Automatic detection method for height of longitudinal rib of disc screw

Abstract

This invention belongs to the field of automatic detection technology and discloses an automatic detection method for the height of the longitudinal ribs of a coiled snail, comprising the following steps: S1, placing the longitudinal ribs of the coiled snail horizontally and acquiring an image of the snail surface using an industrial camera; S2, preprocessing the image of the snail surface and extracting the surface contour; S3, connecting the ends of the longitudinal ribs; S4, removing irregular contours in the middle of the snail; S5, calibrating the pixels, calculating the height of the longitudinal ribs, and outputting the result. This invention can efficiently complete the automatic measurement of the height of the longitudinal ribs of a coiled snail, freeing workers from tedious manual labor and improving work efficiency.

Description

Technical Field

[0001] This invention belongs to the field of automatic detection technology, specifically relating to an automatic detection method for the height of the longitudinal ribs of a spiral coil. Background Technology

[0002] Spiral rebar is a type of hot-rolled ribbed steel bar with a spiral shape and a diameter typically between 6-14 mm.

[0003] As a reinforcing steel bar in engineering construction, the height of the longitudinal ribs of coiled rebar determines the tensile strength of concrete. Currently, the detection of the longitudinal rib height of coiled rebar mainly relies on manual measurement, which has problems such as low work efficiency. According to national standards, the height of the longitudinal ribs at three different locations needs to be tested when coiled rebar leaves the factory, and manual testing often takes 8 to 10 seconds per rebar.

[0004] Currently, there is no mature technology for the automatic detection and optimization of longitudinal ribs in rebar. Patent document CN202010210213.2 discloses a device for measuring the oblique angle of longitudinal ribs in seismic-resistant HRB400E-Z rebars. This method is mainly used to detect the oblique angle of the longitudinal ribs, rather than the height of the longitudinal ribs. Patent document CN202420918523.3 discloses a device for measuring the torsion angle of longitudinal ribs in rebars. This device uses a vernier caliper and a baffle to measure the torsion angle of the longitudinal ribs. However, it should be noted that this device is still a manual measurement, and the work efficiency is not improved. Patent document CN202210623691.5 discloses a method and device based on floating sensing of the position of longitudinal ribs in rebars. This device includes a rebar rotating device, a floating part, and sensors. Its working principle is as follows: first, the rebar is fixed, and the groove of the floating part is made to be on the same plane as the set longitudinal rib of the rebar. Then, the rebar is rotated, and the height of the longitudinal rib is measured by the sensor. The biggest drawback of this device is that fixing the rebar takes a lot of time to ensure measurement accuracy.

[0005] In summary, existing detection technologies cannot efficiently complete the automatic measurement of the height of the longitudinal ribs of coiled spirals. In order to improve work efficiency and liberate workers from tedious physical labor, it is urgent to develop an automatic detection method for the height of the longitudinal ribs of coiled spirals. Summary of the Invention

[0006] The purpose of this invention is to provide an automatic detection method for the height of the longitudinal ribs of coiled screws, in order to solve the problem that existing detection technologies mentioned in the background art cannot efficiently complete the automatic measurement of the height of the longitudinal ribs of coiled screws, thereby improving work efficiency and freeing workers from tedious manual labor.

[0007] To achieve the above objectives, the present invention provides an automatic detection method for the height of the longitudinal ribs of a spiral coil, comprising the following steps:

[0008] S1. Place the longitudinal ribs of the coiled snail horizontally and use an industrial camera to capture images of the surface of the coiled snail.

[0009] S2. Preprocess the image of the spiral snail surface and extract the surface contour of the spiral snail;

[0010] S3. Connect the first and last edges of the longitudinal ribs of the spiral coil;

[0011] S4. Remove the irregular outline in the middle of the spiral;

[0012] S5. Calibrate the pixels, calculate the height of the longitudinal ribs of the spiral, and output the result.

[0013] In one specific implementation, step S2 is as follows:

[0014] S21. Perform grayscale, filtering, and adaptive binarization processing on the surface image of the spiral in sequence;

[0015] S22. After binary processing, edge detection is performed on the image, and edge contours are extracted.

[0016] In one specific implementation, in step S21, the cvtColor, GaussianBlur, and adaptiveThreshold functions are used to perform grayscale, filtering, and adaptive binarization processing on the surface image of the snail.

[0017] In one specific implementation, in step S22, the findContours function is used to extract the edge contour of the spiral.

[0018] In one specific implementation, step S3 is as follows:

[0019] S31. Set the radius range according to the inner diameter of the spiral of the coiled screw;

[0020] S32. Detect the center of each contour circle in sequence, and record the contour and the center of each circle;

[0021] The contours are, in order: l1, l2, ..., l n The centers of the circles are, in order: O1, O2, ..., O n , where O1 is the center of the circle corresponding to contour l1;

[0022] S33. Extract the coordinates of the end point l corresponding to contour l1. 1m (x) 1m y 1m The coordinates of the starting point l corresponding to contour l2 2q (x) 2q y 2q );

[0023] S34. Calculate the center O1(x) of the circle.O1 y O1 The distance between the two points mentioned above is denoted as a. 1m a 2q The formula is as follows:

[0024] ;

[0025] ;

[0026] S35, when a 1m =a 2q When, then with O1 as the center, a 1m Let l be the radius, and point l be... 1m and point l 2q Connect them; when a 1m ≠a 2q In this case, the two points mentioned above will not be connected;

[0027] S36. Extract the coordinates of the last point l corresponding to contour l2 again. 2m (x) 2m y 2m The coordinates of the starting point l corresponding to contour l3 3q (x) 3q y 3q ), calculate the center O2 (x O2 y O2 The distance between the two points mentioned above is used to repeat steps S34 and S35, and so on, until all contours are connected.

[0028] In one specific implementation, in step S32, the HoughCircles function is used to detect the center of the edge contour.

[0029] In one specific implementation, step S4 is as follows:

[0030] S41. Perform contour detection again on the image after step S3, extract the coordinate points of each contour, mark the points with an abscissa of 0, and then compare the ordinates of the above points. The contour corresponding to the point with the smallest ordinate is the inner contour of the spiral. n The contour corresponding to the point with the largest ordinate is the outer contour l of the spiral. w .

[0031] S42. Eliminate the remaining contours.

[0032] In one specific implementation, step S5 specifically includes:

[0033] S51. Pixel calibration is performed, that is, the physical size W of each pixel is calculated, using the following formula:

[0034] ;

[0035] In the formula: K is the length of the camera chip; d w d is the object distance; j U is the focal length, and U is the number of pixels along the length of the image.

[0036] S52. In the inner contour of the spiral, find the points corresponding to the horizontal coordinates U / 4, U / 2, and 3U / 4 respectively, and denote them as follows: , , ;

[0037] S53. Calculate the distance between each point on the outer contour and the above three points respectively, and denote the minimum distance as M1, M2, and M3; M1 is the minimum distance between each point on the outer contour and point T1.

[0038] S54. Calculate the height of the longitudinal ribs of the spiral thread and output the relevant results; the formula is as follows:

[0039] ;

[0040] ;

[0041] ;

[0042] In the formula: d g This refers to the nominal diameter of the spiral snail.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] This invention can efficiently and automatically measure the height of the longitudinal ribs of spiral coils, freeing workers from tedious manual labor and improving work efficiency.

[0045] This invention greatly improves the detection efficiency of the longitudinal rib height of spiral coils. Manual detection often takes 8 to 10 seconds per coil, while this invention only takes 0.5 seconds per coil, increasing the detection efficiency by more than 15 times.

[0046] This invention improves the accuracy of detecting the height of the longitudinal ribs of the spiral coil. Compared with manual detection, the maximum error of this invention is only 0.2%.

[0047] This invention is highly practical, easy for enterprises to adapt, and conducive to in-depth cooperation between industry, academia, and research.

[0048] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The present invention will now be described in further detail. Attached Figure Description

[0049] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0050] Figure 1 This is a flowchart of the spiral longitudinal rib height detection process according to an embodiment of the present invention;

[0051] Figure 2 This is an image of the surface of a coiled snail captured by an industrial camera according to an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the edge contour of a spiral in one embodiment of the present invention;

[0053] Figure 4 This is a schematic diagram of the spiral outline connection according to an embodiment of the present invention; wherein, l1, l2, l3, and l4 are the names of each outline, l 1m (x) 1m y 1m () represents the coordinates of the final point of contour l1, l 2q (x) 2q y 2q () represents the coordinates of the starting point of contour l2;

[0054] Figure 5 This is a schematic diagram of the inner and outer contours of a spiral in an embodiment of the present invention; wherein, l n For the inner contour of the spiral, l w The outer contour of the spiral;

[0055] Figure 6 This is a schematic diagram illustrating the minimum distance calculation of the inner and outer contours of a spiral shell according to an embodiment of the present invention; wherein, , , These are the points with horizontal coordinates U / 4, U / 2, and 3U / 4 on the inner contour of the spiral, respectively. M1, M2, and M3 are the minimum distances between the outer contour of the spiral and T1, T2, and T3, respectively. Detailed Implementation

[0056] The embodiments of the present invention will be described in detail below. The specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0057] This invention provides an automatic detection method for the height of the longitudinal ribs of a spiral coil, comprising the following steps:

[0058] S1. Place the spiral ribs of the spiral horizontally and use an industrial camera to capture images of the spiral surface.

[0059] S2. Preprocess the image of the spiral snail surface and extract the surface contour of the spiral snail;

[0060] Step S2 is as follows:

[0061] S21. Perform grayscale, filtering, and adaptive binarization processing on the surface image of the spiral in sequence;

[0062] In step S21, the cvtColor, GaussianBlur, and adaptiveThreshold functions are used to perform grayscale, filtering, and adaptive binarization processing on the surface image of the snail.

[0063] S22. After binary processing, edge detection is performed on the image, and edge contours are extracted.

[0064] In step S22, the findContours function is used to extract the edge contour of the spiral.

[0065] S3. Connect the first and last edges of the longitudinal ribs of the spiral coil;

[0066] Step S3 is as follows:

[0067] S31. Set the radius range according to the inner diameter of the spiral of the coiled screw;

[0068] S32. Sequentially detect the center of each contour circle and record the contour and center of each circle.

[0069] The contours are, in order: l1, l2, ..., l n The centers of the circles are, in order: O1, O2, ..., O n , where O1 is the center of the circle corresponding to contour l1;

[0070] In step S32, the HoughCircles function is used to detect the center of the edge contour.

[0071] S33. Extract the coordinates of the end point l corresponding to contour l1. 1m (x) 1m y 1m The coordinates of the starting point l corresponding to contour l2 2q (x) 2q y 2q );

[0072] S34. Calculate the center O1(x) of the circle. O1 y O1 The distance between the two points mentioned above is denoted as a. 1m a 2q The formula is as follows:

[0073] ;

[0074] ;

[0075] S35, when a1m =a 2q When, then with O1 as the center, a 1m Let l be the radius, and point l be... 1m and point l 2q Connect them. When a 1m ≠a 2q In this case, the two points mentioned above will not be connected;

[0076] S36. Extract the coordinates of the last point l corresponding to contour l2 again. 2m (x) 2m y 2m The coordinates of the starting point l corresponding to contour l3 3q (x) 3q y 3q ), calculate the center O2 (x O2 y O2 The distance between the two points mentioned above is used to repeat steps S34 and S35, and so on, until all contours are connected.

[0077] S4. Remove the irregular outline in the middle of the spiral;

[0078] Step S4 is as follows:

[0079] S41. Perform contour detection again on the image after step S3, extract the coordinate points of each contour, mark the points with an abscissa of 0, and then compare the ordinates of the above points. The contour corresponding to the point with the smallest ordinate is the inner contour of the spiral. n The contour corresponding to the point with the largest ordinate is the outer contour l of the spiral. w .

[0080] S42. Eliminate the remaining contours.

[0081] S5. Calibrate the pixels, calculate the height of the longitudinal ribs of the spiral, and output the result.

[0082] Step S5 is as follows:

[0083] S51. Pixel calibration is performed, that is, the physical size W of each pixel is calculated, using the following formula:

[0084] ;

[0085] In the formula: K is the length of the camera chip; d w d is the object distance; j U is the focal length, and U is the number of pixels along the length of the image.

[0086] S52. In the inner contour of the spiral, find the points corresponding to the horizontal coordinates U / 4, U / 2, and 3U / 4 respectively, and denote them as follows: , , ;

[0087] S53. Calculate the distance between each point on the outer contour and the above three points respectively, and denote the minimum distance as M1, M2, and M3; M1 is the minimum distance between each point on the outer contour and point T1.

[0088] S54. Calculate the heights h1, h2, and h3 of the longitudinal ribs of the spiral thread and output the relevant results; the formula is as follows:

[0089] ;

[0090] ;

[0091] ;

[0092] In the formula: d g This refers to the nominal diameter of the spiral snail.

[0093] Example 1

[0094] This invention provides an automatic detection method for the height of the longitudinal ribs of a spiral coil, the detection process of which is as follows: Figure 1 As shown. Specifically, it includes the following steps:

[0095] First, the longitudinal ribs of the coiled snail are placed horizontally, and an industrial camera is used to capture images of the snail's surface. The surface images of the coiled snail are as follows: Figure 2 As shown in the image. Then, the cvtColor, GaussianBlur, and adaptiveThreshold functions are used to perform grayscale, filtering, and adaptive binarization processing on the surface image of the coiled snail. After adaptive binarization, the findContours function is used to extract the edge contour of the coiled snail. A schematic diagram of the coiled snail edge contour extraction is shown below. Figure 3 As shown. Next, the radius range is set to (300, 600). The HoughCircles function is used to detect the center of the edge contour, and the contours and their centers are recorded one by one. The contours are named as follows: l1, l2, ..., l n The centers of the circles are, in order: O1, O2, ..., O n O1 is the center of the circle corresponding to contour l1.

[0096] Extract the coordinates of the last point l corresponding to contour l1 respectively. 1m (1110, 446) corresponds to the starting point coordinates l of contour l2. 2q(1155, 450) After calculation, the distances of the two points mentioned above from the center O1 (1472, -2956) are both 3421 pixels. Therefore, these two points are connected. It should be noted that if the distances of the two points from the center are not equal, no connection is made. This process is repeated until all contours are connected. The contour connection diagram is shown below. Figure 4 As shown.

[0097] Perform contour detection on the image again, extract the coordinate points of each contour, mark the points with an x-coordinate of 0, and then compare the y-coordinates of the above points. The contour corresponding to the point with the smallest y-coordinate is the inner contour of the spiral. n The contour corresponding to the point with the largest ordinate is the outer contour l of the spiral. w A schematic diagram of the inner and outer contours is shown below. Figure 5 As shown. Eliminate the remaining contours.

[0098] Based on parameters such as object distance, focal length, and chip size, the physical size of each pixel is calculated to be 0.221mm. Then, on the inner contour, three points corresponding to horizontal coordinates 736, 1472, and 2208 are found, and the minimum distances from these points to the points on the outer contour are calculated to be 41.3, 41.5, and 41.7 pixels, respectively. Finally, based on the physical size of each pixel and the nominal diameter of the screw (8mm), the corresponding longitudinal rib heights are calculated to be 0.564mm, 0.586mm, and 0.608mm. A schematic diagram of the minimum distance calculation is shown below. Figure 6 As shown.

[0099] To verify the accuracy of the present invention, the actual heights of the longitudinal ribs corresponding to the above three points were measured using vernier calipers and found to be 0.565mm, 0.587mm, and 0.607mm respectively. Comparing the test results of the present invention, it can be seen that the maximum error of the present invention is only 0.2%.

[0100] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions and substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An automatic detection method for the height of longitudinal ribs in spiral coils, characterized in that, Includes the following steps: S1. Place the longitudinal ribs of the coiled snail horizontally and use an industrial camera to capture images of the surface of the coiled snail. S2. Preprocess the image of the spiral snail surface and extract the surface contour of the spiral snail; S3. Connect the beginning and end of the longitudinal ribs of the spiral coil, specifically: S31. Set the radius range according to the inner diameter of the spiral of the coiled screw; S32. Detect the center of each contour circle in sequence, and record the contour and the center of each circle; The contours are, in order: l1, l2, ..., l n The centers of the circles are, in order: O1, O2, ..., O n , where O1 is the center of the circle corresponding to contour l1; S33. Extract the coordinates of the end point l corresponding to contour l1. 1m (x) 1m y 1m The coordinates of the starting point l corresponding to contour l2 2q (x) 2q y 2q ); S34. Calculate the center O1(x) of the circle. O1 y O1 The distance between the two points mentioned above is denoted as a. 1m a 2q The formula is as follows: ； ； S35, when a 1m =a 2q When, then with O1 as the center, a 1m Let l be the radius, and point l 1m and point l 2q Connect them; when a 1m ≠a 2q In this case, the two points mentioned above will not be connected; S36. Extract the coordinates of the last point l corresponding to contour l2 again. 2m (x) 2m y 2m The coordinates of the starting point l corresponding to contour l3 3q (x) 3q y 3q ), calculate the center O2 (x O2 y O2 Repeat steps S34 and S35 to find the distance between the two points mentioned above, and repeat this process until all contours are connected. S4. Remove the irregular outline in the middle of the spiral; S5. Calibrate the pixels, calculate the height of the longitudinal ribs of the spiral, and output the result.

2. The automatic detection method for the height of the longitudinal ribs of the spiral coil according to claim 1, characterized in that, Step S2 is as follows: S21. Perform grayscale, filtering, and adaptive binarization processing on the surface image of the spiral in sequence; S22. After binary processing, edge detection is performed on the image, and edge contours are extracted.

3. The automatic detection method for the height of the longitudinal ribs of the spiral coil according to claim 1, characterized in that, In step S21, the cvtColor, GaussianBlur, and adaptiveThreshold functions are used to perform grayscale, filtering, and adaptive binarization processing on the surface image of the snail.

4. The automatic detection method for the height of the longitudinal ribs of the spiral coil according to claim 1, characterized in that, In step S22, the findContours function is used to extract the edge contour of the spiral.

5. The automatic detection method for the height of the longitudinal ribs of the spiral coil according to claim 1, characterized in that, In step S32, the HoughCircles function is used to detect the center of the edge contour.

6. The automatic detection method for the height of the longitudinal ribs of the spiral coil according to claim 1, characterized in that, Step S4 is as follows: S41. Perform contour detection again on the image after step S3, extract the coordinate points of each contour, mark the points with an abscissa of 0, and then compare the ordinates of the above points. The contour corresponding to the point with the smallest ordinate is the inner contour of the spiral. n The contour corresponding to the point with the largest ordinate is the outer contour l of the spiral. w ; S42. Eliminate the remaining contours.

7. The automatic detection method for the height of the longitudinal ribs of the spiral coil according to claim 1, characterized in that, Step S5 is as follows: S51. Pixel calibration is performed, that is, the physical size W of each pixel is calculated, using the following formula: ； In the formula: K is the length of the camera chip; d w d is the object distance; j U is the focal length, and U is the number of pixels along the length of the image; S52. In the inner contour of the spiral, find the points corresponding to the horizontal coordinates U / 4, U / 2, and 3U / 4 respectively, and denote them as follows: , , ; S53. Calculate the distance between each point on the outer contour and the above three points respectively, and denote the minimum distance as M1, M2, and M3; M1 is the minimum distance between each point on the outer contour and point T1. S54. Calculate the height of the longitudinal ribs of the spiral thread and output the relevant results; the formula is as follows: ； ； ； In the formula: d g This refers to the nominal diameter of the spiral snail.

Images