Online temperature compensation method for micromechanical gyroscope bias based on active Q-value control

Abstract

The present invention discloses an online temperature compensation method for zero bias of a micromechanical gyroscope based on active Q-value control, belonging to the technical field of zero bias temperature compensation of micromechanical gyroscopes. The method is based on the fact that the asymmetry of the quality factors of the driving mode and the detection mode is the main inducement of the in-phase zero bias error, and realizes the improvement of the in-phase zero bias by controlling the modal quality factor through parametric excitation. The present invention utilizes the injection signal method to realize the online identification of the intrinsic quality factor and the equivalent quality factor of the detection mode, and realizes the online compensation of the equivalent quality factor through parametric excitation. The present invention solves the drift of the zero bias error caused by the mismatch of the quality factors of the driving mode and the detection mode in a temperature-varying environment, and provides a universal solution for the zero bias temperature stability of high-performance micromechanical gyroscopes.

Description

Technical Field

[0001] The present invention relates to the technical field of zero-bias temperature compensation of a micro-mechanical gyroscope, in particular to an online temperature compensation method for zero-bias of a micro-mechanical gyroscope based on active Q-value control. Background Art

[0002] Micromachined gyros, with their advantages of low cost, small size, low power consumption, and mass production, have dominated the commercial gyroscope market. With the continuous improvement of micromachining technology, the accuracy and stability of micromachined gyros have gradually approached high-performance applications such as inertial navigation. However, bias error caused by the mismatch between modal damping and stiffness is a major factor limiting further improvement in micromachined gyroscope performance.

[0003] Consumer-grade micromechanical gyroscopes operate in open-loop detection mode, using the Coriolis force-induced displacement of the detection modal to characterize angular velocity. In this mode, angular velocity detection accuracy and stability are affected by numerous factors, including phase, frequency differences between modalities, mechanical nonlinearity, and capacitance detection nonlinearity, making stability unguaranteed. Currently, mainstream high-precision micromechanical gyroscopes operate in force-balance mode, suppressing the Coriolis force-induced displacement of the detection modal to zero by applying a balancing force. The magnitude of this force is then used to characterize the gyroscope's angular velocity.

[0004] Compared with the open-loop detection mode, the force balance detection mode has the advantages of high dynamic range, no influence from modal difference, low nonlinearity, and high stability. It is very suitable for the field of inertial sensors with tactical level and above performance.

[0005] However, the zero bias in this mode is also affected by many parameters, such as phase delay in the circuit, the in-phase output and quadrature output of the balancing force, and temperature drift. This causes the zero bias to drift at different temperatures, causing the angular velocity value detected by the gyroscope to not completely match the actual angular velocity. As a result, the attitude angle detected by the gyroscope deviates from the actual value, seriously affecting detection accuracy. Various research institutions have reduced the in-phase error caused by modal damping asymmetry through direct temperature compensation, modeling and analysis of zero bias temperature errors, suppressing the force deflection angle of the driving mode, and active damping adjustment. However, these methods cannot achieve real-time zero bias adjustment and require additional damping adjustment components and a large amount of data fitting compensation. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing micromechanical gyroscope zero bias temperature compensation methods and proposes a micromechanical gyroscope zero bias online temperature compensation method based on active Q value control. The method can achieve real-time zero bias adjustment without the need for additional damping adjustment components and a large amount of data fitting compensation, thereby improving the zero bias temperature stability of the micromechanical gyroscope in a temperature-changing environment.

[0007] The technical solutions of the present invention are as follows:

[0008] The present invention provides a method for online temperature compensation of a micromechanical gyroscope zero bias based on active Q value control, which comprises the following steps:

[0009] 1) The micromechanical gyroscope control system uses a phase-locked loop and an automatic gain control loop to maintain constant frequency and amplitude vibration in the driving mode. In the detection mode, an AC signal with the same frequency as the driving excitation signal is used to balance the force of the signal that is orthogonal to and in phase with the angular velocity signal.

[0010] 2) Real-time modal matching is achieved using the detection modal signal injection method. A parametric excitation voltage is injected into the detection mode, and the zero bias is controlled to 0 by adjusting the amplitude of the parametric excitation voltage at a selected temperature. The equivalent quality factor after parametric excitation is calculated through the phase response of the injected signal under the parametric excitation mode. Using this equivalent quality factor as a reference value, for scenarios requiring temperature compensation, the amplitude of the parametric excitation voltage is calculated in real time, and online temperature compensation of the zero bias error is performed to achieve the purpose of online matching of the equivalent quality factors of the driving mode and the detection mode.

[0011] According to an embodiment of the present invention, step 1) is specifically as follows: using a field programmable gate array to apply a driving excitation signal to the driving mode of the micromechanical gyroscope, causing the gyroscope to start vibrating and generate a vibration signal; a gyroscope detection circuit picks up the vibration displacement signal and demodulates it in the field programmable gate array chip to obtain a displacement amplitude signal and a phase signal of the micromechanical gyroscope; a phase-locked loop locks the micromechanical gyroscope driving mode in a resonant state according to the displacement phase signal and outputs a phase control word; an automatic gain control loop performs closed-loop control on the displacement amplitude signal to maintain a constant amplitude of the micromechanical gyroscope driving mode; the field programmable gate array applies an AC signal with the same frequency, phase, and frequency orthogonal to the driving excitation signal to the detection mode, respectively used to balance the in-phase signal and the quadrature signal coupled from the driving mode to the detection mode, and the amplitude of the in-phase signal is used to represent the magnitude of the angular velocity.

[0012] According to an embodiment of the present invention, in step 2), the use of the detection modal signal injection method to achieve real-time modal matching is specifically as follows:

[0013] a) The injection frequency is 0.01 on the orthogonal suppression electrodes of the micromechanical gyroscope. The low-frequency disturbance signal is detected, and the difference between the upper sideband displacement signal and the lower sideband displacement signal generated by the detection mode is used as the characterization of the mode matching; when the value of the characterization is 0, the mode is considered to be matched;

[0014] b) By adjusting the tuning voltage of the detection mode through closed-loop control, the above-mentioned modal characterization quantity is set to 0 in real time, thereby achieving online modal matching.

[0015] Preferably, the parametric excitation voltage is an AC voltage signal having a frequency twice that of the driving excitation signal, which modulates the stiffness of the detection mode at twice the frequency.

[0016] According to an embodiment of the present invention, the equivalent quality factor after parametric excitation is calculated by the phase response of the injected signal in the parametric excitation mode, specifically: the phase response of the measured force corresponding to the upper sideband signal applied to the detection mode is used as the variation to calculate the real-time equivalent quality factor after parametric excitation.

[0017] According to an embodiment of the present invention, the equivalent quality factor of the zero bias at a selected temperature is controlled to be 0 As a reference value When the ambient temperature changes, the parameter excitation voltage amplitude is calculated in real time, and the calculated parameter excitation voltage amplitude is used. The amplitude of the parametric excitation voltage is adjusted in real time to keep the equivalent quality factor constant. That is, the equivalent quality factor adapts to the change of temperature by changing the amplitude of the parametric excitation voltage, thereby realizing online temperature compensation of the zero bias error from a mechanism perspective.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The present invention realizes real-time adjustment of zero bias, significantly improves the zero bias temperature stability of the micromechanical gyroscope, eliminates the need for additional damping adjustment components and a large amount of data fitting compensation, and reduces system complexity and cost.

[0020] 2) It is applicable to most Coriolis gyroscopes with modal tuning function, does not require additional gyroscope mechanical structure and parameter requirements, and is universal and practical.

[0021] 3) The present invention realizes zero-bias temperature compensation based on the working mechanism of the gyroscope, and performs automatic online compensation, so that the gyroscope has excellent temperature stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a control block diagram of a micro-mechanical gyroscope zero bias online temperature compensation method based on active quality factor control.

[0023] Figure 2 This is the block diagram of the online control of equivalent quality factor based on parametric excitation.

[0024] Figure 3 The figure is a comparison of the zero bias temperature drift results before and after the application of the present invention.

[0025] Figure 4 This is the result of detecting the modal equivalent quality factor and the natural quality factor after applying parametric excitation in the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0027] The present invention provides a micromechanical gyroscope zero bias online temperature compensation method based on active Q value control, and the specific steps are as follows:

[0028] 1) A field-programmable gate array (FPGA) is used to apply a drive excitation signal to the micromechanical gyroscope's drive mode, causing the gyroscope to vibrate and generate a vibration signal. A gyroscope detection circuit detects the vibration displacement signal and demodulates it within the FPGA chip to obtain the micromechanical gyroscope's displacement amplitude and phase signals. A phase-locked loop (PLL) locks the micromechanical gyroscope's drive mode into a resonant state based on the displacement phase signal and outputs a phase control word. An automatic gain control loop performs closed-loop control of the displacement amplitude signal to maintain a constant amplitude in the micromechanical gyroscope's drive mode. The PLL transmits the output phase control word to a voltage-controlled oscillator (VCO), which outputs fixed-frequency cosine and sine components. The cosine component is in phase with the gyroscope's velocity, and the sine component is in phase with the gyroscope's displacement. The phase of the gyroscope's velocity is orthogonal to the phase of its displacement.

[0029] The dynamic equations of the driving mode are as follows:

[0030]

[0031] in is the mass of the moving mass block, is the displacement of the gyro drive mode, and are the damping coefficient and elastic coefficient of the gyro drive mode, is the magnitude of the driving force, is the driving force frequency, and the control principle of the driving mode is shown in Figure 1 .

[0032] 2) In the detection mode, an AC signal with the same frequency as the driving excitation signal is used to balance the orthogonal signal (orthogonal to the angular velocity signal) and the in-phase signal (in-phase with the angular velocity signal) coupled from the driving mode to the detection mode. The balancing force can be decomposed into and drive displacement There are two components related to is the amplitude of the force applied in phase with the angular velocity, is the amplitude of the force applied orthogonally to the angular velocity. Then the dynamic equation of the detection mode is:

[0033]

[0034] To detect the modal displacement, is the damping coefficient of the detected mode, To detect the modal elastic coefficients, is the damping of the driving mode coupled to the detection mode, is the coupling elastic coefficient from the driving mode to the detection mode, is the angular velocity input from the outside world.

[0035] When the loop is fully closed, ,neglect The velocity component of the equilibrium force corresponds to the expression , The magnitude of is used to characterize the angular velocity. The principle of detecting modal force balance is shown in Figure 2 ;

[0036] 3) Realize real-time modal matching by using the detection modal signal injection method, specifically including: injecting a frequency of The low-frequency AC signal modulates the signal on the gyro's orthogonal suppression electrode and the displacement of the driving mode, which can be generated in the detection mode. The difference between the two sideband signals is used as the characterization quantity of the modal matching. The tuning voltage of the detection mode is adjusted through closed-loop control so that the above modal characterization quantity is at 0 in real time, thus realizing online modal matching.

[0037] 4) For Two sideband signals, let the upper sideband signal be , then the force applied to the upper sideband signal in the detection mode is for:

[0038]

[0039] in is the gain coefficient of the signal injected into the orthogonal suppression electrode, is the voltage amplitude of the disturbance signal, is the disturbance signal frequency, is the phase of the driving displacement.

[0040] In the force balance mode, the dynamic equation of the detection mode after parametric excitation is:

[0041]

[0042] in, is the intrinsic quality factor of the detected mode, Detect the resonant frequency of the mode, is the phase of the parametric excitation signal, is the amplitude of the parametric excitation signal, which is determined by the parametric excitation voltage signal and the tuning electrode. It can be seen from the formula that, It is the prerequisite for the parametric excitation to be amplified, so real-time modal matching is required in the control loop.

[0043] In order to obtain the equivalent quality factor of the detection mode, it is necessary to Amplitude gain and phase response Make deduction:

[0044]

[0045] , , ;

[0046] in, is the frequency of the upper sideband signal, is the resonant phase of the driving mode, , is the intermediate variable, It is a prerequisite for obtaining a steady-state solution. is the force applied to the upper sideband signal in the detection mode phase.

[0047] Will , Substituting in, we get

[0048]

[0049] In order to obtain the best amplification effect of parametric excitation, ,get

[0050]

[0051] Further through , , Three variables and phase response The relationship between the detection mode and the equivalent quality factor It can be expressed as:

[0052] .

[0053] The main goal of the present invention is to identify the equivalent quality factor of the detection mode in real time so that it does not change with temperature, thereby ensuring real-time matching with the quality factor of the driving mode. The value of The value is constant, so that the 0° / s zero bias output does not change with temperature.

[0054] Therefore, in the present invention, the zero bias is controlled to 0 by adjusting the amplitude of the parametric excitation voltage at a selected temperature (e.g., -20°C), and the equivalent quality factor after parametric excitation is calculated by the phase response of the injection signal under the parametric excitation mode; the equivalent quality factor is used as a reference value. For scenarios requiring temperature compensation, the amplitude of the parametric excitation voltage is calculated in real time using the following formula:

[0055]

[0056] According to the calculated parametric excitation voltage amplitude The amplitude of the parametric excitation voltage is adjusted in real time to keep the equivalent quality factor constant. That is, the equivalent quality factor adapts to the change of temperature by changing the amplitude of the parametric excitation voltage, thereby realizing online temperature compensation of the zero bias error from a mechanism perspective.

[0057] The present invention is further described below in conjunction with a specific application example and the effects of the present invention are demonstrated.

[0058] The application example steps are as follows:

[0059] Step 1: Equipped with a Kintex-7-based FPGA digital circuit and fully symmetrical analog signal conditioning circuitry, the gyro was placed on a temperature chamber turntable for testing. Following Step 1 above, a phase-locked loop and automatic gain control loop were used to maintain a constant frequency and amplitude in the driving mode.

[0060] Step 2: As in step 2), operate the gyro in force balance mode. As in step 3), perform real-time modal matching using the signal injection method. Place the gyro in a cycle of gradually increasing and decreasing temperatures from -20°C to 50°C, and record the changes in the bias output and intrinsic quality factor.

[0061] Step 3: Inject a parametric excitation signal into the detection mode. At -20°C, adjust the zero bias to 0 by adjusting the amplitude of the parametric excitation signal. Repeat the temperature change process in step 2 and record the zero bias output, intrinsic quality factor change, and equivalent quality factor.

[0062] Step 4: Based on step 3, calculate the zero bias output, intrinsic and equivalent quality factor changes. Change, calculate The method of the present invention is applied to the signal amplitude of the parametric excitation voltage. (Based on the calculated parametric excitation voltage amplitude The amplitude of the parametric excitation voltage is adjusted in real time to keep the equivalent quality factor constant. That is, the equivalent quality factor adapts to temperature changes by changing the amplitude of the parametric excitation voltage to achieve online temperature compensation of the zero bias error. The corresponding results are recorded: zero bias output, intrinsic quality factor change, and equivalent quality factor.

[0063] The present invention compares the results of step three and step four to obtain a comparison of the compensation results of the equivalent quality factor by the fixed parameter excitation amplitude and the parameter excitation amplitude changed online in the present invention, as shown in FIG. Figure 3 As shown, Figure 3 3 and 4 respectively illustrate the equivalent quality factor change and phase response change of the fixed parametric excitation amplitude and the parametric excitation amplitude changed online in the present invention under the temperature change environment.

[0064] The gyroscope in force balance and mode matching state is further placed at room temperature and -20℃~50℃ uniform temperature change; then the gyroscope with fixed parameter excitation amplitude and online variable parameter excitation amplitude is placed at -20℃~50℃ uniform temperature change, and the zero bias output is recorded three times respectively. The results are as follows Figure 4 As shown in the figure, numbers 1, 2, and 3 correspond to the original bias, fixed parametric excitation amplitude bias, and adaptive parametric excitation amplitude bias, respectively. This demonstrates that electrical parametric excitation actively adjusts the equivalent quality factor, suppressing the temperature drift of the in-phase bias. Over a 70°C temperature range, the original 0.23 mdps / K is reduced to 9.7 μdps / K, and the bias instability decreases from 0.295 dph to 0.157 dph. This measurement and control method allows for real-time bias adjustment without the need for additional damping components or extensive data fitting and compensation, making it universally applicable to micromachined gyros.

[0065] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A method for online temperature compensation of micromechanical gyroscope zero bias based on active Q value control, characterized in that: The steps include: 1) The micromechanical gyroscope control system uses a phase-locked loop and an automatic gain control loop to maintain constant frequency and amplitude vibration in the driving mode. In the detection mode, an AC signal with the same frequency as the driving excitation signal is used to balance the force of the signal that is orthogonal to and in phase with the angular velocity signal. 2) Real-time modal matching is achieved using the detection modal signal injection method. A parametric excitation voltage is injected into the detection mode, and the zero bias is controlled to 0 by adjusting the amplitude of the parametric excitation voltage at a selected temperature. The equivalent quality factor after parametric excitation is calculated through the phase response of the injected signal under the parametric excitation mode. Using this equivalent quality factor as a reference value, for scenarios requiring temperature compensation, the amplitude of the parametric excitation voltage is calculated in real time, and online temperature compensation of the zero bias error is performed to achieve the purpose of online matching of the equivalent quality factors of the driving mode and the detection mode.

2. The micromechanical gyroscope zero bias online temperature compensation method according to claim 1, characterized in that: The step 1) specifically comprises: applying a driving excitation signal to the driving mode of the micromechanical gyroscope using a field programmable gate array, causing the gyroscope to start vibrating and generate a vibration signal; a gyroscope detection circuit picking up the vibration displacement signal and demodulating it in the field programmable gate array chip to obtain a displacement amplitude signal and a phase signal of the micromechanical gyroscope; a phase-locked loop locking the micromechanical gyroscope driving mode in a resonant state according to the displacement phase signal and outputting a phase control word; an automatic gain control loop performing closed-loop control of the displacement amplitude signal to maintain a constant amplitude of the micromechanical gyroscope driving mode; and applying an AC signal having the same frequency, phase, and frequency as the driving excitation signal to the detection mode, respectively, to balance the in-phase signal and the quadrature signal coupled from the driving mode to the detection mode. The amplitude of the in-phase signal is used to represent the magnitude of the angular velocity.

3. The micro-mechanical gyroscope zero bias online temperature compensation method according to claim 1, characterized in that: In step 2), the real-time modal matching is achieved by using the detection modal signal injection method, specifically: a) The injection frequency is 0.01 on the orthogonal suppression electrodes of the micromechanical gyroscope. The low-frequency disturbance signal is detected, and the difference between the upper sideband displacement signal and the lower sideband displacement signal generated by the detection mode is used as the characterization of the mode matching; when the value of the characterization is 0, the mode is considered to be matched; b) By adjusting the tuning voltage of the detection mode through closed-loop control, the above-mentioned characterization quantity is set to 0 in real time, thereby achieving online mode matching.

4. The micro-mechanical gyroscope zero bias online temperature compensation method according to claim 3, characterized in that: In step 2), the parametric excitation voltage is an AC voltage signal whose frequency is twice that of the driving excitation signal, and which modulates the stiffness of the detection mode by twice the frequency.

5. The micro-mechanical gyroscope zero bias online temperature compensation method according to claim 1, characterized in that: In step 2), the selected temperature is -20°C.

6. The micro-mechanical gyroscope zero bias online temperature compensation method according to claim 4, characterized in that: In step 2), the equivalent quality factor after parametric excitation is calculated by the phase response of the injected signal in the parametric excitation mode, specifically: the phase response of the force corresponding to the upper sideband signal applied to the detection mode As the variable, combined with the known gyro mechanical parameters, the real-time equivalent quality factor after parameter excitation is calculated by the following formula : ； in, , , is an intermediate variable, satisfying: ， ； To detect the resonant frequency of the mode, is the frequency of the upper sideband signal, is the amplitude of the parametric excitation voltage, and m is the mass of the gyro motion mass block.

7. The micro-mechanical gyroscope zero bias online temperature compensation method according to claim 6, characterized in that: In step 2), the amplitude of the parametric excitation voltage is calculated in real time, specifically: the equivalent quality factor of the zero bias controlled to 0 at the selected temperature is As a reference value , when the ambient temperature changes, the parameter excitation voltage amplitude is calculated in real time according to the following formula: 。 8. The micro-mechanical gyroscope zero bias online temperature compensation method according to claim 1, characterized in that: In step 2), the online temperature compensation of the zero bias error is specifically as follows: based on the calculated parametric excitation voltage amplitude The amplitude of the parametric excitation voltage is adjusted in real time to keep the equivalent quality factor constant. That is, the equivalent quality factor adapts to the change of temperature by changing the amplitude of the parametric excitation voltage, thereby realizing online temperature compensation of the zero bias error from a mechanism perspective.

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