Microelectromechanical system for measuring angular rate
DC CAFC
First Claim
Patent Images
1. A microelectromechanical system (MEMS) for measuring angular rate of a carrier, comprising:
- an angular rate sensor unit receiving dither driver signals, capacitive pickoff excitation signals and a displacement restoring signal and outputting angle rate signals in response to motion of said carrier and dither motion signals;
a central circuitry receiving said angle rate signals in response to said motion of said carrier and said dither motion signals and outputting angular rate signals and digital low frequency inertial element displacement signals; and
a digital signal processing system analyzing said digital low frequency inertial element displacement signals and feeding back said dither driver signals to said angular rate sensor unit.
7 Assignments
Litigations
1 Petition
Accused Products
Abstract
A microelectromechanical system (MEMS) for measuring angular rate of a carrier includes an angular rate sensor unit, microelectronic circuitry, and signal processing to obtain highly accurate, sensitive, stable angular rate measurements of the carrier under dynamic environments. Wherein, the angular rate sensor unit receives dither driver signals, capacitive pickoff excitation signals, and displacement restoring signals to output angle rate signals in response to the motion of the carrier and dither motion signals; the central circuitry receives the angle rate signals in response to the motion of the carrier and dither motion signals to output angular rate signals and digital low frequency inertial element displacement signals; a digital signal processing system analyzes digital low frequency inertial element displacement signals to feed back the dither drive signals to the angular rate sensor unit.
117 Citations
16 Claims
-
1. A microelectromechanical system (MEMS) for measuring angular rate of a carrier, comprising:
-
an angular rate sensor unit receiving dither driver signals, capacitive pickoff excitation signals and a displacement restoring signal and outputting angle rate signals in response to motion of said carrier and dither motion signals;
a central circuitry receiving said angle rate signals in response to said motion of said carrier and said dither motion signals and outputting angular rate signals and digital low frequency inertial element displacement signals; and
a digital signal processing system analyzing said digital low frequency inertial element displacement signals and feeding back said dither driver signals to said angular rate sensor unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
a silicon substrate;
two proof masses which is arranged to be caused a oscillation out of plane by a Coriolis force to sense said motion of said carrier in accordance with Coriolis effect three stators connected with said silicon substrate, wherein one of said stators is connected between inner sides of said two proof masses through two comb drives respectively while other two of said stators are connected with outer sides of said two proof masses through another two comb drives;
a first anchor pad, which is connected with said silicon substrate;
two second anchor pads, which are connected with said silicon substrate; and
a first set and a second set of anchor points connected with said silicon substrate, wherein said first set of anchor points is scattered one end of said two proof masses and connected with said first anchor pad through a first set of beam strings, and said second set of anchor points is scattered another end of said two proof masses and connected with said second anchor pads through a second set of beam strings, so as to enhance and stabilize said oscillation of said two proof masses.
-
-
3. The microelectromechanical system, as recited in claim 1, wherein said central circuitry comprises a dither motion control circuitry and an angle rate signal loop circuitry.
-
4. The microelectromechanical system, as recited in claim 2, wherein said central circuitry comprises a dither motion control circuitry and an angle rate signal loop circuitry.
-
5. The microelectromechanical system, as recited in claim 3, wherein said dither motion control circuitry comprises:
-
a trans impedance amplifier circuit, which is connected to said angular rate sensor unit, changing an 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 a displacement between inertial elements and anchor combs;
a first amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, amplifying said two dither displacement signals by at least ten times and enhancing a 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 first high-pass filter circuit, which is connected to said first amplifier and summer circuit, removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;
a demodulator circuit, which is connected to said first high-pass filter circuit, receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said first high-pass filter, and extracting an in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with a known phase;
a first low-pass filter, which is connected to said demodulator circuit, removing a high frequency noise from said inertial element displacement signal inputted thereto to form a filtered low frequency inertial element displacement signal with a bandwidth less than 3000 Hz;
an amplifier, which is connected with said first low-pass filter, amplifying said filtered low frequency inertial element displacement signal; and
an analog/digital converter, which is connected to said amplifier, converting said filtered low frequency inertial element displacement signal that is an analog signal to produce a digitized filtered low frequency inertial element displacement signal as a digital sampled signal.
-
-
6. The microelectromechanical system, as recited in claim 4, wherein said dither motion control circuitry comprises:
-
a trans impedance amplifier circuit, which is connected to said angular rate sensor unit, changing an 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 a displacement between inertial elements and anchor combs;
a first amplifier and summer circuit, which is connected to said trans impedance amplifier circuit, amplifying said two dither displacement signals by at least ten times and enhancing a 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 first high-pass filter circuit, which is connected to said first amplifier and summer circuit, removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;
a demodulator circuit, which is connected to said first high-pass filter circuit, receiving said capacitive pickoff excitation signals as phase reference signals from an oscillator and said filtered dither displacement differential signal from said first high-pass filter, and extracting an in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with a known phase;
a first low-pass filter, which is connected to said demodulator circuit, removing a high frequency noise from said inertial element displacement signal inputted thereto to form a filtered low frequency inertial element displacement signal with a bandwidth less than 3000 Hz;
an amplifier, which is connected with said first low-pass filter, amplifying said filtered low frequency inertial element displacement signal; and
an analog/digital converter, which is connected to said amplifier, converting said filtered low frequency inertial element displacement signal that is an analog signal to produce a digitized filtered low frequency inertial element displacement signal as a digital sampled signal.
-
-
7. The microelectromechanical system, as recited in claim 3, wherein said angle rate signal loop circuitry comprises:
-
a second high-pass filter circuit, which is connected to said angular rate sensor unit, removing low frequency noise of said angle rate signals which are voltage signals outputted from said angular rate sensor unit thereto to form filtered angle rate signals;
a voltage amplifier circuit, which is connected to said second high-pass filter circuit, amplifying said filtered angle rate signals to an extent of at least 100 milivolts to form amplified angle rate signals;
an amplifier and summer circuit, which is connected to said voltage amplifier circuit, subtracting a difference between angle rates of said amplified angle rate signals to produce a differential angle rate signal;
a demodulator, which is connected to said amplifier and summer circuit, extracting an amplitude of an in-phase differential angle rate signal from said differential angle rate signal and a reference signal from an oscillator;
a low-pass filter, which is connected to said demodulator, removing high frequency noises of an amplitude signal of said in-phase differential angle rate signal to form an angular rate signal output;
an integrator, which is connected with said low-pass filter, integrating said angular rate signal to form a displacement restoring signal without an offset; and
a driver amplifier, which is connected to said integrator, amplifying said displacement restoring signal without said offset to form a driving signal to said angular rate sensor unit.
-
-
8. The microelectromechanical system, as recited in claim 4, wherein said angle rate signal loop circuitry comprises:
-
a second high-pass filter circuit, which is connected to said angular rate sensor unit, removing low frequency noise of said angle rate signals which are voltage signals outputted from said angular rate sensor unit thereto to form filtered angle rate signals;
a voltage amplifier circuit, which is connected to said second high-pass filter circuit, amplifying said filtered angle rate signals to an extent of at least 100 milivolts to form amplified angle rate signals;
an amplifier and summer circuit, which is connected to said voltage amplifier circuit, subtracting a difference between angle rates of said amplified angle rate signals to produce a differential angle rate signal;
a demodulator, which is connected to said amplifier and summer circuit, extracting an amplitude of an in-phase differential angle rate signal from said differential angle rate signal and a reference signal from an oscillator;
a low-pass filter, which is connected to said demodulator, removing high frequency noises of an amplitude signal of said in-phase differential angle rate signal to form an angular rate signal output;
an integrator, which is connected with said low-pass filter, integrating said angular rate signal to form a displacement restoring signal without an offset; and
a driver amplifier, which is connected to said integrator, amplifying said displacement restoring signal without said offset to form a driving signal to said angular rate sensor unit.
-
-
9. The microelectromechanical system, as recited in claim 5, wherein said angle rate signal loop circuitry comprises:
-
a second high-pass filter circuit, which is connected to said angular rate sensor unit, removing low frequency noise of said angle rate signals which are voltage signals outputted from said angular rate sensor unit thereto to form filtered angle rate signals;
a voltage amplifier circuit, which is connected to said second high-pass filter circuit, amplifying said filtered angle rate signals to an extent of at least 100 milivolts to form amplified angle rate signals;
an amplifier and summer circuit, which is connected to said voltage amplifier circuit, subtracting a difference between angle rates of said amplified angle rate signals to produce a differential angle rate signal;
a demodulator, which is connected to said amplifier and summer circuit, extracting an amplitude of an in-phase differential angle rate signal from said differential angle rate signal and a reference signal from said oscillator;
a low-pass filter, which is connected to said demodulator, removing high frequency noises of an amplitude signal of said in-phase differential angle rate signal to form an angular rate signal output;
an integrator, which is connected with said low-pass filter, integrating said angular rate signal to form a displacement restoring signal without an offset; and
a driver amplifier, which is connected to said integrator, amplifying said displacement restoring signal without said offset to form a driving signal to said angular rate sensor unit.
-
-
10. The microelectromechanical system, as recited in claim 6, wherein said angle rate signal loop circuitry comprises:
-
a second high-pass filter circuit, which is connected to said angular rate sensor unit, removing low frequency noise of said angle rate signals which are voltage signals outputted from said angular rate sensor unit thereto to form filtered angle rate signals;
a voltage amplifier circuit, which is connected to said second high-pass filter circuit, amplifying said filtered angle rate signals to an extent of at least 100 milivolts to form amplified angle rate signals;
an amplifier and summer circuit, which is connected to said voltage amplifier circuit, subtracting a difference between angle rates of said amplified angle rate signals to produce a differential angle rate signal;
a demodulator, which is connected to said amplifier and summer circuit, extracting an amplitude of an in-phase differential angle rate signal from said differential angle rate signal and a reference signal from said oscillator;
a low-pass filter, which is connected to said demodulator, removing high frequency noises of an amplitude signal of said in-phase differential angle rate signal to form an angular rate signal output;
an integrator, which is connected with said low-pass filter, integrating said angular rate signal to form a displacement restoring signal without an offset; and
a driver amplifier, which is connected to said integrator, amplifying said displacement restoring signal without said offset to form a driving signal to said angular rate sensor unit.
-
-
11. The microelectromechanical system, as recited in claim 5, wherein said digital signal processing system comprises:
-
a discrete Fast Fourier Transform (FFT) module, receiving said digitized filtered low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with frequency spectrum of said inertial element displacement signal inputted;
a memory array of frequency and amplitude data module, receiving said amplitude data with said frequency spectrum to form an array of said amplitude data with said frequency spectrum;
a maxima detection logic module, processing said array of said amplitude data with said frequency spectrum to choose frequencies having largest amplitudes in a local segment of said frequency spectrum from said array of said amplitude data;
an analysis and selection logic module to perform an analysis on said frequencies being chosen to select a selected frequency and a correct amplitude by computing a ratio of amplitude/area, wherein a frequency range for computing area is between +½ and
−
½
of a peek for each maximum frequency point;
a phase-lock loop served as a very narrow bandpass filter to reject noise of said frequency being selected to form one of said dither driver signals that contains said selected frequency;
a D/A converter, processing said amplitude being selected to form one of said dither driver signals that contains said correct amplitude; and
an amplifier generating and amplifying said dither driver signals to said angular rate sensor unit based on said dither driver signals containing said selected frequency and said correct amplitude.
-
-
12. The microelectromechanical system, as recited in claim 6, wherein said digital signal processing system comprises:
-
a discrete Fast Fourier Transform (FFT) module, receiving said digitized filtered low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with frequency spectrum of said inertial element displacement signal inputted;
a memory array of frequency and amplitude data module, receiving said amplitude data with said frequency spectrum to form an array of said amplitude data with said frequency spectrum;
a maxima detection logic module, processing said array of said amplitude data with said frequency spectrum to choose frequencies having largest amplitudes in a local segment of said frequency spectrum from said array of said amplitude data;
an analysis and selection logic module to perform an analysis on said frequencies being chosen to select a selected frequency and a correct amplitude by computing a ratio of amplitude/area, wherein a frequency range for computing area is between +½ and
−
½
of a peek for each maximum frequency point;
a phase-lock loop served as a very narrow bandpass filter to reject noise of said frequency being selected to form one of said dither driver signals that contains said selected frequency;
a D/A converter, processing said amplitude being selected to form one of said dither driver signals that contains said correct amplitude; and
an amplifier generating and amplifying said dither driver signals to said angular rate sensor unit based on said dither driver signals containing said selected frequency and said correct amplitude.
-
-
13. The microelectromechanical system, as recited in claim 7, wherein said digital signal processing system comprises:
-
a discrete Fast Fourier Transform (FFT) module, receiving said digitized filtered low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with frequency spectrum of said inertial element displacement signal inputted;
a memory array of frequency and amplitude data module, receiving said amplitude data with said frequency spectrum to form an array of said amplitude data with said frequency spectrum;
a maxima detection logic module, processing said array of said amplitude data with said frequency spectrum to choose frequencies having largest amplitudes in a local segment of said frequency spectrum from said array of said amplitude data;
an analysis and selection logic module to perform an analysis on said frequencies being chosen to select a selected frequency and a correct amplitude by computing a ratio of amplitude/area, wherein a frequency range for computing area is between +½ and
−
½
of a peek for each maximum frequency point;
a phase-lock loop served as a very narrow bandpass filter to reject noise of said frequency being selected to form one of said dither driver signals that contains said selected frequency;
a D/A converter, processing said amplitude being selected to form one of said dither driver signals that contains said correct amplitude; and
an amplifier generating and amplifying said dither driver signals to said angular rate sensor unit based on said dither driver signals containing said selected frequency and said correct amplitude.
-
-
14. The microelectromechanical system, as recited in claim 8, wherein said digital signal processing system comprises:
-
a discrete Fast Fourier Transform (FFT) module, receiving said digitized filtered low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with frequency spectrum of said inertial element displacement signal inputted;
a memory array of frequency and amplitude data module, receiving said amplitude data with said frequency spectrum to form an array of said amplitude data with said frequency spectrum;
a maxima detection logic module, processing said array of said amplitude data with said frequency spectrum to choose frequencies having largest amplitudes in a local segment of said frequency spectrum from said array of said amplitude data;
an analysis and selection logic module to perform an analysis on said frequencies being chosen to select a selected frequency and a correct amplitude by computing a ratio of amplitude/area, wherein a frequency range for computing area is between +½ and
−
½
of a peek for each maximum frequency point;
a phase-lock loop served as a very narrow bandpass filter to reject noise of said frequency being selected to form one of said dither driver signals that contains said selected frequency;
a D/A converter, processing said amplitude being selected to form one of said dither driver signals that contains said correct amplitude; and
an amplifier generating and amplifying said dither driver signals to said angular rate sensor unit based on said dither driver signals containing said selected frequency and said correct amplitude.
-
-
15. The microelectromechanical system, as recited in claim 9, wherein said digital signal processing system comprises:
-
a discrete Fast Fourier Transform (FFT) module, receiving said digitized filtered low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with frequency spectrum of said inertial element displacement signal inputted;
a memory array of frequency and amplitude data module, receiving said amplitude data with said frequency spectrum to form an array of said amplitude data with said frequency spectrum;
a maxima detection logic module, processing said array of said amplitude data with said frequency spectrum to choose frequencies having largest amplitudes in a local segment of said frequency spectrum from said array of said amplitude data;
an analysis and selection logic module to perform an analysis on said frequencies being chosen to select a selected frequency and a correct amplitude by computing a ratio of amplitude/area, wherein a frequency range for computing area is between +½ and
−
½
of a peek for each maximum frequency point;
a phase-lock loop served as a very narrow bandpass filter to reject noise of said frequency being selected to form one of said dither driver signals that contains said selected frequency;
a D/A converter, processing said amplitude being selected to form one of said dither driver signals that contains said correct amplitude; and
an amplifier generating and amplifying said dither driver signals to said angular rate sensor unit based on said dither driver signals containing said selected frequency and said correct amplitude.
-
-
16. The microelectromechanical system, as recited in claim 10, wherein said digital signal processing system comprises:
-
a discrete Fast Fourier Transform (FFT) module, receiving said digitized filtered low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with frequency spectrum of said inertial element displacement signal inputted;
a memory array of frequency and amplitude data module, receiving said amplitude data with said frequency spectrum to form an array of said amplitude data with said frequency spectrum;
a maxima detection logic module, processing said array of said amplitude data with said frequency spectrum to choose frequencies having largest amplitudes in a local segment of said frequency spectrum from said array of said amplitude data;
an analysis and selection logic module to perform an analysis on said frequencies being chosen to select a selected frequency and a correct amplitude by computing a ratio of amplitude/area, wherein a frequency range for computing area is between +½ and
−
½
of a peek for each maximum frequency point;
a phase-lock loop served as a very narrow bandpass filter to reject noise of said frequency being selected to form one of said dither driver signals that contains said selected frequency;
a D/A converter, processing said amplitude being selected to form one of said dither driver signals that contains said correct amplitude; and
an amplifier generating and amplifying said dither driver signals to said angular rate sensor unit based on said dither driver signals containing said selected frequency and said correct amplitude.
-
Specification
-
- Resources
Litigation Campaign Assessment
Thank you for your request. You will receive a custom alert email when the Litigation Campaign Assessment is available.
×
Litigation Data
-
Current AssigneeAmerican GNC Corporation
-
Original AssigneeAmerican GNC Corporation
-
InventorsMcCall, Hiram, Lin, Ching-Fang
-
Primary Examiner(s)KWOK, HELEN C
-
Application NumberUS09/662,438Time in Patent Office858 DaysField of Search735/041.2, 735/041.3, 735/041.4, 735/041.5, 735/041.6, 735/040.4, 702/145, 702/147, 700/1, 700/73, 700/302, 700/303, 700/304, 701/1US Class Current73/504.12CPC Class CodesG01C 19/5719 using planar vibrating mass...
