Micro-mechanical gyroscope zero offset on-line temperature compensation method based on Q value active control

Abstract

The invention discloses a micro-mechanical gyroscope zero offset online temperature compensation method based on Q value active control, and belongs to the technical field of micro-mechanical gyroscope zero offset temperature compensation. According to the method, on the basis that asymmetry of quality factors of a driving mode and a detection mode is a main cause of an in-phase zero offset error, improvement of in-phase zero offset is achieved in a mode of controlling the quality factors of the modes through parametric excitation. According to the method, online identification of the intrinsic quality factor and the equivalent quality factor of the detection mode is realized by using a signal injection method, and online compensation of the equivalent quality factor is realized through parametric excitation. The method solves the problem of zero offset error drift caused by mismatching of quality factors of a driving mode and a detection mode in a temperature change environment, and a universal scheme is provided for the zero offset temperature stability of the high-performance micromechanical gyroscope.

Description

Technical Field

[0001] The present invention relates to the technical field of zero-offset temperature compensation for micro-electromechanical gyroscopes, and in particular to an on-line temperature compensation method for zero offset of micro-electromechanical gyroscopes based on Q-value active control. Background Art

[0002] Micro-electromechanical gyroscopes have occupied a dominant position in the commercial gyroscope field due to their advantages such as low cost, small size, low power consumption, and mass production. With the continuous improvement of microfabrication processes, the accuracy and stability of micro-electromechanical gyroscopes have gradually tended to high-performance application fields such as inertial navigation. The zero-offset error caused by the mismatch between inter-modal damping and stiffness is an important factor restricting the further improvement of the performance of micro-electromechanical gyroscopes.

[0003] Consumer-grade micro-electromechanical gyroscopes operate in an open-loop detection mode, and the magnitude of the angular velocity is characterized by the displacement of the detection mode caused by the Coriolis force. In this operating mode, the detection accuracy and stability of the angular velocity are affected by many factors such as phase, frequency difference between modes, mechanical nonlinearity, and capacitance detection nonlinearity. Therefore, the stability cannot be guaranteed. Currently, the mainstream high-precision micro-electromechanical gyroscopes all operate in a force balance mode, that is, the displacement generated by the Coriolis force in the detection mode is suppressed to zero by applying a balancing force, and the magnitude of this force is used to characterize the angular velocity of the gyroscope.

[0004] Compared with the open-loop detection mode, the force balance detection mode has the advantages of high dynamic range, insensitivity to modal differences, low nonlinearity, and high stability, and is very suitable for inertial sensor fields with tactical-level and above performance.

[0005] However, the zero offset in this mode is also affected by many parameters such as circuit phase delay, in-phase output and quadrature output of the balancing force, and these parameters all have temperature drift, resulting in zero offset drift at different temperatures, so that the angular velocity value detected by the gyroscope does not exactly match the true angular velocity. Therefore, the attitude angle detected by the gyroscope deviates from the actual value, seriously affecting the detection accuracy. Each research institution has reduced the in-phase error caused by asymmetric modal damping through direct temperature compensation, modeling and analysis of zero-offset temperature error, suppressing the force deflection angle of the drive mode, and active damping adjustment. However, the above methods cannot achieve real-time adjustment of the zero offset, and additional damping adjustment components and a large amount of data fitting compensation are required. Summary of the Invention

[0006] The present invention aims to overcome the deficiencies of the existing zero-offset temperature compensation methods for micro-electromechanical gyroscopes, and proposes an on-line temperature compensation method for zero offset of micro-electromechanical gyroscopes based on Q-value active control, which can achieve real-time adjustment of the zero offset without additional damping adjustment components and a large amount of data fitting compensation, so as to improve the zero-offset temperature stability of micro-electromechanical gyroscopes in a temperature-changing environment.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention provides a method for on-line temperature compensation of the zero bias of a micro-machined gyroscope based on Q-value active control, which includes the following steps:

[0009] 1) The micro-machined gyroscope control system uses a phase-locked loop and an automatic gain control loop to keep the driving mode vibrating at a constant frequency and constant amplitude; in the detection mode, an AC signal with the same frequency as the driving excitation signal is used to perform force balance on the signals orthogonal and in-phase to the angular velocity signal.

[0010] 2) Use the detection mode signal injection method to achieve real-time mode matching; inject a parametric excitation voltage into the detection mode, and at a selected temperature, control the zero bias to 0 by adjusting the amplitude of the parametric excitation voltage, and calculate the equivalent quality factor after parametric excitation through the phase response of the injected signal in the parametric excitation mode; taking this equivalent quality factor as a reference value, for the scenario that requires temperature compensation, calculate the amplitude of the parametric excitation voltage in real time to perform on-line temperature compensation of the zero bias error, so as to achieve the purpose of on-line matching of the equivalent quality factors of the driving mode and the detection mode.

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

[0012] According to the implementation scheme of the present invention, in step 2), the use of the detection mode signal injection method to achieve real-time mode matching is specifically:

[0013] a) Inject a low-frequency perturbation signal with a frequency of on the quadrature suppression electrode of the micro-machined gyroscope, and use the difference between the upper sideband displacement signal and the lower sideband displacement signal generated by it in the detection mode as a characterization quantity for mode matching; when the value of this characterization quantity is 0, it is considered that the mode is matched.

[0014] b) Adjust the tuning voltage of the detection mode through closed-loop control to make the above mode characterization quantity be 0 in real time, then on-line mode matching is achieved.

[0015] Preferably, the parametric excitation voltage is an AC voltage signal with a frequency twice that of the driving excitation signal, which realizes a two-fold frequency modulation of the stiffness of the detection mode.

[0016] According to an embodiment of the present invention, the equivalent quality factor after parametric excitation is deduced from the phase response of the injected signal in the parametric excitation mode, specifically: taking the phase response of the force corresponding to the upper sideband signal actually applied to the detection mode as the variable, the real-time equivalent quality factor after parametric excitation is deduced.

[0017] According to an embodiment of the present invention, the equivalent quality factor with zero offset controlled to 0 at a selected temperature is used as a reference value , when the ambient temperature changes, the amplitude of the parametric excitation voltage is calculated in real time, and based on the calculated amplitude of the parametric excitation voltage 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 temperature change by changing the amplitude of the parametric excitation voltage, thereby realizing the online temperature compensation of the zero offset error in principle.

[0018] The beneficial effects of the present invention compared with the prior art are as follows:

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

[0020] 2) It is applicable to most Coriolis vibrating gyroscopes with modal tuning functions, without additional gyro mechanical structure and parameter requirements, and has universality and practicality.

[0021] 3) The present invention realizes the temperature compensation of the zero offset from the gyro working mechanism, and it is an automatic online compensation, enabling the gyroscope to have excellent temperature stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the control block diagram of the online temperature compensation method for the zero offset of the micro-machined gyroscope based on the active control of the quality factor according to the present invention.

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

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

[0025] Figure 4 is the result of the equivalent quality factor and the natural quality factor of the detection mode after the application of parametric excitation according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be further described and explained below in conjunction with specific embodiments. The embodiments are only demonstrations of the present disclosure content and do not delimit the scope of limitation. Without conflict, the technical features of each embodiment of the present invention can be combined accordingly.

[0027] The online temperature compensation method for the zero bias of a micro-machined gyroscope based on Q-value active control of the present invention is specifically as follows:

[0028] 1) A field programmable gate array is used to apply a driving excitation signal to the driving mode of the micro-machined gyroscope, so that the gyroscope starts to vibrate and generates a vibration signal. The gyroscope detection circuit picks up the vibration displacement signal and demodulates it in the field programmable gate array chip to obtain the displacement amplitude signal and phase signal of the micro-machined gyroscope. The phase-locked loop locks the driving mode of the micro-machined gyroscope in the resonant state according to the phase signal of the displacement and outputs a phase control word. The automatic gain control loop performs closed-loop control on the displacement amplitude signal to keep the driving mode of the micro-machined gyroscope at a constant amplitude. The phase-locked loop transmits the output phase control word to the voltage-controlled oscillator, and the voltage-controlled oscillator outputs a cosine component and a sine component with a fixed frequency, where the cosine component is in phase with the velocity of the gyroscope, the sine component is in phase with the displacement of the gyroscope, and the phase of the velocity of the gyroscope is orthogonal to the phase of the displacement.

[0029] The dynamic equation of the driving mode is as follows:

[0030]

[0031] Where is the mass of the moving mass block, is the displacement of the driving mode of the gyroscope, and are the damping coefficient and elastic coefficient of the driving mode of the gyroscope respectively, is the amplitude 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 alternating current signal with the same frequency as the driving excitation signal is used to perform force balance on 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 two components related to the driving velocity and the driving displacement . Among them, is the amplitude of the in-phase additional force with the angular velocity, is the amplitude of the orthogonal additional force with 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 of the external input.

[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 mode matching by using the detection mode signal injection method, which includes: 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 factor for signal injection 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, $A$ 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 is the prerequisite for the parametric excitation to be amplified. Therefore, in the control loop, real-time mode matching is required.

[0043] In order to obtain the equivalent quality factor of the detection mode, it is necessary to amplitude gain of and phase response are derived as follows:

[0044]

[0045] , , ;

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

[0047] Substitute , into it, and we get

[0048]

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

[0050]

[0051] Furthermore, through , , the relationship between the three variables and the phase response , the equivalent quality factor of the detection mode can be expressed as:

[0052] .

[0053] The main objective 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. It can be seen from the formula that by changing the value in real time, the value can be controlled to be a constant value, so that the zero-bias output of 0° / s does not change with temperature.

[0054] Therefore, in the present invention, at a selected temperature (e.g., -20°C), the zero offset is controlled to 0 by adjusting the amplitude of the parametric excitation voltage, and the equivalent quality factor after parametric excitation is deduced from the phase response of the injected signal in the parametric excitation mode; using this equivalent quality factor as a reference value , for the scenario requiring temperature compensation, the amplitude of the parametric excitation voltage is obtained in real time through the following formula

[0055]

[0056] According to the calculated amplitude of the parametric excitation voltage 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, thereby realizing online temperature compensation of zero offset error in principle.

[0057] The present invention is further introduced below in combination with a specific application embodiment and the effects of the present invention are demonstrated.

[0058] The steps of the application embodiment are as follows:

[0059] Step 1: An FPGA digital circuit with Kintex - 7 as the core and a fully symmetric analog signal conditioning circuit are carried, and the gyro is placed in a temperature chamber turntable for experiments. Referring to the aforementioned step 1), the driving mode is maintained at a constant frequency and a constant amplitude vibration through a phase - locked loop and an automatic gain control loop;

[0060] Step 2: Referring to the aforementioned step 2), the gyro is operated in the force - balance mode, and referring to the aforementioned step 3), real - time mode matching is achieved through the signal injection method. The gyro is placed in a cyclic environment with a gradually increasing and decreasing temperature from -20°C to 50°C, and the zero - offset output and the change values of the intrinsic quality factor are recorded.

[0061] Step 3: A parametric excitation signal is injected in the detection mode. At -20°C, the zero offset is controlled to 0 by adjusting the amplitude of the parametric excitation signal, and the temperature - change process in step 2 is repeated, recording the zero - offset output, the change of the intrinsic quality factor, and the equivalent quality factor.

[0062] Step 4: Based on step 3, calculate the zero - offset output, the changes of the intrinsic and equivalent quality factors changes, deduce the change and apply the method of the present invention to the signal amplitude of the parametric excitation voltage (According to the calculated amplitude of the parametric excitation voltage The amplitude of the parametric excitation voltage is adjusted in real time to keep the equivalent quality factor at a constant value, that is, the equivalent quality factor adapts to the temperature change by changing the amplitude of the parametric excitation voltage, realizing the online temperature compensation of the zero-offset error). Record the corresponding results: zero-offset output, change in the intrinsic quality factor, and equivalent quality factor.

[0063] By comparing the results of Step 3 and Step 4 of the present invention, the compensation result comparison of the equivalent quality factor between the fixed parametric excitation amplitude and the parametric excitation amplitude that is changed online in the present invention can be obtained, as Figure 3 shown, Figure 3 respectively shows the change in the equivalent quality factor and the change in the phase response of the fixed parametric excitation amplitude and the parametric excitation amplitude that is changed online in the present invention in a temperature-changing environment.

[0064] Further, the gyroscope in the force balance and mode matching state is placed in a constant temperature and a uniform temperature change from -20°C to 50°C; then, with a fixed parametric excitation amplitude and an online-changing parametric excitation amplitude respectively, it is placed in a uniform temperature change from -20°C to 50°C, and the zero-offset output is recorded three times respectively. The results are as Figure 4 shown. The numbers 1, 2, and 3 in the figure respectively correspond to the original zero-offset, the zero-offset of the fixed parametric excitation amplitude, and the zero-offset of the adaptive parametric excitation amplitude. It can be seen that by means of electrical parametric excitation, the equivalent quality factor is actively adjusted, suppressing the temperature drift of the in-phase zero-offset. In the temperature change range of 70°C, the original 0.23 mdps / K is reduced to 9.7 μdps / K, and the zero-offset instability is reduced from 0.295 dph to 0.157 dph. This measurement and control method can adjust the zero-offset in real time, without additional damping adjustment components and a large amount of data fitting compensation, and has universality on micro-machined gyroscopes.

[0065] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the present invention patent. For those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for online temperature compensation of the zero bias of a micro-machined gyroscope based on Q-value active control, characterized in that, It includes the following steps: 1) The micro-machined gyroscope control system uses a phase-locked loop and an automatic gain control loop to keep the driving mode vibrating at a constant frequency and a constant amplitude; in the detection mode, an AC signal with the same frequency as the driving excitation signal is used to perform force balance on the signals orthogonal and in-phase to the angular velocity signal. 2) The real-time mode matching is realized by using the detection mode signal injection method; a parametric excitation voltage is injected into the detection mode, and at the selected temperature, the zero offset is controlled to 0 by adjusting the amplitude of the parametric excitation voltage, and the equivalent quality factor after parametric excitation is deduced from the phase response of the injected signal in the parametric excitation mode; taking this equivalent quality factor as a reference value, for the scenario that requires temperature compensation, the amplitude of the parametric excitation voltage is calculated in real time to perform online temperature compensation of the zero offset error, so as to achieve the purpose of online matching of the equivalent quality factors of the driving mode and the detection mode.

2. The online temperature compensation method for the zero offset of the micromechanical gyro according to claim 1, wherein The specific content of step 1) is as follows: A field programmable gate array is used to apply a driving excitation signal to the driving mode of the micro-machined gyroscope to make the gyroscope start vibrating and generate a vibration signal; the gyroscope detection circuit picks up the vibration displacement signal and demodulates it in the field programmable gate array chip to obtain the displacement amplitude signal and phase signal of the micro-machined gyroscope; the phase-locked loop locks the driving mode of the micro-machined gyroscope in the resonant state according to the phase signal of the displacement and outputs a phase control word; the automatic gain control loop performs closed-loop control on the displacement amplitude signal to keep the driving mode of the micro-machined gyroscope at a constant amplitude; the field programmable gate array applies AC signals with the same frequency and in-phase and the same frequency and orthogonal to the driving excitation signal to the detection mode, which are respectively used to balance the in-phase signal and the orthogonal signal coupled from the driving mode to the detection mode, and the amplitude of this in-phase signal is used to characterize the magnitude of the angular velocity.

3. The online temperature compensation method for the zero bias of a micromechanical gyroscope according to claim 1, wherein In step 2), the realization of real-time mode matching by using the detection mode signal injection method is specifically as follows: a) Inject a low-frequency disturbance signal with a frequency of onto the orthogonal suppression electrodes of the micro-machined gyroscope, and use the difference between the upper sideband displacement signal and the lower sideband displacement signal generated in the detection mode as a characterization quantity for mode matching; when the value of this characterization quantity is 0, it is considered that mode matching is achieved. b) By adjusting the tuning voltage of the detection mode through closed-loop control to make the above-mentioned mode characterization quantity be 0 in real time, the online mode matching is achieved.

4. The online temperature compensation method for the zero bias of the micromachined gyroscope according to claim 3, wherein In step 2), the parametric excitation voltage is an AC voltage signal with a frequency twice that of the driving excitation signal, which realizes a two-fold frequency modulation of the stiffness of the detection mode.

5. The online temperature compensation method for the zero bias of the micromachined gyroscope according to claim 1, wherein In step 2), the selected temperature is -20°C.

6. The online temperature compensation method for the zero bias of the micromachined gyroscope according to claim 4, wherein, In step 2), the equivalent quality factor after parametric excitation is deduced from the phase response of the injected signal in the parametric excitation mode, specifically: taking the phase response of the force corresponding to the upper sideband signal in the detection mode as the variable, and combining the known gyro mechanical parameters, the real-time equivalent quality factor after parametric excitation is deduced by the following formula : ； Among them, , , is an intermediate variable and satisfies: ， ； To detect the resonance 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 gyroscopic moving mass.

7. The online temperature compensation method for the zero bias of the micromachined gyroscope according to claim 1, characterized in that In step 2), the specific method for obtaining the amplitude of the parametric excitation voltage in real time is as follows: the equivalent quality factor with zero bias controlled to 0 at the selected temperature is used as a reference value , and when the ambient temperature changes, the amplitude of the parametric excitation voltage is calculated in real time according to the following formula 。 8. The online temperature compensation method for the zero bias of the micromachined gyroscope according to claim 1, characterized in that, In step 2), the online temperature compensation for the zero-offset error is specifically as follows: Based on the calculated amplitude of the parametric excitation voltage 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 temperature change by changing the amplitude of the parametric excitation voltage, so as to achieve the online temperature compensation for the zero-offset error from the mechanism.

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