CN105571612A - Automatic testing method for key parameters of MEMS gyroscope structure - Google Patents

Abstract

The invention is an automatic testing method for the key parameters of the MEMS gyro structure. The method comprises the following steps: step 1) applying white noise voltage excitation on the drive structure electrode of the MEMS gyro drive mode to generate driving force; step 2) connecting the vibration pickup structure electrode of the MEMS gyro drive mode to the pre-readout circuit ; The response curve is collected in the digital signal processor and processed by FFT to obtain the resonant frequency f of the driving mode; step 3 _{) constructs a sine wave with the resonant frequency f d obtained} in step 2), and is applied to the driving mode of the driving mode On the structural electrodes, after the gyro is confirmed to vibrate, collect the output voltage of the drive mode and detection mode pre-readout circuit to obtain the coupling ratio; step 4) remove the sine wave excitation, and calculate the quality of the drive mode from the decay curve Factor _Qd . Key structural parameters such as resonance frequency, quality factor, coupling voltage ratio, and displacement ratio can be automatically tested.

Description

A kind of MEMS gyro structural key automatically testing parameters method

Technical field

The present invention relates to a kind of automatic test approach, particularly about a kind of automatic test approach of MEMS gyro structural key parameter.

Technical background

MEMS gyro be by the characteristic dimension of microelectronic technique processing at the device of micron dimension, have that volume is little, cost is low, be suitable for batch machining and be easy to the advantage integrated with ASIC.MEMS gyro contains vibrational structure, and the structural key parameters such as its resonance frequency, quality factor q and coupling amount all can affect the overall performance of device.Before instrument assembly, need to screen MEMS gyro gauge outfit, key parameter test is carried out to structure, determines the key property of gyro gauge outfit.Except normal temperature is tested, also need under alternating temperature and change encapsulate the condition of air pressure, test to investigate gauge outfit to these structural key parameters temperature change and pressure change characteristic.MEMS gyro comprises two operation modes, i.e. driven-mode and sensed-mode, and each mode all needs test resonance frequency and quality factor q.

Common method of testing manually adopts each mode of dynamic signal analyzer to gyro gauge outfit to carry out frequency sweep respectively, obtains its amplitude-frequency and phase-frequency response curve, calculated resonance frequency and the quality factor q of each mode of gyro gauge outfit by response curve.The method is applicable to the lower gyro of quality factor, if gyro quality factor are higher, for reaching measuring accuracy, needing to increase frequency sweep and counting to guarantee that frequency resolution is enough high, and increase frequency sweep and count and greatly can extend the sweep check time, and requirements at the higher level are proposed to system hardware.Simultaneously the method also need to carry out in test process to debug, the operation such as thread-changing, the test duration is long and need manpower intervention.

Under temperature match curing conditions, as from-40 DEG C to+85 DEG C, Cooling rate is 1 DEG C/min, each temperature spot all needs to test structural key parameter, need to carry out debug data frequently, change test connection line, will huge workload be expended, need tester midway to monitor, otherwise can omit the test of a certain temperature spot, testing efficiency is not high.Automatical and efficient measurement can not be realized.

Summary of the invention

Goal of the invention

For the problems referred to above, the invention provides a kind of automatic test approach for MEMS gyro structural key parameter, on the basis ensureing measuring accuracy, artificial monitoring in real time can be broken away from, improve testing efficiency.

Technical scheme

The present invention is a kind of MEMS gyro structural key automatically testing parameters method, is applicable to the test of the structural key parameter comprising two operation mode structure MEMS gyro, and described two operation mode structures are driven-mode structure and sensed-mode structure; Described driven-mode structure comprises driven-mode drives structure, driven-mode vibrational structure and driven-mode vibration pickup structure; Described sensed-mode structure comprises sensed-mode drives structure, sensed-mode vibrational structure and sensed-mode vibration pickup structure; Described structural key parameter comprises: the resonance frequency f of driven-mode _d, driven-mode quality factor q _d, driven-mode and sensed-mode coupled voltages ratio;

Wherein, described method comprises the steps:

Step 1) on the drives structure electrode of MEMS gyro driven-mode, apply white noise voltage drive generation driving force;

Step 2) the vibration pickup structure electrode of MEMS gyro driven-mode is connected preposition sensing circuit; Sensing circuit reads the voltage variety that gyro exports, and obtains the response curve of gyro driven-mode; Carry out FFT process in described Response Waveform Acquisition to digital signal processor, obtain the resonance frequency f of driven-mode _d;

Step 3) with step 2) the resonance frequency f that obtains _dstructure is sinusoidal wave, is applied on the drives structure electrode of driven-mode, after determining gyro starting of oscillation, gathers the output voltage of driven-mode and the preposition sensing circuit of sensed-mode, obtains coupling ratio;

Step 4) remove sine-wave excitation, the quality factor q of driven-mode is calculated by die-away curve _d;

At completing steps 3) after, remove sine-wave excitation, the preposition sensing circuit of driven-mode exports gyroscopic vibration die-away curve, is calculated the quality factor q of driven-mode by die-away curve _d.

A kind of MEMS gyro structural key automatically testing parameters method as above, wherein: described structural key parameter also comprises: the resonance frequency f of sensed-mode _s, sensed-mode quality factor q _s; Described method also comprises the steps:

Step 5) on the drives structure electrode of MEMS gyro sensed-mode, apply white noise voltage drive generation driving force;

Step 6) the vibration pickup structure electrode of MEMS gyro sensed-mode is connected preposition sensing circuit; Sensing circuit reads the voltage variety that gyro exports, and obtains the response curve of gyroscope; Carry out FFT process in described Response Waveform Acquisition to digital signal processor, obtain the resonance frequency f of sensed-mode _s;

Step 7) with step 6) the resonance frequency f that obtains _sstructure is sinusoidal wave, is applied on the drives structure electrode of gyroscope, after determining gyro starting of oscillation, removes sine-wave excitation, and the preposition sensing circuit of sensed-mode exports gyroscopic vibration die-away curve, is calculated the quality factor q of sensed-mode by die-away curve _s.

As above for an automatic test approach for MEMS gyro structural key parameter, wherein:

At the quality factor q of Test driver mode _dand the quality factor q of sensed-mode _stime, make with the following method:

If y1 be gyro starting of oscillation, then remove sine-wave excitation after, the gyro oscillatory extinction curve that preposition sensing circuit exports, then have:

$y_1=e^{-\frac{\mathrm{\πf}}{Q}t}\sin \left(2\mathrm{\πft}\right)$

In formula, f is resonance frequency, carries out exponential fitting, obtains the quality factor q of gyro.

Beneficial effect

The present invention is owing to taking above technical scheme, it has the following advantages: owing to adopting automatic test approach, automatically the structural key parameters such as resonance frequency, quality factor and coupled voltages ratio, Displacement Ratio can be tested, and collecting test environment temperature or air pressure, be automatically stored in digital signal processor, test process is without the need to the frequently operation such as debugging, thread-changing, especially artificial monitoring has in real time been broken away from when temperature variation testing, significantly shorten original manual testing's method testing time, raise the efficiency, convenient and easy.The present invention is applicable to the micromachine resonant device architecture crucial parameter measurements such as resonant-type tiny cantilever beam, micro-resonator, micromechanical gyro and resonance type micro accelerometer.

Accompanying drawing explanation

Fig. 1 is the device block diagram for MEMS gyro structural key automatically testing parameters method;

Fig. 2 be the present invention the MEMS gyro gauge head structure schematic diagram that is suitable for;

Fig. 3 is Q value test curve of the present invention;

Fig. 4 is the process flow diagram for MEMS gyro driven-mode structural key automatically testing parameters method.

Embodiment

Below, by reference to the accompanying drawings and embodiment, the present invention is described further.

Fig. 1 is the device block diagram for realizing MEMS gyro structural key automatically testing parameters method of the present invention:

Mainly comprise gyro gauge outfit 1, test circuit 2, high-speed data acquisition card 3 and digital signal processor 4.Gyro gauge outfit 1 is connected to high-speed data acquisition card 3 by test circuit 2, the vibration detection signal of gyro driven-mode and sensed-mode enters digital signal processor 4 by high-speed data acquisition card 3 and carries out process acquisition desired parameters, and digital signal processor 4 can produce pumping signal by capture card 3 and drive gyro gauge outfit 1 simultaneously.

The MEMS gyro that the present invention is directed to is the MEMS gyro comprising two operation mode structures, i.e. driven-mode structure and sensed-mode structure; Described driven-mode structure comprises driven-mode drives structure, driven-mode vibrational structure and driven-mode vibration pickup structure; Described sensed-mode structure comprises sensed-mode drives structure, sensed-mode vibrational structure and sensed-mode vibration pickup structure;

Be illustrated in figure 2 the present invention the MEMS gyro gauge head structure 1 that is suitable for, comprise driven-mode structure 5 and sensed-mode structure 6.Driven-mode structure 5 comprises driven-mode drives structure 7, driven-mode vibrational structure 8 and a driven-mode vibration pickup structure 9, and sensed-mode structure 6 comprises sensed-mode drives structure 13, sensed-mode vibrational structure 14 and a sensed-mode vibration pickup structure 15.

Wherein, drives structure 7,13 can adopt condenser type electrostatic to drive or Piezoelectric Driving.Vibrational structure 8,14 is connected to fixed pivot place by elastic beam, thus formation can vibrational structure.Vibration pickup structure 9,15 can adopt capacitance type structure or piezoelectric type structure.Drives structure 7,13 has drive electrode 11,17, and vibration pickup structure 9,15 has detecting electrode 10,16.Drive electrode 11,17 applies driving voltage, and because drives structure 7,13 adopts electrostatic to drive or Piezoelectric Driving, drives structure 7,13 just produces a driving force 12,18 to movable vibrational structure 8,14.Under driving force 12,18 drives, vibrational structure 8,14 produces vibration, and its displacement variable is obtained by vibration pickup structure 9,15.Vibration pickup structure 9,15 changes the displacement variable got into charge variation amount, and is exported by vibration pickup structure electrode 10,16, and vibration pickup structure electrode 10,16 is connected the test circuit 2 in a Fig. 1.Charge variation amount is converted to voltage variety by test circuit 2, to obtain the vibration information of vibrational structure 8,14.

When gyro reaches resonant condition, its mechanical gain is maximum, so after applying white-noise excitation, the vibration curve of output of gyro is in resonance frequency place amplitude maximum, by gathering the vibration curve of output after white-noise excitation, carrying out FFT process, by detecting peak point, the resonance frequency f of gyro can be obtained.

Fig. 3 is Q value test curve of the present invention, and y1 is after gyro starting of oscillation, removes sine-wave excitation, the gyro oscillatory extinction curve that preposition sensing circuit exports, and y2 is vibration amplitude die-away curve, and curve is relevant with quality factor q with the resonance frequency f of gyro, namely

$y_1=e^{-\frac{\mathrm{\πf}}{Q}t}\sin \left(2\mathrm{\πft}\right)$

By above-mentioned curve and the resonance frequency f that calculates, carry out exponential fitting, the quality factor q of gyro can be obtained.

Fig. 4 is the program flow diagram of the present invention for the automatic test approach embodiment of MEMS gyro driven-mode structural key parameter, and the auto test flow of sensed-mode structural key parameter is similar with it:

After program starts, first initialization is carried out to parameters in algorithm.White-noise excitation signal is produced in digital signal processor 4, gyro gauge outfit driven-mode structure is encouraged by high-speed data acquisition card 3, high-speed data acquisition card 3 gathers the output signal of gyro driven-mode test circuit 2, and in digital signal processor 4, process obtains the resonance frequency f of driven-mode _d; Then construct with f in digital signal processor 4 _dfor the sine wave signal of frequency, gyro gauge outfit driven-mode structure is encouraged by high-speed data acquisition card 3, high-speed data acquisition card 3 gathers the output signal of gyro driven-mode test circuit 2, the whether starting of oscillation of gyro driven-mode is judged in digital signal processor 4, after driven-mode starting of oscillation, gather the output signal of gyroscope test circuit 2, in digital signal processor 4, process obtains coupled voltages ratio, Displacement Ratio simultaneously; Remove sine-wave excitation by digital signal processor 3, collect the die-away curve of driven-mode, in digital signal processor 3, the Fitting Calculation obtains the quality factor q of driven-mode _d; End program after reaching testing time requirement.

The method of the invention is a kind of automatic test approach for MEMS gyro structural key parameter, comprises the steps:

1) on the drives structure electrode of MEMS gyro driven-mode, white-noise excitation is applied;

The drives structure electrode of MEMS gyro driven-mode applies white noise voltage drive and produces driving force, by described drives structure, driving force is applied on described driven-mode vibrational structure, obtain displacement variable; Described driving force is the product of drive voltage signal and conversion coefficient; Described conversion coefficient for this drive voltage signal be applied to described drives structure time, by the scale-up factor of voltage transitions corresponding to power; Described white noise voltage is produced by digital signal processor, amplitude and noise power adjustable.

2) the vibration pickup structure electrode of MEMS gyro driven-mode is connected preposition sensing circuit, obtain the resonance frequency f of driven-mode _d;

The vibration pickup structure electrode of MEMS gyro driven-mode is connected preposition sensing circuit; Be charge variation amount by described displacement variable by described vibration pickup Structure Transformation; Then, by preposition sensing circuit, this charge variation amount is converted to voltage variety, obtains the response curve of gyro driven-mode; Carry out FFT process in described Response Waveform Acquisition to digital signal processor, obtain frequency-amplitude curve, find out the frequency that maximum amplitude is corresponding, the resonance frequency f of driven-mode can be obtained _d.

3) with step 2) the resonance frequency f that obtains _dstructure is sinusoidal wave, is applied on the drives structure electrode of driven-mode, after determining gyro starting of oscillation, gathers the output voltage of driven-mode and the preposition sensing circuit of sensed-mode, obtains coupling ratio;

While sine-wave excitation gyro driven-mode resonant operational, gather the output voltage of driven-mode and the preposition sensing circuit of sensed-mode, obtain coupled voltages ratio, and then coupling Displacement Ratio can be calculated by conversion coefficient;

Described coupled voltages is than being gyroscope and the output voltage ratio of driven-mode front end circuit;

Described conversion coefficient is constant, relevant to the conversion coefficient of voltage variety to charge variation amount, charge variation amount with the displacement variable of driven-mode and sensed-mode, is constant value for appointment gyro.

4) remove sine-wave excitation, calculated the quality factor q of driven-mode by die-away curve _d;

With step 2) the resonance frequency f that obtains _dstructure is sinusoidal wave, is applied on the drives structure electrode of gyro driven-mode, after determining gyro starting of oscillation, removes sine-wave excitation, and the preposition sensing circuit of driven-mode exports gyroscopic vibration die-away curve, is calculated the quality factor q of driven-mode by die-away curve _d; Described sine wave is produced by digital signal processor; The method of described judgement gyro starting of oscillation is the response curve gathering the output of preposition sensing circuit, detects its amplitude and whether reaches requirement; Described die-away curve collects in digital signal processor and processes.

After the test having carried out driven-mode, carry out as step 1 at MEMS gyro sensed-mode), 2), 3) shown in operation, obtain the resonance frequency f of sensed-mode _sand quality factor q _s, concrete steps are as follows:

5) on the drives structure electrode of MEMS gyro sensed-mode, apply white noise voltage drive produce driving force, by described drives structure, driving force is applied on described sensed-mode vibrational structure, obtain displacement variable; Described driving force is the product of drive voltage signal and conversion coefficient; Described conversion coefficient for this drive voltage signal be applied to described drives structure time, by the scale-up factor of voltage transitions corresponding to power; Described white noise is produced by digital signal processor, amplitude and noise power adjustable.

6) the vibration pickup structure electrode of MEMS gyro sensed-mode is connected preposition sensing circuit; Be charge variation amount by described displacement variable by described vibration pickup Structure Transformation; Then, by preposition sensing circuit, this charge variation amount is converted to voltage variety, obtains the response curve of gyroscope; Carry out FFT process in described Response Waveform Acquisition to digital signal processor, obtain frequency-amplitude curve, find out the frequency that maximum amplitude is corresponding, the resonance frequency f of sensed-mode can be obtained _s.

7) with step 6) the resonance frequency f that obtains _sstructure is sinusoidal wave, is applied on the drives structure electrode of gyroscope, after determining gyro starting of oscillation, removes sine-wave excitation, and the preposition sensing circuit of sensed-mode exports gyroscopic vibration die-away curve, is calculated the quality factor q of sensed-mode by die-away curve _s; Described sine wave is produced by digital signal processor;

The method of described judgement gyro starting of oscillation is the response curve gathering the output of preposition sensing circuit, detects its amplitude and whether reaches designated value;

Described die-away curve collects in digital signal processor and processes.

8) temperature and the air pressure of temperature sensor and vacuum meter collecting test environment can as required, be used.

9) information such as the resonance frequency of MEMS gyro two mode recorded, quality factor and coupled voltages ratio/Displacement Ratio, temperature, air pressure are automatically stored in digital signal processor.

In above-mentioned method of testing, the die-away curve in described step 3,7 is relevant with quality factor with the resonance frequency of gyro, and is exponential damping, through exponential fitting, can obtain the quality factor of driven-mode and sensed-mode.

In above-mentioned method of testing, can the time interval between testing time and each test be set.

In addition, as required, can the temperature of collecting test environment and air pressure, and the information such as the resonance frequency of MEMS gyro two mode recorded, quality factor and coupling ratio, temperature, air pressure are automatically stored in digital signal processor.

The present invention is owing to adopting automatic test approach, automatically the structural key parameters such as resonance frequency, quality factor and coupled voltages ratio, Displacement Ratio can be tested, and collecting test environment temperature or air pressure, be automatically stored in digital signal processor, test process, without the need to operations such as frequently debugging, thread-changings, has especially broken away from artificial monitoring in real time when temperature variation testing, compared with original manual testing's method, the test duration that significantly shorten, convenient and easy, improve testing efficiency.The present invention is applicable to the micromachine resonant device architecture crucial parameter measurements such as resonant-type tiny cantilever beam, micro-resonator, micromechanical gyro and resonance type micro accelerometer.

Although be described in detail a kind of MEMS gyro structural key automatically testing parameters method of the present invention by above-described embodiment, but above-mentioned explanation is not limitation of the invention, without departing from the spirit and scope of the invention, various distortion and change can be carried out, such as, optimized method can be selected in the various methods of prior art.

Claims (3)

1. A MEMS gyroscope structure key parameter automatic test method is applicable to the test of the structural key parameters comprising two operating mode structure MEMS gyroscopes, and the two operating mode structures are driving mode structure and detection mode structure; The driving modal structure includes a driving modal driving structure, a driving modal vibration structure and a driving modal vibration pickup structure; the detection modal structure includes a detection modal driving structure, a detection modal vibration structure and a detection modal vibration pickup Structure; the key parameters of the structure include: the resonant frequency f _d of the driving mode, the quality factor Q _d of the driving mode, the coupling voltage ratio of the driving mode and the detection mode; It is characterized in that the method comprises the steps of: Step 1) applying white noise voltage excitation on the driving structure electrode of the MEMS gyroscope driving mode to generate driving force; Step 2) connect the vibration pickup structure electrode of the MEMS gyroscope drive mode to the pre-readout circuit; the readout circuit reads the voltage variation of the gyroscope output, and obtains the response curve of the gyroscope drive mode; the response curve collects digital signals FFT processing is performed in the processor to obtain the resonant frequency f _d of the driving mode; Step 3) Construct a sine wave with the resonant frequency f _d obtained in step 2), apply it on the driving structure electrode of the driving mode, and collect the output of the pre-readout circuit of the driving mode and the detection mode after the gyroscope is determined to vibrate voltage to obtain the coupling ratio; Step 4) remove the sine wave excitation, and calculate the quality factor Q _d of the driving mode from the decay curve; After step 3), the sine wave excitation is removed, and the pre-readout circuit of the driving mode outputs the gyro vibration attenuation curve, and the quality factor Q _d of the driving mode is calculated from the attenuation curve. 2. a kind of MEMS gyroscope structure key parameter automatic testing method as claimed in claim 1, is characterized in that: described structural key parameter also comprises: the resonant frequency f _s of detection mode, the quality factor Q _s of detection mode; The method also includes the steps of: Step 5) applying white noise voltage excitation on the driving structure electrode of the MEMS gyroscope detection mode to generate driving force; Step 6) The vibration pick-up structure electrode of the MEMS gyro detection mode is connected to the pre-readout circuit; the readout circuit reads the voltage variation of the gyro output, and obtains the response curve of the gyro detection mode; the response curve collects digital signals FFT processing is performed in the processor to obtain the resonant frequency f _s of the detected mode; Step 7) Construct a sine wave with the resonant frequency f _s obtained in step 6), apply it on the driving structure electrode of the gyro detection mode, and remove the sine wave excitation after the gyro is determined to vibrate, and detect the pre-readout circuit of the modal Output the gyro vibration attenuation curve, and calculate the quality factor Q _s of the detection mode from the attenuation curve. 3. a kind of automatic testing method that is used for MEMS gyroscope structure key parameter as claimed in claim 2, is characterized in that: When testing the quality factor Q _d of the driving mode and the quality factor Q _s of the detection mode, the following methods are used: Let y1 be the gyro oscillation attenuation curve output by the pre-readout circuit after the gyro starts to oscillate and the sine wave excitation is removed, then: ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;f</span>}}{\mathrm{<span\; class="notranslate">\; Q</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;ft</span>}<span\; class="notranslate">\; )</span>$ In the formula, f is the resonant frequency, and exponential fitting is performed to obtain the quality factor Q of the gyroscope.