CN1546364A - Computer Vision-Based MEMS Testing Device and Method - Google Patents

Abstract

The invention discloses a computer vision-based micro-electro-mechanical system testing device and method. The device mainly includes an optical microscope, a strobe lighting device, a MEMS structure motion excitation device, and a CCD camera. High voltage op amp with multi-stage gain adjustment. The test method includes synchronous control of stroboscopic and driving signals, normalized evaluation of geometric parameters of plane images, motion estimation of fuzzy images, and motion estimation of image matching. The invention has the advantages of: adopting virtual instrument mode to realize function adjustment and expansion; under continuous light illumination, realize normalized evaluation of plane geometric quantity parameters, supplemented by analysis of fuzzy motion images, realize rapid measurement of motion characteristics, and The frequency is not limited; under the strobe lighting, the image matching technology is used to realize the high-precision motion characteristic test.

Description

Testing arrangement and method based on the MEMS of computer vision

Technical field

The present invention relates to a kind of based on the geometric sense parameter of the little vision technique measurement of computer MEMS (MEMS) midplane structure and the apparatus and method of kinetic characteristic.Belong to towards the geometric sense and the mechanical quantity test technology of the photoelectricity noncontact method of MEMS.

Background technology

Measuring technology has important practical significance in MEMS (MEMS) R﹠D process and industrialization process.The means of testing of MEMS mainly is by means of expensive microcosmic testing equipment such as traditional IC testing tool and SEM, AFM at present, but above equipment is not the special equipment at the MEMS test, can't realize the test of MEMS Structure dynamic characteristics, these equipment price costlinesses of while, test speed is slow, measurement category is little, test environment is required harsh.In recent years, along with MEMS steps into the industrialization stage gradually from conceptual phase, more urgent to the demand of test macro.Because measurement by physical dimension and kinetic characteristic, the key property that can reflect the MEMS device indirectly, as: MEMS micro-structural 3 D micromotion situation, material properties and Mechanics of Machinery parameter, MEMS reliability and component failure pattern, failure mechanism etc., so the importance of MEMS technique of dynamic measurement is more outstanding.

The test of MEMS structure is divided into following components: the one, and the measurement of structural plan size; The 2nd, the measurement of structural plan motion; The 3rd, the measurement of structure longitudinal size; The 4th, the measurement of structure lengthwise movement.Because the dynamic characteristic of MEMS structure has determined the key property of MEMS, so technique of dynamic measurement has great importance in the MEMS R﹠D process.

In recent years, method of testing to MEMS device dynamic characteristic under the minute yardstick has been carried out a lot of useful explorations, and some achievements in research with practical value have been obtained, as use the moving image of the MEMS movable part of stroboscopic imaging technique collection period high-speed motion, utilize digital image processing techniques to analyze its dynamic characteristic; Wait by the inferior pixel analytical technology in phase shift interference technology in the accurate laser measurement and the computer vision and to improve certainty of measurement; Utilize the real-time measurement of LDV technology realization MEMS device transient motion etc.

Measuring technique based on the little vision of computer obtains using comparatively widely in the context of detection of MEMS structure motion parameter, and external research institution reported that some carry out the integrated application example of MEMS dynamic test aspect about utilizing the little vision of computer, and wherein the major technology characteristics are to utilize the moment of stroboscopic illumination motion performance period " to freeze ".

By the technology of present this research direction is carried out analysis-by-synthesis and comparison, mainly have the problem of following several respects: the first, method of testing is single, is difficult to satisfy the diversified plane motion of MEMS structure to Testing requirement.The second, the measurement mechanism systematicness is not strong, and extended capability is relatively poor; Three, the little vision algorithm of the computer that is adopted all is directly to adopt static calculation machine visual processing method basically, has certain deviation when handling the ambiguity of dynamic image; Four, the form error to the MEMS structure lacks normalized system evaluation, causes the comparativity of measurement data not strong.

Summary of the invention

The object of the present invention is to provide a kind of apparatus and method, characteristics such as it has, and metering system is various, extended capability strong, measuring frequency wide ranges, certainty of measurement height based on little vision technique measurement MEMS (MEMS) plane geometry amount parameter of computer and dynamic characteristic.

The present invention is realized by following technical proposals.Based on the little vision technique of computer, carry out the device of MEMS (MEMS) plane geometry parameter and dynamic characteristic test, this device comprises by three-dimensional fine motion testboard, light microscope, stroboscopic illumination device, MEMS structure motion exciting bank, ccd video camera, image pick-up card, GPIB control card, AWG, measurement and control computer and forming, as shown in Figure 2, it is characterized in that, light source adopts the LED of high brightness, and is aided with the constant-current drive circuit of high bandwidth and preposition AWG; The MEMS motion drives and adopts with the single-chip high voltage amplifier is the Voltag driving circuit of core, has multistage gain adjustment, is aided with preposition AWG.

Above-mentioned light source is high brightness LED LuxeoTM Star, and the master chip of drive circuit is EL6249C, can produce the stroboscopic signal of 50ns, can realize that motion frequency reaches the measurement of 1MHz.

Above-mentioned motion drive part with the high pressure amplifier PA85 of APEX company as core, circuit is provided with 10X, 20X and adjustable 3 grades of gains are adjusted, can with by the output of preposition AWG ± the 10V voltage signal is amplified to ± 10V～± 200V, as MEMS device drive voltage to be measured, satisfy different MEMS device drive voltage demands.

Adopt said apparatus, carry out the measuring method of MEMS (MEMS) plane geometry amount parameter and dynamic characteristic based on the little vision technique of computer, its process comprise collection, the plane picture feature of stroboscopic and the Synchronization Control that drives signal, MEMS structural images normalization geometric sense parameter evaluation, utilize blurred picture to carry out plane motion to estimate, utilize images match to carry out plane motion to estimate.It is characterized in that, when under the continuous illumination condition, static MEMS structure being carried out the plane geometry parameter measurement:

(1) tested MEMS device is fixed on three-dimensional fine motion testboard; Lighting device is set to the continuous illumination mode, and the MEMS device is thrown light on;

(2) utilize standard P AL system ccd video camera, obtain MEMS by the rest image of geodesic structure, and utilize characteristics of image path trace technology and inferior pixel analytical technology to carry out the normalization evaluation, carry out the measurement of plane geometry amount parameter;

(3) criterion of normalization evaluation is: as profile point, and is preferred searching route with the slotted line of artificial definition with sudden change area grayscale mid point on the image, determines corresponding inferior pixel accuracy table facial contour line in conjunction with the inferior pixel analytical technology of cubic curve match; The center line of determining the envelope straight line according to the surface profile line is as the measuring basis line, to carry out the evaluation of angle, linearity, the depth of parallelism and perpendicularity; Measurement of length is the distance of two measuring basis lines in the slotted line regional area, and the distance of two measurement point respective pixel on the slotted line not.

When under the continuous illumination condition, adopting the blurred picture technology to carry out the plane motion parameter measurement to motion MEMS structure:

(1) the electrode pin end at three-dimensional fine motion testboard applies a motion-activated signal, makes that MEMS's can be carried out the periodic planes motion with certain frequency by geodesic structure;

(2) utilize standard P AL system ccd video camera, obtain MEMS by the plane motion blurred picture of geodesic structure, and adopt image processing techniques such as rim detection and inferior pixel to obtain the size of fuzzy band in the blurred picture, obtain the plane motion amplitude of structure;

(3) drive the frequency of signal with certain step pitch adjustment, make the MEMS structure move with different frequencies, the same fuzzy moving image that obtains under the respective frequencies, promptly obtain the motion amplitude of structure under a series of driving frequencies, obtain the resonant frequency and the quality factor of structure by data analysis.

When under the stroboscopic illumination condition, adopting image matching technology to carry out the plane motion parameter measurement to motion MEMS structure:

(1) lighting device is set to the stroboscopic illumination mode, the MEMS device is carried out stroboscopic illumination, the cycle of stroboscopic signal is identical with the cycle of motion-activated signal, and the time delay that is maintained fixed (guaranteeing certain periodic motion phase place), so the motion of MEMS structure belongs to " freezing " state substantially under stroboscopic illumination;

(2) number of times of same phase place stroboscopic is set, makes standard P AL system ccd video camera carry out multiexposure, multiple exposure, the integrating effect that exposes can obtain MEMS by the movement position under the said fixing phase place of geodesic structure;

(3) phase difference of adjustment stroboscopic signal and motion-activated signal, can obtain MEMS by the movement position image of geodesic structure, by obtaining the moving situation of MEMS structure under out of phase under the certain frequency to movement position image sequence utilization piece coupling and phase place correlation technique analysis-by-synthesis at the corresponding motion stage of out of phase;

(4) phase place is relevant combines with the quadratic surface match, can solve under the finite motion amplitude, and the fast detecting of inferior pixel precision displacement adopts the measurement of the method for exhaustion realization anglec of rotation of the anglec of rotation simultaneously; The piece coupling can realize under the big motion amplitude fast detecting of coarse movement displacement; Under both integrated uses, realize the fast detecting of moving displacement and angle;

(5) drive the frequency of signal with certain step pitch adjustment, make the MEMS structure move with different frequencies, repeating step (2) and (3), can obtain the detailed features of the motion of structure under a series of driving frequencies, not only can obtain the resonant frequency and the quality factor of structure by analysis-by-synthesis, also can obtain the motion state overall process of structure.The invention has the advantages that: adopt the mode of virtual instrument to set up inner functional module, be convenient to the function adjustment and the expansion of system; Under continuous lighting mode, adopt imaging surface signature tracking technology and inferior pixel analysis, realize the normalization evaluation of plane geometry amount parameter, strengthen the comparativity of measurement parameter; Under continuous lighting mode, by analysis of fuzzy moving image to motion structure among the MEMS, determine the motion amplitude of structure under certain frequency, and obtain the parameter such as resonant frequency, quality factor of motion structure with this, have that measuring speed is fast, measuring frequency is unrestricted substantially, advantages of simple structure and simple, utilize plane motion endpoint detections technology simultaneously, reduced the fuzzy influence of stroboscopic illumination situation hypograph estimation based on wavelet transformation; Under the mode of stroboscopic illumination, utilize standard P AL system ccd video camera to realize the collection of the moment image of MEMS high speed periodic motion structure, and be aided with cooperatively interacting of piece coupling and phase matched image processing techniques, realize quick, high-precision plane motion Characteristics Detection.

Description of drawings

Fig. 1 utilizes stroboscopic illumination to realize the basic principle schematic of dynamic characteristic measuring;

Fig. 2 is based on the MEMS test device system block diagram of the little vision technique of computer;

Fig. 3 stroboscopic drive circuit schematic diagram;

Fig. 4 MEMS motion-activated circuit theory diagrams;

The still image of Fig. 5 MEMS resonator;

Fig. 6 utilizes characteristics of image path trace technology to carry out the exemplary plot of geometric measurement;

The realization schematic diagram of the inferior pixel analytical technology of Fig. 7;

The blurred picture of Fig. 8 MEMS resonator motion;

Fig. 9 utilizes frequency scanning and realizes the measurement of the resonant frequency of MEMS resonator based on the amplitude measurement of blurred picture;

Figure 10 MEMS resonator motion phase is 90 ° a instantaneous picture;

Figure 11 MEMS resonator motion phase is 180 ° a instantaneous picture;

Figure 12 MEMS resonator motion phase is 270 ° a instantaneous picture;

Figure 13 MEMS resonator periodic motion curve;

Figure 14 images match calculation flow chart.

The specific embodiment

Embodiment 1:

Present embodiment mainly focuses under the continuous illumination condition, utilizes the little vision technique of computer to realize the measurement of MEMS structural plan geometric sense parameter.

Measure with the control computer and pass through the GPIB control card, the control AWG is exported a direct current voltage drive signals, make stroboscopic illumination device be operated under the continuous illumination state, the MEMS structure is placed on the three-dimensional fine motion testboard under the light microscope, utilize ccd video camera to gather the image of MEMS planar structure, be stored in the computer after the image pick-up card digitlization then and be presented on the computer screen.Fig. 5 is the still image of the planar structure of MEMS resonator, by the image of Fig. 5 is handled and analyzed, just can determine the geometric sense parameter of planar structure.For the geometric sense parameter to the specific plane structure is measured, need artificial selected specific zone: (1) measurement of length: the distance to the edge, 2 place of structure shown in sign 1 among Fig. 6 is measured, earlier respectively pull out 1 schematic lines a and b at edge, 2 place, between 2 schematic lines, pull out 1 slotted line c then again, linear measure longimetry is not a pixel of directly asking for schematic lines a and b measurements line c, but utilize characteristics of image path trace technology and inferior pixel analytical technology according to the position at schematic lines a and b place, extract the edge line of structure, and utilize least square fitting to go out a and near the edge center line of b, near the minimum range slotted line of computer center's line then; (2) measurement of the depth of parallelism: the depth of parallelism to the edge, 2 place of structure shown in sign 2 among Fig. 6 is measured, earlier respectively pull out 1 schematic lines d and e at edge, 2 place, position according to schematic lines d and e place utilizes characteristics of image path trace technology and inferior pixel analytical technology, extract the edge line of structure, and utilize least square fitting to go out d and near the edge center line of e, the depth of parallelism of computer center's line then; (3) measurement of perpendicularity: the perpendicularity to the edge, 2 place of structure shown in sign 3 among Fig. 6 is measured, earlier respectively pull out 1 schematic lines f and g at edge, 2 place, position according to schematic lines f and g place utilizes characteristics of image path trace technology and inferior pixel analytical technology, extract the edge line of structure, and utilize least square fitting to go out f and near the edge center line of g, the perpendicularity of computer center's line then.The measurement of other geometric sense parameter (as: angle, linearity etc.) similarly method is implemented.

In above step, if directly utilize the method for general figure image intensifying, binaryzation and edge extracting to obtain outline line, the resolving power of Ce Lianging can only reach Pixel-level so.In order to obtain the measurement resolution of sub-pix, above step has fully utilized characteristics of image path trace technology and inferior pixel analytical technology, and the edge line of structure is extracted.Concrete implementation step can be expressed as follows: (1) is owing to the geometric measurement parameter all is that profile according to surface texture proposes, and the profile of surface texture is subjected to the influence of processing technology can present certain fluctuation, adopt the method for general figure image intensifying, binaryzation and edge extracting to obtain the outline line of Pixel-level, this outline line is the preferred searching route as following step not as the datum line of measuring; (2) in order to reach the precision of inferior pixel, need on image, to define a slotted line artificially, require this slotted line and met substantially by the profile of geodesic structure; (3) because generally all there is a tangible grey scale change both sides of profile, therefore can on the vertical direction of slotted line, search the position at intermediate grey values place, if intermediate grey values can not be mated with single pixel, so the pixel of middle gray value both sides is carried out the cubic curve process of fitting treatment, promptly carry out inferior pixel analysis, the simple signal as shown in Figure 7, the precision of determining just can reach inferior pixel of structure outline point like this; (4) successively the every bit on the slotted line is carried out step (3) analysis, just can determine a series of tested structure outline points, its certainty of measurement reaches inferior pixel level; (5) when determining each profile point, need carry out the calculating of distance with the preferred searching route that step (1) obtains, the real structure outline point of conduct that selected distance is the shortest; (6) connect above-mentioned profile point and just can access structure outline line, obtain the envelope straight line of outline line then with the method for least square fitting, finally get the datum line of center line for measuring of two envelope straight lines with inferior pixel precision.

Embodiment 2:

Present embodiment is mainly discussed under the continuous illumination condition, utilizes the blurred picture treatment technology to realize the measurement of MEMS structural plan kinematic parameter.

Under the continuous illumination condition, MEMS structure-resonator is by certain frequency, generally more than 10kHz, sine wave drive, produce periodic planar reciprocating, the time for exposure of ccd video camera is a few tens of milliseconds, because the integrating effect of exposure, image appearance in the reciprocating zone of resonator is a fuzzy band, can think that therefore this blurs band reflection resonator motion amplitude under this driving frequency.Fig. 8 is 20kHz for the MEMS resonator in frequency, bias voltage is 20V, the blurred picture that peak-to-peak value moves down for the excitation of 160V sinusoidal drive signals, can record the length of this fuzzy band by image processing techniques, the measurement of size is identical among the measurement of fuzzy strip length and the embodiment 1, so just obtained the motion amplitude of MEMS resonator under the 20kHz driving frequency, in conjunction with inferior pixel analytical technology, the measurement resolution of motion amplitude can reach inferior pixel level.

Drive sinusoidal wave frequency by sweep frequency technique adjustment campaign, obtain the moving image of resonator under a series of driving frequencies, calculate their motion amplitude with identical method.Utilize the motion amplitude that records under these a series of driving frequencies just can utilize the curve fitting method to obtain the amplitude-versus-frequency curve of resonator, thereby obtain the resonant frequency and the pairing motion amplitude of this frequency of resonator.Figure 9 shows that the resonant frequency measurement result of MEMS resonator.The situation of frequency scanning is: 20kHz is an initial frequency, is the frequency sweep step pitch with 0.2kHz, and the termination frequency is 27kHz; The bias voltage of sinusoidal drive signals is 20V, and peak-to-peak value voltage is 160V; According to the measured maximum vibration amplitude that obtains, determine that finally the resonant frequency of this MEMS resonator is 23.4kHz.

Embodiment 3:

Present embodiment is mainly discussed under the stroboscopic illumination condition, utilizes piece coupling and phase place associated picture treatment technology to realize the measurement of MEMS structural plan kinematic parameter.

For the instantaneous state of periodic motion structure is caught, " the freezing " of having adopted the method for stroboscopic illumination to realize motion state in the system, thus make and utilize general ccd video camera just can realize the measurement of high-speed motion state.Fig. 1 realizes the kinetic characteristic basic principle of measurement for utilizing stroboscopic illumination.Measure and control computer and produce the sinusoidal motion pumping signal in cycle and the stroboscopic signal (0 ° and 30 ° as shown in FIG.) of stationary phase by GPIB control card control AWG, the stroboscopic signal of one phase bit continues to occur repeatedly, has sufficiently long effective exposure time to guarantee ccd video camera; Owing to be details in a play not acted out on stage, but told through dialogues when stroboscopic pulse does not occur, the equal state of the stroboscopic pulse reflection periodic motion structure identical with the motion-activated signal period, the state that promptly is equivalent to the high-speed motion structure " is freezed ", be convenient to utilize common CCD camera to carry out IMAQ, be repeatedly the overall width of stroboscopic pulse its effective exposure time.

In the present embodiment, the MEMS structure is subjected to the excitation of 21kHz sine wave drive signal (bias voltage is 20V, and peak-to-peak value voltage is 160V), produces to move back and forth on the Y direction, the one-period that this is sinusoidal wave is divided with 30 ° of phase places, and one-period is totally 12 phase places.Under the original state that moving image is gathered, the width of the pulse of stroboscopic signal is 1.5 μ s, be in 0 ° of phase place of sinusoidal drive signals, before stroboscopic pulse occurs, trigger ccd video camera and begin exposure, on each 0 ° of phase place of 1500 periods of motion, carry out 1 stroboscopic exposure then, last ccd video camera finishes exposure, and the image that collects is transmitted to computer.After above process finishes, the position that the pulse of stroboscopic signal occurs is adjusted to 30 °, repeat above stroboscopic and exposure process, obtain the image of 30 ° of phase places, adjust the phase place of stroboscopic pulse then with 30 ° interval, can obtain the image of MEMS structure motion under out of phase successively, Figure 10,11 and 12 is respectively 90 °, 180 °, the 270 ° MEMS structures under the phase place, can tell the change of motion structure position by the situation of image in the square frame institute enclosing region among Figure 10.By one-period 12 width of cloth images are carried out the images match analysis, can obtain the movement position of structure under the out of phase, as shown in figure 13, can find out that the motion of structure meets sinusoidal drive waveforms substantially.

In images match is handled, in order to realize taking into account of measuring speed and certainty of measurement, adopted the piece coupling, phase place is relevant and method that the quadratic surface match combines is handled.The piece coupling is the most frequently used motion estimation algorithm, and it is big to have detection range, can search in the entire image zone, and is lower to the rotation sensitivity; Phase place is relevant to be a kind of little matching algorithm of geometric distortion that is subjected to of image, once calculates the displacement that just can obtain two width of cloth images, but requires the displacement difference of two width of cloth images can not surpass half of selected peak width, higher to rotating susceptibility; The quadratic surface match can access the picture displacement of inferior pixel level.The process that images match is analyzed is as follows: (1) user selects certain zone on the initial position image that obtains, and this zone should be on moving component, and has relative obvious characteristics; (2) image with correspondence position in the image of institute's favored area and the successive image carries out the phase place correlation computations, if obtain higher relevant peaks, the displacement that shows two width of cloth images is less than half of selected peak width, the position of relevant peaks is the displacement of two width of cloth images, leap to step (6) and carry out the quadratic surface Fitting Analysis, otherwise go beyond the scope or have a bigger anglec of rotation with regard to the displacement that shows image, need and execution in step (3); (3) rough measure that utilizes the piece coupling to carry out the grand movement displacement, the criterion of piece coupling is the minimum average B configuration absolute difference, search strategy is the logarithm search method, in order to satisfy the requirement that measurement image is handled in real time, searching approximate region just stops, can obtain the displacement of this zone and original area this moment, the phase place of carrying out next step then is relevant; (4) with piece match search in the image of institute's favored area and the successive image to the image in zone carry out the phase place relevant treatment, because the requirement of algorithm is satisfied in the displacement of feature structure on two width of cloth images, therefore generally can obtain higher relevant peaks, promptly obtain the displacement of two width of cloth associated pictures, this displacement and step (3) obtain the total displacement amount of region of search displacement sum for motion, jump to step (6) and carry out the quadratic surface Fitting Analysis, otherwise show that there is certain anglec of rotation in the relevant image of two width of cloth, make relevant peaks too small, need execution in step (5); (5) in certain angular regions, retrieve with the dichotomy traversal, piece image is wherein rotated a certain angle, the phase place of carrying out two width of cloth images then is relevant, obtain relevant peaks, determine the angle of next step rotation according to the size of relevant peaks, approach one by one and will obtain relevant peaks maximum in the certain angle zone, the anglec of rotation that this moment is corresponding and the position of relevant peaks are the displacement and the angular deflection amount of two width of cloth images; (6) through above step, can obtain the translation and the angular deflection amount of two width of cloth images, this side-play amount is the Pixel-level precision, need to adopt inferior pixel analysis, adopt the thought of surface fitting method to be this moment: with the optimal match point on the pixel level is the center, carry out surface fitting by similarity measurement, calculate the exact position of extreme point then by corresponding mathematical method.This device adopts the relevant coefficient correlation of phase place as the similarity measurement feature, selects quadratic surface as fitting function, adopts multivariable least square regression method to determine the exact position of extreme point in calculating.Above flow process as shown in figure 14.By further evaluation, the rotation accuracy of detection of measurement mechanism can reach 0.1 degree, and the translation accuracy of detection can reach 1/50 pixel.

Following formula is the fundamental formular of phase place related operation.

$\frac{F_1(\mathrm{\ξ},\mathrm{\η})\·{F_2}^{*}(\mathrm{\ξ},\mathrm{\η})}{|F_1(\mathrm{\ξ},\mathrm{\η})\·{F_2}^{*}(\mathrm{\ξ},\mathrm{\η})|}{e}^{j2\mathrm{\π}(\mathrm{\ξ}{x}_0+\mathrm{\η}{y}_0)}...\left(1\right)$

Wherein, F ₁And F ₂Be respectively the result of the Fourier transform of two width of cloth images (image that the different motion phase place is gathered).By the theory of (1) formula and Fourier transform as can be known, this phase spectrum has comprised the position translation information of two width of cloth images, and it is that a spectrum amplitude is 1 power spectrum in full frequency-domain.(1) formula is carried out inverse Fourier transform as can be known, and the phase place correlation function is one and is positioned at two figure positions skews (x0, the δ impulse function of y0) locating also is referred to as relevant peaks.Complete when similar when two width of cloth images, its value is 1, otherwise is 0.Therefore, utilize the phase place related operation result of two width of cloth images to determine the shift offset of image in the present invention, determine moving situation with this.

The present invention adopts the quadratic surface match to carry out the analysis of inferior pixel.The thought of surface fitting method is: with the optimal match point on the pixel level is the center, carries out surface fitting by similarity measurement, calculates the exact position of extreme point then by corresponding mathematical method.This device adopts the relevant coefficient correlation of phase place as the similarity measurement feature, selects quadratic surface as fitting function, adopts multivariable least square regression method to determine the exact position of extreme point in calculating.

The quadratic surface fitting function adopts formula to be:

PC(x，y)＝ax ²+by ²+cxy+dx+ey+f

Wherein, (x is corresponding to position (x, phase place correlation y) y) to PC.Above-mentioned function can be write as following form:

AX＝B

In the formula,

$A=\left[\begin{array}{cccccc}{x_0}^2& {y_0}^2& x_0{y}_0& x_0& y_0& 1\\ {x_1}^2& {y_1}^2& x_1{y}_1& x_1& y_1& 1\\ \underset{.}{\overset{.}{.}}& \underset{.}{\overset{.}{.}}& \underset{.}{\overset{.}{.}}& \underset{.}{\overset{.}{.}}& \underset{.}{\overset{.}{.}}& \underset{.}{\overset{.}{.}}\\ {x_8}^2& {y_8}^2& x_8{y}_8& x_8& y_8& 1\end{array}\right]$ $X=\left[\begin{array}{c}a\\ b\\ c\\ d\\ e\\ f\end{array}\right]$ $B=\left[\begin{array}{c}P{C}_0\\ P{C}_1\\ \underset{.}{\overset{.}{.}}\\ P{C}_8\end{array}\right]$

The present invention adopts multivariable least square regression method in The Fitting Calculation, make calculating simple, accurate.In computational process, as regression coefficient, and the value of hypothesis stochastic variable B depends on the independent variable in the matrix A with vectorial X, regression coefficient ask for the coefficient that is fitting function.After trying to achieve the coefficient of fitting function, can utilize following formula to try to achieve the exact position of the image shift of inferior pixel precision.

$x=\frac{2\mathrm{db}-\mathrm{ce}}{c^2-4\mathrm{ab}}$ $y=\frac{2\mathrm{ae}-\mathrm{dc}}{c^2-4\mathrm{ab}}$

By said process, can obtain the curve movement of MEMS structure under certain driving frequency.If the interval of phase place is reduced, resulting curve movement will be more accurate, for the MEMS structure Design provides more reference information; If adopt the driving frequency scanning identical with embodiment 2, will obtain a series of curve movements corresponding with driving frequency, by calculating peak swing wherein, can depict amplitude frequency curve shown in Figure 9 equally, determine the resonant frequency of motion structure.

Claims (4)

1. A test device for micro-electro-mechanical systems based on computer vision. The device consists of a three-dimensional micro-motion test bench, an optical microscope, a strobe lighting device, a MEMS structure motion excitation device, a CCD camera, an image acquisition card, a GPIB control card, an arbitrary waveform generator, and a measurement and control computer. It is characterized in that: The light source adopts a high-brightness light-emitting diode LED, supplemented by a high-bandwidth constant current drive circuit and a pre-arbitrary waveform generator; the MEMS motion drive adopts a voltage drive circuit with a single-chip high-voltage operational amplifier as the core, with multi-stage gain adjustment , supplemented by a pre-arbitrary waveform generator. 2. The MEMS test device based on computer vision according to claim 1, characterized in that: the light source is a high-brightness light-emitting diode LuxeoTM Star, and the main chip of the driving circuit is EL6249C, which can generate a strobe signal of 50 ns, and can Realize the measurement of motion frequency up to 1MHz. 3. The computer vision-based MEMS testing device according to claim 1, characterized in that: the motion drive part uses the high-voltage operational amplifier PA85 of APEX Company as the core, and the circuit is provided with 10X, 20X and adjustable 3-level gain Adjustment, the ±10V voltage signal output by the pre-arbitrary waveform generator can be amplified to ±10V~±200V, which can be used as the driving voltage of the MEMS device to be tested to meet the driving voltage requirements of different MEMS devices. 4, adopt the method for testing by the test device based on the micro-electro-mechanical system of computer vision according to claim 1, its process comprises the synchronous control of strobe and drive signal, the collection of MEMS structure image, the normalization of plane image feature Estimating geometric parameters, using fuzzy images to estimate planar motion, and using image matching to estimate planar motion, characterized in that: When measuring planar geometric parameters of stationary MEMS structures under continuous illumination conditions: (1) Fix the MEMS device to be tested on the three-dimensional micro-motion test bench; set the lighting device to continuous lighting mode to illuminate the MEMS device; (2) Utilize the standard PAL CCD camera to obtain the still image of the MEMS structure under test, and use image feature path tracking technology and sub-pixel analysis technology to perform normalized evaluation and measure the plane geometric parameters; (3) The criterion for normalization evaluation is: take the gray midpoint of the sudden change area on the image as the contour point, and use the artificially defined measurement line as the optimal search path, and combine the sub-pixel analysis technology of cubic curve fitting to determine the corresponding Sub-pixel precision surface contour line; according to the surface contour line, the center line of the envelope straight line is determined as the measurement reference line for the evaluation of angle, straightness, parallelism and perpendicularity; the measurement of length is the two measurement references in the local area of the measurement line The distance of the line, rather than the distance between the pixels corresponding to two measurement points on the measurement line; When using fuzzy image technology to measure planar motion parameters of moving MEMS structures under continuous lighting conditions: (1) Apply a motion excitation signal to the electrode pin end of the three-dimensional micro-motion test bench, so that the MEMS structure under test can perform periodic planar motion at a certain frequency; (2) Utilize the standard PAL system CCD camera to obtain the planar motion blur image of the measured structure of MEMS, and use image processing techniques such as edge detection and sub-pixels to obtain the size of the fuzzy band in the blur image, and obtain the planar motion range of the structure; (3) Adjust the frequency of the driving signal with a certain step, so that the MEMS structure moves at different frequencies, and also obtain the fuzzy moving image at the corresponding frequency, that is, the motion amplitude of the structure at a series of driving frequencies, through data analysis Obtain the resonant frequency and quality factor of the structure; When using image matching technology to measure planar motion parameters of moving MEMS structures under stroboscopic lighting conditions: (1) Set the lighting device as stroboscopic lighting mode, and perform stroboscopic lighting on MEMS devices. The cycle of the stroboscopic signal is the same as that of the motion excitation signal, and a fixed delay time is maintained (to ensure a certain periodic motion phase), so The movement of the MEMS structure is basically in a "frozen" state under strobe lighting; (2) The number of times of stroboscopic flashes of the same phase is set, so that the standard PAL CCD camera is exposed multiple times, and the integral effect of the exposure can be obtained to obtain the moving position of the MEMS measured structure under the above-mentioned fixed phase; (3) By adjusting the phase difference between the stroboscopic signal and the motion excitation signal, the motion position image of the MEMS structure under test in different phases corresponding to the motion stage can be obtained, which can be obtained by comprehensive analysis of the motion position image sequence using block matching and phase correlation techniques The motion status of MEMS structure at different phases at a certain frequency; (4) The combination of phase correlation and quadratic surface fitting can solve the problem of rapid detection of sub-pixel precision displacement under limited motion range, and at the same time, the exhaustive method of rotation angle is used to realize the measurement of rotation angle; block matching can realize large Under the range of motion, the rapid detection of rough motion displacement; under the comprehensive application of the two, the rapid detection of motion displacement and angle is realized; (5) Adjust the frequency of the driving signal with a certain step, so that the MEMS structure moves at different frequencies, repeat steps (2) and (3), and the detailed characteristics of the structure's motion under a series of driving frequencies can be obtained, through Comprehensive analysis can not only obtain the resonant frequency and quality factor of the structure, but also obtain the whole process of the structure's motion state.

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