Disclosure of Invention
Aiming at the technical problems of the Lissajous FM gyro system in the prior art, the invention provides a Lissajous modulation and self-correction test system of the FM gyro, which adopts the following technical scheme:
a frequency modulation gyro Lissajous modulation and self-correction test system comprises an FDC circuit, an ADC circuit, an IQ demodulation circuit, a coherent demodulation circuit, a phase modulator, a phase-locked loop circuit, an automatic gain control circuit, a numerical control oscillator, a multiplier, an adder, an error control circuit, a DAC circuit, a low-pass filter and an electrical interface;
the two FDC circuits are respectively a first FDC circuit and a second FDC circuit;
the two ADC circuits are respectively a first ADC circuit and a second ADC circuit;
two IQ demodulation circuits are provided, namely a first IQ demodulation circuit and a second IQ demodulation circuit;
the coherent demodulation circuit and the phase modulator are respectively provided with one phase modulator;
the two phase-locked loop circuits are respectively a first phase-locked loop circuit and a second phase-locked loop circuit;
the two automatic gain control circuits are respectively a first automatic gain control circuit and a second automatic gain control circuit;
the two numerically-controlled oscillators are respectively a first numerically-controlled oscillator and a second numerically-controlled oscillator;
the number of the multipliers is two, namely a first multiplier and a second multiplier; one adder is provided;
the two error control circuits are respectively a first error control circuit and a second error control circuit;
the two DAC circuits are respectively a first DAC circuit and a second DAC circuit;
the number of the low-pass filters is three, and the three low-pass filters are respectively a first low-pass filter, a second low-pass filter and a third low-pass filter;
the number of the electrical interfaces is six, namely a first electrical interface, a second electrical interface, a third electrical interface, a fourth electrical interface, a fifth electrical interface and a sixth electrical interface;
the input end of the first FDC circuit and the input end of the first ADC circuit are connected with the sixth electrical interface, and the input end of the second FDC circuit and the input end of the second ADC circuit are connected with the fifth electrical interface;
the output end of the first ADC circuit is connected with the input end of the first IQ demodulation circuit; the output end of the first IQ demodulation circuit is respectively connected with the input ends of the first phase-locked loop circuit and the first automatic gain control circuit;
the output end of the second ADC circuit is connected with the input end of the second IQ demodulation circuit; the output end of the second IQ demodulation circuit is respectively connected with the input ends of the second phase-locked loop circuit and the second automatic gain control circuit;
the output ends of the first phase-locked loop circuit and the first automatic gain control circuit are connected with the input end of the first numerical control oscillator;
the output ends of the second phase-locked loop circuit and the second automatic gain control circuit are connected with the input end of the second numerical control oscillator;
the output end of the first digital controlled oscillator is respectively connected to the input end of the first multiplier, the input end of the second multiplier, the input end of the first error control circuit and the input end of the first DAC circuit; the output ends of the first error control circuit and the first DAC circuit are respectively connected with the fourth electrical interface and the first electrical interface;
the output end of the second digital controlled oscillator is connected with the input end of the first multiplier, the input end of the second error control circuit and the input end of the second DAC circuit; the output ends of the second error control circuit and the second DAC circuit are respectively connected with the third electrical interface and the second electrical interface;
the output end of the first multiplier is connected with the input ends of the first low-pass filter and the phase modulator in sequence; the output end of the second multiplier is sequentially connected with the input ends of the second low-pass filter and the phase modulator;
the output end of the phase modulator is connected with the input end of the coherent demodulation circuit; the output ends of the first FDC circuit and the second FDC circuit are respectively connected to the input end of the adder, and the output end of the adder is connected with the input end of the coherent demodulation circuit;
the output end of the coherent demodulation circuit is connected with a third low-pass filter, and the third low-pass filter is connected with a rate signal output interface.
Preferably, the frequency modulation gyroscope comprises a first driving input electrode, a second driving input electrode, a first tuning input electrode, a second tuning input electrode, a first sensing output electrode and a second sensing output electrode;
the first driving input electrode is connected with the first electrical interface, and the second driving input electrode is connected with the second electrical interface;
the first tuning input electrode is connected with the fourth electrical interface, and the second tuning input electrode is connected with the third electrical interface;
the first sensing output electrode is connected with the sixth electrical interface, and the second sensing output electrode is connected with the fifth electrical interface.
Preferably, the frequency modulation gyroscope adopts an MEMS gyroscope equivalent circuit, which includes a first vibration mode circuit, a second vibration mode circuit, and a coupling circuit located between the first vibration mode circuit and the second vibration mode circuit;
the first vibration mode circuit comprises a first resistor, a first capacitor and a first inductor which are sequentially connected in series;
the second vibration mode circuit comprises a second resistor, a second capacitor and a second inductor which are sequentially connected in series;
the coupling circuit comprises an operational amplifier, a mutual inductor, a VGA and a potentiometer;
six operational amplifiers are respectively a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier, a fifth operational amplifier and a sixth operational amplifier;
sixteen transformers are respectively a first transformer, a second transformer, a third transformer, a fourth transformer, a fifth transformer, a sixth transformer, a seventh transformer, an eighth transformer, a ninth transformer, a tenth transformer, an eleventh transformer, a twelfth transformer, a thirteenth transformer, a fourteenth transformer, a fifteenth transformer and a sixteenth transformer;
the two VGAs are respectively a first VGA and a second VGA;
eight potentiometers are provided, namely a first potentiometer, a second potentiometer, a third potentiometer, a fourth potentiometer, a fifth potentiometer, a sixth potentiometer, a seventh potentiometer and an eighth potentiometer;
the input end of the first mutual inductor is connected with a first driving input electrode, and the output end of the first mutual inductor is connected in series with a first vibration mode circuit;
the input end of the second mutual inductor is connected with a second driving input electrode, and the output end of the second mutual inductor is connected in series with a second vibration mode circuit;
the positive phase input end and the negative phase input end of the first operational amplifier are respectively connected to one end part of the first capacitor, and the output end of the first operational amplifier is connected to the input end of the twelfth transformer; the output end of the twelfth mutual inductor is connected in series with a second vibration mode circuit;
the positive phase input end and the negative phase input end of the sixth operational amplifier are respectively connected to one end part of the second capacitor, and the output end of the sixth operational amplifier is connected to the input end of the sixth mutual inductor; the output end of the sixth mutual inductor is connected in series with the first vibration mode circuit;
the input end of the fifth mutual inductor is connected in series with the first vibration mode circuit, and the output end of the fifth mutual inductor is respectively connected with the positive phase input end and the negative phase input end of the second operational amplifier; the output end of the second operational amplifier is connected to the input end of the eleventh mutual inductor;
the output end of the eleventh mutual inductor is connected in series with a second vibration mode circuit;
the input end of the thirteenth mutual inductor is connected with the second vibration mode circuit in series, and the output end of the thirteenth mutual inductor is connected with the positive phase input end and the negative phase input end of the fifth operational amplifier respectively; the output end of the fifth operational amplifier is connected to the input end of the fourth mutual inductor;
the output end of the fourth transformer is connected in series with the first vibration mode circuit;
the input end of the seventh mutual inductor is connected in series with the first vibration mode circuit, and the output end of the seventh mutual inductor is respectively connected with the positive phase input end and the negative phase input end of the third operational amplifier; the output end of the third operational amplifier is sequentially connected with the input ends of the first VGA and the tenth mutual inductor;
the output end of the tenth mutual inductor is connected in series with a second vibration mode circuit;
the input end of the fifteenth transformer is connected in series with the second vibration mode circuit, and the output end of the fifteenth transformer is connected with the positive phase input end and the negative phase input end of the fourth operational amplifier respectively; the output end of the fourth operational amplifier is sequentially connected with the second VGA and the input end of the third mutual inductor;
the output end of the third mutual inductor is connected in series with the first vibration mode circuit;
one end of the first potentiometer is connected with the positive phase input end of the first operational amplifier, and the other end of the first potentiometer is grounded;
the second potentiometer is connected between the negative phase input end of the first operational amplifier and the output end of the first operational amplifier;
the third potentiometer is connected between the negative phase input end of the second operational amplifier and the output end of the second operational amplifier;
the fourth potentiometer is connected between the negative phase input end of the third operational amplifier and the output end of the third operational amplifier;
one end of the fifth potentiometer is connected with the positive phase input end of the sixth operational amplifier, and the other end of the fifth potentiometer is grounded;
the sixth potentiometer is connected between the negative phase input end of the sixth operational amplifier and the output end of the sixth operational amplifier;
the seventh potentiometer is connected between the negative phase input end of the fifth operational amplifier and the output end of the fifth operational amplifier;
the eighth potentiometer is connected between the negative phase input end of the fourth operational amplifier and the output end of the fourth operational amplifier;
the input end of the eighth mutual inductor is connected with the first tuning input electrode, and the output end of the eighth mutual inductor is connected in series with the first vibration mode circuit; the input end of the fourteenth mutual inductor is connected with the second tuning input electrode, and the output end of the fourteenth mutual inductor is connected in series with the second vibration mode circuit;
the input end of the ninth mutual inductor is connected with the first vibration mode circuit in series, and the output end of the ninth mutual inductor is connected with the first induction output electrode; and the input end of the sixteenth mutual inductor is connected in series with the second vibration mode circuit, and the output end of the sixteenth mutual inductor is connected with the second induction output electrode.
The invention has the following advantages:
as described above, the invention provides a frequency modulation gyro Lissajous modulation and self-correction test system, aiming at the defect that the existing Lissajous frequency modulation gyro lacks a self-correction system, an ADC (analog to digital converter) auxiliary novel topological structure is designed for frequency tracking control and amplitude stabilization control, and the topological structure is a closed-loop operation mode and is used for resolving a driving signal and an angular rate signal separately, so that high-stability control of vibration frequency and amplitude is realized, and zero drift errors caused by mismatching of resonance frequency change and damping are suppressed.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
examples
As shown in fig. 1, the present invention relates to a frequency modulation gyro lissajous modulation and self-calibration test system, which comprises an FDC circuit, an ADC circuit, an IQ demodulation circuit, a coherent demodulation circuit, a phase modulator, a phase locked loop circuit, an automatic gain control circuit, a digitally controlled oscillator, a multiplier, an adder, an error control circuit, a DAC circuit, a low-pass filter and an electrical interface.
The FDC circuit, the ADC circuit, the IQ demodulation circuit, the coherent demodulation circuit, the phase modulator, the phase-locked loop circuit, the automatic gain control circuit, the IQ demodulation circuit, the error control circuit, the DAC circuit and the like can adopt mature schemes.
There are two FDC circuits, afirst FDC circuit 201a and asecond FDC circuit 201 b.
There are two ADC circuits, afirst ADC circuit 202a and asecond ADC circuit 202 b.
There are two IQ demodulation circuits, namely a firstIQ demodulation circuit 203a and a secondIQ demodulation circuit 203 b.
Thecoherent demodulation circuit 204 and thephase modulator 205 are each provided with one.
There are two pll circuits, a first pll circuit 206a and a second pll circuit 206 b.
The automatic gain control circuit includes a first automaticgain control circuit 207a and a second automaticgain control circuit 207 b.
The two dcgs are afirst dcg 208a and asecond dcg 208 b.
There are two multipliers, afirst multiplier 209a and asecond multiplier 209 b; there is oneadder 210.
There are two error control circuits, a first error control circuit 211a and a seconderror control circuit 211 b.
There are two DAC circuits, afirst DAC circuit 212a and a second DAC circuit 212 b.
The low pass filters include a firstlow pass filter 213a, a second low pass filter 213b, and a thirdlow pass filter 213 c.
There are six electrical interfaces, which are the first electrical interface 111a, the secondelectrical interface 111b, the thirdelectrical interface 111c, the fourthelectrical interface 111d, the fifthelectrical interface 111e, and the sixthelectrical interface 111 f.
The input end of thefirst FDC circuit 201a is connected to the sixthelectrical interface 111f, and the output of the first vibration mode of the fm gyroscope is connected to the input end of thefirst FDC circuit 201a through the sixthelectrical interface 111 f.
The input end of thesecond FDC circuit 201b is connected to the fifthelectrical interface 111e, and the output of the second vibration mode of the fm gyro is connected to the input end of thesecond FDC circuit 201b through the fifthelectrical interface 111 e.
In addition, the output of the first vibration mode of the fm gyroscope is further connected to the input terminal of thefirst ADC circuit 202a through the sixthelectrical interface 111f, and thefirst ADC circuit 202a is configured to convert the analog signal into a digital signal.
The output of the second vibration mode of the fm gyroscope is further connected to the input of asecond ADC circuit 202b through a fifthelectrical interface 111e, and thesecond ADC circuit 202b is configured to convert the analog signal into a digital signal.
An output terminal of thefirst ADC circuit 202a is connected to an input terminal of the firstIQ demodulation circuit 203 a. The output signal of thefirst ADC circuit 202a is IQ-demodulated in the firstIQ demodulation circuit 203a to obtain an in-phase signal and a quadrature signal.
The output terminal of the firstIQ demodulation circuit 203a is connected to the input terminals of the first phase-locked loop circuit 206a and the first automaticgain control circuit 207a, respectively, and is capable of locking the resonance frequency point and controlling the excitation gain.
The output end of thesecond ADC circuit 202b is connected to the input end of the secondIQ demodulation circuit 203 b; the output signal of thesecond ADC circuit 202b is IQ-demodulated in the secondIQ demodulation circuit 203b to obtain an in-phase signal and a quadrature signal.
The output terminal of the secondIQ demodulation circuit 203b is connected to the input terminals of the second phase-locked loop circuit 206b and the second automaticgain control circuit 207b, respectively, and is capable of locking the resonance frequency point and controlling the excitation gain.
The outputs of the first phase locked loop circuit 206a and the first automaticgain control circuit 207a are coupled to the input of a first digitally controlledoscillator 208a, which is capable of generating an excitation signal. The outputs of the second phase locked loop circuit 206b and the second automaticgain control circuit 207b are connected to the input of a second numerically controlledoscillator 208b capable of generating an excitation signal.
The outputs of the first and second numerically controlledoscillators 208a, 208b are connected to the inputs of first andsecond multipliers 209a, 209b, respectively.
The output of thefirst multiplier 209a is coupled to an input of a first low-pass filter 213a, the output of the first low-pass filter 213a being coupled to an input of thephase modulator 205.
The output of thesecond multiplier 209b is connected to the input of a second low-pass filter 213 b; the output of second low pass filter 213b is connected to the other input ofphase modulator 205.
The output ofphase modulator 205 is connected to the input ofcoherent demodulation circuit 204.
The sine and cosine signals generated by the first and second digitally controlledoscillators 208a and 208b are multiplied and filtered before being input to thephase modulator 205, and the output of thephase modulator 205 provides a reference signal for thecoherent demodulation circuit 204.
Furthermore, the output of the first digitally controlledoscillator 208a is coupled to an input of a first error control circuit 211a, and the output of the second digitally controlledoscillator 208b is coupled to an input of a seconderror control circuit 211 b.
The output end of the first error control circuit 211a is connected to the fourthelectrical interface 111d, and the tuning signal generated by the first error control circuit 211a is input to the first tuning electrode of the fm gyroscope through the fourthelectrical interface 111 d.
The output end of the seconderror control circuit 211b is connected to the thirdelectrical interface 111c, and the tuning signal generated by the seconderror control circuit 211b is input to the second tuning electrode of the fm gyroscope through the thirdelectrical interface 111 c.
Furthermore, the output of the first digitally controlledoscillator 208a is also connected to the input of the firstD AC circuit 212 a; the output of thefirst DAC circuit 212a is connected to the first electrical interface 111 a. The first D-AC circuit 212a is configured to convert the digital signal into an analog signal, and then input the analog signal to the first driving input electrode of the fm gyro as a driving excitation signal of the first vibration mode.
The output of the second numerically controlledoscillator 208b is also connected to an input of a second DAC circuit 212b, the output of the second DAC circuit 212b being connected to the secondelectrical interface 111 b. The second D-AC circuit 212b is configured to convert the digital signal into an analog signal, and then input the analog signal to the second driving input electrode of the fm gyro as a driving excitation signal of the second vibration mode.
The outputs of thefirst FDC circuit 201a and thesecond FDC circuit 201b are connected to the inputs of anadder 210, respectively, and their outputs are added in theadder 210, and the output of theadder 210 is connected to the input of thecoherent demodulation circuit 204.
The output end of thecoherent demodulation circuit 204 is connected to the input end of the third low-pass filter 213c, and the output end of the third low-pass filter 213c is connected to the ratesignal output interface 214, so as to filter and output the demodulated signal.
The trend of the signal flow in the frequency modulation gyro Lissajous modulation and self-correction test system is as follows:
1. thefirst FDC circuit 201a is connected to the sixthelectrical interface 111f, and is configured to extract a frequency signal of an induction output signal of the firstinduction output electrode 110 a; thesecond FDC circuit 201b is connected to the fifthelectrical interface 111e, and is configured to extract a frequency signal of the sensing output signal of the secondsensing output electrode 110 b.
2. Thefirst ADC circuit 202a is connected to the sixthelectrical interface 111f, and is configured to perform analog-to-digital conversion on the sensing output signal of the firstsensing output electrode 110a, i.e. convert the analog signal into a digital signal. The digital signal is IQ-demodulated by the firstIQ demodulation circuit 203a, and the demodulated signal enters the first phase-locked loop circuit 206a and the first automaticgain control circuit 207 a.
Thesecond ADC circuit 202b is connected to the fifthelectrical interface 111e, and is configured to perform analog-to-digital conversion on the sensing output signal of the secondsensing output electrode 110b, i.e. convert the analog signal into a digital signal. The digital signal is IQ-demodulated by the secondIQ demodulation circuit 203b, and the demodulated signal enters the second phase-locked loop circuit 206b and the second automaticgain control circuit 207 b.
In the embodiment of the invention, the frequency tracking uses the phase-locked loop circuit, the actual resonance frequency of the gyroscope is influenced by the environment and the residual stress is released, the actual resonance frequency of the gyroscope is constantly changed, if the gyroscope is driven by using a fixed frequency, the driving frequency is inconsistent with the resonance frequency of the gyroscope, so that the gyroscope generates zero drift, the frequency of the numerical control oscillator is maintained at each tracking point by using the phase-locked loop to track the two-mode resonance frequency points, and the gyroscope always works in a resonance state, so that the gyroscope is ensured to have higher sensitivity and the error caused by the parts is effectively reduced.
Meanwhile, the amplitude of two modes of the gyroscope is stably controlled through the automatic gain control circuit, so that the measurement stability and precision of the gyroscope are ensured. Due to the anisotropic characteristic of silicon materials and the tolerance in the manufacturing process, the damping coefficients/quality factors of two modes are different, and the mismatch error of the damping can cause the serious nonlinear drift of the gyroscope; in the long-term operation process, the damping coefficient can also generate slow change due to heating and stress release, so that the angular rate of the gyroscope can randomly walk, the gyroscope can be equivalently driven into two damping matching modes by using the automatic gain control circuit, the amplitude instability in the long-term operation can be counteracted, and the medium-term and long-term zero point stability of the gyroscope is finally effectively improved.
3. The first PLL circuit 206a and thefirst AGC circuit 207a output signals to afirst VCO 208a to generate a two-axis digital sin (ω) signalxt) and cos (. omega.) ofxt). The second PLL circuit 206b and thesecond AGC circuit 207b output signals to a seconddigital oscillator 208b to generate a two-axis digital signal sin (ω)yt) and cos (. omega.) ofyt)。
4. The signals output by thefirst FDC circuit 201a and thesecond FDC circuit 201b are added and enter thecoherent demodulation circuit 204, and the MEMS gyro signal is processed by the FDC circuit and then outputs omegazsin (Δ ω t).
In the formula, Δ ω changes continuously and has a low frequency, and harmonic distortion is easily generated in the process of coherent demodulation of a traditional signal, so that the signal-to-noise ratio of the signal is reduced, and great challenge is brought to improvement of zero instability of the output angular rate of the gyroscope.
The embodiment of the invention can recover the accurate demodulation reference signal by using the combination of the numerical control oscillator, the filter and the phase modulator.
5. The signal generated by the first digitally controlledoscillator 208a and the signal generated by the second digitally controlledoscillator 208b are multiplied to obtain:
the high frequency component cos [ (omega) can be filtered after passing through the first low pass filter and the second low pass filterx+ωy)t]And sin [ (omega)x+ωy)t]The remaining component cos [ (omega [ #]x-ωy)t]And sin [ (omega)x-ωy)t]The reference signal is demodulated for the key.
Because a low-pass filter can introduce phase delay, the invention recovers demodulation reference signals cos (delta omega t) and sin (delta omega t) with accurate phases through a 32-bit dual-channel phase modulator 205 designed by FPGA, and considers phase change caused by operation and transmission in an actual system, and the scheme also designs a phase modulator to ensure the orthogonal/in-phase relation of the demodulation reference signals and the demodulated signals.
6. Demodulated signals cos (Δ ω t) and sin (Δ ω t) output by thephase modulator 205 enter thecoherent demodulation circuit 204, and coherent demodulation and filtering are performed by using the accurate demodulated signals, so that accurate rate output signals can be obtained;
the rate output signal obtained by coherent demodulation and filtering is output via the ratesignal output port 214.
7. The output signal of the first digitally controlledoscillator 208a enters the first error control circuit 211a, and the tuning signal generated by the first error control circuit 211a is input to the first tuning electrode of the fm gyro through the fourthelectrical interface 111 d.
The output signal of the second digital controlledoscillator 208b enters the seconderror control circuit 211b, and the tuning signal generated by the seconderror control circuit 211b is input to the second tuning electrode of the fm gyro through the thirdelectrical interface 111 c.
The frequency cracking is a key parameter for accurately resolving the angular rate of the frequency modulation gyroscope, and directly determines the zero position of the gyroscope. In reality, because the gyroscope tube core has undesirable factors such as temperature change, residual stress release and the like, the resonant frequencies of the two modes are constantly changed in the running state, and the change directions of the resonant frequencies are inconsistent due to the anisotropy of the monocrystalline silicon material. In other words, the gyro frequency difference Δ ω is a key parameter, and is shifted with time, thereby seriously affecting the zero-point stability, especially the stability of the middle and long periods of the gyro.
In order to minimize the influence of frequency cracking on the system, the present embodiment proposes a dc tuning voltage control method. Under the Lissajous frequency modulation operation mode, two modes of the gyroscope are respectively driven by a numerical control oscillator and matched with respective phase-locked loop circuits, so that frequency cracking numerical values of the two modes can be extracted in real time. After extracting the frequency-resolved values, the tuning voltage may be input to the thirdelectrical interface 111c and the fourthelectrical interface 111d to dynamically tune the frequency difference between the two XY modes.
8. The output signal of the first digitally controlledoscillator 208a enters thefirst DAC circuit 212a, and thefirst DAC circuit 212a converts the digital signal into an analog signal and then enters the first electrical interface 111a, thereby completing the phase-locked loop and the automatic gain control.
The output signal of the second digital controlledoscillator 208b enters the second DAC circuit 212b, and the second DAC circuit 212b converts the digital signal into an analog signal and then enters the secondelectrical interface 111b, thereby completing the phase-locked loop and the automatic gain control.
Compared with the prior art, the Lissajous modulation and self-correction test system in the embodiment has the following advantages:
the invention adopts a frequency modulation method and utilizes the FDC circuit to extract frequency signals, thereby solving the problem that amplitude signals are easy to interfere in an amplitude modulation scheme.
Secondly, the invention adopts a Lissajous frequency modulation method, can demodulate rate signals without mode matching, and solves the problems that the commonly used orthogonal frequency modulation in the current frequency modulation system has strong stability dependence on resonance frequency points and extremely high requirement on circuit symmetry.
The current Lissajous frequency modulation system is an open loop system and lacks a self-correcting system.
According to the invention, the system forms a closed loop through an ADC (analog to digital converter) auxiliary topological structure, and the drift in the mechanical system is counteracted through a phase-locked loop, automatic gain control and an error correction loop, so that the problem that the external interference cannot be corrected by self during open-loop operation of the current frequency modulation system is solved.
The closed loop is that an analog signal of a gyro system is converted into a digital signal by an ADC (analog to digital converter) circuit, the signal is demodulated into an in-phase signal and a quadrature signal by an IQ (in-phase and quadrature) demodulation circuit, a numerically-controlled oscillator is controlled by a phase-locked loop circuit and an automatic gain control circuit to generate an excitation signal, the excitation signal is converted into an analog signal by a DAC (digital to analog converter) circuit and is fed back to an excitation input end of the gyro system to form a system excitation closed loop; the excitation signal generates an error control signal through an error control circuit and feeds the error control signal back to the tuning input end of the gyro system to form a system error control closed loop.
As shown in fig. 2, the fm gyro further includes a first electrical interface 111a, a secondelectrical interface 111b, a thirdelectrical interface 111c, a fourthelectrical interface 111d, a fifthelectrical interface 111e, and a sixthelectrical interface 111 f.
The first electrical interface 111a is connected to the firstdriving input electrode 108a, and the first electrical interface 111a is configured to receive an input driving signal in the first vibration mode and input the input driving signal to the firstdriving input electrode 108 a.
The secondelectrical interface 111b is connected to the seconddriving input electrode 108b, and the secondelectrical interface 111b is configured to receive an input driving signal of the second vibration mode and input the input driving signal to the seconddriving input electrode 108 b.
The thirdelectrical interface 111c is connected to the secondtuning input electrode 109b, and the thirdelectrical interface 111c is configured to receive the tuning voltage signal of the second vibration mode and input the tuning voltage signal to the secondtuning input electrode 109 b.
The fourthelectrical interface 111d is connected to the firsttuning input electrode 109a, and the fourthelectrical interface 111d is configured to receive the tuning voltage signal of the first vibration mode and input the tuning voltage signal to the firsttuning input electrode 109 a.
The fifthelectrical interface 111e is connected to the secondsensing output electrode 110b, and the second vibration mode of the fm gyroscope is output to the fifthelectrical interface 111e through the secondsensing output electrode 110 b.
The sixthelectrical interface 111f is connected to the firstsensing output electrode 110a, and the first vibration mode output of the fm gyroscope is output to the sixthelectrical interface 111f through the firstsensing output electrode 110 a.
Because most of the existing frequency modulation gyros are mechanical gyros, the gyros have the following problems when a modulation system is verified:
1. due to the fact that the MEMS gyroscopes are different in types and production processes, even different in production batches, the problems and introduced errors are different, the zero point of the MEMS gyroscope is very sensitive to temperature change due to the mechanical characteristics of the MEMS gyroscope, the effect of the same circuit modulation system on different gyroscopes is very different, and therefore the effect of the modulation system is not reasonable when the conventional MEMS gyroscope is used.
2. Because the MEMS mechanical structure error cannot be accurately represented, many electronic errors and mechanical errors introduced by a circuit in the existing Lissajous FM gyroscope are mixed together, the modal coupling effect is not clear, and the error source causing zero drift in an electronic system cannot be determined and optimized correspondingly.
3. At present, the software with larger use amount has too low simulation speed, and the simulation time is too long for one time after the required precision is reached, so that the rapid test is inconvenient.
4. In the testing process, because the mechanical structure of the gyroscope is fixed, the internal parameters of the gyroscope cannot be changed, the testing result is simplified, the gyroscope can only be replaced to change the parameters of the tested object, and the performance of the system is not convenient to be checked by using a large number of experimental results.
Based on the above, the embodiment of the invention further provides an MEMS gyroscope equivalent circuit, the MEMS gyroscope equivalent circuit is a circuit which is built by using devices such as capacitors, inductors and resistors and completely simulates the internal working principle of the MEMS gyroscope, the mechanical error of the gyroscope is changed by controlling the value of the devices, and the two-mode coupling condition is simulated by an independent voltage source.
As shown in fig. 2 and 3, the MEMS gyro equivalent circuit includes a first vibration mode circuit, a second vibration mode circuit, and a coupling circuit located between the first vibration mode circuit and the second vibration mode circuit.
The first vibration mode circuit comprises afirst resistor 101a, afirst capacitor 102a and afirst inductor 103a, wherein thefirst resistor 101a, thefirst capacitor 102a and thefirst inductor 103a are sequentially connected in series to form an RLC resonance circuit.
The second vibration mode circuit comprises asecond resistor 101b, a second capacitor 102b and asecond inductor 103b, and thesecond resistor 101b, the second capacitor 102b and thesecond inductor 103b are sequentially connected in series to form an RLC resonance circuit.
The coupling circuit is realized by a mutual inductor and an operational amplifier, and an error control circuit is adopted for inputting a tuning input electrode for restoring the function of the gyroscope.
As shown in fig. 3, the coupling circuit includes an operational amplifier, a transformer, a VGA, and a potentiometer.
Six operational amplifiers are provided, namely a firstoperational amplifier 104a, a second operational amplifier 104b, a thirdoperational amplifier 104c, a fourthoperational amplifier 104d, a fifthoperational amplifier 104e and a sixth operational amplifier 104 f.
There are sixteen transformers, which are respectively afirst transformer 105a, asecond transformer 105b, athird transformer 105c, afourth transformer 105d, afifth transformer 105e, asixth transformer 105f, aseventh transformer 105g, aneighth transformer 105h, a ninth transformer 105i, atenth transformer 105j, aneleventh transformer 105k, a twelfth transformer 105l, athirteenth transformer 105m, a fourteenth transformer 105n, a fifteenth transformer 105o, and asixteenth transformer 105 p.
There are two VGAs, a first VGA106a and a second VGA106 b.
The number of the potentiometers is eight, and the potentiometers are respectively afirst potentiometer 107a, asecond potentiometer 107b, athird potentiometer 107c, afourth potentiometer 107d, afifth potentiometer 107e, asixth potentiometer 107f, aseventh potentiometer 107g and aneighth potentiometer 107 h.
The input end of thefirst transformer 105a is connected with a firstdriving input electrode 108a for inputting an excitation signal, and the output end of thefirst transformer 105a is connected in series to the first vibration mode circuit.
The input end of thesecond transformer 105b is connected with a seconddriving input electrode 108b for inputting an excitation signal, and the output end of thesecond transformer 105b is connected in series to the second vibration mode circuit.
The non-inverting and inverting input terminals of the firstoperational amplifier 104a are connected to one end of thefirst capacitor 102a, respectively, and the output terminal of the firstoperational amplifier 104a is connected to the input terminal of the twelfth transformer 105 l.
Athird resistor 101c is connected between thefirst capacitor 102a and the positive-phase input terminal of the firstoperational amplifier 104a, and afourth resistor 101d is connected between thefirst capacitor 102a and the negative-phase input terminal of the firstoperational amplifier 104 a.
The output end of the twelfth transformer 105l is connected in series to the second vibration mode circuit.
Since the two input terminals of the firstoperational amplifier 104a are respectively connected to one end of thefirst capacitor 102a, the voltage across thefirst capacitor 102a can be amplified, which is equivalent to rigid coupling.
The non-inverting and inverting input terminals of the sixth operational amplifier 104f are connected to one end of the second capacitor 102b, respectively, and the output terminal of the sixth operational amplifier 104f is connected to the input terminal of thesixth transformer 105 f.
Afifth resistor 101e is connected between the second capacitor 102b and the positive phase input terminal of the second operational amplifier 104b, and asixth resistor 101f is connected between the second capacitor 102b and the negative phase input terminal of the second operational amplifier 104 b.
The output end of thesixth transformer 105f is connected in series to the first vibration mode circuit.
Since the two input terminals of the sixth operational amplifier 104f are respectively connected to one end of the second capacitor 102b, the voltage across the second capacitor 102b can be amplified, which is equivalent to rigid coupling.
The input end of thefifth transformer 105e is connected in series to the first vibration mode circuit, and the output end of thefifth transformer 105e is connected to the positive phase input end and the negative phase input end of the second operational amplifier 104b, respectively. The output end of the second operational amplifier 104b is connected to the input end of theeleventh transformer 105k, and the output end of theeleventh transformer 105k is connected in series to the second vibration mode circuit.
Since the input end of thefifth transformer 105e is connected in series to the first vibration mode circuit, and the output end is connected to the input end of the second operational amplifier 104, the current in the first vibration mode circuit can be amplified to be a voltage, which is equivalent to damping coupling.
The input end of thethirteenth transformer 105m is connected in series to the second vibration mode circuit, and the output end of thethirteenth transformer 105m is connected to the positive phase input end and the negative phase input end of the fifthoperational amplifier 104e, respectively. The output end of the fifthoperational amplifier 104e is connected to the input end of thefourth transformer 105d, and the output end of thefourth transformer 105d is connected in series to the first vibration mode circuit.
Since the input end of thethirteenth transformer 105m is connected in series to the second vibration mode circuit, and the output end is connected to the input end of the fifthoperational amplifier 104e, the current in the second vibration mode circuit can be amplified to be a voltage, which is equivalent to damping coupling.
The input end of theseventh transformer 105g is connected in series to the first vibration mode circuit, and the output end of theseventh transformer 105g is connected to the positive phase input end and the negative phase input end of the thirdoperational amplifier 104c, respectively.
The output end of the thirdoperational amplifier 104c is connected to the first VGA106a and the input end of thetenth transformer 105j in sequence, and the output end of thetenth transformer 105j is connected to the second vibration mode circuit in series.
Since the input end of theseventh transformer 105g is connected in series to the first vibration mode circuit, and the output end is connected to the input end of the thirdoperational amplifier 104c, the current in the circuit can be amplified to be a voltage, which is equivalent to an angular rate signal.
The input end of the fifteenth transformer 105o is connected in series to the second vibration mode circuit, and the output end of the fifteenth transformer 105o is connected to the positive phase input end and the negative phase input end of the fourthoperational amplifier 104d, respectively.
The output end of the fourthoperational amplifier 104d is connected to the input ends of the second VGA106b and thethird transformer 105c in sequence, and the output end of thethird transformer 105c is connected to the first vibration mode circuit in series.
Since the input end of the fifteenth transformer 105o is connected in series to the second vibration mode circuit, and the output end is connected to the input end of the fourthoperational amplifier 104d, the current in the circuit can be amplified to be a voltage, which is equivalent to an angular rate signal.
Thefirst potentiometer 107a has one terminal connected to the non-inverting input terminal of the firstoperational amplifier 104a and the other terminal connected to ground.
Thesecond potentiometer 107b is connected between the negative phase input terminal and the output terminal of the firstoperational amplifier 104 a.
Thethird potentiometer 107c is connected between the negative phase input terminal and the output terminal of the second operational amplifier 104 b.
Thefourth potentiometer 107d is connected between the negative phase input terminal and the output terminal of the thirdoperational amplifier 104 c.
One end of thefifth potentiometer 107e is connected to the non-inverting input terminal of the sixth operational amplifier 104f, and the other end is grounded.
Thesixth potentiometer 107f is connected between the negative-phase input terminal and the output terminal of the sixth operational amplifier 104 f.
Theseventh potentiometer 107g is connected between the negative phase input terminal and the output terminal of the fifthoperational amplifier 104 e.
Theeighth potentiometer 107h is connected between the negative-phase input terminal and the output terminal of the fourthoperational amplifier 104 d.
Thefirst potentiometer 107a, thesecond potentiometer 107b, thethird potentiometer 107c, thefourth potentiometer 107d, thefifth potentiometer 107e, thesixth potentiometer 107f, theseventh potentiometer 107g, and theeighth potentiometer 107h are all high-precision digital potentiometers.
The output end of theeighth transformer 105h is connected in series to the first vibration mode circuit, and the input end of theeighth transformer 105h is connected to the firsttuning input electrode 109a, so that the tuning function of the first vibration mode circuit is realized.
The output end of the fourteenth transformer 105n is connected in series to the second vibration mode circuit, and the input end of the fourteenth transformer 105n is connected to the secondtuning input electrode 109b, so that the tuning function of the second vibration mode circuit is realized.
The input end of the ninth transformer 105i is connected in series to the first vibration mode circuit, and the output end of the ninth transformer 105i is connected with the firstsensing output electrode 110a, so that the first vibration mode circuit outputs a circuit signal.
The input end of thesixteenth transformer 105p is connected in series to the second vibration mode circuit, and the output end of thesixteenth transformer 105p is connected with the secondsensing output electrode 110b, so that the second vibration mode circuit outputs a circuit signal.
The signal flow in the MEMS gyroscope equivalent circuit runs as follows:
1. the Coriolis force of the first vibration mode circuit is input to a differential amplifier circuit constructed by a fourth operational amplifier 104dThe current in the second vibration mode circuit obtained through the fifteenth transformer 105o is amplified by 2L lambda times, the amplification factor is adjusted through theeighth potentiometer 107h, and then the current is amplified by omega through the second VGA106bZAnd the amplification is equivalent to the angular rate, and then the amplification is carried out by-2L lambda times through the thirdmutual inductor 105c reversely connected in series into the first vibration mode circuit.
2. The coriolis force of the second vibration mode circuit is input to a differential amplifier circuit built by a thirdoperational amplifier 104c, the current obtained by aseventh transformer 105g in the first vibration mode circuit is amplified by 2L λ, the amplification factor is adjusted by afourth potentiometer 107d, and then the current is amplified by omega through a first VGA106aZAnd the amplification is equivalent to the angular rate, and then the amplification is carried out by-2L lambda times through thetenth transformer 105j reversely connected in series into the second vibration mode circuit.
3. The damping coupling of the first vibration mode circuit is input into a transimpedance amplifier built up from a fifthoperational amplifier 104e which amplifies the current in the second vibration mode circuit obtained through athirteenth transformer 105m to RxyThe voltage multiplied by the damping coupling factor (i.e., the damping coupling factor of the second vibration mode to the first vibration mode), the amplification factor being controlled by theseventh potentiometer 107g, is then serially connected into the first vibration mode circuit through thefourth transformer 105 d.
4. Damping coupling in second vibration mode circuit transimpedance amplifier built up from second operational amplifier 104b amplifies the current in the first vibration mode circuit derived throughfifth transformer 105e to RyxThe voltage multiplied by the damping coupling factor (i.e., the damping coupling factor of the first vibration mode to the second vibration mode), the amplification factor being controlled by thethird potentiometer 107c, is then connected in series into the second vibration mode circuit through theeleventh transformer 105 k.
5. Rigid coupling input in the first vibration mode circuit the transimpedance amplifier built up from the sixth operational amplifier 104f amplifies the voltage across the second capacitor 102b in the second vibration mode circuit
Multiple (i.e. stiffness coupling multiple of the second vibration mode to the first vibration mode), amplification multiple from fifth
vibration modeThe potentiometer 107e and the
sixth potentiometer 107f are controlled (specifically, the amplification factor is changed by controlling the introduced resistance of the
fifth potentiometer 107e and the
sixth potentiometer 107 f), and then are connected in series into the first vibration mode circuit through the
sixth transformer 105 f.
Wherein, cyRepresents the size, c, of the second capacitor 102byxRepresenting the coupling capacitance magnitude obtained in the derivation of the formula.
6. Rigid coupling in second vibration mode circuit transimpedance amplifier built up from first
operational amplifier 104a amplifies the voltage across
first capacitor 102a in the first vibration mode circuit
The amplification factor (i.e., the stiffness coupling factor of the first vibration mode to the second vibration mode) is controlled by the
first potentiometer 107a and the
second potentiometer 107b (specifically, the amplification factor is changed by controlling the magnitude of the introduced resistance of the
first potentiometer 107a and the
second potentiometer 107 b), and then the
first potentiometer 105k is connected in series into the second vibration mode circuit.
Wherein, cxRepresents the size, c, of thefirst capacitor 102axyRepresenting the coupling capacitance magnitude obtained in the derivation of the formula.
7. The tuning input in the first vibration mode circuit is input by the dc power supply of the firsttuning input electrode 109a, and is connected in series to the first vibration mode circuit through theeighth transformer 105 h. The tuning input in the second vibration mode circuit is input by the dc power supply of the secondtuning input electrode 109b, and is connected in series to the second vibration mode circuit through the fourteenth transformer 105 n.
The invention is used for carrying out rapid test verification on the gyro measurement and control circuit through the MEMS gyro equivalent circuit. The invention can self-define the mechanical error of the equivalent gyroscope, verify the influence of each error on the system and facilitate the subsequent circuit debugging; the invention makes up the defect of unstable parameters caused by adopting the entity gyroscope in the traditional debugging method; the invention obtains diversified gyro models by changing the equivalent gyro circuit parameters, thereby obtaining a large number of samples through tests and facilitating the research of gyro error models.
Compared with the existing mechanical MEMS gyroscope, the MEMS gyroscope equivalent circuit has the following advantages:
the MEMS gyroscope equivalent circuit adopts a circuit to simulate the function of the MEMS gyroscope, is more stable and is not easily interfered by the outside compared with the mechanical structure of the MEMS gyroscope, and solves the problem that the test system is inaccurate due to low stability of the MEMS gyroscope, high possibility of being influenced by factors such as temperature and the like.
And secondly, the MEMS gyroscope equivalent circuit is set by the multiple of the amplifier, parameters such as damping coupling, stiffness coupling, angular rate signals and the like are changed according to requirements, and the damping coupling and the stiffness coupling are set to be zero, so that the electronic error introduced by a subsequent circuit can be clearly seen, and the defect that the mechanical error and the electronic error cannot be separated when the MEMS gyroscope is used for carrying out a performance test on a gyroscope modulation system, and thus the correction cannot be well carried out is overcome.
The operating speed of the MEMS gyroscope equivalent circuit can obtain an output result within a few seconds after parameters are changed, and software simulation needs several hours or more time if high precision is required, so that the method for testing the MEMS gyroscope equivalent circuit can save the experimental time and solve the problem of low simulation speed.
The invention can change the resonance frequency by changing the resistance, capacitance and inductance of the first and second vibration mode circuits, increase the diversity of the tested gyroscope, change the defect that the gyroscope with different resonance frequency needs to be replaced when the multi-resonance frequency data is needed to be obtained in the test process, obtain a large amount of experimental data and better test the diversified adaptability of the test control circuit.
It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.