CN102353346B - Method and system for detection of verticality of CCD installation of laser cutting machine with automatically edge searching performance - Google Patents

Abstract

The invention relates to a method and a system for detection of a verticality of CCD installation of a laser cutting machine with an automatically edge searching performance. The method comprises the following steps that: a laser head of a laser cutting machine is directly utilized; a circle and a center of circle mark patterns that are formed by laser light spots are typed on calibration papers, which are paved fixedly at five different areas at a working plane of a cutting bed; marked images at the five different areas are shot through a CCD; an image processing technology is utilized and circumference point coordinates and center point coordinates of the marked images are respectively extracted; and an extreme values of distance of from the center point to all the circumference points are calculated and a verticality between a CCD shaft and the cutting bed is calculated by a calculation model. In addition, the invention also relates to a detection system for a verticality of CCD installation of a laser cutting machine with an automatical edge searching performance. And the detection system mainly comprises three software modules: a control module, an image processing module, and a data processing module. According to the invention, problems on slow detection speed, low efficiency and poor precision and the like during detection on a verticality of CCD installation of a laser cutting machine with an automatically edge searching performance are solved and an automatic capability of the system is also improved.

Description

Detection method and the system of automatic seeking limit verticality of CCD installation of laser cutting machine

Technical field

The present invention relates to the laser application technique field, particularly relate to intelligent detecting method and the system of a kind of automatic seeking limit verticality of CCD installation of laser cutting machine.

Background technology

Cut automatic seeking limit technology based on computer vision is take optics as the basis, merges the system ensemble that the multi-door modern sciences such as electronics, control science, computer technology and image processing techniques are integrated.It obtains the image of Laser Processing object by Vision Builder for Automated Inspection, then utilize image processing algorithm to being processed by the image of acquisition target in computing machine, automatic lifting takes out the marginal information of processing object image, and according to the marginal information of image and corresponding relation and the proportionate relationship of practical operation object, be converted into the cephalomotor control information of cut, pass to the control system of laser cutting machine, realize target automatic seeking limit is accurately sheared.The precision on raising automatic seeking limit is the gordian technique that laser cutting machine is realized intelligent cutting, raising automatization level.In the system on laser automatic seeking limit, the degree of accuracy of target object edge extracting directly affects the cutting accuracy of aims of systems object.Do not reach processing request if seek the limit precision, will cause line of cut and the real profile of being cut pattern to have the deviation that is difficult to tolerate, cause a large amount of cutting waste products.Affect machine vision edge extracting precision and have many-sided factor, except effective image processing algorithm, whether the optical axis direction of the installation of CCD is vertical with machined surface, directly restricting the quality that Vision Builder for Automated Inspection is obtained image, thereby the system that affects is to the extraction accuracy at processing object edge.In general, machine is before dispatching from the factory, and system installs and all will pass through strict detection, but because laser cutting machine is moved and vibration when working, tends to cause alignment error, need to the installment state to CCD detect before machine moves.At present, CCD is installed whether satisfy its optical axis perpendicular cuts bed workplace requirement, often adopt artificial visually examine's method or utilize spirit-leveling instrument to measure, then adopt three adjustment screws on the CCD erecting device that it is adjusted, these methods are loaded down with trivial details, inefficiency not only, and precision also is difficult to meet the demands, and has a strong impact on the precision on realizing of Robot Vision automatic seeking limit.

Summary of the invention

technical matters to be solved by this invention is to provide intelligent detecting method and the system of a kind of automatic seeking limit verticality of CCD installation of laser cutting machine, under the condition of not adding miscellaneous equipment and device, get spot pattern by computer control feasible region laser and carry out mark, auto Image Collection and processing, accurately extract the coordinate of gauge point figure, and utilize given computation model to calculate the verticality that CCD installs, thereby it is slow to solve automatic seeking limit verticality of CCD installation of laser cutting machine detection speed, the problems such as the low and low precision of efficient, the automatization level of raising system.

The technical solution adopted for the present invention to solve the technical problems is: the detection method of a kind of automatic seeking limit verticality of CCD installation of laser cutting machine is provided, comprises the following steps:

(1) directly utilize the laser head of laser cutting machine, get circle and the center mark pattern that is formed by laser facula on the fixing demarcation paper of laying of five zoness of different of cutting bed vise workplace;

(2) absorb the marking image of five zoness of different by CCD;

(3) utilize image processing techniques, extract respectively circumference and the centre point coordinate of marking image;

(4) calculate the center of circle to the extreme value of circumference each point distance, obtained the verticality of CCD optical axis and cutting bed vise by computation model.

Described step (1) comprises following substep: at four angles of cutting bed vise and five zones in centre position, tile regularly respectively five and demarcate paper, the laser head of controlling cutting machine is demarcated at each and is got marked circle and the center of circle that the radius that is comprised of laser facula fixes on paper and carry out mark, the marked region size is limited in the visual field of a CCD imaging, location alignment point when the center mark point of each mark zone is adopted image for CCD, and in the process that verticality detects, five positions of demarcating paper remain unchanged.

Described step (2) comprises following substep: each zone marker figure is gathered, first driven CCD roughly moves to the zone of appointment, then field-of-view image is obtained in dynamic acquisition and processing, extract the coordinate of surveyed area center mark point, be used for controlling CCD position adjustment, make the center mark point adjust to the center that CCD gathers image, lock the visual field, carry out the marking image collection.

Described step (3) comprises following substep: utilize image processing techniques, size according to laser facula, design size different disposal template is carried out mixed noise filtering and is processed, and adopt the sub-pixel positioning algorithm, accurately extract the coordinate of circumference gauge point and center mark point in image.

Described step (4) comprises following substep: to each marker region image that gathers, after accurately extracting the marker graphic coordinate, calculate center mark and put the extreme value of each circumference gauge point distance, comprising two equal maximal values of different directions and two minimum value that do not wait of different directions and time minimum value, the substitution computation model calculates the verticality that CCD installs; The same processing done in five zones, tries to achieve respectively the CCD verticality in five zones, and the verticality of averaging and installing as CCD.

The technical solution adopted for the present invention to solve the technical problems is: the detection system of a kind of automatic seeking limit verticality of CCD installation of laser cutting machine also is provided, comprises cutting bed vise, described cutting bed vise is provided with can be along the mounting bracket of cutting bed vise both sides translation; Described mounting bracket is provided with can be along laser cutting machine and the CCD of mounting bracket slip; Described laser cutting machine is connected with computer system respectively with CCD, and described computer system comprises: control module, image processing module and data processing module; Described control module be used for to be controlled five zones of laser cutting machine on cutting bed vise, according to preassigned position and radius, accurately gets circular on paper and mark is carried out in the center of circle demarcating, and controls described CCD calibration graph is gathered; Described image processing module is used for the image that gathers is carried out pre-service, utilizes the sub-pixel positioning algorithm, accurately extracts each point coordinate in the mark center of circle and circumference in every two field picture; Described data processing module is used for calculating required parameter according to the coordinate that extracts marker graphic, and the substitution computation model, obtains CCD optical axis and the verticality of cutting bed surface.

Beneficial effect

Owing to having adopted above-mentioned technical scheme, the present invention compared with prior art, have following advantage and good effect: the present invention utilizes the existing apparatus of cutting machine, and the method that adopts image to process realizes the Intelligent Measurement of automatic seeking limit verticality of CCD installation of laser cutting machine.The present invention can replace artificial visually examine's method or adopt the method for spirit-leveling instrument to carry out the detection of CCD verticality, and it is slow to overcome manual detection speed, the shortcomings such as the low and low precision of efficient, what realization need not manual intervention has noncontact, highly sensitive, high precision, a high efficiency full-automatic detection, and what help to improve laser cutting machine seeks limit precision and automatization level.

Description of drawings

Fig. 1 is the detection system structural representation of automatic seeking limit verticality of CCD installation of laser cutting machine;

Fig. 2 detects visual field sign figure distribution schematic diagram;

Fig. 3 is the process flow diagram of the detection method of automatic seeking limit verticality of CCD installation of laser cutting machine;

Fig. 4 is that the CCD mounting bracket is adjusted schematic diagram;

Fig. 5 is the projection model schematic diagram.

Embodiment

Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only to be used for explanation the present invention and be not used in and limit the scope of the invention.Should be understood that in addition those skilled in the art can make various changes or modifications the present invention after the content of having read the present invention's instruction, these equivalent form of values fall within the application's appended claims limited range equally.

As shown in Figure 1, the present invention realizes that Intelligent laser cutting machine tool device vision CCD installs the automatic detection of verticality, and it does not need to add and other extra equipment are installed, and only utilizes the intrinsic equipment of laser cutting machine, can complete detection.The detection system of automatic seeking limit verticality of CCD installation of laser cutting machine comprises cutting bed vise 1, and described cutting bed vise 1 is provided with can be along the mounting bracket 2 of cutting bed vise both sides translation; Described mounting bracket 2 is provided with can be along laser cutting machine 3 and the CCD4 of mounting bracket slip; Described laser cutting machine 3 is connected with computer system respectively with CCD4.Computer system comprises control module, image processing module and data processing module.Described control module be used for to be controlled five zones of laser cutting machine on cutting bed vise, according to preassigned position and radius, accurately gets circular on paper and mark is carried out in the center of circle demarcating, and controls described CCD calibration graph is gathered.Described image processing module is used for the image that gathers is carried out pre-service, utilizes the sub-pixel positioning algorithm, accurately extracts each point coordinate in the mark center of circle and circumference in every two field picture.Described data processing module is used for calculating required parameter according to the coordinate that extracts marker graphic, and the substitution computation model, obtains CCD optical axis and the verticality of cutting bed surface.

This system adopts following equipment: (1) CCD model is HV1303UM, major parameter: resolution is the CMOS CCD of 1280*1024; Optical dimensions is 1/1.8; The highest 1,300,000 pixels; The highest horizontal resolution is 1280; The digital-to-analog conversion precision is 10bit; The high s/n ratio of 45dB (AGC OFF); Can control (AGC) by open/close automatic gain, the digital gain multiple is: * 2, * 1, * 0.5, * 0.25; For the light source of 550nm, its sensitivity is: 2.1V/Lux-s; Can be from the black-to-white level weighing apparatus correcting mode of motion tracking (ATW)/manually setting; Can accept two kinds of power supply supplies of 24V AC and 12V DC; (2) unit type of laser cutting machine: V-SPIN-1006-W60CA, controller model: CA-II.The X-axis ratio of gear: 1: 1, Y-axis ratio of gear: 2: 3; The X-axis drive model is 3ND583B; The Y-axis drive model is 3ND583B; X-axis motor model is 573S09-L; Y-axis motor model is 573S15-L; The focus lamp model is ZNSE2.0FL; Laser type: CO ₂Water-cooled amorphous laser (to nonmetal effective, voltage, pulse dual control system); (3) LED light source: YHFL-100-100-W electric parameter 24V/11.5W, eight grades of controlled change light intensity are arranged, when environment temperature is 25 ℃, surpass 30000 hours (damping capacity as 50% time) take the 50% continuous reliably working of white light source brightness; (4) computer system: Lenovo Qitian M7300:CPU, Intel Duo i3550, double-core/four threads, frequency 3.2GHz L2 cache 2 * 256KB, three grades of buffer memory 4MB; Board chip set Intel H57, the mainboard memory size is 2GB; Type of memory is DDR31333; Hard-disk capacity 500GB, rotating speed 7200 turns, SATAII; The video card type is solely aobvious AMD Radeon HD4350, video memory capacity 512MB, and display sizes is 17 inches.

the detection system of automatic seeking limit verticality of CCD installation of laser cutting machine is after system boot, the initialization of advanced line correlation, and adopt spirit-leveling instrument to carry out horizontal detection and horizontal adjustment to the cutting bed vise of laser machine, then carry out laser by the laser cutting machine of computer system control in five zones in four angles of cutting bed vise and centre position and accurately get mark ready, the zone at four angles is designated as respectively the a-quadrant, the B zone, C zone and D are regional, the zone in centre position is designated as the E zone, rule is got the center of circle and the fixing circular pattern of radius that is comprised of laser facula, marker graphic distributes as shown in Figure 2, its size is limited in the visual field of a CCD imaging.The alignment point of position when wherein, the center of circle of each mark zone is CCD collection image.

To the collection of marking image, the CCD that is driven with laser head binding one by control module completes, and after CCD was navigated to the center mark point and is positioned at the center that gathers image, the locking visual field also gathered image, as shown in Figure 1.After the image that obtains five marked regions is carried out respectively the filtering processing, gauge point (center of circle and circumference) is carried out sub-pixel positioning, accurately extract the subpixel coordinates value of each signature form point in image.Each is detected the visual field, process central coordinate of circle and each point coordinate of circumference that extracts according to image, calculate the center of circle to the extreme value of circumference each point distance, comprise two equal maximal values of different directions and two minimum value that do not wait of different directions and time minimum value, then calculate according to computation model the verticality that CCD installs.

The intelligent detecting method of automatic seeking limit verticality of CCD installation of laser cutting machine, as shown in Figure 3, implementation step is as follows:

(a) startup system and carry out initialization carries out the horizontal alignment of laser cutting machine cutting bed vise.

(b) open detection program, at first according to as shown in Figure 2 predefined five regional location a-quadrants, B zone, C is regional, D is regional and E is regional, fixing tiling is upper respectively demarcates paper, and in testing process, its position of demarcating paper strictly remains unchanged; The laser head of controlling again diced system is got the fixing circle of radius and the center of circle as the test badge figure on the demarcation paper in each zone.

(c) control module is positioned ccd image sensor for respectively 5 by the zone of laser engraving mark, process by dynamic image, the position coordinates in the center of circle, the certification mark visual field, and the position that is used for control CCD is adjusted, until the center mark point is positioned at the center of image, the lock-in detection this moment visual field gathers marker region image.

(d) utilize filtering and noise reduction and binary conversion treatment, and adopt the sub-pixel positioning algorithm, extract respectively the accurate coordinates of each two field picture center of circle and each gauge point of circumference.

(e) to each marked region, calculate the mark center of circle in image to the extreme value of each circumference gauge point distance, the substitution computation model is obtained the verticality that CCD installs.

(f) processing of the described method of (e) step is carried out respectively in five zones, calculated the installation verticality of each regional CCD, ask at last it average, as the verticality information of laser cutting machine CCD installation.

(g) show that the CCD that detects installs verticality information.

According to said method, in the CCD of reality installs adjustment process, automatically detect CCD by system verticality information is installed, and according to showing detection information, the operator can judge whether the installment state of CCD meets the demands, and when CCD installation verticality does not meet the demands, can adjust by 5 couples of CCD4 of adjusting mechanism shown in Figure 4, and duplicate detection-adjustment process repeatedly, until the accuracy requirement of its verticality is satisfied in the installation of CCD4.

In testing process, only need adopt five to be fixed on five zones of cutting bed vise greatly in the demarcation paper of CCD visual field, as the sign of laser dotting, gather marking image for machine vision.Demarcate the position of paper in testing process, must strictly remain unchanged.

In order to improve the accuracy of detection of marking image, said method first adopts image filtering to process the inhibition noise, improves the signal to noise ratio (S/N ratio) of image; In the leaching process of laser labelling location and positional information, adopt the sub-pix algorithm, improve gauge point image coordinate extraction accuracy.

The method of image denoising has a lot, and mean filter and medium filtering are two kinds of common methods.The image of the noise that they are applicable dissimilar is processed, and medium filtering has denoising ability preferably to salt-pepper noise, and mean filter has denoising ability preferably to Gaussian noise.But, because the machine vision imaging environment of automatic seeking limit laser cutting machine is comparatively complicated, in testing process, the image that the Vision Builder for Automated Inspection of laser cutting machine is obtained may be subject to the interference of two kinds of noises simultaneously, and independent medium filtering or mean filter all are difficult to the denoising effect that reaches best.This method is according to the size of laser facula, and design 3*3 processing template is carried out the mixed noise wave filter, with respect to traditional filtering algorithm, removes noise effects comparatively desirable, helps to realize the stable accurate coordinates that extracts laser-marking.

Consider the size of the pixel that laser facula is shared in said method, at first selected filtering processing window is the 3*3 size, and adopts following method of discrimination that noise type is differentiated.At first obtain the variance Q of pixel in filter window ², and set threshold values T.Q at that time ²During＞T, think the pollution that is subject to salt-pepper noise in this spectral window; Work as Q ²During＜T, think the pollution that is subject to Gaussian noise in this spectral window.According to above-mentioned determination methods, if in filter window, pixel is polluted by salt-pepper noise, obtain gray scale maximal value and minimum value in spectral window, then remove interior those of spectral window and equal the pixel of maximal value and minimum value, if in spectral window, residual pixel is non-vanishing, obtain the mean value M of residual pixel, and calculate the absolute value E of mean pixel gray-scale value and filter window mid point pixel grey scale value difference.The threshold value T of this absolute value and setting relatively, if absolute value E greater than threshold value T, exports residual pixel average M, if absolute value E less than threshold value T, output filtering window mid point grey scale pixel value.Wherein the local property of the selection of threshold value T and image interrelates.Can suitably weaken denoising and preserve details in bright area; In dark areas, suppress noise as far as possible.If in filter window, residual pixel is zero, enlarges filter window and be of a size of 5 * 5, and repeat above algorithm.If do not polluted by salt-pepper noise in filter window, first calculate the gradient absolute value of pixel in filter window, if Grad greater than a certain given threshold value T, is directly exported former pixel.Otherwise, grey scale pixel value average in the output filtering window.Repeat above-mentioned algorithm, process until complete the filtering of all pixels, complete image except making an uproar processing.

In order accurately to detect the verticality that CCD installs, the accurate location of regional laser labelling figure is crucial.In said method, adopt the sub-pixel positioning algorithm to extract the coordinate of identification point, guarantee the high precision of its location.Sub-pixel positioning algorithm based on second order spatial moment operator carries out hi-Fix to Position of Laser-Spot Center.At first image is being carried out on pretreated basis, gray level image to laser facula strengthens and binary conversion treatment, then adopt the LOG operator to carry out rim detection to image, make the hot spot edge accurately surely arrive single pixel precision, then use second order spatial moment operator further to segment, make the location, edge reach sub-pixel precision, then obtain coordinates of laser spot center by the Fitting Calculation.Due to the size of considering LASER SPECKLE, be of a size of sample window with 5*5, design six spatial moment computing templates, within comprising the marginal point neighborhood, use these six templates and the hot spot circle that forms circle diagram shape to carry out convolution algorithm, judge according to the threshold value of setting, obtain the sub-pixel location at hot spot edge, through the Fitting Calculation, obtain the sub-pixel location coordinate of circular laser facula and center of circle laser facula again.Need to prove, in real system was measured, ellipse or irregular figure might appear in the laser facula of detection, at this moment, light spot image need to be carried out match according to the circle model, so that accurate Calculation spot center sub-pixel location coordinate.

Obtaining the algorithm of CCD optical axis and cut surface verticality in said method determines by the following method.Because the imageing sensor camera head of practical application laser cutting machine Vision Builder for Automated Inspection is all the perspective projection imaging system, the variation of optical axis can cause that scene point motion conditions on the picture plane of CCD is inconsistent.Transmission projection can produce transparent effect in image, the projection that imaging is actual is three-dimensional scenic on the two-dimensional imaging plane.Because the direction of imaging plane with respect to scene changes, can cause optical axis direction to change.In the perspective projection system, the variation of optical axis can cause that projected image produces very large impact.Only have when the scene target during from the imaging hole infinity, perspective projection just becomes parallel projection.Based on the pinhole imaging system principle of sensor and camera head, the essence of the perspective that the variation of optical axis produces is the variation of the relative viewing angle on three dimensions, is embodied in the image processing of two dimension, is actually three-dimensional affine variation to two dimension.So based on the laser cutting machine of machine vision, can be according to the collinear theory of perspective projection, utilize homogeneous coordinate transformation to set up from cut bed plane to the coordinate transform relation of CCD imaging plane.First set up 3 coordinate systems in said method: (1) cut bed plane coordinate system OXYZ, this coordinate is the plane at practical operation object place, namely the OXY face, remain unchanged in measuring process; (2) eye coordinate O _sX _sY _sZ _s, this coordinate is take viewpoint as true origin, Z _sPoint coordinates is the initial point of OXYZ; (3) CCD imaging plane coordinate system O ' X ' Y ', this is plane coordinate system, CCD imaging front is positioned at O ' X ' Y ' plane.The relation of three coordinate systems as shown in Figure 5.Projection transformational relation from cut bed plane coordinate system OXYZ to CCD imaging plane coordinate system O ' X ' Y ' can represent with following coordinate transform:

$x^{\′}=F\×\frac{-x\sin \mathrm{\α}+y\cos \mathrm{\α}}{-x\cos \mathrm{\α}\cos \mathrm{\β}-y\sin \mathrm{\α}\cos \mathrm{\β}+R}$ (1)

$y^{\′}=F\×\frac{-x\cos \mathrm{\α}\sin \mathrm{\β}-y\sin \mathrm{\α}\sin \mathrm{\β}}{-x\cos \mathrm{\α}\cos \mathrm{\β}-y\sin \mathrm{\α}\cos \mathrm{\β}+R}$

Wherein, (x, y) be on the OXY coordinate surface a bit, the subpoint that (x ', y ') is it on O ' X ' Y ' plane, F is the focal length of CCD, the A point is O _sPoint is at the subpoint on OXY plane, and R is O _sThe distance that point is ordered to O, α is the angle of OX axle and OA, and β is O _sThe angle of O and OA, it is the angle that CCD optical axis and laser are sheared the bed plane, the angle that namely will detect.Make (x, y) point be r to initial point distance, with the angle of Y-axis be θ, x=rcos θ is arranged, y=rsin θ.If (x, y) is imaged as (x ', y ') by CCD, (x ', y ') point to initial point as the distance of plane initial point O ' is

And with x=rcos θ, y=rsin θ substitution formula (1), and order:

$\left\{\begin{array}{c}M=\cos \mathrm{\θ}\sin \mathrm{\α}\\ N=\cos \mathrm{\θ}\sin \mathrm{\θ}\sin \mathrm{\α}\cos \mathrm{\α}\\ G=\sin \mathrm{\θ}\cos \mathrm{\α}\\ H=\cos \mathrm{\θ}\cos \mathrm{\α}\sin \mathrm{\β}\\ W=2\cos \mathrm{\θ}\sin \mathrm{\θ}\sin \mathrm{\α}\cos \mathrm{\α}{\sin }^2\mathrm{\β}\\ J=\sin \mathrm{\θ}\sin \mathrm{\α}\sin \mathrm{\β}\end{array}\right.$

Can obtain following relational expression:

$r^{\&prime;}=\left|F\right|\&times;\frac{\sqrt{M^2-2N+{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000070466230000011.png,HDA0000070466230000031.png"\; state="\{\{state\}\}">G</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HDA0000070466230000011.png,HDA0000070466230000031.png"\; state="\{\{state\}\}">H</figure-callout>}}^2+2W+{\mathrm{<figure-callout\; id="2"\; label="J"\; filenames="HDA0000070466230000011.png,HDA0000070466230000031.png"\; state="\{\{state\}\}">J</figure-callout>}}^2}}{|-x\cos \mathrm{\&alpha;}\cos \mathrm{\&beta;}-y\sin \mathrm{\&alpha;}\cos \mathrm{\&beta;}+R|}---\left(2\right)$

In order to obtain the value of β, in cut automatic seeking edge system, getting radius in the zone of appointment with laser head is r, the center of circle is the standard laser hot spot mark circular pattern of S, in testing process, sets S and coordinate origin O point and overlaps, and with the center of circle of the center alignment tab of CCD circle, the image of picked-up marker graphic adopts the coordinate of image processing method certification mark circle diagram shape in imaging plane coordinate O ' X ' Y ', in computed image central coordinate of circle to all circumferential point coordinates apart from r ' _iThe marker graphic of getting due to laser cutting machine is standard circular, therefore α and θ angle do not affect the detection of vertical angle in the computing of reality, for convenience of calculation, getting it is 90 °, and (2) formula abbreviation is:

$r_i^{\&prime;}=\left|F\right|\&times;\frac{r\sqrt{{\left(\cos \mathrm{\&theta;}\right)}^2+{\left(\sin \mathrm{\&theta;}\sin \mathrm{\&beta;}\right)}^2}}{|-y\cos \mathrm{\&beta;}+R|}---\left(3\right)$

Obvious condition R＞＞r is satisfied, and cos β ≈ 0 is arranged, | and-ycos β+R| ≈ R, but the following formula abbreviation is:

$r_i^{\&prime;}=K\&times;r\sqrt{1-{\sin }^2\mathrm{\&theta;}(1-{\sin }^2\mathrm{\&beta;})}---\left(4\right)$

The amplification coefficient of K=|F|/R imaging system wherein.The r ' that following formula records when being CCD optical axis and imaging plane out of plumb _i, as can be known along with the variation at θ angle, r ' _iValue is arranged:

r′ _imax＝K×r (5)

r′ _imin＝K×rsinβ (6)

In standard marked circle image, along with the variation of angle θ, r ' _iTwo maximum value and two minimal values will be arranged, two maximum value maximal value for equating, unequal when two minimal values, and r ' is arranged _Imin1＜r ' _Imin2, can be got by formula (4):

r′ _imax＝K×r (7)

So can obtain:

K＝r′ _imax/r (8)

Again because: r ' _Imin2=K * r * sin β can obtain calculating the formula of the verticality of CCD optical axis and cutting planes:

β＝arcsin(r′ _imin2/r′ _imax) (9)

Can find out from formula (9), ask the value of β and the laser cutting machine radius of a circle r that makes marks irrelevant, the precision for guaranteeing to detect can make the mark radius of a circle more as far as possible according to the size in the CCD visual field, to improve accuracy of detection.Utilize formula (9) can obtain the vertical angle β of laser machine cutting bed vise plane and CCD optical axis.

Adopt above-mentioned relation, the coordinate relation of the mark coordinate of the reality by being positioned at cutting bed vise and image correspondence markings point that gauge point is gathered, the above relational expression of substitution just can calculate the deflection angle of CCD, thereby calculate the verticality of the installation of CCD.In the calculating of above-mentioned corresponding relation, the accuracy of detection of deflection angle is installed in order to take care of yourself CCD, the present invention proposes the implementation method that the testing result to a plurality of subregions is averaging and improves accuracy of detection, namely reach respectively the region division a-quadrant as shown in Figure 2 near four angles in the centre of cut bed, C zone, B zone, D zone and E are regional, as shown in Figure 5, detect respectively the installation deviation angle of CCD with identical method, ask at last its average installation deviation angle as final CCD.

Claims (2)

1. the detection method of an automatic seeking limit verticality of CCD installation of laser cutting machine, is characterized in that, comprises the following steps:

(1) directly utilize the laser head of laser cutting machine, get circle and the center mark pattern that is formed by laser facula on the fixing demarcation paper of laying of five zoness of different of cutting bed vise workplace; Described step (1) comprises following substep: at four angles of cutting bed vise and five zones in centre position, tile regularly respectively five and demarcate paper, the laser head of controlling cutting machine is demarcated at each and is got marked circle and the center of circle that the radius that is comprised of laser facula fixes on paper and carry out mark, the marked region size is limited in the visual field of a CCD imaging, location alignment point when the center mark point of each mark zone is adopted image for CCD, and in the process that verticality detects, five positions of demarcating paper remain unchanged;

(2) absorb the marking image of five zoness of different by CCD; Described step (2) comprises following substep: each zone marker figure is gathered, first driven CCD roughly moves to the zone of appointment, then field-of-view image is obtained in dynamic acquisition and processing, extract the coordinate of surveyed area center mark point, be used for controlling CCD position adjustment, make the center mark point adjust to the center that CCD gathers image, lock the visual field, carry out the marking image collection;

(3) utilize image processing techniques, extract respectively circumference and the centre point coordinate of marking image; Described step (3) comprises following substep: utilize image processing techniques, size according to laser facula, design size different disposal template is carried out mixed noise filtering and is processed, and adopt the sub-pixel positioning algorithm, accurately extract the coordinate of circumference gauge point and center mark point in image;

(4) calculate the center of circle to the extreme value of circumference each point distance, obtain CCD by computation model verticality is installed; Described step (4) comprises following substep: to each marker region image that gathers, after accurately extracting the marker graphic coordinate, calculate center mark and put the extreme value of each circumference gauge point distance, comprising two equal maximal values of different directions and two minimum value that do not wait of different directions and time minimum value, the substitution computation model calculates CCD verticality is installed; The same processing done in five zones, and the CCD that tries to achieve respectively five zones installs verticality, and averages and as CCD, verticality is installed.

2. the detection system of an automatic seeking limit verticality of CCD installation of laser cutting machine that adopts the described detection method of claim 1, comprise cutting bed vise, and described cutting bed vise is provided with can be along the mounting bracket of cutting bed vise both sides translation; Described mounting bracket is provided with can be along laser cutting machine and the CCD of mounting bracket slip; Described laser cutting machine is connected with computer system respectively with CCD, it is characterized in that, described computer system comprises: control module, image processing module and data processing module; Described control module be used for to be controlled five zones of laser cutting machine on cutting bed vise, according to preassigned position and radius, accurately gets circular on paper and mark is carried out in the center of circle demarcating, and controls described CCD calibration graph is gathered; Described image processing module is used for the image that gathers is carried out pre-service, utilizes the sub-pixel positioning algorithm, accurately extracts each point coordinate in the mark center of circle and circumference in every two field picture; Described data processing module is used for calculating required parameter according to the coordinate that extracts marker graphic, and the substitution computation model, obtains CCD verticality is installed.

Images