Gyroscope interface system and method with quadrature error compensation and modal matching

Abstract

The present invention provides a gyroscope interface system and method with orthogonal error compensation and mode matching, including a driving module and a sensing module, wherein the driving module and the sensing module are both connected to an orthogonal compensation module, and the orthogonal compensation module is used to extract the orthogonal error caused by the coupling between the driving mode and the sensing mode from the output signal of the sensing mode, convert it into an orthogonal feedback signal and feed it back to the mass block of the gyroscope to reduce the coupling between the driving mode and the sensing mode; the mode matching module is controlled by a register to change the driving voltage on the sensing mode, thereby changing the effective elastic coefficient and the resonant frequency of the sensing mode. The present invention can effectively suppress the orthogonal error caused by the coupling between the driving mode and the sensing mode, reduce the resonant frequency difference between the driving mode and the sensing mode, and improve the linearity and sensitivity of the gyroscope when working in a closed-loop mode.

Description

Technical Field

[0001] The present invention relates to the technical field of gyroscope interface, and in particular to a gyroscope interface system and method with orthogonal error compensation and modal matching. Background Art

[0002] Prior art document: MEMS gyroscope with frequency adjustment and electrostatic elimination of orthogonal error, application number, CN201710198481.5. The prior art document discloses that the structure of the MEMS gyroscope includes a driving axis and a sensing axis, and the interface circuit of the MEMS gyroscope includes a driving loop, a sensing loop and a digital processing unit.

[0003] The driving loop obtains the driving capacitance change signal and converts it into a driving signal. The driving signal makes the driving axis of the gyroscope vibrate, and the driving loop works stably. The sensing loop obtains the sensing capacitance change signal and generates a sensing signal. The sensing signal makes the sensing axis of the gyroscope vibrate, and the driving loop works stably.

[0004] The driving loop is used to convert the driving capacitance change signal into a driving response, and the sensing loop is used to convert the sensing capacitance change signal into a sensing response. Both the driving loop and the sensing loop are connected to a digital processing unit, which receives the driving response and the sensing response and outputs the test result of the MEMS gyroscope.

[0005] Assume that the MEMS gyroscope has angular velocity in the z-axis direction, the x-direction is the driving axis, and the y-direction is the sensing axis. The directions of the two axes are exactly perpendicular, so that the coupling between the driving mode and the sensing mode is very likely to produce orthogonal errors. The sensing response contains Coriolis shift signals and orthogonal displacement signals. The orthogonal displacement signals introduce orthogonal error signals, which affect the performance of the MEMS gyroscope. Summary of the invention

[0006] In view of this, the problem to be solved by the present invention is to provide a gyroscope interface system and method with orthogonal error compensation and modal matching, which can effectively suppress the orthogonal error and frequency difference caused by the coupling between the driving mode and the sensing mode, and improve the linearity and sensitivity of the gyroscope when working in a closed-loop mode.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a MEMS gyroscope interface control method with orthogonal error compensation, comprising:

[0008] Phase modulation, obtain drive input signal , will drive the input signal The phase modulation is a cosine signal;

[0009] Demodulation to obtain the sensing input signal , using the cosine signal as reference to demodulate the sensing input signal To obtain the orthogonal error;

[0010] Feedback, the orthogonal error amount is converted into an orthogonal error signal and fed back to the mass block of the gyroscope.

[0011] Furthermore, the orthogonal error amount is processed by low-pass filtering and digital-to-analog conversion to generate an orthogonal error signal.

[0012] Furthermore, when the MEMS gyroscope is in closed-loop mode, phase modulation and demodulation are continuously performed and the quadrature error signal is fed back to the mass block until the demodulated quadrature error amount is zero.

[0013] A MEMS gyroscope interface system with orthogonal error compensation includes a driving module and a sensing module, wherein the driving module and the sensing module are both connected to a mass block through an orthogonal compensation module;

[0014] The orthogonal compensation module includes a first phase modulator connected to the driving module and a second phase modulator connected to the sensing module. The output ends of the first phase modulator and the second phase modulator are connected to a demodulator. The output end of the demodulator is connected to a PI controller. The output end of the PI controller is connected to a DAC digital-to-analog converter. The DAC digital-to-analog converter outputs an orthogonal error signal.

[0015] Furthermore, the driving module includes a first sampling port, a first driving port and a first output port, and the sensing module includes a second sampling port, a second driving port and a second output port; the first output port and the second output port are both connected to the processing module, the processing module is used to output the MEMS gyroscope detection results, the first sampling port is used to collect the voltage change signal of the driving capacitor, the second sampling port is used to collect the voltage change signal of the sensing capacitor, the first driving port is used to drive the driving axis, and the second driving port is used to drive the sensing axis.

[0016] A MEMS gyroscope interface control method with mode matching includes calculating the effective elastic coefficient of a sensing mode, determining the resonant frequency of the sensing mode based on the effective elastic coefficient, and adjusting the driving voltage on the sensing mode based on the resonant frequency to change the effective elastic coefficient and the resonant frequency of the sensing mode.

[0017] Further, the sensing mode includes a mass block and a stator, the stator includes two stator electrodes placed opposite to each other, the mass block is located between the two stator electrodes, and a driving voltage VDC is applied between the stator and the mass block;

[0018] The method for obtaining the resonant frequency is: calculating the electrostatic force of the mass block ,when When , the elastic coefficient introduced by the electrostatic force is:

[0019] ,

[0020] Where y is the moving distance of the mass block on the sensing axis;

[0021] The effective elastic coefficient of the sensing mode is:

[0022] ,

[0023] in, is the mechanical elastic coefficient of the mass block;

[0024] The resonant frequency of the sensing mode is:

[0025] .

[0026] A MEMS gyroscope interface system with modal matching includes a sensing modality, wherein the sensing modality is connected to a register via a modal matching module, and the modal matching module includes a PWM controller.

[0027] The advantages and positive effects of the present invention are:

[0028] (1) By setting the drive input signal Phase modulation is used for cosine signal, and then the cosine signal is used as the reference to demodulate the sensing input signal , the orthogonal error caused by the coupling between the driving mode and the sensing mode can be extracted, and the orthogonal error can be converted into an orthogonal error signal and fed back to the mass block of the gyroscope, which can effectively suppress the orthogonal error caused by the coupling between the driving mode and the sensing mode, thereby reducing the coupling between the driving mode and the sensing mode, and then reducing the orthogonal error, greatly improving the linearity and sensitivity of the MEMS gyroscope.

[0029] (2) The sensing mode includes the mass block and the stator. The parameters such as the electrostatic force and the moving distance between the mass block and the stator are obtained to calculate the resonant frequency of the sensing mode. The driving voltage and frequency between the mass block and the stator are adjusted according to the resonant frequency to reduce the resonant frequency difference between the driving mode and the sensing mode, thereby improving the sensitivity of the MEMS gyroscope when working in closed-loop mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 It is an overall structural diagram of the MEMS gyroscope interface system with orthogonal error compensation of the present invention;

[0032] Figure 2It is a system diagram of an orthogonal compensation module of a MEMS gyroscope interface system with orthogonal error compensation of the present invention;

[0033] Figure 3 It is a system diagram of a modal matching module of a MEMS gyroscope interface system with modal matching of the present invention;

[0034] Figure 4 It is a sensing modal structure diagram of the MEMS gyroscope interface system with modal matching of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0038] The present invention provides a MEMS gyroscope interface system with orthogonal error compensation, such as Figure 1 As shown, it includes a driving module connected to the driving shaft and a sensing module connected to the sensing shaft. When the driving module operates in a closed loop, it continuously collects the voltage change signal of the driving shaft capacitor, and converts the voltage change signal into a driving signal and transmits it to the driving shaft, so that the driving shaft vibrates continuously. When the sensing module operates in a closed loop, it continuously collects the voltage change signal of the sensing shaft capacitor, and converts the voltage change signal into a sensing signal and transmits it to the sensing shaft, so that the sensing shaft vibrates continuously.

[0039] Both the driving module and the sensing module are connected to the processing module. The driving module is used to convert the voltage change signal of the driving axis capacitance into the driving input, and the sensing module converts the voltage change signal of the sensing axis capacitance into the sensing input. The processing module determines the MEMS gyroscope detection result based on the driving input and the sensing input and outputs it.

[0040] In order to offset the orthogonal error caused by the coupling between the driving mode and the sensing mode, an orthogonal compensation module is provided. The orthogonal compensation module determines the orthogonal error amount based on the driving input and the sensing input, and converts it into an orthogonal error signal. The output end of the orthogonal compensation module is connected to the mass block of the gyroscope, and the orthogonal error signal drives the mass block to offset the orthogonal error caused by the coupling.

[0041] The orthogonal compensation module includes a first phase modulator connected to the driving module and a second phase modulator connected to the sensing module. The output ends of the first phase modulator and the second phase modulator are connected to the demodulator. The output end of the demodulator is connected to the PI controller. The output end of the PI controller is connected to the DAC digital-to-analog converter. The DAC digital-to-analog converter outputs an orthogonal error signal.

[0042] An embodiment of the present application is: the driving module includes a first sampling port, a first driving port and a first output port, and the sensing module includes a second sampling port, a second driving port and a second output port; the first output port and the second output port are both connected to the processing module, the processing module is used to output the detection result of the MEMS gyroscope, the first sampling port is used to collect the voltage change signal of the driving capacitor, the second sampling port is used to collect the voltage change signal of the sensing capacitor, the first driving port is used to drive the driving axis, and the second driving port is used to drive the sensing axis.

[0043] like Figure 2 As shown, based on the above gyroscope interface system, a MEMS gyroscope interface control method with orthogonal error compensation is included: including phase modulation, obtaining a driving input signal , will drive the input signal The phase modulation is a cosine signal;

[0044] Assume that the MEMS gyroscope has an angular velocity in the z-axis direction, the x-direction is the driving axis, and the y-direction is the sensing axis. The driving input is: ,in, represents the magnitude of the driving force, is the frequency of the driving force, The first phase modulator is used to adjust the driving input Phase modulation is in cosine form, and the unit cosine signal is used as a reference signal to demodulate the sensing input .

[0045] Demodulation to obtain the sensing input signal , using the cosine signal as the reference to sense the input signal Demodulate and low-pass filter to obtain the orthogonal error.

[0046] The sensing inputs are: ,in, To sense the vibration force amplitude, To sense the phase of the vibration force.

[0047] The sensing input can also be expressed as a Coriolis shift signal and a quadrature shift signal:

[0048] ,in, is the vibration amplitude caused by the Coriolis force, is the vibration amplitude caused by the orthogonal force. The orthogonal displacement introduces the orthogonal error signal, which is the signal quantity we hope to eliminate. Since the Coriolis displacement and the orthogonal displacement are orthogonal to each other, the orthogonal error signal can be extracted by the orthogonal demodulation method.

[0049] Sensing input signal The demodulated output is:

[0050] .

[0051] The reference phase angle for demodulation is selected as , so that ,but , Based on this demodulation, low-pass filtering can be performed to obtain the orthogonal error, that is, .

[0052] Feedback, the orthogonal error amount is converted into an orthogonal error signal and fed back to the mass block of the gyroscope.

[0053] The PI controller adjusts the PI output according to the error, and then converts the digital quantity into an analog quantity (orthogonal feedback signal) through a digital-to-analog converter (DAC). The orthogonal feedback signal drives the mass block of the gyroscope to continuously offset the orthogonal error on the sensing mode, thereby reducing the coupling between the driving mode and the sensing mode until the orthogonal error is zero.

[0054] One embodiment of the present invention is that when the MEMS gyroscope is in a closed-loop mode, phase adjustment and demodulation are continuously performed to feed back the quadrature error signal to the mass block of the gyroscope until the demodulated quadrature error amount is zero.

[0055] like Figure 3 and Figure 4 As shown, a MEMS gyroscope interface system with mode matching, wherein the sensing modes include a mass block and a stator, and a driving voltage is loaded between the mass block and the stator. Figure 3The sensing axis direction of the middle sensing mode is the vertical direction. A mode matching module is provided between the sensing mode and the register, the register is used to output the control word, the mode matching module includes a PWM controller, and the register outputs the driving voltage through the PWM controller.

[0056] Adjusting the control word in the register can adjust the driving voltage, thereby changing the effective elastic coefficient of the sensing mode; adjusting the PWM controller frequency can adjust the driving voltage frequency to reduce the resonant frequency difference between the driving mode and the sensing mode, thereby improving the sensitivity of the gyroscope when working in closed-loop mode.

[0057] Based on the above gyroscope interface system, a MEMS gyroscope interface control method with modal matching is provided, which includes calculating the effective elastic coefficient of the sensing mode, determining the resonant frequency of the sensing mode based on the effective elastic coefficient; and adjusting the driving voltage on the sensing mode based on the resonant frequency to change the effective elastic coefficient and the resonant frequency of the sensing mode.

[0058] An embodiment of the present application is as follows: the stator in the sensing mode includes two stator electrodes placed opposite to each other, the mass block is located between the two stator electrodes, and a driving voltage VDC is applied between the stator and the mass block;

[0059] The resonant frequency is calculated as:

[0060]

[0061] in, represents the total force in the vertical direction of the mass block, is the mechanical force caused by the mechanical elastic coefficient of the mass block, and are the electrostatic forces generated by the modal matching actuation voltage, is the electrostatic force, is the effective elastic coefficient, is the mechanical elastic coefficient of the mass block, is the moving distance of the mass block on the sensing axis (moving distance in the vertical direction), is the distance between the mass block and the stator when the mass block does not move.

[0062] when When , the elastic coefficient introduced by the electrostatic force is:

[0063] ,

[0064] The effective elastic coefficient of the sensing mode is calculated based on the elastic coefficient:

[0065] ,

[0066] The resonant frequency of the sensing mode is calculated based on the effective elastic coefficient:

[0067] ,

[0068] How to adjust the drive voltage: Based on the resonant frequency Generate a control word and store it in a register, the register outputs the control word, and outputs a driving voltage through a PWM controller to change the effective elastic coefficient of the sensing mode. The PWM controller receives a PWM frequency control signal, which is used to adjust the operating frequency of the PWM controller, thereby controlling the frequency component generated by the mode matching driving signal to prevent it from falling into the frequency band of the effective signal. Changing the effective elastic coefficient and resonant frequency of the sensing mode can effectively improve the sensitivity of the gyroscope when working in a closed-loop mode.

[0069] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A method for controlling a MEMS gyroscope interface with orthogonal error compensation, characterized in that: include, Phase modulation, obtain drive input signal , will drive the input signal The phase modulation is a cosine signal; Demodulation to obtain the sensing input signal , using the cosine signal as reference to demodulate the sensing input signal To obtain the orthogonal error; Feedback, the orthogonal error amount is converted into an orthogonal error signal and fed back to the mass block of the gyroscope; The orthogonal error is processed by low-pass filtering and digital-to-analog conversion to generate an orthogonal error signal; when the MEMS gyroscope is in closed-loop mode, phase modulation and demodulation are continued and the orthogonal error signal is fed back to the mass block until the demodulated orthogonal error is zero; Sensing input signal The demodulated output is: ,in: is the vibration amplitude caused by the Coriolis force, is the vibration amplitude caused by the orthogonal force, To sense the phase of the vibration force, is the phase of the driving force, is the frequency of the driving force; The reference phase angle for demodulation is selected as , so that ,but , , based on this demodulation, low-pass filtering can be performed to obtain the orthogonal error, that is, .

2. A MEMS gyroscope interface system with orthogonal error compensation, based on the MEMS gyroscope interface control method with orthogonal error compensation according to claim 1, characterized in that: It includes a driving module and a sensing module, wherein both the driving module and the sensing module are connected to the mass block through an orthogonal compensation module; The orthogonal compensation module includes a first phase modulator connected to the driving module and a second phase modulator connected to the sensing module. The output ends of the first phase modulator and the second phase modulator are connected to a demodulator. The output end of the demodulator is connected to a PI controller. The output end of the PI controller is connected to a DAC digital-to-analog converter. The DAC digital-to-analog converter outputs an orthogonal error signal.

3. The MEMS gyroscope interface system with orthogonal error compensation according to claim 2, characterized in that: The driving module includes a first sampling port, a first driving port and a first output port, and the sensing module includes a second sampling port, a second driving port and a second output port; the first output port and the second output port are both connected to the processing module, and the processing module is used to output the detection result of the MEMS gyroscope, the first sampling port is used to collect the voltage change signal of the driving capacitor, and the second sampling port is used to collect the voltage change signal of the sensing capacitor, the first driving port is used to drive the driving axis, and the second driving port is used to drive the sensing axis.

4. A method for controlling a MEMS gyroscope interface with modal matching, based on a MEMS gyroscope interface system with orthogonal error compensation as claimed in any one of claims 2 to 3, characterized in that: The method includes calculating the effective elastic coefficient of the sensing mode, determining the resonant frequency of the sensing mode based on the effective elastic coefficient, and adjusting the driving voltage on the sensing mode based on the resonant frequency to change the effective elastic coefficient and the resonant frequency of the sensing mode.

5. The MEMS gyroscope interface control method with modal matching according to claim 4, characterized in that: The sensing mode includes a mass block and a stator, the stator includes two stator electrodes placed opposite to each other, the mass block is located between the two stator electrodes, and a driving voltage VDC is applied between the stator and the mass block; The method for obtaining the resonant frequency is: calculating the electrostatic force of the mass block , is the distance between the mass block and the stator when the mass block does not move. When , the elastic coefficient introduced by the electrostatic force is: ， Where y is the moving distance of the mass block on the sensing axis; The effective elastic coefficient of the sensing mode is: ， in, is the mechanical elastic coefficient of the mass block; The resonant frequency of the sensing mode is: 。 6. A MEMS gyroscope interface system with modal matching, based on the MEMS gyroscope interface control method with modal matching according to any one of claims 4 to 5, characterized in that: It includes a sensing modality, wherein the sensing modality is connected to a register via a modality matching module, and the modality matching module includes a PWM controller.

Images