CN118328897B - Method for measuring slot hole size of sheet metal workpiece - Google Patents

Abstract

The invention relates to the technical field of machine vision measurement, and discloses a method for measuring the size of a slot hole of a sheet metal workpiece, comprising the following steps: S1: establishing a standard parameter file; S2: logging into an operating system and performing image acquisition; S3: measuring a contour to be detected in the acquired image; S4: comparing an actual value of a measurement result with a standard value in the standard parameter file: if it is less than a tolerance value, output "OK"; otherwise, output "NG"; S5: saving measurement result data; compared with the prior art, the method for measuring the size of a slot hole of a sheet metal workpiece of the invention does not require manual interactive operation on an image to determine features to be measured, overcomes the cumbersome operation of selecting an image through a mouse and fitting it into features when the number of workpiece measurement features is large, and only requires comparing the measurement result with standard data to determine whether it is within the accuracy range, thereby effectively improving the measurement efficiency of such products.

Description

A method for measuring the size of a slot hole of a sheet metal workpiece

Technical Field

The invention relates to the technical field of machine vision measurement, and in particular to a method for measuring the size of a slot hole of a sheet metal workpiece.

Background Art

Sheet metal workpieces are parts or workpieces processed using sheet metal processing technology. In the field of industrial manufacturing, the hole and groove dimensional accuracy of sheet metal workpieces is an important factor in determining product quality.

In traditional measurement, the use of tools such as vernier calipers and micrometers requires contact with the workpiece, which can easily cause scratches on the workpiece surface. In addition, manual inspection is labor-intensive, and the measurement process is easily affected by physiological factors and external interference, making it inefficient.

With the outstanding performance of visual measurement systems in identification, positioning and measurement tasks, visual measurement systems have begun to gradually replace manual measurement.

Currently, most visual measurement devices on the market are imagers or visual measuring instruments, but they are not suitable for sheet metal workpiece measurement. When a sheet metal workpiece has many features to measure, it is necessary to first capture the image and then fit the features one by one on the image, which is inefficient.

Summary of the invention

The purpose of the present invention is to provide a method for measuring the size of a slot hole of a sheet metal workpiece, which is used to solve the above-mentioned technical problem.

A method for measuring the size of a slot hole of a sheet metal workpiece comprises the following steps:

S1: Create standard parameter file:

S11: Convert the PRT.1 file of Pro/ENGINEER to DWG file;

S12: Keep the dimension table information of the DWG file and export it as a CSV file;

S13: Convert the CSV file into an Excel file to obtain an original standard parameter table;

S14: sorting the profiles in the original standard parameter table to obtain a standard parameter file;

The method to sort the contours in the original standard parameter table is:

S141: Record the total number of contours to be detected, the minimum row and column values, and the maximum row and column values: the row value is the basis for distinguishing which row the contours to be sorted start from, and the column value is the basis for distinguishing which contours start from a row;

S142: Determine the rows and columns where all contours are located;

S143: sorting and numbering the contours of the same type according to the row and column values: among the contours of the same type, the contour with the smallest row and column value is the first contour, the contour with the smallest column value is the first contour in the row, and the contour with the largest column value is the last contour in the row;

S2: Log in to the operating system and collect images;

S3: Measure the contour to be detected in the acquired image:

S31: distinguishing contour shapes according to sub-pixel contour roundness and rectangularity;

S32: reordering the selected contours of the same type: reordering and numbering the contours of the same type using the same method as the method of sorting the contours in the original standard parameter table in step S14;

S33: fitting the corresponding contour features and measuring them;

S4: Compare the actual value of the measurement result with the standard value in the standard parameter file: if it is less than the tolerance value, output "OK"; otherwise, output "NG";

S5: Save the measurement result data.

According to an embodiment of the present invention, in step S142, if a contour vertically spans at least two adjacent rows, the contour belongs to the row where its maximum row value falls.

According to one embodiment of the present invention, after step S143: sorting and numbering the same type of contours in sequence according to the row and column values, it also includes step S144: deleting the symbols and data representing the hole depth, countersink and maximum entity requirements in the original standard parameter table, adding symbols representing length information, and after S33: fitting the corresponding contour features and measuring them, the length information is represented by the added length information symbol.

According to one embodiment of the present invention, in step 31, the standard for distinguishing contour shapes based on sub-pixel contour roundness and rectangularity is: the shape of the sub-pixel contour roundness in [0.7, 1.0] is a circle, the shape of the sub-pixel contour rectangularity in [0.8, 0.9] is a groove, and the shape of the sub-pixel contour rectangularity in [0.92, 0.99] is a rounded rectangle.

According to an embodiment of the present invention, in step S33, the method of fitting the corresponding contour features and measuring includes:

According to the order of the circular contours in step S32, the shapes of the sub-pixel contours with roundness in [0.7, 1.0] are sequentially fitted into circles, and the coordinates of the center of the circle and the radius are recorded to obtain the measurement results of the circular holes;

According to the order of the slot profiles in step S32, the shapes with sub-pixel profile rectangularity in [0.8, 0.9] are sequentially fitted into slots. The slot hole consists of a rectangle and two semicircles. The slot profile is fitted into a circle and a straight line to obtain the center and radius parameters, and the minimum circumscribed rectangle of the slot is obtained, and then the overall length of the slot is obtained, and the measurement result of the slot hole is obtained;

According to the sorting of the rounded rectangles in step S32, the shapes with sub-pixel contour rectangularity in [0.92, 0.99] are fitted into rounded rectangles in turn to obtain the minimum circumscribed rectangle of the rounded rectangle, and the length and width of the rounded rectangle are obtained to obtain the measurement result of the rounded rectangle hole.

According to one embodiment of the present invention, before measuring the contour, the operator first logs into the operating system and creates an empty folder for the product to be inspected. The folder is used as a location for storing saved templates, standard parameter files and parameter measurement result files thereof. The standard parameter file established in step S1 and the measurement result data file in step S5 are stored in the folder.

According to an embodiment of the present invention, in step S2: after logging into the operating system, there are three options: S21: template operation, S22: connecting to a camera, and S23: performing measurement;

If there is a template stored in the above folder, the user can select S22: Connect Camera option, the industrial camera will perform image acquisition and send the acquired pictures to the computer, the computer determines the workpiece type based on the acquired pictures, and reads the template from the above folder after the judgment is successful, performs template matching on the image, and then selects S23 option and enters step S3;

If there is no template stored in the above folder, after the user logs in to the operating system, select S21: Template operation, open the template operation interface, connect the camera to capture images, use the captured images to create a template, save the created template to the above folder, return to the system interface, and enter the S22 option.

According to one embodiment of the present invention, the method for creating a template using a captured image is as follows: the operator uses the image captured by the industrial camera to draw an angled rectangle in the image frame, selects the image area and angle to be created as a template, forms a template, and then saves the template to the above-mentioned folder, so that it can be used as a template for comparison with subsequent images obtained through option S22 to determine the type of workpiece.

According to one embodiment of the present invention, in step S4, the method for comparing the actual value of the measurement result with the standard value in the standard parameter file is: use an angled rectangle to fit the virtual intersection of two lines in the upper left corner of the workpiece, and record the relative position of each detection feature and the intersection, and compare and judge according to the dimensional data whose relative position in the standard parameter file is consistent with the measured recorded relative position.

According to an embodiment of the present invention, in step S5: when saving the measurement result data, the measurement result data file is simultaneously output as an Excel table and a PDF file for storage.

Compared with the prior art, the method for measuring the slot size of a sheet metal workpiece of the present invention has the following advantages:

The method for measuring the slot hole size of a sheet metal workpiece of the present invention does not require manual interactive operation on the image to determine the features to be measured, and overcomes the cumbersome operation of selecting the image by mouse and fitting it into features when the number of workpiece measurement features is large. It only needs to compare the measurement result with the standard data to determine whether it is within the accuracy range, which can effectively improve the measurement efficiency of such products.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a PRT.1 file;

Figure 2 is a profile distribution diagram;

Fig. 3 is a schematic diagram of relative position points;

Figure 4 is an example of creating a template file;

Figure 5 is a schematic diagram of PDF file export;

Figure 6 is a schematic diagram of Excel file export;

FIG7 is a flow chart of a method for measuring the size of a slot hole in a sheet metal workpiece;

Figure 8 is a software flow chart of the visual measurement system.

The realization of the functions and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

DETAILED DESCRIPTION

The following will disclose multiple embodiments of the present invention with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. That is, in some embodiments of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

In order to overcome the shortcomings of the prior art, the present invention proposes a method for measuring the slot hole size of a sheet metal workpiece. By performing measurement after modeling processing, not only can the size measurement of various types of slots and holes of the sheet metal workpiece be realized, but also the measurement of different sheet metal workpieces can be realized by creating templates.

Before introducing the present invention, the visual inspection system that supports the measurement method of the present invention is first introduced. The functions of the measurement system must include real-time acquisition of workpiece images, workpiece image processing, real-time measurement of workpiece dimensions, and display of the result interface. The measurement system mainly includes two aspects: hardware and software. The hardware part is mainly composed of four parts: light source, camera, stage, and host computer. The software part is mainly composed of image processing algorithm and interactive interface design. The software system is based on Windows 11, 64-bit operating system, combined with Halcon and C# programming to realize image processing and measurement to realize a multi-type sheet metal workpiece visual measurement system. The system software part is mainly based on the Visual Studio 2022 platform, using the WinForm framework design interface in the C# language, the Halcon visual library to develop high-precision measurement software, and the SQLite database to manage the system's account data, etc. When performing dimensional measurement, the camera resolution and the size of the screen will affect the measurement accuracy. When the required measurement accuracy is known, the minimum resolution required for the camera can be calculated by the formula To calculate, where ε is the directional system accuracy, L is the length of the field of view, and N is the number of directional pixels. For the measurement system of the present invention, the accuracy requirement is 0.1mm and the field of view width and height is 320mm, so it can be solved that at least 3200 pixels are required in a single direction to meet the minimum requirement. Usually in production practice, considering factors such as pixel error and system stability, a camera with a resolution of 3 to 4 times or more of the minimum requirement is generally selected. Because the measurement system of the present invention does not need to measure moving objects, the frame rate requirement is relatively low, so a global shutter or rolling shutter camera can be selected; because this measurement system is a parameter measurement system, a black and white camera can be used. In summary, the present invention uses Hikvision's MV-CH500-90TM-F-NF CMOS global shutter black and white industrial camera, which has a resolution of 7008*7000 and a frame rate of 15.5 fps; in order to reduce the impact of parallax and lens distortion on imaging quality, the present invention uses Ruican's XF-10MDT01090436×120DSS-D-L90 dual telecentric lens, which has a magnification of 0.109, a distortion rate of less than 0.066%, a working distance of 120mm, and a field of view of 110mm. For the selection of light sources, strip light sources, ring light sources, backlight sources, coaxial light sources, etc. can usually be selected. Compared with other light sources, backlight sources have the advantages of improving contrast, eliminating shadows, and enhancing edge features, so the measurement system of the present invention uses backlight sources as the measurement system light source.

Based on the above measurement system, a method for measuring the size of a slot hole of a sheet metal workpiece according to the present invention comprises the following steps:

S1: Create standard parameter file:

S11: Convert the PRT.1 file of Pro/ENGINEER to DWG file;

S12: Keep the dimension table information of the DWG file and export it as a CSV file;

S13: Convert the CSV file into an Excel file to obtain an original standard parameter table;

S14: Sort the profiles in the original standard parameter table to obtain a standard parameter file.

The method to sort the contours in the original standard parameter table is:

S141: Record the total number of contours to be detected, the minimum row and column values, and the maximum row and column values: the row value is the basis for distinguishing which row the contours to be sorted start from, and the column value is the basis for distinguishing which contours start from a row;

S142: Determine the rows and columns where all contours are located; if a contour spans at least two adjacent rows, the contour belongs to the row where its maximum row value falls;

S143: sorting and numbering the contours of the same type according to the row and column values: among the contours of the same type, the contour with the smallest row and column value is the first contour, the contour with the smallest column value is the first contour in the row, and the contour with the largest column value is the last contour in the row;

The following is a detailed description of a method for sorting the profiles in the original standard parameter table using an embodiment:

Please refer to FIG2. As shown in FIG2, the rectangular box is the contour to be sorted, and the number is the sorted result. The following will take the image in FIG2 as an example to introduce in detail the method for reordering the contour to be detected: As shown in FIG2, the contours in the image are in three rows and three columns from top to bottom and from left to right. The contour in the first row and the first column is the first contour, which is also the first contour in the first row, recorded as contour 1. When a horizontal line is swept across the image from top to bottom, contour 1 is detected. At least one horizontal line B passes through contour 4 and contour 2 at the same time. In this row, contour 1 is the beginning of the first row, contour 2 belongs to the first row, and contour 4 spans the first row and the second row. Here, it is necessary to judge whether contour 4 belongs to the first row or the second row. A horizontal line is swept across the image pixel by pixel from top to bottom. When it touches the rectangle, the row value corresponding to the straight line is marked as the minimum row value of the rectangle. When it leaves the rectangle, the row value of the straight line is marked as the maximum row value of the rectangle. Line A is the minimum row value of contour 4, line D is the maximum row value of contour 4, and line C is the minimum row value of contour 3. Since the minimum row value of contour 3 is greater than the minimum row value of contour 4 and less than the maximum row value of contour 4, and the maximum row value of contour 4 is less than the maximum row value of contour 3, contour 4 is determined to belong to the second row. In this row, the column value of contour 3 is less than the column value of contour 4, and the column value of contour 4 is less than the column value of contour 5, so contour 3 is the beginning of the second row; similarly, contour 6 can be obtained as the beginning of the third row; after obtaining the starting contour of each row, the sequence numbers of other contours in the same row are determined. In the first row, the column value of contour 2 is greater than that of contour 1, so it is named contour 2; in the second row, contour 4 has been determined as the sorted contour of the second row, and its column value is greater than that of contour 3, so it is named contour 4, and the column value of contour 5 is greater than that of contour 4, so it is named contour 5; similarly, the sorting of contours 6 and 7 can be obtained. In the above manner, the contours to be detected can be re-sorted.

S144: deleting the symbols and data representing the hole depth, countersink and maximum entity requirements in the original standard parameter table, adding a symbol representing the length information, and after fitting the corresponding contour features and measuring them in S33: the length information is represented by the added length information symbol;

After sorting and numbering, some parameter names and standard values need to be manually modified. Because in the GDT font, n is the diameter symbol, x represents the hole depth symbol, v represents the countersink symbol, and M represents the maximum entity requirement. Since the visual measurement system in the present invention is a 2D visual measurement system, it is impossible to measure depth information such as hole depth, so it is necessary to manually exclude parameters x, M and v, and the specific parameters of the groove are marked on the workpiece design drawing rather than in the parameter table, so it is necessary to manually add the parameters of the groove into the table, where the length information of the groove is not represented by letters in the original parameters, so the present invention uses a combination of letter l and the actual standard parameter value to represent its standard value and add it to the standard parameter file.

S2: Log in to the operating system and collect images;

The operating system has an administrator interface and an operator interface. The main function of the administrator interface is to add, delete, and modify the administrator's rights of internal accounts. The main function of the operator interface is to connect to the camera, collect images, display, measure, create templates, compare data information, save and export, etc. When measuring the contour to be detected, the operator interface is logged in;

Before measuring the contour, the operator first logs into the operating system and creates an empty folder for the product to be inspected. The folder is used as the location for storing the saved templates, standard parameter files and their parameter measurement result files. The standard parameter file established in step S1 and the measurement result data file in step S5 are stored in this folder.

When measuring, in order to obtain the placement angle of the workpiece and the standard parameter file information, it is necessary to create a template for the workpiece in advance so as to obtain the workpiece angle and matching information later; the created template is stored in the created folder.

After logging into the operating system from the operator interface, there are three options: S21: Template operation, S22: Connect camera, and S23: Perform measurement.

If there are templates stored in the above folder, the user can select S22: Connect camera option, the industrial camera will perform image acquisition and send the acquired pictures to the computer. The computer determines the type of workpiece based on the acquired pictures, and reads the template from the above folder after the judgment is successful, performs template matching on the image, and then selects S23 option and enters step S3.

If there is no template stored in the above folder, after the user logs in to the operating system, select S21: Template operation, open the template operation interface, connect the camera to capture images, use the captured images to create templates, save the created templates to the above folder, return to the system interface, and enter the S22 option.

Please refer to Figure 4. The method for creating a template using the captured image is as follows: the operator uses the image captured by the industrial camera to draw an angled rectangle in the image frame, selects the image area and angle to be created as a template, forms a template, and then saves the template to the above folder so that it can be used as a template for comparison with subsequent images obtained through option S22 to determine the type of workpiece.

S3: Measure the contour to be detected in the acquired image:

S31: distinguishing contour shapes according to sub-pixel contour roundness and rectangularity;

The standard for distinguishing contour shapes based on sub-pixel contour roundness and rectangularity is: the shape with sub-pixel contour roundness in [0.7, 1.0] is a circle, the shape with sub-pixel contour rectangularity in [0.8, 0.9] is a groove, and the shape with sub-pixel contour rectangularity in [0.92, 0.99] is a rounded rectangle.

S32: reordering the selected contours of the same type: reordering and numbering the contours of the same type using the same method as the method of sorting the contours in the original standard parameter table in step S14;

S33: Fitting corresponding contour features and measuring them.

Methods for fitting corresponding contour features and measuring include:

According to the order of the circular contours in step S32, the shapes of the sub-pixel contours with roundness in [0.7, 1.0] are sequentially fitted into circles, and the coordinates of the center of the circle and the radius are recorded to obtain the measurement results of the circular holes;

According to the order of the slot profiles in step S32, the shapes with sub-pixel profile rectangularity in [0.8, 0.9] are sequentially fitted into slots. The slot hole consists of a rectangle and two semicircles. The slot profile is fitted into a circle and a straight line to obtain the center and radius parameters, and the minimum circumscribed rectangle of the slot is obtained, and then the overall length of the slot is obtained, and the measurement result of the slot hole is obtained;

According to the sorting of the rounded rectangles in step S32, the shapes with sub-pixel outline rectangularity in [0.92, 0.99] are sequentially fitted into rounded rectangles to obtain the minimum circumscribed rectangle of the rounded rectangle, and the length and width of the rounded rectangle are obtained to obtain the measurement result of the rounded rectangle hole;

S4: Compare the actual value of the measurement result with the standard value in the standard parameter file: if it is less than the tolerance value, output "OK"; otherwise, output "NG".

The method for comparing the actual value of the measurement result with the standard value in the standard parameter file is as follows: use an angled rectangle to fit the virtual intersection of the two lines in the upper left corner of the workpiece, and record the relative position of each detection feature and the intersection, and compare and judge the dimensional data that is consistent with the relative position in the standard parameter file and the measured recorded relative position.

When the measurement results are compared with the standard parameter file, the result number after the measurement results are sorted is not necessarily the same as the standard parameter file sorting, so the measurement results need to be re-sorted. When the measurement system measures the workpiece to obtain the diameter parameters, it also records the position information for comparison with the standard parameters. Because the position information provided in the standard parameter file uses the upper left corner of the workpiece as the workpiece origin rather than the relative position of the image origin. The present invention uses an angled rectangle to fit the workpiece and then solves the virtual intersection of its two sides closest to the origin, and records the relative position of each detection feature and the intersection. As shown in Figure 3, when assigning values to circular holes, the relative position of the center of the circle and the intersection is used, the relative position of the center of the upper arc and the intersection is used for slot-type holes, and the relative position of the midpoint of the upper edge and the intersection is used for rounded rectangular holes as the position information written.

After the measurement system obtains the relative position parameter information in the standard parameters and the measurement results, it compares them one by one. When the relative position of the workpiece detection feature (circular hole, slotted hole, rounded rectangular hole) to the workpiece origin is the same as that in the standard parameter file, the standard value in the standard parameter file is written into the column of the standard value to be filled in the measurement result; the actual measured value is filled in the column of the actual value; then the standard value and the actual value are calculated by difference to obtain the absolute value. If it is less than the tolerance, "OK" is output in the column of the measurement result to be filled, otherwise "NG" is output;

S5: Save the measurement result data: When saving the measurement result data, the measurement result data file is simultaneously exported as an Excel table and a PDF file for storage. The sheet metal workpiece slot hole size measurement method of the present invention exports PDF and Excel file formats for the convenience of manual recording and reference. PDF files can avoid font garbled characters and inconsistent formats of different devices; Excel files are conducive to manual statistical data.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The method for measuring the slot hole size of the sheet metal workpiece is characterized by comprising the following steps of:

s1: establishing a standard parameter file:

S11: the PRT.1 file of Pro/ENGINEER is transferred to a DWG file;

S12: reserving size table information of the DWG file and exporting the size table information into a CSV file;

s13: converting the CSV file into an Excel file to obtain an original standard parameter table;

s14: sequencing the outlines in the original standard parameter table to obtain a standard parameter file;

The method for sequencing the outlines in the original standard parameter table comprises the following steps:

S141: recording the total number, the minimum rank value and the maximum rank value of the outlines to be detected: the row values are the basis for distinguishing which row the contours to be ordered start, and the column values are the basis for distinguishing which contours start;

S142: determining the rows and columns of all outlines;

S143: the contours of the same type are orderly ordered and numbered according to the rank value: among the similar contours, the contour with the smallest row and column value is the first contour, the contour with the smallest column value is the first contour of the row, and the contour with the largest column value is the last contour of the row;

S2: logging in an operating system to collect images;

S3: measuring the contour to be detected in the acquired image:

S31: distinguishing the outline shape according to the roundness and the rectangularity of the sub-pixel outline;

S32: reordering the screened profiles of the same type: re-ordering and numbering the same types of contours by adopting the same method as the method for ordering contours in the original standard parameter table in the step S14;

S33: fitting out corresponding contour features and measuring;

S4: comparing the actual value of the measurement result with the standard value in the standard parameter file: if the tolerance value is smaller than the tolerance value, outputting OK; otherwise, outputting 'NG';

S5: and saving the measurement result data.

2. The method according to claim 1, wherein in step S142, if one contour spans at least two adjacent rows longitudinally, the contour belongs to the row in which the maximum row value falls.

3. The method for measuring the slot size of a sheet metal workpiece according to claim 1, wherein in step S143: after the contours of the same type are sequentially ordered and numbered according to the rank values, the method further comprises the step S144 of: deleting the symbols and data representing the hole depth, the counter bore and the maximum entity requirement in the original standard parameter table, adding the symbols representing the length information, and in S33: after fitting the corresponding profile features and measuring, the length information is symbolized with increased length information.

4. The method according to claim 1, wherein in step 31, the criterion for distinguishing the contour shape according to the roundness and the rectangle degree of the subpixel contour is: the shape of the roundness of the sub-pixel outline [0.7,1.0] is circular, the shape of the rectangle of the sub-pixel outline [0.8,0.9] is groove-shaped, and the shape of the rectangle of the sub-pixel outline [0.92,0.99] is round rectangle.

5. The method for measuring slot dimensions of sheet metal workpieces according to claim 4, wherein in step S33, the method for fitting and measuring the corresponding profile features comprises:

Sequentially fitting the shapes of the circular outlines of the sub-pixels with the roundness of [0.7,1.0] into circles according to the sequence of the circular outlines in the step S32, and recording the circle center coordinates and the radius of the circles to obtain the measurement result of the circular holes;

According to the sequence of the groove profile in the step S32, sequentially fitting the shape with the sub-pixel profile rectangle degree of [0.8,0.9] into a groove shape, wherein the groove shape hole consists of a rectangle and two semi-circles, fitting the groove shape profile into a circle and a straight line to obtain circle center and radius parameters, obtaining the minimum external rectangle of the groove shape, further obtaining the overall length of the groove shape, and obtaining the measurement result of the groove shape hole;

and (3) according to the sorting of the rounded rectangle in the step S32, sequentially fitting the shape with the sub-pixel outline rectangle degree of [0.92,0.99] into the rounded rectangle to obtain the minimum circumscribed rectangle of the rounded rectangle, and obtaining the length and the width of the rounded rectangle to obtain the measurement result of the rounded rectangular hole.

6. The method according to claim 1, wherein before measuring the contour, an operator logs in to an operating system and creates an empty folder for the product to be tested, which is used as a place for storing the saved templates, standard parameter files and parameter measurement result files thereof, and the standard parameter files created in step S1 and the measurement result data files in step S5 are stored in the folder.

7. The method for measuring the slot size of a sheet metal workpiece according to claim 6, wherein in step S2: after logging into the operating system, there are: s21: template operation, S22: connection camera, S23: three options for measurement are performed;

If templates are stored in the folder, the user may select S22: connecting camera options, acquiring images by the industrial camera, sending acquired pictures to a computer, judging the type of a workpiece by the computer according to the acquired pictures, reading templates from the folders after judging successfully, matching the templates with the images, selecting an S23 option and entering a step S3;

If the folder does not store templates, after the user logs in the operating system, S21 is selected: and (3) template operation, namely opening a template operation interface, connecting a camera to acquire a picture, creating a template by using the acquired picture, storing the created template in the folder, returning to a system interface, and entering an S22 option.

8. The method for measuring the slot size of a sheet metal workpiece according to claim 7, wherein the method for creating the template by using the acquired picture is as follows: the operator draws an angled rectangle in the image frame by using the image acquired by the industrial camera, selects the image area and the angle to be created into the template to form the template, and then saves the template into the folder so as to be used as the template to compare the subsequent images acquired by the option S22, thereby judging the type of the workpiece.

9. The method for measuring the slot size of the sheet metal workpiece according to claim 1, wherein in the step S4, the method for comparing the actual value of the measurement result with the standard value in the standard parameter file is as follows: and fitting the workpiece with an angled rectangle to obtain a virtual intersection point of two lines at the left upper corner of the workpiece, recording the relative positions of each detection feature and the intersection point, and comparing and judging according to the size data of which the relative positions of the standard parameter files are consistent with the measured relative positions.

10. The method for measuring the slot size of a sheet metal workpiece according to claim 1, wherein in step S5: when the measurement result data is stored, the measurement result data file outputs an Excel form and a PDF file for storage.