CN103940374B - Group's hole perpendicularity detecting system that group's hole perpendicularity detection method of a kind of view-based access control model measurement and the view-based access control model of employing the method are measured - Google Patents

Abstract

The present invention relates to group's hole perpendicularity detecting system that a kind of view-based access control model is measured, including: industrial camera, reference location device, cold light source and system for detecting verticality；Part to be measured has two datum planes being parallel to each other, and group hole is uniformly distributed and is applied between two datum planes；Industrial camera just to datum plane, obtains the picture rich in detail in two side group holes under the illumination of cold light source；Reference location device is arranged on datum plane；System for detecting verticality is by the image in reference location device correction group hole, and is calculated the coordinate data in two group holes by image, two groups of coordinate datas calculate the perpendicularity in group hole.Further relate to group's hole perpendicularity detection method that a kind of view-based access control model is measured.The advantage that the present invention has simple in construction, easy to operate, efficiency is high, error is little, belongs to field of measuring technique.

Description

A method for detecting verticality of group holes based on vision measurement and group holes based on vision measurement using the method Verticality detection system

technical field

The invention relates to the field of measurement technology, in particular to a system and method for detecting verticality of group holes based on visual measurement and image processing.

Background technique

The function of the steam generator in the primary circuit of the nuclear power plant is to transfer the heat of the heat carrier in the reactor to the secondary circuit, so that the medium on the secondary circuit side generates steam with a certain pressure, which is dried by the primary and secondary steam-water separators and then supplied to the steam turbine. It directly affects the power and efficiency of the power station. While the steam generator is used for steam heat exchange to provide steam power, it also plays the role of blocking radioactive heat transfer agent. It belongs to Class I equipment in terms of safety level and must have extremely high reliability and safety. Tube sheet processing is one of the most technically demanding and most difficult key processes in steam generators. According to the design, the total thickness of the tube sheet of the steam generator is 584.58mm, of which the nickel-based alloy surfacing layer is 6.4mm. Tube sheet processing is to gun-drill 9280 rectangularly arranged middle 1930 tube holes on the tube sheet. The tube sheet has two reference planes parallel to each other, and the group of holes are evenly distributed and run through between the two reference planes. are perpendicular to the reference plane. The deviation of the verticality of the deep hole will directly affect the installation of the support plate later, and whether it can pass through the U-shaped tube bundle with a length of more than ten meters smoothly and accurately in nearly ten thousand tube holes.

The traditional deep hole verticality measurement method is to use the mandrel to simulate the central axis, insert the mandrel into the hole to be measured, and use the end face as the reference plane to measure the angular deviation between the central axis and the end face. However, if the measured hole size is small or the hole depth is large, the measurement error is large and the mandrel is difficult to manufacture. In addition, there is also a method of using three-coordinate measurement in the prior art, but it is not suitable for tube-sheet parts due to the expensive equipment and the limitation of the site and the size of the workpiece.

To sum up, the prior art has the following limitations and defects in the verticality measurement of deep holes: 1. Manually read and record the measurement data, with large errors, low measurement accuracy and low measurement efficiency; 2. The existing technology uses core With the rod simulation method, the measurement length of the measured hole is limited by the length of the mandrel, which cannot achieve convenient and quick measurement, and because the mandrel and the measured hole are clearance fit, the error caused is relatively large; 3, due to the hole The quantity is very large, the measurement time is long, and the measurement record data is easily confused. Therefore, a fast, efficient, and high-precision non-contact detection method is urgently needed for its perpendicularity detection.

Contents of the invention

Aiming at the technical problems existing in the prior art, the object of the present invention is to provide a non-contact system and method for detecting verticality of group holes based on visual measurement, which can automatically measure group holes and calculate perpendicularity.

In order to achieve the above object, the present invention adopts following technical scheme:

A group hole verticality detection system based on visual measurement, including: industrial camera, reference positioning device, cold light source and verticality detection system; the test piece has two reference planes parallel to each other, and the group holes are evenly distributed and run through the two Between two datum planes; the industrial camera faces the datum plane, and obtains clear images of the group holes on both sides under the illumination of the cold light source; the datum positioning device is installed on the datum plane; the verticality detection system corrects the image of the group holes through the datum positioning device , and calculate the coordinate data of the two groups of holes through the image, and calculate the verticality of the group of holes from the two sets of coordinate data.

In the DUT, the hole group includes a plurality of holes arranged in a rectangular array, and the axes of the holes are perpendicular to the reference plane. That is, multiple holes are parallel to each other and run through between two datum planes.

The reference positioning device includes four standard rulers surrounded by a rectangle; the standard ruler surrounds the group of holes to be measured.

Both ends of the scale are equipped with bright artificial light reflection marks, the measurement accuracy of the scale is less than 5um, the flatness of the lower end surface of the scale is less than 10um, and the maximum thickness difference of the scale is 20um. Among them, the high-brightness artificial retroreflective mark is used for coordinate calibration of industrial cameras; the length of the reference ruler is measured and calibrated by the three-coordinate machine and the accuracy is better than 5um after temperature correction. The measurement accuracy of the reference ruler refers to the relative length of the measured The degree of deviation from the measured true value; the flatness of the lower end surface of the standard ruler after milling is better than 10um. The flatness of the lower end surface of the standard ruler and the maximum thickness of the standard ruler are preferred to ensure that the standard ruler and the reference surface are closely attached.

The material of the scale is high-strength chromium-tungsten-manganese alloy. In addition, the scale can also be selected from other materials with small expansion coefficient or relatively stable requirements.

The reference ruler is fixed into a rectangle by screws; the reference positioning device also includes several positioning columns connected with the reference ruler. The positioning column is a conical body and a fixed hole is selected on the test piece for axis coincidence.

The verticality detection system includes: image processing system, data processing module and output display module; the image processing system processes the clear image and obtains the center coordinates of each hole; the data processing module converts the center coordinates of each hole to verticality; output The display module outputs the final result.

The image processing system includes: reading image module, image preprocessing module, coordinate edge position module, Canny module, edge recognition module and ellipse fitting module; image preprocessing module includes: image grayscale submodule, image filtering submodule and Image binarization sub-module. The function of the image reading module is to extract the frame frequency of the video image and the resolution information of the image. The image preprocessing module is to perform grayscale processing, filtering processing and binarization processing on the image. The coordinate edge position module is to process the image The edge position is identified, the Canny module and the edge recognition module are used to extract and refine the edge of the image respectively, and the ellipse fitting module further trims the edge of the extracted circle to obtain the best ellipse.

A method for detecting verticality of group holes based on visual measurement, comprising the steps of:

a. Divide and mark the group of holes on the datum plane on one side of the test piece: when measuring for the first time, mark the upper left hole as (1, 1) hole, and the label increases from left to right and from top to bottom ,Right now Where n is a positive integer greater than 1, and the reference positioning device is installed on the side reference plane to surround the group holes;

b. Install an industrial camera to obtain a clear image of the reference plane on one side in step a under the illumination of a cold light source;

c. The verticality detection system processes the image obtained in step b, determines the center and edge of the hole, uses the high-precision known length value of the reference positioning device as the control condition, and obtains the orthographic image of the hole feature through image geometric correction , after proportional correction, the actual value of the hole feature quantity is obtained, and the coordinate conversion is performed with the center of the hole (1,1) as the origin, and the coordinates of the center of each hole in the measured area are obtained and stored;

d. Rotate the part to be tested 180° on the horizontal plane to obtain a clear image and measure the reference plane on the other side, or directly obtain a clear image and measure the reference plane on the other side. At this time, the first hole mark in the upper right corner is (1',1'), and the label increases from right to left and from top to bottom, namely After being processed by the verticality detection system, the center coordinates of each hole in the measured area are obtained under the new coordinates with the center of the hole (1', 1') as the origin, and stored;

e. Extract two sets of coordinate data, and compare the center coordinates (x _a , y _b ) of the (a, b) holes corresponding to the datum planes on both sides of the same hole and the center coordinates (x _a ′ ) of the (a', b') holes, y _b′ ), get Among them, a and b are selected from positive integers from 1 to n; the depth of the deep hole is H, then the verticality of the hole can be obtained, and the angle θ of the axis deviation of the hole is:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; tan</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

f. Repeat step e to obtain the verticality of all holes, judge whether it is qualified, and output the result.

In steps c to e, the image is first read by the image reading module, and then the obtained image is processed by the image grayscale sub-module by the image pre-processing module, filtered by the image filtering sub-module, and finally image binary The sub-module proposes the values of the center and edge of each hole, and finally uses the length of the reference positioning device as the control reference to list the error equations using the length constraints, and solves the necessary external orientation elements of the picture, and corrects the tilt and upright photography according to the image coordinates Theoretically, the actual coordinates of the holes on the surface of the test piece are obtained.

Generally speaking, the present invention has the following advantages: simple structure, convenient operation, high efficiency and small error.

(1) The verticality detection system of group holes based on visual measurement of the present invention uses image processing system software to automatically calculate the verticality of each deep hole, and displays and stores it, effectively reducing errors in human reading, recording and calculation.

(2) The group hole verticality detection system based on visual measurement of the present invention only needs to obtain the surface image of the test piece, without the need for complex and cumbersome steps such as alignment and centering required by traditional measurement methods. Therefore, both simplification The measurement method is improved, and the processing accuracy requirements of the system components are greatly reduced.

(3) The verticality detection system of a group of holes based on visual measurement of the present invention can simultaneously measure multiple deep holes in batches, and greatly improves the detection efficiency on the premise of satisfying the measurement accuracy.

Description of drawings

FIG. 1 is a schematic structural diagram of a verticality detection system for group holes based on visual measurement according to the present invention.

Fig. 2 is a schematic structural diagram of the reference positioning device of the present invention.

Figures 3a and 3b are schematic diagrams of the images acquired by the two measurements.

Figure 4 is a structural block diagram of the verticality detection system.

Fig. 5 is an algorithm flow chart of the image processing system.

Among them, 1 is the reference positioning device, 2 is the reference plane, 3 is the workpiece to be tested, 4 is the cold light source, 5 is the industrial camera, 6 is the computer (in which the verticality detection system is integrated), and 11 is the high-brightness artificial return light reflection Sign, 12 is a screw, and 13 is a reference ruler, and 14 is a positioning column, and 21-28 are holes.

detailed description

The present invention will be further described in detail in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural diagram of a group hole verticality detection system based on visual measurement in the present invention. As can be seen from Fig. 1, a group hole verticality detection system based on visual measurement includes: a reference positioning device, a cold light source, an industrial camera and computer. The reference positioning device is adsorbed on the reference plane on one side of the DUT, and the output end of the industrial camera is connected to the computer. The object to be tested is the tube sheet of a steam generator, which has two reference planes parallel to each other. The group holes are evenly distributed and run through between the two reference planes. The axis of each hole is perpendicular to the reference plane, and one end of the group holes is on the reference plane. are evenly arranged along the rectangular array. When measuring, the first reference plane is detected first, and the reference positioning device is installed on this surface, and the industrial camera and cold light source are also facing the surface; after the measurement of the first reference plane is completed, the second base level for testing.

There are four reference rulers in the reference positioning device, and the two ends of the reference ruler are affixed with high-brightness artificial retroreflective marks. The length of the reference ruler is measured and calibrated by the three-coordinate machine and the temperature is corrected. The accuracy is better than 5um. The material of the scale should have a small or relatively stable expansion coefficient. In this example, a high-strength chromium-tungsten-manganese alloy is selected. The flatness of the lower end surface of the standard ruler is better than 10um after milling, and the maximum thickness difference is 20um. The processed four standard rulers are fixed with screws to form a rectangle and form a reference positioning device together with the positioning column. When measuring, the standard ruler surrounds the holes to be measured.

The verticality detection system includes an image processing system, a data processing module and an output display module. The image processing system processes the acquired images to obtain the center coordinates of each hole, and the data processing module performs verticality conversion after receiving the center coordinates of each hole, and outputs the final result through the output display module.

The image processing system is in the form of software installed in the computer, including a reading image module, an image preprocessing module, a coordinate edge position module, a Canny module, an edge recognition module and an ellipse fitting module.

The image pre-processing module processes the acquired pictures through the image grayscale sub-module, and then the image filtering sub-module performs filtering, and finally the image binarization sub-module proposes the value of each point.

After the image processing system obtains the image, it takes the length of the scale as the control reference and uses the length constraint to list the error equations to solve the necessary external orientation elements of the image. According to the image coordinate tilt correction and upright photography theory, the reference of the plate tube is obtained. The actual coordinates of the holes to be measured on the surface; finally, the characteristic geometric analysis of each hole is carried out to realize the measurement.

Utilize above-mentioned detection system to the detection method of group hole perpendicularity, it is characterized in that this method comprises the following steps, (take 100 holes on the test piece as example):

1. Divide and mark the holes to be measured on the two datum planes of the group of holes. Mark the first datum plane first, as shown in the dotted line area in Figure 3a. When measuring for the first time, mark the upper left hole as (1, 1) The hole, that is, hole 21, the label increases from left to right from top to bottom, that is (10,1) is the hole 22, (10,10) is the hole 23, (1,10) is the hole 24; and the reference positioning device is installed on the reference plane.

2. Install the industrial camera so that the plane of the camera lens is parallel to the reference plane. Adjust the cold light source and camera focal length to obtain high-quality images.

3. The computer processes the received digital image, accurately determines the center and edge of the circular hole, uses the high-precision known length value of the scale as the control condition, and obtains the orthographic image of the tube hole feature through image geometric correction. Correction, to get the actual value of the characteristic value of the tube hole, coordinate conversion is performed with the center of the (1,1) hole as the origin, from left to right is the positive direction of the X-axis, and from top to bottom is the positive direction of the Y-axis, and the obtained Coordinates of the center of each hole in the survey area, and store the first set of data obtained.

4. Rotate the test piece by 180° or measure the second datum plane on the other side of the test piece. At this time, the first hole in the upper right corner is marked as (1',1'), That is hole 25, the label increases from right to left, from top to bottom, that is Wherein, (10′, 1′) is the hole 26 , (1′, 10′) is the hole 27 , and (10′, 10′) is the hole 28 . After computer image processing, the center coordinates of each hole in the measured area are obtained under the new coordinates with the center of the hole (1',1') as the origin, and the second set of data is stored, and the positive direction of the X axis is from right to left , from top to bottom is the positive direction of the Y axis.

5. Extract two sets of data, and compare the center coordinates corresponding to the two ends of the same hole, such as (1,1) and (1’, 1’), to obtain

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

The hole depth of the deep hole is H (H is the distance between the two reference planes directly measured), then the verticality of the hole can be obtained. The angle θ at which the axis of the hole deviates is:

θ=tan ^-1 (L/H);

The same method obtains the verticality of all holes, and judges whether it is qualified or not, and displays the final result.

In addition to verticality, various parameters such as surface aperture and hole bridge can be obtained.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. group's hole perpendicularity detection method that a view-based access control model is measured, it is characterised in that: comprise the steps:

A. by the group hole subregion on the side datum plane of part to be measured and mark: when measuring for the first time, by upper left hole Be demarcated as (1,1) hole, label by left-to-right, be incremented by from top to bottom, i.e.Its Middle n is the positive integer more than 1, and is installed on by reference location device on this side datum plane, by this district group Hole surrounds；

B. mounting industrial camera, obtains the picture rich in detail of side datum plane in step a under the illumination of cold light source；

C. the image obtained in step b is processed by system for detecting verticality, determines the center and peripheral in hole, profit By the high accuracy known length value of reference location device as control condition, pass through geometric rectification of imagery, it is thus achieved that The orthograph picture of hole characteristic, corrects through ratio, obtains the actual value of hole characteristic amount, with the circle in (1,1) hole The heart is that initial point carries out Coordinate Conversion, obtains the central coordinate of circle in each hole, surveyed region, and stores；

D., part to be measured rotates 180 ° in the horizontal plane opposite side datum plane is obtained picture rich in detail and measures, Or directly opposite side datum plane obtained picture rich in detail and measure, now first hole in the upper right corner Be labeled as (1 ', 1 '), label by the right side to left, be incremented by from top to bottom, i.e.Obtain with (1 ', 1 ') after system for detecting verticality processes Under the new coordinate that the center of circle in hole is initial point the central coordinate of circle in each hole, survey region, and store；

E. two groups of coordinate datas are extracted, relatively (a, b) central coordinate of circle in hole of correspondence both sides, same hole datum plane (x_a, y_b) and the central coordinate of circle (x in (a ', b ') hole_a′, y_b′), it is thus achieved that

Wherein, a and b positive integer in 1 to n is chosen； The hole depth in this hole is H, then can obtain the perpendicularity in this hole, and the angle, θ of the axis runout in this hole is:

$\mathrm{\&theta;}={\tan }^{-1}\left(\frac{L}{H}\right);$

F. repeat step e and obtain porose perpendicularity, and judge whether qualified, result is exported.

2. the group's hole perpendicularity detection method measured according to a kind of view-based access control model described in claim 1, it is characterised in that: In described step c to e, first by reading image module reading picture, then by image pre-processing module by acquired Picture through image gray processing submodule process after, image filtering submodule be filtered, by image two-value Beggar's module proposes the numerical value of the center and peripheral in each hole, finally using the length of reference location device as control Benchmark processed, utilizes length constraint to list error equation group, calculates the necessary elements of exterior orientation of picture, Theoretical according to image coordinate correcting inclination and normal case photography, obtain the actual coordinate in group hole, part surface to be measured.

3. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 1 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: including: industrial camera, origin reference location fill Put, cold light source and system for detecting verticality；

Part to be measured has two datum planes being parallel to each other, and group hole is uniformly distributed and is applied between two datum planes； Industrial camera just to datum plane, obtains the picture rich in detail in two side group holes under the illumination of cold light source；

Reference location device is arranged on datum plane；

System for detecting verticality is by the image in reference location device correction group hole, and calculates two groups by image The coordinate data in hole, is calculated the perpendicularity in group hole by two groups of coordinate datas.

4. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 3 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: in described part to be measured, group hole includes multiple The hole of rectangular array arrangement, the axis in hole is perpendicular to datum plane.

5. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 3 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: described reference location device includes four rhizospheres Rectangular station meter；In group hole to be measured is enclosed in by station meter.

6. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 5 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: the two ends of described station meter are provided with highlighted people Work retro-reflective target, the certainty of measurement of station meter is less than 5um, and the flatness of the lower surface of station meter is less than 10um, the maximum gauge difference of station meter is 20um.

7. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 5 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: the material of described station meter is high intensity chromium Tungsten manganese alloy.

8. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 5 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: described station meter is screwed as square Shape；Reference location device also includes some locating dowels connected with station meter.

9. use the one of group's hole perpendicularity detection method that a kind of view-based access control model described in claim 3 measures based on Group's hole perpendicularity detecting system of vision measurement, it is characterised in that: described system for detecting verticality includes: figure As processing system, data processing module and output display module；

Image clearly is carried out processing and obtaining the centre coordinate in each hole by image processing system；

The centre coordinate in each hole is carried out perpendicularity conversion by data processing module；

Final result is exported by output display module.

10. a kind of base of group's hole perpendicularity detection method that the employing a kind of view-based access control model described in claim 9 is measured Group's hole perpendicularity detecting system in vision measurement, it is characterised in that:

Described image processing system includes: read image module, image pre-processing module, coordinate marginal position module, Canny module, limb recognition module and ellipse fitting module；

Image pre-processing module includes: image gray processing submodule, image filtering submodule and image binaryzation submodule Block.