A Closed-Loop Control System for a Coriolis Resonant Gyroscope and a Method for Suppressing Feedthrough Noise

Abstract

This invention discloses a closed-loop control system for a Coriolis resonant gyroscope and a method for suppressing feedthrough noise, avoiding errors in the gyroscope control loop caused by feedthrough noise. The invention employs chopper excitation to reserve a sampling window free from feedthrough interference for the signal. Then, it controls the alternating operation of the excitation data selector and the readout data selector, and uses a digital low-pass filter to remove high-frequency chopper signals. This prevents feedthrough noise from being introduced into the Coriolis resonant gyroscope's control loop, improves the gyroscope's operating accuracy, and ensures the stability of the control system, making it of significant practical value.

Description

Technical Field

[0001] This invention belongs to the technical field of Coriolis resonant gyroscopes, specifically relating to a closed-loop control system for a Coriolis resonant gyroscope and a method for suppressing feedthrough noise. Background Technology

[0002] Micro-Electro-Mechanical Systems (MEMS) technology is a cutting-edge 21st-century technology built on micrometer / nanometer technology. It is used to design and manufacture tiny mechanical and electronic devices. The Coriolis gyroscope is a novel type of angular velocity sensor that has evolved with the development of MEMS technology. Compared to traditional gyroscopes, Coriolis gyroscopes are smaller, less expensive, and offer higher reliability and longer lifespan, making them widely used in consumer electronics and military / maritime applications.

[0003] Limitations in micromechanical fabrication processes lead to parasitic capacitance, known as feedthrough capacitance, between the excitation and readout electrodes of a Coriolis resonant gyroscope. This feedthrough capacitance creates an additional closed loop in the gyroscope's drive circuit, causing it to operate in an incorrect state. Currently, there are two main approaches to address this issue: The first involves improving the mechanical structure of the Coriolis resonant gyroscope, including using glass instead of silicon as the substrate material, changing push-pull drive to direct drive, and adding a bias electrode between the excitation and readout electrodes. The second approach uses circuit design to suppress feedthrough noise, such as increasing the polarization voltage, using high-frequency modulation, and parametric excitation. Structural improvements are time-consuming and costly; therefore, suppressing feedthrough noise through circuit design is more feasible. Increasing the polarization voltage and parametric excitation schemes have simple circuit structures and are easy to implement, but their feedthrough suppression is relatively low. Carrier modulation schemes can achieve higher feedthrough suppression ratios, but this requires a high-frequency carrier and diode demodulation, increasing high-frequency noise and reducing temperature stability. Furthermore, the loop amplifier circuit exhibits some nonlinearity. Therefore, these methods have certain limitations. Summary of the Invention

[0004] To address the aforementioned problems, this invention discloses a closed-loop control system for a Coriolis resonant gyroscope and a method for suppressing feedthrough noise. By using chopping excitation to reserve a sampling window for the signal without feedthrough interference, the alternating operation of the excitation data selector and the readout data selector is controlled, and a digital low-pass filter is used to remove high-frequency chopping signals. This avoids introducing feedthrough noise into the control loop of the Coriolis resonant gyroscope, improves the gyroscope's working accuracy, and ensures the stability of the control system.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for suppressing feedthrough noise in a Coriolis resonant gyroscope includes the following steps:

[0007] S1, use the excitation data selector to generate a chopper excitation signal, and reserve a sampling window for the signal without feedthrough interference;

[0008] S2 uses a D / A converter to convert the chopped digital signal into an analog signal, which is then used to excite the gyroscope;

[0009] S3 uses a C / V converter to convert the change in the internal capacitance of the gyroscope into a voltage quantity, while the feedthrough capacitor also participates in the conversion;

[0010] S4 uses an A / D converter to convert the voltage signal into a digital signal;

[0011] S5, use the readout data selector to select the A / D conversion result, retain only the sampled values ​​during the time period without feedthrough interference, at which time the effective signal is in chopped form;

[0012] S6 uses an effective chopper signal for low-pass processing to restore an ideal signal without feedpass interference.

[0013] Based on the above method, this invention designs a closed-loop control system for a Coriolis resonator gyroscope based on feedthrough noise suppression, including a first C / V converter, a second C / V converter, a first A / D converter, a second A / D converter, a drive control unit, a force feedback control unit, a numerically controlled oscillator, a first D / A converter, and a second D / A converter, wherein...

[0014] The first C / V converter is connected to the drive resonator of the gyroscope and is used to convert the change of the comb capacitance at the drive end of the gyroscope into an analog voltage. At the same time, the drive end coupling signal is also converted. The first A / D converter converts the drive analog voltage signal into a digital signal. The drive control unit controls the phase and amplitude of the drive excitation. The first D / A converter converts the drive excitation digital signal into an analog signal.

[0015] The second C / V converter is connected to the detection resonator of the Coriolis gyroscope and is used to convert the change in the comb capacitance of the gyroscope detection end into an analog voltage. At the same time, the detection end coupling signal is also converted. The second A / D converter converts the detected analog voltage signal into a digital signal. The force feedback control unit controls the force feedback signal. The second D / A converter converts the force feedback digital signal into an analog signal.

[0016] The numerically controlled oscillator generates two mutually orthogonal sinusoidal signals sin(ω). d t) and cos(ω) d t) is used both as the base signal for the gyroscope excitation signal and as the reference signal for the demodulator.

[0017] Preferably, the drive control unit is used to suppress drive-end feedthrough noise and control the phase and amplitude of the drive-end signal, including a first data selector, a second data selector, a first digital low-pass filter, a first digital demodulator, and a first PID control unit. The force feedback control unit is used to suppress detection-end feedthrough noise and suppress Coriolis and quadrature signals at the detection end, including a third data selector, a fourth data selector, a second digital low-pass filter, a second digital demodulator, and a second PID control unit.

[0018] The first data selector in T drive The third data selector maintains the output of the drive control unit during the time period and outputs a zero value at other times. drive The force feedback control unit maintains its output during the specified time period, and outputs a zero value at other times.

[0019] The second data selector in T sense The fourth data selector maintains the converted digital information of the first A / D converter during the time period and outputs a zero value at other times. sense The system retains the converted digital information of the second A / D converter during the specified time period and outputs zero values ​​at other times.

[0020] The first and second digital low-pass filters are used to restore the effective signal without feedthrough interference, and their cutoff frequencies are between the effective signal frequency and the chopping frequency.

[0021] The first and second digital demodulators are least mean square digital demodulators, and their demodulation reference is a mutually orthogonal sinusoidal signal output from a voltage-controlled oscillator, denoted as sin(ω). d t) and cos(ω) d For the first digital demodulator, t), with sin(ω) d The phase information of the driving signal can be calculated based on t), with cos(ω) as the reference. d The amplitude information of the driving signal can be calculated based on t). For the second digital demodulator, sin(ω) is used as the reference. d The Coriolis component of the detected signal can be calculated using t as a reference, with cos(ω) as the basis. d Using t as a reference, the orthogonal components of the detection signal can be calculated.

[0022] Preferably, the first C / V converter and the second C / V converter are charge amplifiers;

[0023] Preferably, the first A / D converter and the second A / D converter are successive approximation A / D converters;

[0024] Preferably, the switching frequencies of the first, second, third, and fourth data selectors are all on the order of 10 kilohertz, and the sampling rates of the first and second A / D converters are on the order of 100 kilohertz.

[0025] Preferably, the drive control unit and the force feedback control unit are implemented by a field-programmable gate array (FPGA).

[0026] The beneficial effects of this invention are:

[0027] (1) The method for suppressing feedthrough noise of a Coriolis resonator gyroscope based on chopper excitation provided by the present invention uses chopper excitation to reserve a sampling window for the signal without feedthrough interference, sets the signal to zero during the non-sampling time period to suppress feedthrough noise, uses a low-pass filter rate to filter out residual chopper components, and finally restores an effective signal with uniform sampling rate and no feedthrough noise interference.

[0028] (2) Based on the above method, a closed-loop control system for a Coriolis resonator gyroscope based on feedthrough noise suppression was built, realizing the amplitude and phase stabilization of the drive loop and the closed-loop detection and orthogonal correction of the force feedback control loop. Attached Figure Description

[0029] Figure 1 This is a block diagram illustrating the system implementation of the present invention.

[0030] Figure 2 This is the control timing sequence for each data selector in this invention.

[0031] Figure 3 This is a schematic diagram of the key signal output in the feedthrough suppression process of this invention. Detailed Implementation

[0032] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] like Figure 1As shown, this invention provides a closed-loop control system for a Coriolis resonator gyroscope based on feedthrough noise suppression, including a gyroscope drive resonator 1, a gyroscope detection resonator 2, a drive feedthrough capacitor 3, a detection feedthrough capacitor 4, a first C / V converter 5, a second C / V converter 6, a first A / D converter 7, a second A / D converter 8, a drive control unit 9, a force feedback control unit 10, a numerically controlled oscillator 11, a first D / A converter 12, and a second D / A converter 13. The drive control unit includes a first data selector 91, a second data selector 92, a first digital low-pass filter 93, a first digital demodulator 94, and a first PID control unit 95. The force feedback control unit includes a third data selector 101, a fourth data selector 102, a second digital low-pass filter 103, a second digital demodulator 104, and a second PID control unit 105.

[0034] The first C / V converter 5 is connected to the gyroscope drive resonator 1 and is used to convert the change of the comb capacitance at the gyroscope drive end into an analog voltage. The drive feedthrough capacitor 3 is also involved in the conversion. The first A / D converter 7 converts the drive analog voltage signal into a digital signal. The drive control unit 9 controls the phase and amplitude of the drive excitation. The first D / A converter 12 converts the drive excitation digital signal into an analog signal.

[0035] The second C / V converter 6 is connected to the resonator 2 of the Coriolis gyroscope and is used to convert the change in the comb capacitance of the gyroscope detection end into an analog voltage. The detection feedthrough capacitor 4 is also involved in the conversion. The second A / D converter 8 converts the detected analog voltage signal into a digital signal. The force feedback control unit 10 controls the force feedback signal. The second D / A converter 13 converts the force feedback digital signal into an analog signal.

[0036] The numerically controlled oscillator 11 generates two mutually orthogonal sinusoidal signals sin(ω). d t) and cos(ω) d t) is used both as the base signal for the gyroscope excitation signal and as the reference signal for the demodulator.

[0037] The first digital demodulator 94 and the second digital demodulator 104 are implemented using the Least Mean Square (LMS) digital demodulation algorithm. This algorithm is based on the minimum error mean square criterion and improves the method for estimating the mean square error gradient by taking the gradient of the square of a single error sample as the estimated value of the mean square error gradient. The LMS algorithm can be expressed by the following formula:

[0038]

[0039] Where W(n) is the weighted vector of the input signal, X(n) is a set of input vectors composed of the input signals, y(n) is the output vector, e(n) is the error signal, and μ is the step size factor when updating the weight vector. For the first digital demodulator 94, sin(ω d Using t as a reference, the phase information of the signal can be calculated, with cos(ω) d The amplitude information of the signal can be calculated based on t); for the second digital demodulator 104, sin(ω) is used as the reference. d The Coriolis component of the signal can be calculated using t as a reference, with cos(ω) as the basis. d Using t) as a reference, the orthogonal components of the signal can be calculated;

[0040] Figure 2 The control timing of each data selector is shown. Figure 3 The output waveforms of key signals in the feedthrough suppression process are shown. Among them, the first data selector 91 and the third data selector 101 are excitation data selectors, and the second data selector 92 and the fourth data selector 102 are readout data selectors.

[0041] The first data selector 91 in T drive During the time period, the output of the drive control unit is maintained, and a zero value is output at other times to generate a drive chopper excitation signal; the third data selector 101 in T drive The force feedback control unit maintains its output during the time period and outputs a zero value at other times, generating a force feedback chopper excitation signal.

[0042] The second data selector 92 in T sense The first A / D converter maintains the converted digital information during the time period, and outputs a zero value at other times to generate a drive readout chopper signal; the fourth data selector 102 maintains the converted digital information during the T time period. sense The conversion digital information of the second A / D converter is maintained during the time period, and a zero value is output at other times to generate a detection readout chopper signal;

[0043] The first digital low-pass filter 93 has a cutoff frequency lower than the chopping frequency, generating a drive readout sinusoidal signal without feedthrough noise; the second digital low-pass filter 103 has a cutoff frequency lower than the chopping frequency, generating a detection readout sinusoidal signal without feedthrough noise.

[0044] The first C / V converter 5 and the second C / V converter 6 are charge amplifiers.

[0045] The first A / D converter 7 and the second A / D converter 8 are successive approximation A / D converters.

[0046] The switching frequencies of the first data selector 91, the second data selector 92, the third data selector 101, and the fourth data selector 102 are all in the kilohertz range, and the sampling rates of the first A / D converter 7 and the second A / D converter 8 are in the 100 kilohertz range.

[0047] The drive control unit 9 and the force feedback control unit 10 are implemented by a field-programmable gate array (FPGA).

[0048] The method for suppressing feedthrough noise of the Coriolis resonator gyroscope includes the following steps:

[0049] S1, the first data selector 91 in T drive Maintain the output of the drive control unit during the time period, in T sense Time period and T delay The time period outputs a zero value, generating a digital signal to drive the chopper; the third data selector 91 outputs a zero value during the T time period. drive Maintain the output of the force feedback control unit during the time period, in T sense Time period and T delay The time period outputs a zero value, generating a force feedback chopper excitation digital signal;

[0050] S2, the first D / A converter 12 is used to convert the driving chopper excitation digital signal into a driving analog signal and apply it to the gyroscope driving resonator 1; the second D / A converter 13 is used to convert the feedback chopper excitation digital signal into a force feedback analog signal and apply it to the gyroscope detection resonator 2.

[0051] S3, the first C / V converter 5 is used to convert the change in the comb capacitance at the driving end of the gyroscope into a driving detection analog voltage, while the driving feedthrough capacitor 3 participates in the conversion; the second C / V converter 6 is used to convert the change in the comb capacitance at the detection end of the gyroscope into an analog voltage, while the detection feedthrough capacitor 4 participates in the conversion.

[0052] S4, the analog input is converted to a digital signal using the first A / D converter 7, and the analog input is converted to a digital signal using the second A / D converter 8. At this time, the feedthrough noise existing in the digital signal only exists in T. drive During the time period, in T sense Time period and T delay The value is zero during the time period;

[0053] S5, Second data selector 92 in T sense The digital information converted by the first A / D converter is retained within the time period, in T drive Time period and T delay The time period outputs a zero value, generating a drive readout chopper signal; the fourth data selector 102 in T senseThe converted digital information of the second A / D converter is maintained during the time period, in T drive Time period and T delay The time period outputs a zero value, generating a detection readout chopper signal;

[0054] S6 performs low-pass processing on the drive readout chopper signal and the detection readout chopper signal respectively to restore the ideal signal without feedthrough interference.

[0055] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A closed-loop control system for a Coriolis resonant gyroscope, characterized in that, The system includes a first C / V converter, a second C / V converter, a first A / D converter, a second A / D converter, a drive control unit, a force feedback control unit, a numerically controlled oscillator, a first D / A converter, and a second D / A converter. The drive control unit includes a second data selector, a first digital low-pass filter, a first digital demodulator, and a first PID control unit, all connected in sequence to the first A / D converter. The force feedback control unit includes a fourth data selector, a second digital low-pass filter, a second digital demodulator, and a second PID control unit, all connected in sequence to the second A / D converter, and a third data selector. The first C / V converter is connected to the gyroscope driver resonator and is used to convert the change of the comb capacitance at the gyroscope drive end into an analog voltage. The drive feedthrough capacitor is also involved in the conversion. The first A / D converter converts the drive analog voltage signal into a digital signal. The drive control unit controls the phase and amplitude of the drive excitation. The first D / A converter converts the drive excitation digital signal into an analog signal and outputs it to the gyroscope driver resonator and the drive feedthrough capacitor. The second C / V converter is connected to the resonator of the Coriolis gyroscope and is used to convert the change in the comb capacitance of the gyroscope detection end into an analog voltage. The detection feedthrough capacitor is also involved in the conversion. The second A / D converter converts the detected analog voltage signal into a digital signal. The force feedback control unit controls the force feedback signal. The second D / A converter converts the force feedback digital signal into an analog signal and outputs it to the gyroscope detection resonator and the detection feedthrough capacitor. The first PID control unit generates amplitude control information V of the drive signal. amp and phase control information V pha The phase control information adjusts the output frequency ω of the numerically controlled oscillator in real time. d The numerically controlled oscillator generates two mutually orthogonal signals sin(ω). d t) and cos(ω) d t) serves as the reference for the first and second digital demodulators; The second PID control unit receives the two mutually orthogonal signals and generates Coriolis control information V. coli and orthogonal control information V qu Columbia Control Information V coli and orthogonal control information V qu The summation is then output to the third data selector, where the amplitude control information V is... amp with cos(ω) d The product of t) is then output to the first data selector.

2. The closed-loop control system for a Coriolis resonant gyroscope according to claim 1, characterized in that, To maintain the chopping mode of the feedthrough signal, the first C / V converter and the second C / V converter are charge amplifiers.

3. The closed-loop control system for a Coriolis resonant gyroscope according to claim 1, characterized in that, The conversion results of the A / D converter are discrete, and the first A / D converter and the second A / D converter are successive approximation A / D converters.

4. The closed-loop control system for a Coriolis resonant gyroscope according to claim 1, characterized in that, The switching frequency of the four data selectors is on the order of 10 kilohertz, and the sampling rate of the A / D converter is on the order of 100 kilohertz.

5. A method for suppressing feedthrough noise of a Coriolis resonator gyroscope, comprising a closed-loop control system for a Coriolis resonator gyroscope according to any one of claims 1-4, characterized in that: Includes the following steps: S1, the first data selector in T drive Maintain the output of the drive control unit during the time period, in T sense Time period and T delay The time period outputs a zero value, generating a digital signal to drive the chopper; the third data selector at T... drive Maintain the output of the force feedback control unit during the time period, in T sense Time period and T delay The time period outputs a zero value, generating a force feedback chopper excitation digital signal; S2, the first D / A converter is used to convert the driving chopper excitation digital signal into a driving analog signal and apply it to the gyroscope driving resonator; the second D / A converter is used to convert the feedback chopper excitation digital signal into a force feedback analog signal and apply it to the gyroscope detection resonator; S3, the first C / V converter is used to convert the change of the comb capacitance at the gyroscope drive end into the analog voltage quantity of the drive detection, while the drive feedthrough capacitor participates in the conversion; The second C / V converter is used to convert the change in the comb capacitance at the detection end of the conversion gyroscope into an analog voltage quantity, while the feedthrough capacitance is detected to participate in the conversion. S4, the analog input is converted to a digital signal using a first A / D converter, and then converted to a digital signal using a second A / D converter. At this time, the feedthrough noise existing inside the digital signal only exists in T. drive During the time period, in T sense Time period and T delay The value is zero during the time period; S5, the second data selector in T sense The digital information converted by the first A / D converter is retained within the time period, in T drive Time period and T delay The time period outputs a zero value, generating a drive readout chopper signal; the fourth data selector at T... sense The converted digital information of the second A / D converter is maintained during the time period, in T drive Time period and T delay The time period outputs a zero value, generating a detection readout chopper signal; S6 performs low-pass processing on the drive readout chopper signal and the detection readout chopper signal respectively to restore the ideal signal without feedthrough interference.

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