阅读说明：本技术 一种微机械陀螺的基于自激驱动的非线性控制系统和方法 (Self-excitation drive-based nonlinear control system and method for micromechanical gyroscope ) 是由 张琰珺 马志鹏 金仲和 郑旭东 于 2020-12-25 设计创作，主要内容包括：本发明公开了一种微机械陀螺的基于自激驱动的非线性控制系统和方法,包含位移检测模块、相位偏移模块、幅度控制模块以及驱动模块。其中,检测模块通过载波调制和解调的方式对代表微机械陀螺谐振位移信号进行降噪处理,经过带通滤波器处理得到等效振动位移的正弦电压信号；相位偏移模块将正弦电压信号转为定幅方波电压信号,同时提取谐振频率和幅度,并将方波电压信号进行相移；幅度控制模块通过自动增益控制方法将谐振幅度控制在参考幅度上,生成目标方波电压信号；驱动模块通过一个推挽电路将目标方波信号施加在陀螺的驱动电极上,实现陀螺的闭环控制。本发明原理简单,实现方便,能应用于各类非线性情况下的陀螺以及其他谐振器高精度控制。(The invention discloses a self-excitation driving based nonlinear control system and a self-excitation driving based nonlinear control method for a micromechanical gyroscope. The detection module performs noise reduction processing on a resonance displacement signal representing the micromechanical gyroscope in a carrier modulation and demodulation mode, and a sinusoidal voltage signal of equivalent vibration displacement is obtained through processing of a band-pass filter; the phase shift module converts the sinusoidal voltage signal into a constant-amplitude square wave voltage signal, extracts the resonant frequency and amplitude at the same time, and shifts the phase of the square wave voltage signal; the amplitude control module controls the resonance amplitude on a reference amplitude through an automatic gain control method to generate a target square wave voltage signal; the driving module applies a target square wave signal to a driving electrode of the gyroscope through a push-pull circuit to realize closed-loop control of the gyroscope. The invention has simple principle and convenient realization, and can be applied to the high-precision control of the gyroscope and other resonators under various nonlinear conditions.)

1. A self-excitation drive based nonlinear control system of a micromechanical gyroscope, comprising:

the displacement detection module comprises a detection electrode, a capacitance/voltage conversion module, a modulation module, a demodulation module and a band-pass filter;

the modulation module is used for carrying out carrier modulation on the frequency of the capacitance change signal in the micromechanical gyroscope; the detection electrode is used for detecting a capacitance change signal generated by the resonance displacement of the gyroscope; the capacitance/voltage conversion module is used for converting the capacitance change signal into a voltage detection signal; the demodulation module is used for demodulating a voltage detection signal obtained after the carrier modulation; the band-pass filter is used for filtering noise in the voltage detection signal and outputting a voltage signal containing resonance displacement information;

a phase shift module comprising a comparator and a phase shifter;

the comparator is used for converting the voltage signal containing the resonance displacement information into a square wave voltage signal with fixed amplitude, extracting the resonance frequency and the resonance amplitude of the signal, and outputting a target square wave voltage signal after amplitude adjustment; the phase shifter is used for delaying time according to the resonance frequency of a signal and a preset reference phase and shifting the phase of the target square wave voltage signal;

the amplitude control module is used for comparing the resonance amplitude extracted by the comparator with a preset reference amplitude to obtain a deviation value; obtaining an amplitude correction value of the square wave voltage signal through proportional, integral and differential calculation to generate a target square wave voltage signal;

a driving module including a DA converter and a push-pull circuit;

the DA converter is used for converting the phase-shifted target square wave signal from a digital form into an analog signal form; the push-pull circuit is used for generating a differential driving voltage signal according to the analog signal and applying the differential driving voltage signal to a driving electrode of the micro-mechanical gyroscope to realize closed-loop control of the gyroscope self-excitation loop.

2. A self-excitation drive-based nonlinear control system of a micromechanical gyroscope according to claim 1, wherein the band-pass filter in the displacement detection module is in a cascade connection structure of an IIR low-pass filter and an IIR high-pass filter.

3. A self-excitation drive based nonlinear control system for a micromachined gyroscope of claim 1 wherein the phase shift module comprises two comparators:

a first comparator: when the displacement equivalent voltage input is a positive value, the output is a preset positive amplitude value, and when the displacement equivalent voltage input is a negative value, the output is a preset negative amplitude value, the voltage signal containing the resonance displacement information is converted into a square wave voltage signal with constant amplitude, and the method is a positive/negative half period counting mode;

a second comparator: when the speed equivalent voltage input is a positive value, the output is a preset positive amplitude value, when the speed equivalent voltage is a negative value, the output is a preset negative amplitude value, the voltage signal containing the resonance displacement information is converted into a square wave voltage signal with constant amplitude, and the method is a half-period rising/falling counting mode.

4. A self-excitation drive based nonlinear control system of a micromachined gyroscope of claim 3, wherein the method for extracting the resonant frequency in the phase shift module is as follows: and when the output of the two comparators is a positive value/a negative value, respectively recording the clock cycles of the two comparators to obtain the values of the positive half period and the negative half period of the voltage signal containing the resonance displacement information, adding the values to obtain the period of the voltage signal containing the resonance displacement information, and updating the period value once when each positive/negative half period is finished to finish the real-time frequency extraction.

5. A self-excitation drive based nonlinear control system of a micromachined gyroscope of claim 4, wherein the extracted frequency is corrected in real time by a method comprising: the resonant frequency of the extracted signal is counted in the same way with the first comparator and corrected with respect to the second comparator count.

6. A self-excitation drive based nonlinear control system of a micromechanical gyroscope according to claim 4 or 5, wherein the phase shifter in the phase shift module continuously inputs a target square wave voltage signal into the array and transfers the signal in the array to a next register at each clock rising edge; and calculating the number of a register where the output signal is located according to the signal frequency and the target phase input in real time, thereby completing the phase shift of the square wave signal.

7. A control method for self-excited driving of a micromechanical gyroscope using a system according to any of claims 1-6, characterized in that it comprises the following steps:

1) initializing a micro-mechanical gyroscope;

2) starting closed loop detection, and setting a reference phase and a reference amplitude;

3) generating a carrier signal in the FPGA, applying the carrier signal to a mass block of the micromechanical gyroscope through a DA converter and an amplifying circuit, carrying out carrier modulation on a capacitance change signal generated by the vibration displacement of the micromechanical gyroscope, and obtaining a digital voltage signal through a capacitance/voltage conversion module; demodulating and band-pass filtering the digital voltage signal in the FPGA, and filtering noise in the voltage signal to obtain a digital voltage signal containing resonance displacement information;

4) adopting a comparator to convert a digital voltage signal containing resonance displacement information into a square wave voltage signal with fixed amplitude, and extracting the resonance frequency and the resonance amplitude of the signal in real time, wherein the resonance frequency is extracted and corrected in real time in a positive/negative half-cycle counting mode and a rising/falling half-cycle counting mode;

5) comparing the resonance amplitude extracted by the comparator with a preset reference amplitude to obtain a deviation value; obtaining an amplitude correction value of the square wave voltage signal through proportional, integral and differential calculation to generate a target square wave voltage signal;

6) delaying the target square wave voltage signal through a phase shifter according to the resonance frequency of the signal and a preset reference phase, and phase-shifting the target square wave voltage signal;

7) converting the phase-shifted target square wave signal from a digital form into an analog signal form, generating a differential driving voltage signal through a push-pull circuit, and applying the differential driving voltage signal on a driving electrode of the micromechanical gyroscope to realize closed-loop control of a self-excitation loop of the gyroscope;

8) the closed loop works stably, the phase and the amplitude of a target square wave signal tend to be stable, and the self-excited resonance state of constant phase and constant amplitude can be maintained under the disturbance of an external environment.

Technical Field

The invention relates to the field of micromechanical gyroscopes, in particular to a self-excitation driving based nonlinear control system and method of a micromechanical gyroscope.

Background

A micro-mechanical gyroscope is a sensor for measuring angular velocity, and is widely used in the fields of consumer electronics, industry, aerospace, military and the like due to its advantages of small size, light weight, low power consumption, low cost, easy integration and the like. Within a certain range, the sensitivity and the signal-to-noise ratio of a gyro signal can be improved by improving the gyro resonance displacement amplitude, so that the performance of the gyro is improved. The nonlinear stiffness generated by mechanical and electrostatic forces becomes more prominent as the amplitude of the gyro resonance displacement increases. Under the nonlinear condition, the amplitude-frequency characteristic and the phase-frequency characteristic of the gyroscope have an unstable region, so that the stable operation of the gyroscope is difficult to realize.

Under the nonlinear condition, the relationship between the amplitude and the phase and the relationship between the frequency and the phase are all in single-value function relationship, and two points with zero slope exist in a frequency-phase curve, so that the gyroscope has the potential of stable operation in the nonlinear state. In order to realize stable operation of the micro-mechanical gyroscope under a large-amplitude condition, stable control is required to be performed on the phase and amplitude of the operation of the gyroscope.

The phase control method of the gyroscope generally has two types: the first type is a Phase Locked Loop (PLL), and the second type is a self-excited drive. The phase control of the phase-locked loop obtains a phase error signal by comparing a gyro working phase signal with a reference phase, and then feeds the phase error signal back to the proportional, integral and differential controllers for processing, and adjusts the frequency of the driving force signal in real time to enable the gyro working phase signal to be equal to the reference phase, thereby realizing frequency tracking; the self-excitation drive is based on the principle that the sum of phase shifts inside a loop is integral multiple of 2 pi, and the working phase of the gyroscope is controlled by adding a phase shift link.

In the existing report, the phase-locked loop adopted in the prior report has limited gyro phase Control capability under the condition of prominent nonlinearity, and when the phase-locked loop is used in cooperation with Amplitude Gain Control (AGC), the phase-locked loop and the AGC are difficult to decouple, so that the application requirements in the micromechanical gyro under the nonlinear condition are difficult to meet. Therefore, the invention adopts a nonlinear phase control method based on self-excitation driving.

In the phase control method based on self-excitation driving in the existing report, the phase control function is realized by adopting an analog circuit mode, the flexibility is limited, the real-time extraction of the resonance frequency and amplitude is difficult, the integration degree is low, and the application in various nonlinear micromechanical gyroscope or resonator structures is difficult to meet. Therefore, in practical application, how to more flexibly realize stable control of the phase under the nonlinear condition is an unsolved problem in the field of micromechanical gyroscopes.

Disclosure of Invention

In order to solve the technical problems, the invention provides a self-excitation drive-based nonlinear control system and method for a micromechanical gyroscope.

In order to achieve the purpose, the invention adopts the following technical scheme:

one of the objects of the present invention is to provide a self-excited driving based nonlinear control system of a micromechanical gyroscope, comprising:

the displacement detection module comprises a detection electrode, a capacitance/voltage conversion module, a modulation module, a demodulation module and a band-pass filter;

the modulation module is used for carrying out carrier modulation on the frequency of the capacitance change signal in the micromechanical gyroscope; the detection electrode is used for detecting a capacitance change signal generated by the resonance displacement of the gyroscope; the capacitance/voltage conversion module is used for converting the capacitance change signal into a voltage detection signal; the demodulation module is used for demodulating a voltage detection signal obtained after the carrier modulation; the band-pass filter is used for filtering noise in the voltage detection signal and outputting a voltage signal containing resonance displacement information;

a phase shift module comprising a comparator and a phase shifter;

the comparator is used for converting the voltage signal containing the resonance displacement information into a square wave voltage signal with fixed amplitude, extracting the resonance frequency and the resonance amplitude of the signal, and outputting a target square wave voltage signal after amplitude adjustment; the phase shifter is used for delaying time according to the resonance frequency of a signal and a preset reference phase and shifting the phase of the target square wave voltage signal;

the amplitude control module is used for comparing the resonance amplitude extracted by the comparator with a preset reference amplitude to obtain a deviation value; obtaining an amplitude correction value of the square wave voltage signal through proportional, integral and differential calculation to generate a target square wave voltage signal;

a driving module including a DA converter and a push-pull circuit;

the DA converter is used for converting the phase-shifted target square wave signal from a digital form into an analog signal form; the push-pull circuit is used for generating a differential driving voltage signal according to the analog signal and applying the differential driving voltage signal to a driving electrode of the micro-mechanical gyroscope to realize closed-loop control of the gyroscope self-excitation loop.

Another object of the present invention is to provide a self-excited driving nonlinear control method using the above system, comprising the steps of:

1) initializing a micro-mechanical gyroscope;

2) starting closed loop detection, and setting a reference phase and a reference amplitude;

3) generating a carrier signal in the FPGA, applying the carrier signal to a mass block of the micromechanical gyroscope through a DA converter and an amplifying circuit, carrying out carrier modulation on a capacitance change signal generated by the vibration displacement of the micromechanical gyroscope, and obtaining a digital voltage signal through a capacitance/voltage conversion module; demodulating and band-pass filtering the digital voltage signal in the FPGA, and filtering noise in the voltage signal to obtain a digital voltage signal containing resonance displacement information;

4) adopting a comparator to convert a digital voltage signal containing resonance displacement information into a square wave voltage signal with fixed amplitude, and extracting the resonance frequency and the resonance amplitude of the signal in real time, wherein the resonance frequency is extracted and corrected in real time in a positive/negative half-cycle counting mode and a rising/falling half-cycle counting mode;

5) comparing the resonance amplitude extracted by the comparator with a preset reference amplitude to obtain a deviation value; obtaining an amplitude correction value of the square wave voltage signal through proportional, integral and differential calculation to generate a target square wave voltage signal;

6) delaying the target square wave voltage signal through a phase shifter according to the resonance frequency of the signal and a preset reference phase, and phase-shifting the target square wave voltage signal;

7) converting the phase-shifted target square wave signal from a digital form into an analog signal form, generating a differential driving voltage signal through a push-pull circuit, and applying the differential driving voltage signal on a driving electrode of the micromechanical gyroscope to realize closed-loop control of a self-excitation loop of the gyroscope;

8) the closed loop works stably, the phase and the amplitude of a target square wave signal tend to be stable, and the self-excited resonance state of constant phase and constant amplitude can be maintained under the disturbance of an external environment.

Compared with the prior art, the invention has the beneficial effects that:

1) the phase deviation module and the amplitude control module are realized based on a digital mode of an FPGA, and compared with an analog realization mode in the prior report, the phase deviation module and the amplitude control module have higher integration degree and wider application range; the implementation mode is simple, the flexibility degree is high, and the modification cost is low; the control precision is high, the temperature characteristic is better, and the noise immunity is strong.

2) The comparator in the phase deviation module can finish the real-time extraction of the signal frequency and the mutual error correction in two modes (positive/negative half cycle counting and rising/falling half cycle counting), can finish the extraction of the signal amplitude simultaneously, and ensures the accuracy of the frequency extraction result.

3) The working phase control method is real-time and controllable under the nonlinear influence, and can enable the micro-mechanical gyroscope to work in a phase adjustable mode; in the phase control process under the nonlinear influence, the phase shift operation of the target signal is completed by the preset reference phase in a phase shifter delay time mode, so that the working phase of the gyroscope is equivalently changed, and the whole adjusting process is convenient and controllable.

4) The invention is based on the self-excitation driving principle, and has better phase control capability under the condition of nonlinear influence compared with a phase-locked loop. The invention adopts square wave drive, can convert the voltage signal containing resonance displacement information into a square wave voltage signal of real-time input amplitude, and has high stability and good noise resistance. Meanwhile, the amplitude can be controlled through an AGC loop, and the amplitude control loop and the phase control loop are decoupled with each other, so that the control precision of the phase and the amplitude is improved.

Drawings

FIG. 1 is a block diagram of a closed loop control of a micromachined gyroscope of the present invention;

FIG. 2 is a simulation result diagram of the micromechanical gyroscope self-excitation driving nonlinear control method in the invention.

Detailed Description

The invention is further described below with reference to the figures and examples.

As shown in fig. 1, taking a micro-mechanical ring gyroscope as an example, the micro-mechanical ring gyroscope of the present invention includes:

(1) the displacement detection module comprises a detection electrode, a capacitance/voltage conversion module, a modulation module, a demodulation module and a band-pass filter;

the detection electrode is used for detecting a capacitance change signal generated by the resonance displacement of the gyroscope; the capacitance/voltage conversion module is used for converting the capacitance change signal into a voltage detection signal; the modulation module is used for modulating the signal and modulating the capacitance change signal to a higher frequency; the demodulation module restores the carrier modulation signal; the band-pass filter adopts a structure of cascading the IIR low-pass filter and the IIR high-pass filter, is used for filtering noise outside a bandwidth in the voltage detection signal, such as a carrier frequency-doubling signal after carrier demodulation, an odd frequency-doubling high-frequency signal contained in a square wave driving signal, a direct-current signal and the like, and outputs a voltage signal containing resonance displacement information. In this embodiment, the voltage signal containing the resonance displacement information is a sinusoidal voltage signal of equivalent resonance displacement.

(2) The phase shift module comprises a comparator and a phase shifter;

the comparator converts the voltage signal containing the resonance displacement information into a square wave voltage signal with constant amplitude, and extracts the resonance frequency and the resonance amplitude of the signal; the phase shifter delays the time according to the resonance frequency of the signal and a preset reference phase, and phase-shifts the square wave voltage signal; the square wave voltage signal after phase shifting is output to the driving module, and the phase closed-loop control of the gyroscope is realized.

In one embodiment of the present invention, the comparator in the phase shift module outputs a real-time input amplitude when the input is positive and outputs a negative real-time input amplitude when the input is negative, thereby converting the voltage signal containing the resonance displacement information into a constant square wave voltage signal. More specifically, the phase shift module includes two comparators:

a first comparator: when the displacement equivalent voltage input is a positive value, the output is a preset positive amplitude value, and when the displacement equivalent voltage input is a negative value, the output is a preset negative amplitude value, the voltage signal containing the resonance displacement information is converted into a square wave voltage signal with constant amplitude, and the method is a positive/negative half period counting mode;

a second comparator: when the speed equivalent voltage input (i.e. the change rate of the displacement equivalent voltage) is a positive value, the output is a preset positive amplitude, and when the speed equivalent voltage is a negative value, the output is a preset negative amplitude, the voltage signal containing the resonance displacement information is converted into a constant amplitude square wave voltage signal, and the method is a counting mode of rising/falling half cycles.

The method for extracting the resonant frequency in the phase shift module comprises the following steps: when the outputs of the two comparators are positive values/negative values, the clock cycles are respectively recorded, the values of the positive half period and the negative half period of the voltage signal containing the resonance displacement information are obtained, the values are added to obtain the period of the voltage signal containing the resonance displacement information, and the period value is updated once when each positive/negative half period is finished, so that the real-time frequency extraction is completed. Meanwhile, the frequency of the signal obtained by counting by the first comparator is mutually corrected with the counting of the second comparator in the same way to ensure the correctness of the frequency extraction result.

In one embodiment of the present invention, the register is used to perform phase shift on the square wave voltage signal, specifically: a digital phase shifter in the phase shift module continuously inputs a target square wave voltage signal into the array, and transfers the signal in the array to a next register at each clock rising edge; and calculating the number of a register where the output signal is located according to the signal frequency and the target phase input in real time, thereby completing the phase shift of the square wave signal.

(3) An amplitude control module;

comparing the resonance amplitude extracted by the comparator with a reference amplitude by an amplitude gain control method to obtain a deviation value, and obtaining an amplitude correction value of the square wave voltage signal through proportional, integral and differential calculation to generate a target square wave voltage signal;

(4) a driving module including a DA converter and a push-pull circuit;

the DA converter is used for converting a digital target square wave signal into an analog target square wave signal, and the push-pull circuit is used for generating a differential driving voltage signal and applying the differential driving voltage signal to a driving electrode of the gyroscope to realize closed-loop control of a self-excitation loop of the gyroscope.

In the displacement detection module, a carrier signal is generated in the FPGA and is applied to a mass block of the micromechanical gyroscope through a DA converter and an amplifying circuit, the carrier is applied to modulate a capacitance change signal generated by the vibration displacement of the micromechanical ring gyroscope, and a digital voltage signal is obtained through a CV interface circuit and an AD converter; demodulating and band-pass filtering the signals in the FPGA to obtain digital voltage signals representing resonance displacement information;

the phase shift module converts a digital voltage signal representing resonance displacement information into a fixed-amplitude square wave voltage signal through a comparator, and the comparator finishes the real-time extraction of signal frequency and the amplitude extraction of the signal in two real-time frequency extraction modes (positive/negative half-cycle counting and rising/falling half-cycle counting); the square wave voltage signal is subjected to phase shift by using a register, so that the purpose of phase control is achieved;

the amplitude control module compares the extracted resonance amplitude with a reference amplitude in an FPGA (field programmable gate array) by an automatic gain control method to obtain a deviation value, obtains an amplitude correction value of a square wave control voltage signal through proportional, integral and differential calculation, and generates a target square wave control voltage signal by combining a unit phase-shifting square wave signal output by the phase offset module to realize the purpose of amplitude control;

the driving module converts the digital target square wave signal into an analog target square wave signal through a DA converter, and generates a differential driving voltage signal by utilizing an analog push-pull circuit, and the differential driving voltage signal is applied to a driving electrode of the gyroscope to realize gyroscope driving closed-loop control.

Under the closed-loop working state, the phase deviation module and the amplitude control module control the working phase and amplitude of the gyroscope to be in a reference state, so that the stable work of the gyroscope under the condition of large nonlinear influence is realized. The control method of the system mainly comprises the following steps:

1) in the initialization process, due to the existence of external noise, the micro-mechanical gyroscope generates weak resonant motion under the action of thermal noise, and the resonant frequency of the gyroscope can be extracted through the displacement detection module;

2) starting closed loop, setting a reference phase and a reference amplitude, converting a sinusoidal voltage signal containing resonance displacement acquired by a displacement detection module into a square wave voltage signal with fixed amplitude by a phase offset module, updating the resonance frequency and the amplitude in real time, calculating the number of registers required for realizing phase shift according to the reference phase and the updated resonance frequency, and finishing phase shift operation; meanwhile, the amplitude control module can calculate the amplitude of a target square wave signal according to the reference amplitude and the updated amplitude, the target square wave signal is generated by combining the phase offset module, and the driving module up-converts the phase-shifted square wave voltage signal into a driving force applied to the gyroscope structure through a driving electrode of the parallel plate capacitor structure, so that the gyroscope sensitive structure is excited, and the closed loop of a self-excitation loop is completed;

3) and the closed loop stably works, the phase and the amplitude of the target square wave signal tend to be relatively stable after a period of time, and the self-excited resonance state of constant phase and constant amplitude can be maintained under the disturbance of the external environment.

In one embodiment of the present invention, step 2) is the core process of the present invention, and the specific process of step 2) is further described as follows:

2.1) generating a carrier signal in the FPGA, applying the carrier signal on a mass block of the micromechanical gyroscope through a DA converter and an amplifying circuit, carrying out carrier modulation on a capacitance change signal generated by the vibration displacement of the micromechanical gyroscope, and obtaining a digital voltage signal through a capacitance/voltage conversion module; demodulating and band-pass filtering the digital voltage signal in the FPGA, and filtering noise in the voltage signal to obtain a digital voltage signal containing resonance displacement information;

2.2) converting a digital voltage signal containing resonance displacement information into a square wave voltage signal with fixed amplitude by adopting a comparator, and extracting the resonance frequency and the resonance amplitude of the signal in real time, wherein the resonance frequency is extracted and corrected in real time in a positive/negative half-cycle counting mode and a rising/falling half-cycle counting mode;

2.3) comparing the resonance amplitude extracted by the comparator with a preset reference amplitude to obtain a deviation value; obtaining an amplitude correction value of the square wave voltage signal through proportional, integral and differential calculation to generate a target square wave voltage signal;

2.4) delaying the time through a phase shifter according to the resonance frequency of the signal and a preset reference phase, and phase-shifting the target square wave voltage signal;

2.5) converting the phase-shifted target square wave signal from a digital form into an analog signal form, generating a differential driving voltage signal through a push-pull circuit, and applying the differential driving voltage signal on a driving electrode of the micromechanical gyroscope to realize closed-loop control of a gyroscope self-excitation loop;

in order to prove the control effect of the invention, the micromechanical gyroscope self-excitation driving nonlinear control method is subjected to simulation analysis, and the simulation result is shown in fig. 2. The amplitude of the displacement signal gradually tends to be stable in the self-excitation driving closed loop, the sine displacement signal is converted into a fixed-amplitude square wave signal after passing through the comparator, the phase shifter delays the fixed-amplitude square wave signal by a preset reference phase, and the loop normally operates according to the conditions in the design.

The foregoing lists merely illustrate specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.