CN110160514B - Multi-loop digital closed-loop control device of silicon MEMS gyroscope - Google Patents
Multi-loop digital closed-loop control device of silicon MEMS gyroscope Download PDFInfo
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- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
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Abstract
The invention discloses a multi-loop digital closed-loop control device of a silicon MEMS gyroscope, which comprises a silicon micro-gyroscope detection module at the front end, an analog interface module at the middle end and an FPGA module at the rear end, wherein the front end and the rear end are connected through the middle end to form three closed-loop control loops. The front end consists of a detection mechanism, a pair of detection output electrodes, a force feedback mechanism, a pair of force feedback electrodes, an orthogonal correction mechanism, an orthogonal correction electrode, a frequency tuning mechanism and a frequency tuning electrode; the middle end consists of a C/V converter, an instrument amplifier, an analog/digital converter and four groups of digital/analog converters; the back end is composed of an input submodule and two demodulation submodules. The invention can realize the real-time on-line mode automatic matching of the silicon micro gyroscope, and simultaneously realize closed loop detection and quadrature error correction in a matched manner; the FPGA module is used for realizing a control algorithm, so that interference caused by temperature change and mutual coupling between loops can be effectively restrained, the algorithm complexity is low, and the tuning precision is high.
Description
Technical Field
The invention relates to the technical field of Micro Electro Mechanical Systems (MEMS) and micro inertial navigation measuring instruments, in particular to a multi-loop digital closed-loop control device of a silicon MEMS gyroscope.
Background
The silicon micro gyroscope, as a miniature inertial sensor capable of measuring angular rate, has the advantages of small volume, low power consumption, high integration level and the like, and is widely applied to civil and military fields, and particularly comprises automobile rollover monitoring, consumer electronic product steering detection, attitude angle control and the like. Nevertheless, existing silicon micro-gyroscopes still lag behind fiber optic gyroscopes, ring laser gyroscopes, and other high precision gyroscopes in terms of bias stability. Therefore, how to further improve the performance of the silicon micro gyroscope is still a research hot spot. The mode matching technology, the closed loop detection and the quadrature error correction technology are all important means for improving the precision of the silicon micro gyroscope. The mode matching technology can effectively improve the bias stability and the mechanical sensitivity of the silicon micro gyroscope by eliminating the resonance frequency difference between the driving mode and the detection mode of the silicon micro gyroscope, and can further improve the accuracy of detecting the Goldng acceleration signal by matching with the closed loop detection and the quadrature error correction technology. The traditional analog circuit is easy to be interfered by factors such as temperature, electromagnetic field and the like, a large number of devices are consumed to realize some simple algorithms, and the FPGA system is used for digitizing a control loop, so that the interference of external factors can be reduced, and a large number of control algorithms can be realized by utilizing the capability of high-speed parallel data processing, so that the control of applying the FPGA system to the silicon micro gyroscope has good application prospect.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the invention provides a multi-loop digital closed-loop control device of a silicon MEMS gyroscope.
The technical scheme is as follows: a silicon MEMS gyroscope multi-loop digital closed loop control apparatus, the apparatus comprising: the device comprises a silicon micro-gyroscope detection module at the front end, an analog interface module at the middle end and an FPGA module at the rear end, wherein the silicon micro-gyroscope detection module and the FPGA module are connected through the analog interface module to form three closed-loop control loops;
the silicon micro gyroscope detection module comprises:
a pair of force feedback electrodes ef+ and Ef-, applying an analog voltage signal generated by the first digital-to-analog converter or the second digital-to-analog converter to the force feedback mechanism;
the force feedback mechanism converts the analog voltage signal into electrostatic force and generates excitation action on the detection mechanism;
further, the force feedback mechanism comprises a pair of force feedback polar plates connected with the force feedback electrodes Ef and Ef-respectively and a movable polar plate applied with carrier signals; the force feedback electrode ef+ and Ef-are connected with a digital bilateral input signal Vi or an analog signal which is converted and output by a digital detection feedback signal Vf through a first digital-to-analog converter; the analog signal output by the first digital-to-analog converter is converted by the force feedback polar plate to generate electrostatic force, and the push or pull movable polar plate generates displacement along the detection direction and acts on the detection mechanism;
the detection mechanism converts the excitation generated by the force feedback mechanism into capacitance variation; under the action of the correction force of the orthogonal correction mechanism and the analog direct current tuning voltage of the frequency tuning mechanism, the orthogonal signal and the detection modal frequency are changed;
further, the detection mechanism comprises a pair of detection output polar plates (11, 12) connected with detection output electrodes Es+ and Es-and a movable polar plate (10) for receiving a high-frequency carrier signal applied by external equipment; the movable polar plate (10) generates corresponding displacement according to the action of the force feedback mechanism, so that the capacitance between the movable polar plate (10) and the detection output polar plates (11, 12) is changed; the detection output electrodes Es+ and Es-transmit the capacitance conversion quantity to the C/V converter;
a pair of detection output electrodes Es+ and Es-, and detecting and outputting the capacitance variation of the detection mechanism under the action of the force feedback mechanism;
an orthogonal correction electrode Eq for applying the analog orthogonal correction voltage outputted from the third D/A converter to the orthogonal correction mechanism;
the orthogonal correction mechanism converts the digital orthogonal correction signal Vq into a correction force in the detection direction of the silicon micro gyroscope, and acts on the detection mechanism to eliminate the orthogonal error of the silicon micro gyroscope;
a frequency tuning electrode Et for applying the analog DC tuning voltage outputted from the fourth D/A converter to the frequency tuning mechanism;
the frequency tuning mechanism changes the detection mode resonance frequency according to the structural rigidity of the detection direction of the silicon micro gyroscope under the action of the simulated direct current tuning voltage generated by the frequency tuning electrode Et and the static negative rigidity effect, and completes the mode matching of the silicon micro gyroscope;
further, the frequency tuning mechanism comprises a tuning pole plate connected to a frequency tuning electrode Et, and a common pole plate applied with a carrier signal, wherein the frequency tuning electrode Et is connected to an analog signal which is converted and output by a fourth digital-to-analog converter by a digital direct current tuning signal Vt; the electrostatic force between the tuning polar plate and the common polar plate is balanced in the driving and detecting directions of the silicon micro gyroscope, and is used for changing the rigidity of the silicon micro gyroscope in the detecting direction according to the change of the direct current tuning signal Vt, so that the detecting mode resonant frequency is matched to the driving mode resonant frequency.
The analog interface module includes:
a C/V converter for converting the capacitance variation of the pair of detection output electrodes Es+, es-output into a voltage signal;
the instrument amplifier is used for carrying out differential amplification on the amplitude of the voltage signal converted by the C/V converter to obtain an analog response signal Vo, wherein the analog response signal Vo comprises bilateral input signal Vi response amplitude information before mode matching, and comprises a Goldrake acceleration signal and a quadrature error signal after mode matching;
the analog/digital converter converts the analog response signal Vo subjected to differential amplification by the instrument amplifier into digital quantity and outputs the digital quantity to the FPGA module;
the first digital-to-analog converter converts a digital bilateral input signal Vi generated by the input submodule into an analog voltage signal and outputs the analog voltage signal to the force feedback electrodes Ef & lt+ & gt and Ef & lt- >
the second digital-to-analog converter converts the digital detection feedback signal Vf demodulated by the first demodulation submodule into an analog voltage signal and outputs the analog voltage signal to the force feedback electrodes ef+ and Ef-;
a third digital-to-analog converter for converting the digital quadrature correction signal Vq demodulated by the first demodulation sub-module into an analog signal and outputting the analog signal to the quadrature correction electrode Eq;
a fourth digital-to-analog converter for converting the digital DC tuning signal Vt demodulated by the second demodulation submodule into an analog DC tuning voltage and outputting the analog DC tuning voltage to the frequency tuning electrode Et;
the FPGA module comprises:
an input submodule for generating and outputting a digital bilateral input signal Vi and a pair of demodulation reference sinw by adopting a complex multiplication algorithm 1 t、sinw 2 t；
The first demodulation submodule adopts a square demodulation algorithm to extract the amplitude difference of the analog response signal Vo, and performs PI (proportion-integral) control on the amplitude difference to obtain a digital direct current tuning signal Vt;
and the second demodulation submodule demodulates the analog response signal Vo by adopting a multiplication demodulation algorithm after the mode matching is finished, and generates a digital detection feedback signal Vf and a digital quadrature correction signal Vq.
Further, the input submodule includes:
the complex-phase multiplying sub-module generates a sine value and a cosine value of continuous equal-quantity increased angles by adopting a complex multiplication algorithm and outputs the sine value and the cosine value to the digital oscillator;
the digital oscillator can control the initial angle and the angle increment of the complex multiplication algorithm by setting corresponding frequency control words and phase control words on the digital oscillator, so as to control the frequency and the initial phase of the output signal of the digital oscillator, and realize two paths of input sub-signals cosw 1 t、cosw 2 t and two-way demodulator-sub-standard sine 1 t、sinw 2 Direct synthesis of t, where the frequency w 1 And w 2 And driving mode resonance frequency w d The difference value is equal, and the difference value is required to be larger than the resonance frequency difference between the detection mode and the driving mode so as to avoid the saturation of the direct current tuning signal;
a first adder for inputting the sub-signal cosw 1 t、cosw 2 t are added to generate a bilateral input signal Vi.
Further, the first demodulation submodule comprises a digital demodulator and a digital PI control submodule;
the digital demodulator includes:
a first multiplier for outputting digital quantity and input sub-signal cosw from A/D converter 1 t is multiplied to generate a first path of product signal;
a second multiplier for outputting digital quantity and demodulation sub-standard sine from the A/D converter 1 t is multiplied to generate a second path of product signal;
a third multiplier for analog-to-digital conversion ofDigital quantity output by the device and input sub-signal cosw 2 t is multiplied to generate a third multiplication signal;
a fourth multiplier for outputting digital quantity and demodulation sub-standard sine from the A/D converter 2 t is multiplied to generate a fourth path of product signal;
the first, second, third and fourth path product signals are all signals comprising a similar direct current component and an alternating current component;
the first IIR filter is used for carrying out low-pass filtering on the first, second, third and fourth paths of product signals to respectively obtain first, second, third and fourth types of direct current signals; the DC-like signal comprises amplitude response and phase response information of two sub-signals of a bilateral input signal Vi;
the squarer is used for carrying out square operation on the first, second, third and fourth types of direct current signals to obtain squares of the first, second, third and fourth types of direct current signals;
the second adder is used for carrying out addition operation on the squares of the first class direct current signal and the second class direct current signal to obtain a square sum of the first class direct current signal;
the third adder is used for carrying out addition operation on squares of third and fourth types of direct current signals to obtain a second type of direct current signal square sum;
the first subtracter is used for summing squares of the first class direct current signal and the second class direct current signal to obtain amplitude differences of two sub-signal amplitude responses of the bilateral input signal;
the digital PI control submodule includes:
the reference value presetting module is set to be 0, and when the amplitude difference of the amplitude responses of the two sub-signals of the bilateral input signal is the reference value, the digital PI control sub-module stops working to obtain an accurate direct current tuning signal;
the second subtracter is used for obtaining the difference value between the amplitude difference of the amplitude responses of the two sub-signals of the bilateral input signal and the reference value;
and the first digital PI controller is used for PI controlling the difference value output by the second subtracter so as to generate a direct current tuning signal Vt.
Further, the second demodulation sub-module includes:
a fifth multiplier for converting the digital quantity converted by the analog-to-digital converter and the driving signal sine d t is multiplied, the digital quantity comprises a Goldrake acceleration signal and an orthogonal error signal, and the product is a fifth path of product signal comprising a DC-like component and an AC-like component; the driving signal sine d t is introduced by the drive mode loop of the MEMS gyroscope, where w d Is the driving mode resonant frequency;
a sixth multiplier for converting the digital quantity converted by the analog-to-digital converter and the driving detection signal cosw d t is multiplied, the digital quantity comprises a Goldrake acceleration signal and an orthogonal error signal, and the product is a sixth path of product signal comprising a DC-like component and an AC-like component; the drive detection signal cosw d t is introduced by the drive circuit, where w d Is the driving mode resonant frequency;
the second IIR filter is used for carrying out low-pass filtering on the fifth path of product signals and outputting fifth direct current signals;
the third IIR filter is used for carrying out low-pass filtering on the sixth path of product signals and outputting sixth direct current signals;
the third subtracter is used for carrying out difference operation on the fifth type direct current signal and the reference value 0 of the second digital PI controller;
the fourth subtracter is used for carrying out difference operation on the sixth direct current signal and a reference value 0 of the third digital PI controller;
the second PI controller is used for performing proportional-integral control on the difference value output by the third subtracter, and generating and outputting the amplitude of the detection feedback signal;
the third PI controller is used for performing proportional-integral control on the difference value output by the fourth subtracter to generate and output an orthogonal correction signal Vq;
seventh multiplier for comparing the amplitude of the detection feedback signal with the driving detection signal cosw d t to obtain a detection feedback signal Vf, where w d Is the drive mode resonant frequency.
The beneficial effects are that:
(1) The invention uses the FPGA module to realize the frequency tuning of the silicon micro gyroscope; the control loop is digitized by using a control algorithm of detection feedback and orthogonal correction, so that the control loop has high-efficiency data processing capability, and meanwhile, the interference on a control system caused by factors such as temperature change, mutual coupling among loops and the like can be effectively inhibited;
(2) According to the invention, the tuning voltage is fed back to the gyroscope detection mode, so that closed-loop control is realized, and compared with a pre-tuning method, the closed-loop control can realize real-time online mode matching;
(3) The invention uses the symmetry of the silicon micro gyroscope detection mode amplitude response to correct the mode matching degree, avoids the difficulty of measuring the mode frequency in real time, and can obtain higher tuning precision;
(4) The invention adopts a detection feedback mode to detect the God acceleration, so that the influence on the working bandwidth caused by the increase of the mechanical sensitivity of the silicon micro gyroscope after the mode matching can be effectively reduced; and meanwhile, an orthogonal correction loop is used for eliminating the orthogonal error of the silicon micro gyroscope, so that the detection accuracy is effectively improved.
Description of the drawings:
FIG. 1 is a schematic diagram of the overall structure of the present invention;
FIG. 2 is a schematic diagram of an input sub-module;
FIG. 3 is a schematic diagram of a first demodulation sub-module;
FIG. 4 is a schematic diagram of a second demodulation sub-module;
FIG. 5 is a schematic diagram of a frequency tuning mechanism;
FIG. 6 is a schematic diagram of an orthographic correction mechanism;
fig. 7 is a schematic diagram of the force feedback mechanism and the detection mechanism.
Detailed Description
Fig. 1 is a schematic diagram of the overall structure of a multi-loop digital closed-loop control device for a silicon MEMS gyroscope according to the present invention, the device includes: the device comprises a silicon micro-gyroscope detection module positioned at the front end, an analog interface module positioned at the middle end and an FPGA module positioned at the rear end, wherein the silicon micro-gyroscope detection module and the FPGA module are connected through the analog interface module to form three closed-loop control loops.
The silicon micro gyroscope detection module consists of a pair of force feedback electrodes Ef & lt+ & gt and Ef-, a force feedback mechanism, a detection mechanism, a pair of detection output electrodes Es & lt+ & gt and Es-, an orthogonal correction electrode Eq, an orthogonal correction mechanism, a frequency tuning electrode Et and a frequency tuning mechanism.
In this embodiment, the analog interface module includes: the C/V converter using MB6S chip, the instrument amplifier using AD8221 chip, the A/D converter using AD7767 chip, and the first, second, third and fourth D/A converter with the model of CS 4344.
In this embodiment, the FPGA module employs an EP3C55F484I7 chip, and the module includes an input sub-module, a first demodulation sub-module, and a second demodulation sub-module.
An input submodule in the FPGA module is connected with the first digital-to-analog converter, and digital bilateral input signals Vi generated by the input submodule are converted into analog voltage signals. The first digital-to-analog converter is connected to the force feedback electrodes ef+ and Ef-, respectively, and applies an analog bilateral input signal to the force feedback mechanism. The force feedback mechanism is used for converting the analog voltage signal into an electrostatic force, and the electrostatic force obtained after the conversion of the analog bilateral input signal can excite the detection mechanism.
The detection output electrodes es+ and Es-are used for outputting the capacitance variation of the detection mechanism under the action of the input signal, and the capacitance variation cannot be directly measured, so that the capacitance variation is converted into a voltage signal by using a C/V converter. The C/V converter is connected with the instrument amplifier and used for carrying out differential amplification on the amplitude of the voltage signal. The amplified analog signal is an analog response signal Vo containing the response amplitude information of the bilateral input signal, so that the analog response signal Vo is converted into digital quantity by an analog-to-digital converter and is input into an FPGA module for amplitude extraction and processing.
The first demodulation submodule is used for extracting the amplitude difference of the response signal Vo, generating a digital direct-current tuning signal Vt, converting the digital direct-current tuning signal Vt into an analog direct-current tuning voltage through a fourth digital-to-analog converter connected with the first demodulation submodule, inputting the analog direct-current tuning voltage into the frequency tuning electrode Et, and further acting on the frequency tuning mechanism. According to the static negative stiffness effect, when the frequency tuning mechanism is acted by direct current voltage, the change of structural stiffness of the silicon micro gyroscope in the detection direction is brought, and further the change of detection mode resonance frequency is caused, so that the purpose of mode matching is realized.
Since the mechanical sensitivity of the gyroscope is increased due to the mode matching, in order to reduce the influence of the mechanical sensitivity on the working bandwidth of the gyroscope, the coriolis acceleration is detected by using a closed loop detection mode, and meanwhile, the quadrature error is eliminated by using a quadrature error correction mechanism. Further, when the mode matching is completed, the response signal Vo contains the coriolis acceleration signal and the quadrature error signal.
The second demodulation submodule is used for converting the demodulated digital detection feedback signal Vf into an analog detection feedback signal through a second digital-to-analog converter connected with the demodulation submodule, and inputting the analog detection feedback signal to the force feedback electrodes ef+ and Ef-; meanwhile, the second demodulation sub-module outputs the digital quadrature correction signal Vq to a third digital-to-analog converter connected with the second demodulation sub-module, converts the digital quadrature correction signal Vq into an analog signal and then inputs the analog signal to the quadrature correction electrode Eq. The force feedback mechanism applies the electrostatic force generated by the analog detection feedback signal to the detection mechanism to form closed loop detection feedback, and meanwhile, when the orthogonal correction mechanism receives the orthogonal correction signal, a correction force in a detection direction is generated and acts on the detection mechanism, so that the orthogonal error is eliminated.
The FPGA module is mainly used for completing bilateral input signals V i Demodulation reference, DC tuning signal V t And a generation algorithm for detecting the feedback signal Vf and the quadrature correction signal Vq.
Fig. 2 shows a schematic diagram of the structure of an input sub-module for generating an input signal and demodulation reference. The input submodule mainly comprises a complex-phase multiplier submodule, a digital oscillator and a first adder. The complex multiplication submodule generates a sine value and a cosine value of continuous equal-quantity increasing angles and outputs the sine value and the cosine value to the digital oscillator. By setting the corresponding frequency control word and phase control word of the digital oscillator, two paths of input sub-signals cosw can be directly synthesized 1 t、cosw 2 t and two-path demodulation reference sine 1 t、sinw 2 t, wherein,frequency w 1 And w 2 The difference value between the detection mode and the driving mode is equal to the resonance frequency of the driving mode, and the difference value is required to be larger than the resonance frequency difference between the detection mode and the driving mode. Input sub-signal cosw 1 t、cosw 2 t generates a bilateral input signal Vi by means of a first adder.
Fig. 3 shows a schematic diagram of a first demodulation sub-module for generating a tuning voltage signal. The first demodulation submodule mainly comprises a digital demodulator and a digital PI control submodule. The digital demodulator consists of a four-way multiplier, a first IIR filter, a squarer, a second adder, a third adder and a first subtracter. Response signal V o After being input into an FPGA module through an analog-to-digital converter, the FPGA module is respectively connected with two paths of input signals cosw 1 t、cosw 2 t and two-path demodulation reference sine 1 t、sinw 2 t is multiplied by a first multiplier, a second multiplier, a third multiplier and a fourth multiplier, the four-way products comprise signals similar to direct current components and alternating current components, and in order to filter the alternating current components in the products, a first IIR filter is used for carrying out low-pass filtering on the four-way products. The filtered DC-like signal comprises a reference signal V o In order to extract amplitude information, square summing is carried out on four paths of direct current signals by using a squarer, a second adder and a third adder, and the two paths of square sums are subjected to difference through a first subtracter, so that amplitude differences of two paths of response signals are obtained. Because the silicon micro gyroscope detects the symmetry of modal amplitude response, in the complete modal matching state, the amplitude difference is 0, so that the reference value in the digital PI control submodule is set to 0, and the difference value between the amplitude difference and the reference value is obtained through the second subtracter and is input into the first digital PI controller, and the direct-current tuning signal Vt is generated.
Fig. 4 shows a schematic diagram of the structure of a second demodulation sub-module for generating the detection feedback signal and the quadrature correction signal. The second demodulation submodule mainly comprises fifth, sixth and seventh multipliers, a second IIR filter, a third subtracter, a fourth subtracter, a second PI controller and a third PI controller. Wherein, the Goldrake acceleration signal and the quadrature error signal are input into the FPGA module through the A/D converter and then are combined with the signal sinw d t、cosw d t are multiplied by a fifth multiplier and a sixth multiplier respectively to generate a fifth-path product signal and a sixth-path product signal which contain similar direct-current components and alternating-current components, wherein w is as follows d Is the frequency of the driving signal and the signal sine d t、cosw d t is introduced by the drive circuit. And the fifth and sixth path product signals are respectively subjected to low-pass filtering through a second and third IIR filters, the filter output only keeps similar direct current signals, and when the driving mode reaches a resonance state and the quadrature error is completely restrained, the similar direct current signals of the detection feedback loop and the quadrature correction loop are stabilized at 0, so that the reference values of the second and third digital PI controllers are set to 0. The difference between the quasi-DC signal and the reference value is obtained by the third subtracter and the fourth subtracter, and is input into the second digital PI controller and the third digital PI controller, and the output of the second digital PI controller and the third digital PI controller are respectively the amplitude of the detection feedback signal and the quadrature correction signal Vq. Detecting the amplitude of the feedback signal and the signal cosw d t is multiplied by a seventh multiplier to obtain a detection feedback signal Vf.
Fig. 5, which shows a schematic diagram of a frequency tuning mechanism, consists of a tuning plate 1 and a common plate 2, wherein the tuning plate 1 is connected to a frequency tuning electrode Et. The digital dc tuning signal Vt is converted into an analog signal by the fourth d/a converter and then input to the frequency tuning electrode Et, while a carrier signal is applied to the common plate 2, and the electrostatic forces between the tuning plate 1 and the common plate 2 remain balanced in the driving and detecting directions. Meanwhile, according to the electrostatic negative stiffness effect, the applied direct current tuning signal Vt can cause the stiffness 3 in the detection direction of the silicon micro gyroscope to change, so that the change of the detection mode resonance frequency is caused, and the frequency tuning function is realized.
As in fig. 6, which shows a schematic diagram of an orthographic correction mechanism consisting of a correction plate 4 and a common plate 5, wherein the correction plate 4 is connected to an orthographic correction electrode Eq. The third digital orthogonal correction signal Vq is converted into an analog signal by a digital-to-analog converter, then the analog signal is input to the orthogonal correction electrode Eq, and meanwhile, a carrier signal is applied to the common electrode plate 5, and the orthogonal correction force 6 is generated in the detection direction due to the fact that the electrostatic force generated by the direct-current orthogonal correction signal Vq in the detection direction has unbalance due to the fact that the upper and lower distances between the comb teeth of the common electrode plate 5 and the correction electrode plate 4 are unequal, so that the correction of the orthogonal error of the detection mode is achieved.
Fig. 7 shows a schematic diagram of the force feedback mechanism and the detection mechanism. The force feedback mechanism is formed by a pair of force feedback plates 7 and 8 and a movable plate 9, wherein the force feedback plates 7 and 8 are respectively connected with force feedback electrodes ef+ and Ef-. The digital bilateral input signal Vi is converted into an analog signal by a first digital-to-analog converter and then is input to the force feedback electrodes ef+ and Ef-. At the same time, a carrier signal is applied to the active plate 9. The bilateral input signal Vi or the detection feedback signal Vf is converted by the first digital-to-analog converter or the second digital-to-analog converter to generate an electrostatic force to displace the "push" or "pull" movable electrode plate 9 along the detection direction, so as to act on the detection mechanism 4. The movable plate 10 in the detecting mechanism 4 will generate a corresponding displacement, and the capacitance between the movable plate 10 and the detecting output plates 11 and 12 will change. The detection output electrodes es+ and Es-are connected to the detection output plates 11 and 12, respectively, and the capacitance conversion amount is transmitted to a C/V converter and converted into a voltage signal for subsequent processing.
Claims (6)
1. A silicon MEMS gyroscope multi-loop digital closed loop control device, the device comprising: the device comprises a silicon micro-gyroscope detection module at the front end, an analog interface module at the middle end and an FPGA module at the rear end, wherein the silicon micro-gyroscope detection module and the FPGA module are connected through the analog interface module to form three closed-loop control loops;
the silicon micro gyroscope detection module comprises:
a pair of force feedback electrodes ef+ and Ef-, applying the analog voltage signal Vo generated by the first digital-to-analog converter or the second digital-to-analog converter to the force feedback mechanism;
the force feedback mechanism converts the analog voltage signal Vo into electrostatic force and generates excitation action on the detection mechanism;
the detection mechanism converts the excitation generated by the force feedback mechanism into capacitance variation; under the action of the correction force of the orthogonal correction mechanism and the analog direct current tuning voltage of the frequency tuning mechanism, the orthogonal signal and the detection modal frequency are changed;
a pair of detection output electrodes Es+ and Es-, and detecting and outputting the capacitance variation of the detection mechanism under the action of the force feedback mechanism;
an orthogonal correction electrode Eq for applying the analog orthogonal correction voltage outputted from the third D/A converter to the orthogonal correction mechanism;
the orthogonal correction mechanism converts the digital orthogonal correction signal Vq into a correction force in the detection direction of the silicon micro gyroscope, and acts on the detection mechanism to eliminate the orthogonal error of the silicon micro gyroscope;
a frequency tuning electrode Et for applying the analog DC tuning voltage outputted from the fourth D/A converter to the frequency tuning mechanism;
the frequency tuning mechanism changes the detection mode resonance frequency according to the structural rigidity of the detection direction of the silicon micro gyroscope under the action of the simulated direct current tuning voltage generated by the frequency tuning electrode Et and the static negative rigidity effect, and completes the mode matching of the silicon micro gyroscope;
the analog interface module includes:
a C/V converter for converting the capacitance variation of the pair of detection output electrodes Es+, es-output into a voltage signal;
the instrument amplifier is used for carrying out differential amplification on the amplitude of the voltage signal converted by the C/V converter to obtain an analog response signal Vo, wherein the analog response signal Vo comprises bilateral input signal Vi response amplitude information before mode matching, and comprises a Goldrake acceleration signal and a quadrature error signal after mode matching;
the analog/digital converter converts the analog response signal Vo subjected to differential amplification by the instrument amplifier into digital quantity and outputs the digital quantity to the FPGA module;
the first digital-to-analog converter converts a digital bilateral input signal Vi generated by the input submodule into an analog voltage signal and outputs the analog voltage signal to the force feedback electrodes Ef & lt+ & gt and Ef & lt- >
the second digital-to-analog converter converts the digital detection feedback signal Vf demodulated by the first demodulation submodule into an analog voltage signal and outputs the analog voltage signal to the force feedback electrodes ef+ and Ef-;
a third digital-to-analog converter for converting the digital quadrature correction signal Vq demodulated by the first demodulation sub-module into an analog signal and outputting the analog signal to the quadrature correction electrode Eq;
a fourth digital-to-analog converter for converting the digital DC tuning signal Vt demodulated by the second demodulation submodule into an analog DC tuning voltage and outputting the analog DC tuning voltage to the frequency tuning electrode Et;
the FPGA module comprises:
an input submodule for generating and outputting a digital bilateral input signal Vi and a pair of demodulation reference sinw by adopting a complex multiplication algorithm 1 t、sinw 2 t；
The first demodulation submodule adopts a square demodulation algorithm to extract the amplitude difference of the analog response signal Vo, and performs PI control on the amplitude difference to obtain a digital direct current tuning signal Vt;
the second demodulation submodule demodulates the analog response signal Vo by adopting a multiplication demodulation algorithm after the mode matching is finished to generate a digital detection feedback signal Vf and a digital quadrature correction signal Vq;
the frequency tuning mechanism comprises a tuning pole plate (1) connected to a frequency tuning electrode Et, and a common pole plate (2) applied with a carrier signal, wherein the frequency tuning electrode Et is connected with an analog signal which is converted and output by a fourth digital-to-analog converter by a digital direct current tuning signal Vt; the electrostatic force between the tuning polar plate (1) and the common polar plate (2) is balanced in the driving and detecting directions of the silicon micro gyroscope, and the electrostatic force is used for changing the rigidity (3) of the silicon micro gyroscope in the detecting direction according to the change of the direct current tuning signal Vt so as to enable the detecting mode resonance frequency to be matched to the driving mode resonance frequency;
the orthogonal correction mechanism comprises a correction plate (4) connected to an orthogonal correction electrode Eq and a common plate (5) to which a carrier signal is applied; the orthogonal correction electrode Eq is connected with an analog signal which is converted and output by a digital orthogonal correction signal Vq through a third digital-to-analog converter, and the upper and lower distances between the comb teeth of the common polar plate (5) and the correction polar plate (4) are unequal, so that an orthogonal correction force (6) in the detection direction is generated according to the unbalance of the electrostatic force generated by the direct current orthogonal correction signal Vq in the detection direction, and the orthogonal error of the detection mode is corrected.
2. The silicon MEMS gyroscope multi-loop closed-loop control apparatus based on the digitizing technique as claimed in claim 1, wherein: the force feedback mechanism comprises a pair of force feedback polar plates (7, 8) connected with force feedback electrodes Ef and Ef-respectively and a movable polar plate (9) applied with carrier signals; the force feedback electrode ef+ and Ef-are connected with a digital bilateral input signal Vi or an analog signal which is converted and output by a digital detection feedback signal Vf through a first digital-to-analog converter; the analog signal output by the first D/A converter is converted by the force feedback polar plates (7, 8) to generate electrostatic force, and the push or pull movable polar plate (9) generates displacement along the detection direction and acts on the detection mechanism.
3. The silicon MEMS gyroscope multi-loop closed-loop control apparatus based on the digitizing technique as claimed in claim 1, wherein: the detection mechanism comprises a pair of detection output polar plates (11, 12) connected with detection output electrodes Es+ and Es-and a movable polar plate (10) for receiving carrier signals applied by external equipment; the movable polar plate (10) generates corresponding displacement according to the action of the force feedback mechanism, so that the capacitance between the movable polar plate (10) and the detection output polar plates (11, 12) is changed; the detection output electrodes es+ and Es-transmit the capacitance conversion amount to the C/V converter.
4. The silicon MEMS gyroscope multi-loop digital closed loop control apparatus of claim 1, wherein the input submodule comprises:
the complex-phase multiplying sub-module generates a sine value and a cosine value of continuous equal-quantity increased angles by adopting a complex multiplication algorithm and outputs the sine value and the cosine value to the digital oscillator;
the digital oscillator controls the initial angle and angle increment of the complex multiplication algorithm by setting corresponding frequency control words and phase control words on the digital oscillator, thereby controlling the frequency and initial phase of the output signal of the digital oscillator and directly synthesizing two paths of input sub-signals cosw 1 t、cosw 2 t and two-way demodulator-sub-standard sine 1 t、sinw 2 t, where the frequency w 1 And w 2 And driving mode resonance frequency w d The difference value is equal, and the difference value is required to be larger than the resonance frequency difference between the detection mode and the driving mode;
a first adder for inputting the sub-signal cosw 1 t、cosw 2 t are added to generate a bilateral input signal Vi.
5. The silicon MEMS gyroscope multi-loop digital closed loop control apparatus of claim 1, wherein the first demodulation sub-module comprises a digital demodulator and a digital PI control sub-module;
the digital demodulator includes:
a first multiplier for outputting digital quantity and input sub-signal cosw from A/D converter 1 t is multiplied to generate a first path of product signal;
a second multiplier for outputting digital quantity and demodulation sub-standard sine from the A/D converter 1 t is multiplied to generate a second path of product signal;
a third multiplier for outputting the digital quantity and the input sub-signal cosw from the A/D converter 2 t is multiplied to generate a third multiplication signal;
a fourth multiplier for outputting digital quantity and demodulation sub-standard sine from the A/D converter 2 t is multiplied to generate a fourth path of product signal;
the first, second, third and fourth path product signals are all signals containing similar direct current components and alternating current components;
the first IIR filter is used for carrying out low-pass filtering on the first, second, third and fourth paths of product signals to respectively obtain first, second, third and fourth types of direct current signals; the DC-like signal comprises amplitude response and phase response information of two sub-signals of a bilateral input signal Vi;
the squarer is used for carrying out square operation on the first, second, third and fourth types of direct current signals to obtain squares of the first, second, third and fourth types of direct current signals;
the second adder is used for carrying out addition operation on the squares of the first class direct current signal and the second class direct current signal to obtain a square sum of the first class direct current signal;
the third adder is used for carrying out addition operation on squares of third and fourth types of direct current signals to obtain a second type of direct current signal square sum;
the first subtracter is used for summing squares of the first class direct current signal and the second class direct current signal to obtain amplitude differences of two sub-signal amplitude responses of the bilateral input signal;
the digital PI control submodule includes:
the reference value presetting module is set to be 0, and when the amplitude difference of the amplitude responses of the two sub-signals of the bilateral input signal is the reference value, the digital PI control sub-module stops working to obtain an accurate direct current tuning signal;
the second subtracter is used for obtaining the difference value between the amplitude difference of the amplitude responses of the two sub-signals of the bilateral input signal and the reference value;
and the first digital PI controller is used for PI controlling the difference value output by the second subtracter and generating a direct current tuning signal Vt.
6. The silicon MEMS gyroscope multi-loop closed-loop control apparatus of claim 1, wherein the second demodulation submodule comprises:
a fifth multiplier for converting the digital quantity converted by the analog-to-digital converter and the driving signal sine d t is multiplied, the digital quantity comprises a Goldrake acceleration signal and an orthogonal error signal, and the product is a fifth path of product signal comprising a DC-like component and an AC-like component; the driving signal sine d t is introduced by the drive mode loop of the MEMS gyroscope, where w d Is the driving mode resonant frequency;
a sixth multiplier for converting the digital quantity converted by the analog-to-digital converter and the driving detection signal cosw d t is multiplied, the digital quantity comprises a Goldrake acceleration signal and an orthogonal error signal, and the product is a sixth path of product signal comprising a DC-like component and an AC-like component; the drive detection signal cosw d t is introduced by the drive circuit, where w d Is the driving mode resonant frequency;
the second IIR filter is used for carrying out low-pass filtering on the fifth path of product signals and outputting fifth direct current signals;
the third IIR filter is used for carrying out low-pass filtering on the sixth path of product signals and outputting sixth direct current signals;
the third subtracter is used for carrying out difference operation on the fifth type direct current signal and the reference value 0 of the second digital PI controller;
the fourth subtracter is used for carrying out difference operation on the sixth direct current signal and a reference value 0 of the third digital PI controller;
the second PI controller is used for performing proportional-integral control on the difference value output by the third subtracter, and generating and outputting the amplitude of the detection feedback signal;
the third PI controller is used for performing proportional-integral control on the difference value output by the fourth subtracter to generate and output an orthogonal correction signal Vq;
seventh multiplier for comparing the amplitude of the detection feedback signal with the driving detection signal cosw d t to obtain a detection feedback signal Vf, where w d Is the drive mode resonant frequency.
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