CN111551552A - Appearance quality detection method for circular hole punching net - Google Patents

Abstract

The invention provides a method for detecting the appearance quality of a round hole punching net. The present invention is mainly divided into four steps: firstly, preprocessing the image of the circular hole punching net to be detected; A vertical line intersects the first column of circular holes, and gradually adjust and determine the final position of these four lines; third, use prior knowledge to batch set virtual upper, lower, left and right vertical lines. Obtain the intersection points of each circular hole and each virtual line; finally, judge the appearance defects of the circular hole punching net and calculate the center coordinates of each circular hole and its radius, hole spacing and other parameters. The invention has the advantages of strong versatility, is suitable for appearance detection and parameter determination of various types of round hole punching nets, and has high detection speed and high precision.

Description

Appearance quality detection method of round hole punching net

technical field

The invention relates to a detection technology for the appearance quality of a round hole punching net, in particular to a method for detecting parameters of round holes in the round hole punching net and detecting appearance defects.

Background technique

The round hole punching net is made of metal plate as raw material, and punched by a punching machine on the metal plate with a number of circular holes with the same radius, equal horizontal spacing, equal vertical spacing, and regular distribution. The round hole punching mesh is usually made of galvanized steel plate, stainless steel plate, copper plate, aluminum plate, nickel plate and alloy plate. The products are mainly used in chemical machinery, pharmaceutical equipment, food and beverage machinery, cigarette rolling machinery, harvesters, dry cleaning machines, ironing tables, muffler equipment, refrigeration equipment (central air conditioning) speakers, handicraft production, papermaking, hydraulic accessories, pharmaceutical equipment, filtration equipment and other industries.

Due to the complexity of the structure of the perforated mesh and the limitation of the precision of the mechanical control system, the perforated mesh inevitably has various defects. The appearance defects of the round hole punching net mainly include uneven thickness distribution of the round hole punching net, non-standard punching hole diameter, horizontal hole spacing and vertical hole spacing and other parameters, and the edge of the punching ring is incomplete. The surface features of the product are the reflection of its important performance indicators. These possible defects will lead to serious safety problems in subsequent use. Therefore, the online inspection of its surface appearance has important practical significance.

The punching process is the main process in the manufacturing process of the round hole punching mesh. Punching hole diameter, horizontal hole spacing, and vertical hole spacing are the key technical indicators. In the stamping process, due to various reasons, defects such as uneven blind hole spacing and connecting holes appear. This will have a great impact on the performance and quality of the product. At present, the parameter measurement and defect detection of round hole punching nets rely heavily on manual sampling. This will bring many negative impacts and inconveniences to production. First, more labor is needed and the labor intensity is high. Second, it is time-consuming to check whether each product is defective, and the false detection rate and missed detection rate are high. In recent years, with the rapid development of machine vision technology, detection methods based on machine vision have been well developed and applied in the field of surface defect detection. Hough transform and least squares method are widely used in circle parameter detection to obtain information such as the radius and center of each circle (ie punching hole) in the image. On this basis, the horizontal hole distance and vertical hole between punching holes are calculated one by one Distance and other parameters, because there are many circles and edge points on the circle, it is necessary to analyze all circles in the image, which requires a large amount of calculation and takes a long time, and it is difficult to meet the requirements of real-time monitoring. For the method of using a custom template to subtract the image to be tested from the standard template, due to the inevitable deviation within the allowable tolerance range during the mechanical stamping process, the standard template cannot actually be obtained, which brings about the implementation of this method. certain difficulties.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, the present invention proposes an automatic detection method for the appearance defects of a circular hole punching net, which uses four lines (two horizontal lines and two vertical lines) to obtain eight edge points on each circle, and uses four lines (two horizontal lines and two vertical lines). A small number of intersection points are used to calculate the coordinates of the center of the circular hole and its radius, hole spacing and other parameters. The method can replace manual sampling inspection, realize high-speed and high-precision quality inspection of round-hole punching plates, and make round-hole punching nets meet the appearance qualification standards. The present invention obtains the image of the circular hole punching mesh area through a high-precision industrial CCD camera, and the specific content is as follows:

S100. Preprocess the image of the hole punching mesh whose size is (m, n);

S200. Virtually set initial horizontal lines H ₁₁ , H ₂₁ and vertical lines Z ₁₁ , Z ₂₁ , gradually adjust the position of the initial virtual line and obtain the final intersection point of the circular hole and the virtual line in the circular hole punching mesh image;

S300. Set the virtual upper horizontal line H _1p , the lower horizontal line H _2p , the left vertical line Z _1q and the right vertical line Z _2q in batches, and obtain the circular holes in the image of the circular hole punching net and the virtual lines H _1p and H that are set in batches The intersection point of _2p , Z _1q and Z _2q , where p is the circle in the p-th row in the perforated mesh image, q is the circle in the q-th column in the perforated mesh image, and H _1p represents the horizontal line on the p-th row , H _2p represents the lower horizontal line of the pth row, Z _1q represents the left vertical line of the qth column, and Z _2q represents the right vertical line of the qth column;

S400. Determine the appearance defects of the circular holes, and use a small number of intersections to calculate the dimensional parameters such as the coordinates of the circle center, the radius, the horizontal hole spacing and the vertical hole spacing of each circular hole. The present invention has the following advantages:

1. The present invention has strong versatility and is suitable for the appearance inspection of various types of round hole punching nets;

2. The present invention is not limited to the individual detection of each circle, but uses a small number of points on the circular hole to calculate the radius of each circular hole and its center, the distance between the circular hole and the circular hole and other parameters, even if machining exists. Tolerances within the allowable range can also be applied, with high speed and high precision.

Description of drawings

Fig. 1 is the method flow chart of the present invention;

Fig. 2 is the explanatory diagram of the hole distance of round hole punching;

Fig. 3 is an explanatory diagram of the horizontal hole distance of the circular hole punching net;

Fig. 4 is an explanatory diagram of the longitudinal hole distance of the circular hole punching net;

Figure 5 is an illustration of the left width of the round hole punching net;

Figure 6 is an illustration of the width of the right side of the round hole punching net;

Fig. 7 is the initial horizontal and vertical line positioning diagram;

Fig. 8 is a virtual horizontal and vertical line intersecting a circle;

FIG. 9 is a coordinate diagram where a virtual horizontal and vertical line intersects a circle.

Detailed ways

The implementation of the present invention will be described by taking the quality inspection of the round hole punching net produced by Haohui Precision Instrument Co., Ltd. as an example. The round hole punching mesh is mainly used in dry cleaning machines, ironing tables, noise reduction equipment, speakers and other equipment; the appearance inspection mainly includes the parameters of each round hole (radius, center, etc.), horizontal hole distance and vertical hole distance, etc.; Before, input the model CX161 of the round hole punching mesh to be tested and its related a priori parameters, including the total width d ₆ =160.003mm, the right width d ₄ =11.171mm, the left width d ₅ =24.099mm, the horizontal hole distance d ₂ = 2.597mm, the longitudinal hole distance d ₃ =1.493mm, and the hole diameter d ₁ =1.965mm, as shown in Figure 2, Figure 3, Figure 4, Figure 5, and Figure 6.

Converting the parameters in the above world coordinate system into the image coordinate system, the purpose of calibration is to determine the quantitative correspondence between the actual size of the measured object and the number of pixels in the image captured by the camera, so that the image distance corresponds to the true distance of the measured object. Up, the actual testing of the implementation parameters is required. When the present invention is implemented, the standard part imaging method is used to calibrate the transformation of the above coordinate system. The specific calibration process is as follows:

①Place the calibration plate 5.6*5.6mm with a precision of 1um on the stage of the measurement system, and ensure that the edge of the calibration plate is parallel to the coordinate axis of the camera imaging screen;

② Collect the image of the calibration plate, identify the left and right mark circles, the upper and lower mark circles on the calibration plate, and obtain the pixel value between the upper and lower mark circles and the center of the left and right mark circles;

③ Divide the actual distance of the up and down and left and right marked circles by the pixel value between them to obtain the pixel equivalent under the condition of fixed focal length and fixed object distance. In order to improve the detection accuracy, 12 decimal places are reserved for the pixel equivalent. The pixel equivalent in the X-axis direction of the camera is 0.003826796100mm, and the pixel equivalent in the Y-axis direction is 0.003827779593mm.

According to the transformation relationship between the world coordinate system and the image coordinate system calibrated above, the parameters in the world coordinate system are converted into the image coordinate system, and the total width d ₆ ′, the right width d ₅ ′, the left width d ₄ ′, and the horizontal hole are obtained. Distance d ₂ ', longitudinal hole distance d ₃ ', hole diameter d ₁ '.

Place the round hole punching net horizontally on the belt conveyor, and enter the inspection station at a fixed speed from left to right. In the inspection workstation, the high-precision industrial CCD camera is vertically downward, and the top ring light source is used for illumination to obtain the image of the round hole punching net. In conjunction with Fig. 2, the concrete realization steps of the present invention are as follows:

S100. Preprocess the image of the hole punching mesh with size (m, n):

S110. Use median filtering to filter out noise, use Otsu algorithm to obtain a threshold, and perform binarization processing on the image.

S200. In the image of the hole punching net, virtually set initial horizontal and vertical lines, gradually adjust the position of the initial virtual line, and obtain the final intersection point of the hole and the virtual line in the picture of the hole punching net:

S210. Virtually set two horizontal lines and two vertical lines in the image, denoted as upper horizontal line H ₁₁ and lower horizontal line H ₂₁ , left vertical line Z ₁₁ and right vertical line Z ₂₁ , wherein H ₁₁ and H ₂₁ It intersects with the circle in the first row, Z ₁₁ and Z ₂₁ intersect with the circle in the first column, the initial ordinate of the upper horizontal line H ₁₁ is yy ₀₁ , the initial ordinate of the lower horizontal line H ₂₁ is yy ₁₁ , and the left vertical line Z ₁₁ The initial abscissa is xx ₀₁ , and the initial abscissa of the right vertical line Z ₂₁ is xx ₁₁ , as shown in Figure 7;

S220. Let t=1, k=1, g=0, h=0, e=0, for the upper horizontal line H ₁₁ whose ordinate is yy ₀₁ , execute S230 to determine its final position yy _01last ;

S230. For the horizontal line whose vertical coordinate is yy in the image, search from left to right to obtain the pixel coordinate point where this horizontal line intersects the circle:

f ₁ =I(i+1,yy)-I(i,yy) i∈[1,m) (1)

Among them, I(i, yy) is the pixel value of the image at position (i, yy), p is the circle in the p-th row in the perforated screen image, and q is the circle in the q-th column in the perforated screen image; H _t (x _tpq ) is the abscissa value of the p-th row and q column when the horizontal line satisfies f ₁ >0; H _t (y _tpq ) is the ordinate value of the p-th row and q column when the horizontal line satisfies f ₁ >0; C _k (x _kpq ) is the abscissa value of the p-th row and q column when the horizontal line satisfies f ₁ <0; C _k (y _kpq ) is the ordinate value of the p-th row and q column when the horizontal line satisfies f ₁ <0;

If h=0 and g=0, execute S231;

If h=0 and g=1, then g=g+1, and execute S231;

If h=0 and g=3, execute S231;

If h=1, execute S322;

If h=2, execute S323;

其中N为该行圆的数量；S231. Calculate the mean value of H _t -C _k , namely:

where N is the number of circles in the row;

If g=0, execute step S232;

If g=2, execute step S233;

If g=3, execute step S234;

S232.g=g+1, yy=yy+1, if g=1, execute S230, otherwise execute S233;

S233.c _t =b _t2 -b _t0 , g=g+1, b _t3 =b _t2 ;

S234. If t=1 and c _t >0, it means that the horizontal line is in the upper half of the circle in the p-th row, then perform the following operations:

且e<r，则yy＝yy+1，e＝e+1，执行S230；like

And e<r, then yy=yy+1, e=e+1, and execute S230;

且e<r，则该行圆的最终位置为yy，即yy_last＝yy；like

And e<r, the final position of the circle is yy, that is, yy _last = yy;

且e>r，则判断该行圆有缺陷圆；like

And e>r, then it is judged that this row of circles has a defective circle;

If t=1 and c _t <0, then yy ₀₁ =yy ₀₁ -10, and execute S220;

If t=2 and c _t < 0, it means that the horizontal line is in the lower half of the circle in the p-th row, then perform the following operations:

且e<r，则yy＝yy-1，e＝e+1，执行S230；like

And e<r, then yy=yy-1, e=e+1, and execute S230;

且e<r，则该行圆的最终位置为yy，即yy_last＝yy；like

And e<r, the final position of the circle is yy, that is, yy _last = yy;

且e>r，则判断该行圆有缺陷圆；like

And e>r, then it is judged that this row of circles has a defective circle;

If t=2 and c _t >0, then yy ₁₁ =yy ₁₁ +10, and execute S240;

in,

If t=1 and k=1, then yy _01last =yy _last ; if t=2 and k=2, then yy _11last =yy _last ;

If t=2 and k=2, execute S250, otherwise execute S240;

S240. Let t=2, k=2, g=0, h=0, e=0, for the lower horizontal line H ₂₁ whose ordinate is yy ₁₁ , execute S230 to determine its final position yy _11last ;

S250. Let t=3, k=3, g=0, h=0, e=0, for the left vertical line Z ₁₁ whose abscissa is xx ₀₁ , execute S260 to determine its final position xx _01last ;

S260. For the vertical line whose abscissa is xx in the image, search from top to bottom to obtain the pixel coordinate point where this vertical line intersects the circle:

f ₂ =I(xx,j+1)-I(xx,j) j∈[1,n) (3)

Among them, I(xx, j) is the pixel value of the image at the position (xx, j), p is the p-th row circle in the circular hole punching mesh image, and q is the q-th column circle in the circular hole punching mesh image; H _t (x _tpq ) is the abscissa value of the p-th row and q column when the vertical line satisfies f ₂ >0; H _t (y _tpq ) is the ordinate value of the p-th row and q column when the vertical line satisfies f ₂ >0 value; C _k (x _kpq ) is the abscissa value of the p-th row q column when the vertical line satisfies f ₂ <0; C _k (y _kpq ) is the p-th row q column when the vertical line satisfies f ₂ <0 ordinate value;

If h=0 and g=0, execute S261;

If h=0 and g=1, then g=g+1, and execute S261;

If h=0 and g=3, execute S261;

If h=1, execute S324;

If h=2, execute S400;

其中M为该列圆的数量，S261. Calculate the mean value of _Ht - _Ck , namely:

where M is the number of circles in the column,

If g=0, go to step S262;

If g=2; then execute step S263;

If g=3, execute step S264;

S262.g=g+1, xx=xx+1, if g=1, execute S260, otherwise execute S263;

S263.c _t =b _t2 -b _t0 , g=g+1, b _t3 =b _t2 ;

S264. If t=3 and c _t >0 means that the horizontal line is in the left half of the circle in the qth column, perform the following operations:

且e<r，则xx＝xx+1，e＝e+1，执行S260；like

And e<r, then xx=xx+1, e=e+1, and execute S260;

且e<r，则该列圆的最终位置为xx，即xx_last＝xx；like

And e<r, then the final position of this column of circles is xx, that is, xx _last =xx;

且e>r，则判断该列圆有缺陷圆；like

And e>r, then it is judged that this column of circles has defective circles;

If t=3 and c _t <0, then xx ₀₁ =xx ₀₁ -10, and execute S250;

If t=4 and c _t < 0, the horizontal line is in the right half of the circle in the qth column, then perform the following operations:

且e<r，则xx＝xx-1，e＝e+1，执行S260；like

And e<r, then xx=xx-1, e=e+1, execute S260;

且e<r，则该列圆的最终位置为yy，即xx_last＝xx；like

And e<r, then the final position of this column of circles is yy, that is, xx _last =xx;

且e>r，则判断该列圆有缺陷圆；like

And e>r, then it is judged that this column of circles has defective circles;

If t=4 and c _t >0, then xx ₁₁ =xx ₁₁ +10, and execute S270;

in,

If t=3 and k=3, then xx _01last =xx _last ; if t=4 and k=4, then xx _11last =xx _last ;

If t=4 and k=4, execute S300, otherwise execute S270;

S270. Let t=4, k=4, g=0, h=0, e=0, for the right vertical line Z ₂₁ whose abscissa is xx ₁₁ , perform S260 to determine its final position xx _11last .

S300. Set the virtual upper horizontal line H _1p , the lower horizontal line H _2p , the left vertical line Z _1q and the right vertical line Z _2q in batches, and obtain the circular holes in the image of the circular hole punching net and the virtual lines H _1p and H that are set in batches _2p , Z _1q , Z _2q intersection, where p is the circle in the p-th row in the perforated mesh image, q is the circle in the q-th column in the perforated mesh image, H _1p represents the upper horizontal line on the p-th row, H _2p represents the lower horizontal line of the pth row, Z _1q represents the left vertical line of the qth column, and Z _2q represents the right vertical line of the qth column, as shown in Figure 8. The specific method is as follows:

S310. The upper horizontal line H ₁₁ takes the finally determined yy _01last as the starting ordinate, and sets virtual upper horizontal lines in batches at every interval d ₃ ', namely:

yy _0p =yy _01last +(p-1)*d′ ₃ ; (5)

The lower horizontal line H ₂₁ takes the finally determined yy _11last as the starting ordinate, and sets virtual lower horizontal lines in batches at every interval d ₃ ′, namely:

yy _1p =yy _11last +(p-1)*d′ ₃ ; (6)

The left vertical line Z ₁₁ takes the finally determined xx _01last as the starting abscissa, and sets virtual left vertical lines in batches at every interval d ₂ ', namely:

xx _{0q =xx 01last +} (q-1)*d′ ₂ ; (7)

The right vertical line Z ₂₁ takes the finally determined xx _11last as the starting abscissa, and sets virtual right vertical lines in batches at every interval d ₂ ', namely:

xx _1q =xx _11last +(q-1)*d′ ₂ ; (8)

Among them, p is the circle in the p-th row in the image of the circular hole punching net, and q is the circle in the q-th column in the picture of the circular hole punching net;

S320. Calculate the intersection points of the virtual lines H _1p , H _2p , Z _1q , and Z _2q set in batches and the holes in the hole punching mesh image, and the specific methods are as follows:

S321. For any upper horizontal line H _1p , set t=1, k=1, yy=yy _0p , h=1, execute S230, and obtain the intersection point H ₁ (x _1pq , y _1pq ), C ₁ (x _1pq , y _1pq );

S322. For any lower horizontal line H _2p , set t=2, k=2, yy=yy _1p , h=2, execute S230, and obtain the intersection point H ₂ (x _2pq , y _2pq ), C ₂ (x _2pq , y _2pq );

S323. For any left vertical line Z _1q , let t=3, k=3, xx=xx _0q , h=1, execute S260 to obtain the intersection point H ₃ (x _3pq , y _3pq ), C ₃ (x _3pq , y _3pq );

S324. For any right vertical line Z _2q , let t=4, k=4, xx=xx _1q , h=2, execute S260 to obtain the intersection point H ₄ (x _4pq , y _4pq ), C ₄ (x _4pq , y _4pq ).

S400. Judge the appearance defects of round holes, and use a small number of intersection points to calculate the dimensional parameters such as the center coordinates, radius, horizontal hole spacing and vertical hole spacing of each round hole:

S410. Calculate the coordinate difference, and the specific operations are as follows:

u ₁ =H ₁ (x _1pq )-H ₁ (x _1p(q-1) ); v ₁ =H ₃ (y _3pq )-H ₃ (y _3(p-1)q ); (9)

u ₂ =C ₁ (x _1pq )-C ₁ (x _1p(q-1) ); v ₂ =C ₃ (y _3pq )-C ₃ (y _3(p-1)q ); (10)

u ₃ =H ₂ (x _2pq )-H ₂ (x _2p(q-1) ); v ₃ =H ₄ (y _4pq )-H ₄ (y _4(p-1)q ); (11)

u ₄ =C ₂ (x _2pq )-C ₂ (x _2p(q-1) ); v ₄ =C ₄ (y _4pq )-C ₄ (y _4(p-1)q ); (12)

u ₅ =H ₁ (x _1pq )-C ₁ (x _1p(q-1) ); v ₅ =H ₃ (y _3pq )-C ₃ (y _3(p-1)q ); (13)

u ₆ =H ₂ (x _2pq )-C ₂ (x _2p(q-1) ); v ₆ =H ₄ (y _4pq )-C ₄ (y _4(p-1)q ); (14)

S420. Determine the appearance defect of the round hole, and the specific operations are as follows:

Set the threshold T=15, and perform the following operations:

u' ₁ =u ₁ (w ₁ +1)-u ₁ (w ₁ ); v' ₁ =v ₁ (s ₁ +1)-v ₁ (s ₁ ); (15)

u' ₂ =u ₂ (w ₁ +1)-u ₁ (w ₁ ); v' ₂ =v ₂ (s ₁ +1)-v ₂ (s ₁ ); (16)

u' ₃ =u ₃ (w ₁ +1)-u ₃ (w ₁ ); v' ₃ =v ₃ (s ₁ +1)-v ₃ (s ₁ ); (17)

u' ₄ =u ₄ (w ₁ +1)-u ₄ (w ₁ ); v' ₄ =v ₄ (s ₁ +1)-v ₄ (s ₁ ); (18)

u' ₅ =u ₅ (w ₂ +1)-u ₅ (w ₂ ); v' ₅ =v ₅ (s ₂ +1)-v ₅ (s ₂ ); (19)

u' ₆ =u ₆ (w ₂ +1)-u ₆ (w ₂ ); v' ₆ =v ₆ (s ₂ +1)-v ₆ (s ₂ ); (20)

where w ₁ ∈ [1, max(q)-1), w ₂ ∈ [1, max(q)-2), s ₁ ∈ [1, max(p)-1), s ₂ ∈ [1, max(p)-2); p is the circle in the p-th row in the image of the circular hole punching net, and q is the circle in the q-th column in the picture of the circular hole punching net;

则圆孔存在外观缺陷；like

The round hole has appearance defects;

S430. Calculate the coordinates and radius of the center of the circle, and the specific operations are as follows:

Select _three points H ₃ (x _3pq , y _3pq ), H _{4 ( x 4pq} , y _4pq ), H _{4 (} x _4pq , y _{4pq )} , C ₁ (x _1pq , y _1pq );

Let A(x ₀ , y ₀ )=H ₃ (x _3pq , y _3pq ), B(x ₁ , y ₁ )=H ₄ (x _4pq , y _4pq ), C(x ₂ , y ₂ )=C ₁ (x _1pq , y _1pq )

The center of the circle is (x _c , y _c ), the radius is r,

in,

S440. Calculate the horizontal and vertical hole spacing,

Lateral hole spacing:

Longitudinal hole spacing:

Among them, (p, q) is the circle in the p-th row and the q-th column in the perforated mesh image, that is, the q-th circle from left to right on the p-row or the p-th circle from top to bottom on the q-th column. ;

S450. According to the transformation relationship between the calibrated world coordinate system and the image coordinate system, convert the parameters calculated in the image coordinate system into the world coordinate system, and obtain the circle center coordinates, Dimensional parameters such as radius, horizontal hole spacing and vertical hole spacing;

S460. Compare the center coordinate, radius, horizontal hole spacing and vertical hole spacing of each circular hole in the image of the circular hole punching net in the world coordinate system with the factory standard center coordinate, radius, horizontal hole spacing and vertical hole spacing, and detect Whether the round hole meets the standard.

Claims (3)

1. A method for detecting the appearance quality of a circular hole punched net at least comprises the following steps:

s100, preprocessing a round hole punching net image with the size of (m, n);

s200, virtually setting an initial transverse line H₁₁、H₂₁And vertical line Z₁₁、Z₂₁Gradually adjusting the position of the initial virtual line and obtaining the final intersection point of the circular hole and the virtual line in the circular hole punching net image;

s300, setting virtual upper transverse lines H in batches_1pLower horizontal line H_2pLeft vertical line Z_1qAnd right vertical line Z_2qAnd obtaining the round holes in the round hole punching net image and the batch set virtual line H_1p、H_2p、Z_1q、Z_2qThe point of intersection of (a) with (b),

H₁(x_1pq,y_1pq)、H₂(x_2pq,y_2pq)、H₃(x_3pq,y_3pq)、H₄(x_4pq,y_4pq)

C₁(x_1pq,y_1pq)、C₂(x_2pq,y_2pq)、C₃(x_3pq,y_3pq)、C₄(x_4pq,y_4pq)

wherein p is the p-th row circle in the circular hole punching net image, q is the q-th row circle in the circular hole punching net image, H_1pDenotes the upper transverse line corresponding to the circle of the p-th row, H_2pIndicates the lower horizontal line, Z, corresponding to the p-th row circle_1qIndicates the left vertical line, Z, corresponding to the q-th column circle_2qA right vertical line corresponding to the q-th column circle;

s400, judging the appearance defects of the round holes, and calculating the size parameters of the round holes, such as circle center coordinates, radius, transverse hole distance, longitudinal hole distance and the like by using a small number of intersection points.

2. The method for detecting the appearance quality of the circular hole punched net according to claim 1, wherein an initial transverse line H is set virtually₁₁、H₂₁And vertical line Z₁₁、Z₂₁Step S200 is a process of gradually adjusting the position of the initial virtual line and obtaining a final intersection point of the circular hole and the virtual line in the image to be measured, and at least includes the following steps:

s210, virtually setting two horizontal lines and two vertical lines in the image, and respectively marking the horizontal lines and the vertical lines as upper horizontal lines H₁₁And a lower transverse line H₂₁Left vertical line Z₁₁And right sideVertical line Z₂₁, wherein ,H₁₁ and H₂₁Intersecting the first row of circles, Z₁₁ and Z₂₁Intersecting the first row of circles at an upper transverse line H₁₁Has an initial ordinate of yy₀₁Lower horizontal line H₂₁Has an initial ordinate of yy₁₁Left vertical line Z₁₁Has an initial abscissa of xx₀₁Right vertical line Z₂₁Has an initial abscissa of xx₁₁；

S220. let t be 1, k be 1, g be 0, h be 0, e be 0, yy for ordinate₀₁Upper transverse line H of₁₁And executing S230 to determine the final position yy thereof_01last；

S230, searching a horizontal line with yy ordinate in the image from left to right, and acquiring a pixel coordinate point of the intersection of the horizontal line and the circle:

f₁＝I(i+1,yy)-I(i,yy) i∈[1,m) (1)

wherein I (I, yy) is the pixel value of the image at the position (I, yy), p is the p-th row circle in the round hole punching net image, and q is the q-th column circle in the round hole punching net image; h_t(x_tpq) Satisfy f for the horizontal line₁>The abscissa value of the p-th row at 0 and the q-th column; h_t(y_tpq) Satisfy f for the horizontal line₁>The ordinate value of the p-th row at 0 and q-th column; c_k(x_kpq) Satisfy f for the horizontal line₁<The abscissa value of the p-th row at 0 and the q-th column; c_k(y_kpq) Satisfy f for the horizontal line₁<The ordinate value of the p-th row at 0 and q-th column;

if h is 0 and g is 0, performing S231;

if h is 0 and g is 1, g is g +1, S231 is performed;

if h is 0 and g is 3, performing S231;

if h is 1, executing S322;

if h is 2, performing S323;

s231. calculating H_t-C_kI.e.:

where N is the number of the row of circles,

if g is equal to 0, go to step S232;

if g is 2, go to step S233;

if g is 3, go to step S234;

s232.g ═ g +1, yy ═ yy +1, if g ═ 1, then S230 is performed, otherwise S233 is performed;

S233.c_t＝b_t2-b_t0，g＝g+1，b_t3＝b_t2；

s234, if t is 1 and c_t>0 indicates that the horizontal line is in the upper half of the p-th row circle, the following is performed:

if it is

And e<r, then yy +1, e +1, perform S230;

if it is

And e<r, then the final position of the row of circles is yy, i.e., yy_last＝yy；

If it is

And e>r, judging that the row circle has a defective circle;

if t is 1 and c_t<0, then yy₀₁＝yy₀₁-10, performing S220;

if t is 2 and c_t<0 indicates that the horizontal line is in the lower half of the p-th row circle, the following is performed:

if it is

And e<r, then yy-1, e-e +1, perform S230;

if it is

And e<r, then the final position of the row of circles is yy, i.e., yy_last＝yy；

If it is

And e>r, judging that the row circle has a defective circle;

if t is 2 and c_t>0, then yy₁₁＝yy₁₁+10, go to S240;

wherein ,

d′₁is a circular hole standard aperture known a priori;

if t is 1 and k is 1, yy_01last＝yy_last(ii) a If t is 2 and k is 2, yy_11last＝yy_last；

If t is 2 and k is 2, performing S250, otherwise performing S240;

s240. let t be 2, k be 2, g be 0, h be 0, e be 0, yy for ordinate₁₁Lower transverse line H₂₁And executing S230 to determine the final position yy thereof_11last；

S250. let t be 3, k be 3, g be 0, h be 0, e be 0, and xx for the abscissa₀₁Left vertical line Z of₁₁Go to step S260 to determine its final position xx_01last；

S260, searching a vertical line with the abscissa xx in the image from top to bottom, and acquiring a pixel coordinate point of the intersection of the vertical line and a circle:

f₂＝I(xx,j+1)-I(xx,j) j∈[1,n) (3)

wherein I (xx, j) is a pixel value of the image at the position (xx, j), p is a p-th row circle in the round hole punching net image, and q is a q-th column circle in the round hole punching net image; h_t(x_tpq) Satisfy f for the vertical line₂>The abscissa value of the p-th row at 0 and the q-th column; h_t(y_tpq) Satisfy f for the vertical line₂>The ordinate value of the p-th row at 0 and q-th column; c_k(x_kpq) Satisfy f for the vertical line₂<The abscissa value of the p-th row at 0 and the q-th column; c_k(y_kpq) Satisfy f for the vertical line₂<The ordinate value of the p-th row at 0 and q-th column;

if h is 0 and g is 0, perform S261;

if h is 0 and g is 1, then g is g +1, go to S261;

if h is 0 and g is 3, perform S261;

if h is 1, performing S324;

if h is 2, executing S400;

s261. calculate H_t-C_kI.e.:

where M is the number of circles in the column,

if g is equal to 0, go to step S262;

if g is 2, go to step S263;

if g is 3, go to step S264;

s262, g +1, xx +1, if g +1, then S260 is executed, otherwise S263 is executed;

S263.c_t＝b_t2-b_t0，g＝g+1，b_t3＝b_t2；

s264. if t is 3 and c_t>0 indicates that the horizontal line is in the left half of the q-th column circle, the following operations are performed:

if it is

And e<r, then xx +1, e +1, go to S260;

if it is

And e<r, the final position of the row of circles is xx, namely xx_last＝xx；

If it is

And e>r, judging that the row of circles has a defective circle;

if t is 3 and c_t<0, then xx₀₁＝xx₀₁-10, performing S250;

if t is 4 and c_t<0 indicates that the horizontal line is in the right half of the q-th column circle, the following is performed:

if it is

And e<r, then xx-1, e-e +1, go to S260;

if it is

And e<r, then the final position of the column of circles is yy, i.e., xx_last＝xx；

If it is

And e>r, judging that the row of circles has a defective circle;

if t is 4 and c_t>0, then xx₁₁＝xx₁₁+10, go to S270;

wherein ,

d′₁is a circular hole standard aperture known a priori;

if t is 3 and k is 3, xx_01last＝xx_last(ii) a If t is 4 and k is 4, xx_11last＝xx_last；

If t is 4 and k is 4, performing S300, otherwise performing S270;

s270, let t be 4, k be 4, g be 0, h be 0, e be 0, and xx for the abscissa₁₁Right vertical line Z of₂₁Go to step S260 to determine its final position xx_11last。

3. The method for detecting the appearance quality of the circular hole punching net according to claim 1, wherein the method for detecting the appearance defects of the circular holes is characterized by comprising the following steps of detecting the appearance defects of the circular holes and calculating the dimensional parameters such as the center coordinates, the radius, the transverse hole spacing, the longitudinal hole spacing and the like of the circular hole punching net by using a small number of intersection points, wherein the step S400 at least comprises the following steps:

s410, calculating the coordinate difference value,

u₁＝H₁(x_1pq)-H₁(x_1p(q-1))；v₁＝H₃(y_3pq)-H₃(y_3(p-1)q)； (9)

u₂＝C₁(x_1pq)-C₁(x_1p(q-1))；v₂＝C₃(y_3pq)-C₃(y_3(p-1)q)； (10)

u₃＝H₂(x_2pq)-H₂(x_2p(q-1))；v₃＝H₄(y_4pq)-H₄(y_4(p-1)q)； (11)

u₄＝C₂(x_2pq)-C₂(x_2p(q-1))；v₄＝C₄(y_4pq)-C₄(y_4(p-1)q)； (12)

u₅＝H₁(x_1pq)-C₁(x_1p(q-1))；v₅＝H₃(y_3pq)-C₃(y_3(p-1)q)； (13)

u₆＝H₂(x_2pq)-C₂(x_2p(q-1))；v₆＝H₄(y_4pq)-C₄(y_4(p-1)q)； (14)

s420, judging the defects of the round hole,

u′₁＝u₁(w₁+1)-u₁(w₁)；v′₁＝v₁(s₁+1)-v₁(s₁)； (15)

u′₂＝u₂(w₁+1)-u₁(w₁)；v′₂＝v₂(s₁+1)-v₂(s₁)； (16)

u′₃＝u₃(w₁+1)-u₃(w₁)；v′₃＝v₃(s₁+1)-v₃(s₁)； (17)

u′₄＝u₄(w₁+1)-u₄(w₁)；v′₄＝v₄(s₁+1)-v₄(s₁)； (18)

u′₅＝u₅(w₂+1)-u₅(w₂)；v′₅＝v₅(s₂+1)-v₅(s₂)； (19)

u′₆＝u₆(w₂+1)-u₆(w₂)；v′₆＝v₆(s₂+1)-v₆(s₂)； (20)

wherein ,w₁∈[1,max(q)-1)，w₂∈[1,max(q)-2)，s₁∈[1,max(p)-1)，s₂∈ [1, max (p) -2 ], p is the p-th row circle in the circular hole punching mesh image, q is the q-th row circle in the circular hole punching mesh image;

if it is

Then the round hole has appearance defects, wherein T is a threshold value;

s430, calculating the coordinates and the radius of the circle center,

at H₁、H₂、H₃、H₄、C₁、C₂、C₃、C₄Selecting three points H from the eight points₃(x_3pq,y_3pq)、H₄(x_4pq,y_4pq)、C₁(x_1pq,y_1pq)；

Let A (x)₀,y₀)＝H₃(x_3pq,y_3pq)、B(x₁,y₁)＝H₄(x_4pq,y_4pq)、C(x₂,y₂)＝C₁(x_1pq,y_1pq)

The circle center is marked as (x)_c,y_c) Radius ofr，

wherein ,

s440, calculating the transverse pitch and the longitudinal pitch,

transverse pitch:

longitudinal pitch:

wherein, (p, q) is the qth row and qth column of circles in the round hole punching net image, namely the qth circle from left to right in the row p or the qth circle from top to bottom in the row q;

s450, converting parameters calculated under the image coordinate system into the world coordinate system according to the conversion relation between the calibrated world coordinate system and the image coordinate system to obtain dimensional parameters such as circle center coordinates, radiuses, transverse hole distances, longitudinal hole distances and the like of all round holes in the round hole punching net image under the world coordinate system;

and S460, comparing the circle center coordinate, the radius, the transverse pitch and the longitudinal pitch of each round hole in the round hole punching net image in the world coordinate system with the circle center coordinate, the radius, the transverse pitch and the longitudinal pitch of the factory standard, and detecting whether the round holes meet the standard.

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