; and

an analog/digital converter, which is connected to said low-pass filter, for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

17. The angular rate producer, as recited in claim 11, wherein said dither motion control circuitry further comprises:

a trans impedance amplifier circuit, which is connected to said vibrating type angular rate detecting unit, for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

an amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal; and

an analog/digital converter, which is connected to said low-pass filter, for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

18. The angular rate producer, as recited in claim 12, wherein said dither motion control circuitry further comprises:

a trans impedance amplifier circuit, which is connected to said vibrating type angular rate detecting unit, for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

an amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal; and

an analog/digital converter, which is connected to said low-pass filter, for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

19. The angular rate producer, as recited in claim 13, wherein said dither motion control circuitry further comprises:

a trans impedance amplifier circuit, which is connected to said vibrating type angular rate detecting unit, for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

an amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal; and

an analog/digital converter, which is connected to said low-pass filter, for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

20. The angular rate producer, as recited in claim 14, wherein said dither motion control circuitry further comprises:

a trans impedance amplifier circuit, which is connected to said vibrating type angular rate detecting unit, for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

an amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal; and

an analog/digital converter, which is connected to said low-pass filter, for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

21. The angular rate producer, as recited in claim 1, wherein said oscillation of said inertial elements residing inside said vibrating type angular rate detecting unit is driven by a high frequency sinusoidal signal with precise amplitude.

22. The angular rate producer, as recited in claim 20, wherein said oscillation of said inertial elements residing inside said vibrating type angular rate detecting unit is driven by a high frequency sinusoidal signal with precise amplitude.

23. The angular rate producer, as recited in claim 20, wherein said digitized low frequency inertial element displacement signal is first represented in term of a spectral content thereof by using discrete Fast Fourier Transform (FFT), which is an efficient algorithm for computing discrete Fourier transform (DFT), which dramatically reduces said computation load imposed by said DFT, which is used to approximate said Fourier transform of a discrete signal.

24. The angular rate producer, as recited in claim 23, wherein after said digitized low frequency inertial element displacement signals are represented in terms of their spectral content by using discrete Fast Fourier Transform (FFT), Q (Quality Factor) Analysis is applied to their spectral content to determine said frequency with global maximal Q value which is a function of basic geometry, material properties, and ambient operating conditions, said vibration of said inertial elements of said vibrating type angular rate detecting unit at said frequency with global maximal Q value resulting in minimal power consumption and canceling terms that affect said excited mode.

25. The angular rate producer, as recited in claim 24, further comprising a phase-locked loop and D/A converter for controlling and stabilizing said selected frequency and amplitude.

26. The angular rate producer, as recited in claim 16, wherein, in order to find said frequencies having highest Quality Factor (Q) values, said digital processing system includes:

a discrete Fast Fourier Transform (FFT) module, which is arranged for transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

a memory array of frequency and amplitude data module for receiving said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

a maxima detection logic module for partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing those frequencies with said largest amplitudes in said local segments of said frequency spectrum;

a Q analysis and selection logic module, which is adapted for performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein said range for computing bandwidth is between +−

½

of said peek for each maximum frequency point.

27. The angular rate producer, as recited in claim 18, wherein, in order to find said frequencies having highest Quality Factor (Q) values, said digital processing system includes:

a discrete Fast Fourier Transform (FFT) module, which is arranged for transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

a memory array of frequency and amplitude data module for receiving said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

a maxima detection logic module for partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing those frequencies with said largest amplitudes in said local segments of said frequency spectrum;

a Q analysis and selection logic module, which is adapted for performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein said range for computing bandwidth is between +−

½

of said peek for each maximum frequency point.

28. The angular rate producer, as recited in claim 20, wherein, in order to find said frequencies having highest Quality Factor (Q) values, said digital processing system includes:

a discrete Fast Fourier Transform (FFT) module, which is arranged for transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

a memory array of frequency and amplitude data module for receiving said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

a maxima detection logic module for partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing those frequencies with said largest amplitudes in said local segments of said frequency spectrum;

a Q analysis and selection logic module, which is adapted for performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein said range for computing bandwidth is between +−

{fraction (1/2+L )} of said peek for each maximum frequency point.

29. The angular rate producer, as recited in claim 8, wherein said digital processing system further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter.

30. The angular rate producer, as recited in claim 26, wherein said digital processing system further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter.

31. The angular rate producer, as recited in claim 27, wherein said digital processing system further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter.

32. The angular rate producer, as recited in claim 28, wherein said digital processing system further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter.

33. The angular rate producer, as recited in claim 8, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

34. The angular rate producer, as recited in claim 26, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

35. The angular rate producer, as recited in claim 27, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

36. The angular rate producer, as recited in claim 28, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

37. The angular rate producer, as recited in claim 30, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

38. The angular rate producer, as recited in claim 31, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

39. The angular rate producer, as recited in claim 32, wherein said digital processing system further includes a D/A converter for processing said selected amplitude to form said dither drive signal with correct amplitude, and an amplifier for generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

40. The angular rate producer, as recited in claim 13, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

41. The angular rate producer, as recited in claim 14, wherein said angle rate signal loop circuitry firer comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

42. The angular rate producer, as recited in claim 19, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

43. The angular rate producer, as recited in claim 20, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

44. The angular rate producer, as recited in claim 23, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

45. The angular rate producer, as recited in claim 28, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

46. The angular rate producer, as recited in claim 32, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

47. The angular rate producer, as recited in claim 36, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

48. The angular rate producer, as recited in claim 39, wherein said angle rate signal loop circuitry further comprises:

an amplifier and summer circuit, which is connected to a torque amplifier of said vibrating type angular rate detecting unit, for amplifying said torque signals and enhancing said sensitivity for more than ten times;

a high-pass filter circuit, which is connected to said amplifier and summer circuit, for removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

a demodulator circuit, which is connected to said high-pass filter circuit, for receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal from said high-pass filter circuit, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

a low-pass filter, which is connected to said demodulator circuit, for removing high frequency noise from said inertial element rotation signal input thereto to form a low frequency inertial element rotation signal as output angular rate signals.

49. An angular rate producing process for measuring a vehicle angular rate, comprising the steps of:

(a) receiving dither drive signal to maintain an oscillation of at least one set of inertial elements in an angular rate detecting unit with constant momentum, and producing angular motion-induced signals with respect to said vehicle angular rate and inertial element dither motion signals;

(b) converting said angular motion-induced signals from said angular rate detecting unit in an interfacing circuitry into consistent and repeatable angular rate signals that are proportional to said vehicle angular rate, and converting said inertial element dither motion signals from said angular rate detecting unit in said interfacing circuitry into digital element displacement signals with predetermined phase; and

(c) inputting said digital element displacement signals into a digital processing system and producing said dither drive signal for locking high-quality factor frequency and amplitude of said oscillating inertial elements in said angular rate detecting unit.

50. The angular rate producing process, as recited in claim 49, wherein said angular rate detecting unit is a vibrating type angular rate detecting unit for detecting vehicle angular motions through Corilois Effect and outputting said angular motion-induced signals which are voltage proportional to angular rate and torque signals.

51. The angular rate producer, as recited in claim 50, wherein said step (c) comprises the steps of:

(c-1) receiving said digital inertial element displacement signals with known phase from said interfacing circuitry for finding frequencies which have highest Quality Factor (Q) Values,

(c-2) locking said frequencies, and

(c-3) locking an amplitude to produce said dither drive signal, including high frequency sinusoidal signals with a precise amplitude, to said angular rate detecting unit to keep said inertial elements oscillating at a predetermined resonant frequency.

52. The angular rate producer, as recited in claim 50, wherein said step (b) comprises the steps of:

(b-1) providing reference pickoff signals by an oscillator;

(b-2) receiving said inertial element dither motion signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator in a dither motion control circuitry and producing said digital inertial element displacement signals with known phase; and

(b-3) receiving said angular motion-induced signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator in an angle signal loop circuitry, and transforming said angular motion-induced signals into said angular rate signals.

53. The angular rate producer, as recited in claim 51, wherein said step (b) comprises the steps of:

(b-1) providing reference pickoff signals by an oscillator;

(b-2) receiving said inertial element dither motion signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator in a dither motion control circuitry and producing said digital inertial element displacement signals with known phase; and

(b-3) receiving said angular motion-induced signals from said vibrating type angular rate detecting unit and said reference pickoff signals from said oscillator in an angle signal loop circuitry, and transforming said angular motion-induced signals into said angular rate signals.

54. The angular rate producer, as recited in claim 53, wherein said steps (b-3) further comprises the steps of:

(b-3-1) receiving said angular motion-induced signals by a high-pass filter circuit connected to said vibrating type angular rate detecting unit and removing low frequency noise of said angular motion-induced signals, which are AC voltage signals output from vibrating type angular rate detecting unit, to form filtered angular motion-induced signals;

(b-3-2) amplifying said filtered angular motion-induced signals by a voltage amplifier circuit to an extent of at least 100 milivolts to form amplified angular motion-induced signals;

(b-3-3) subtracting a difference between said angle rates of said amplified angular motion-induced signals in an amplifier and summer circuit to produce a differential angle rate signal;

(b-3-4) extracting an amplitude of said in-phase differential angle rate signal from said differential angle rate signal and said capacitive pickoff excitation signals from said oscillator in a demodulator which is connected to said amplifier and summer circuit; and

(b-3-5) removing a high frequency noise of said amplitude signal of said in-phase differential angle rate signal in a low-pass filter connected to said demodulator to form said angular rate signal output.

55. The angular rate producer, as recited in claim 54, wherein said step (b-3) further comprises the steps of:

(b-3-6) integrating said angular rate signal by an integrator connected with said low-pass filter to form a displacement restoring signal, and

(b-3-7) amplifying said displacement restoring signal by a driver amplifier connected to said integrator to form a driving signal, including a re-torque signal, to said vibrating type angular rate detecting unit to maintain said inertial elements of said vibrating type angular rate detecting unit without offset.

56. The angular rate producing process, as recited in claim 53, wherein said step (b-2) further comprises the steps of:

(b-2-1) changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

(b-2-2) amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

(b-2-3) removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

(b-2-4) receiving said capacitive pickoff excitation signals as phase reference signals from said oscillator and said filtered dither displacement differential signal and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

(b-2-5) removing high frequency noise from said inertial element displacement signal to form a low frequency inertial element displacement signal; and

(b-2-6) converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

57. The angular rate producing process, as recited in claim 54, wherein said step (b-2) further comprises the steps of:

(b-2-1) changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

(b-2-2) amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

(b-2-3) removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

(b-2-4) receiving said capacitive pickoff excitation signals as phase reference signals from said oscillator and said filtered dither displacement differential signal and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

(b-2-5) removing high frequency noise from said inertial element displacement signal to form a low frequency inertial element displacement signal; and

(b-2-6) converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

58. The angular rate producing process, as recited in claim 55, wherein said step (b-2) further comprises the steps of:

(b-2-1) changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs;

(b-2-2) amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

(b-2-3) removing residual dither drive signal and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

(b-2-4) receiving said capacitive pickoff excitation signals as phase reference signals from said oscillator and said filtered dither displacement differential signal and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

(b-2-5) removing high frequency noise from said inertial element displacement signal to form a low frequency inertial element displacement signal; and

(b-2-6) converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal.

59. The angular rate producing process, as recited in claim 58, wherein said digitized low frequency inertial element displacement signal is first represented in term of a spectral content thereof by using discrete Fast Fourier Transform (FFT), which is an efficient algorithm for computing discrete Fourier transform (DFT), which dramatically reduces said computation load imposed by said DFT, which is used to approximate said Fourier transform of a discrete signal.

60. The angular rate producing process, as recited in claim 59, further comprising an additional step of controlling and stabilizing said selected frequency and amplitude.

61. The angular rate producing process, as recited in claim 50, wherein said step (c-1) further comprises the steps of:

(3-1-1) transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

(3-1-2) receiving said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

(3-1-3) partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing those frequencies with said largest amplitudes in said local segments of said frequency spectrum;

(3-1-4) performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein said range for computing bandwidth is between +−

½

of said peek for each maximum frequency point.

62. The angular rate producing process, as recited in claim 58, wherein said step (c-1) further comprises the steps of:

(3-1-1) transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

(3-1-2) receiving said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

(3-1-3) partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing those frequencies with said largest amplitudes in said local segments of said frequency spectrum;

(3-1-4) performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein said range for computing bandwidth is between +−

½

of said peek for each maximum frequency point.

63. The angular rate producing process, as recited in claim 61, wherein said step (3-2) further comprises the steps of (3-2-1) rejecting noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter.

64. The angular rate producing process, as recited in claim 62, wherein said step (3-2) further comprises the steps of (3-2-1) rejecting noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter.

65. The angular rate producing process, as recited in claim 61, wherein said step (3-2) further comprises the steps of processing said selected amplitude to form said dither drive signal with correct amplitude, and generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

66. The angular rate producing process, as recited in claim 62, wherein said step (3-2) further comprises the steps of processing said selected amplitude to form said dither drive signal with correct amplitude, and generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

67. The angular rate producing process, as recited in claim 63, wherein said step (3-2) further comprises the steps of processing said selected amplitude to form said dither drive signal with correct amplitude, and generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

68. The angular rate producing process, as recited in claim 64, wherein said step (3-2) further comprises the steps of processing said selected amplitude to form said dither drive signal with correct amplitude, and generating and amplifying said dither drive signal to said angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

69. The angular rate producing process, as recited in any of the claims 56 to 68, wherein said step (2-2) further comprises the steps of:

(b-2-7) amplifying said torque signals and enhancing said sensitivity for more than ten times;

(b-2-8) removing residual drive signals and noise from said torque signal to form a filtered torque drive differential signal;

(b-2-9) receiving said carrier reference signals as phase reference signals from said oscillator and said filtered torque drive differential signal, and extracting said in-phase portion of said filtered torque drive differential signal to produce an inertial element rotation rate signal with known phase; and

(b-2-10) removing high frequency noise from said inertial element rotation signal to form a low frequency inertial element rotation signal as output angular rate signals.