A bolt through-hole rate calculation method based on laser point cloud measured values

Abstract

The application provides a bolt hole rate calculation method based on laser point cloud measured values, which comprises the following steps: obtaining the planar projection point cloud of the first screw hole and the second screw hole on the intersection plane between the first screw hole and the second screw hole based on the circular feature information of the first screw hole and the second screw hole in the current screw hole group; obtaining a binary image based on the planar projection point cloud; calculating the maximum inscribed circle radius in the binary image, comparing the maximum inscribed circle radius with the bolt radius and outputting the comparison result; repeating the above steps to obtain the comparison results of the remaining screw hole groups; then taking the ratio of the number of the screw hole groups through which the bolt can pass to the number of all the screw hole groups as the bolt hole rate. Through the method, the structural feature information inside the screw hole group can be reflected on the planar projection point cloud obtained by projection, a more accurate screw hole group model is introduced, and the parameter calibration process is optimized, so that the error problem caused by ignoring the screw hole roundness and structural feature information in the prior art is effectively solved.

Description

Technical Field

[0001] This application relates to the field of bolt assembly technology, specifically to a method for calculating the bolt through-hole ratio based on measured values ​​of laser point clouds. Background Technology

[0002] Laser scanning technology and point cloud data are increasingly used in industrial fields, especially in precision assembly and quality control. In the construction of large buildings such as bridges, particularly steel structures, bolted connections are one of the most common connection methods. Proper bolt installation is crucial for ensuring the stability and safety of the structure. Therefore, monitoring and verifying the alignment accuracy of bolt holes has become an important quality control step.

[0003] Traditional methods typically require manual inspection to determine the alignment of bolt holes. This approach is not only inefficient but also susceptible to human error. With advancements in laser scanning technology, laser point clouds can be used to quickly and accurately acquire the geometric information of components. By analyzing this point cloud data, automated algorithms can be developed to assess the through-hole rate of bolt holes, i.e., the proportion of pre-assembled bolts that can pass smoothly through the holes.

[0004] An efficient method for calculating bolt through-hole ratio based on laser point clouds can provide engineers with real-time quality feedback, helping them make quick decisions, ensure construction quality, and ultimately reduce costs and improve construction efficiency. However, current through-hole ratio calculation methods used in digital pre-assembly processes are often based on circular holes fitted from point clouds, simplifying the calculation by calculating the distance between the circular holes, ignoring the roundness of the bolt holes and the fitting error of the circular holes, resulting in the final result often being too high or too low. This invention overcomes the shortcomings of traditional methods by using measured point cloud values ​​for deviation calculation and converting the three-dimensional point cloud into an image, solving the problem of finding the maximum inscribed circle of irregular images, thus improving the accuracy of bolt through-hole ratio. Summary of the Invention

[0005] This application provides a method for calculating the bolt through-hole ratio based on measured values ​​of laser point clouds. This method can solve the technical problem that when calculating the bolt through-hole ratio using existing technologies, only the distance between the circular holes is simplified, ignoring the errors caused by the roundness and structural features of the bolt holes, resulting in the final result often being too large or too small.

[0006] In a first aspect, embodiments of this application provide a method for calculating the bolt through-hole rate based on measured values ​​of laser point clouds, comprising: obtaining a planar projection point cloud on the intersecting plane between the first and second screw holes in the current screw hole group based on the circular feature information of the first screw hole and the second screw hole; obtaining a binary image based on the planar projection point cloud; calculating the maximum inscribed circle radius in the binary image, comparing the maximum inscribed circle radius with the bolt radius and outputting the comparison result; repeating the above steps to obtain the comparison results of the remaining screw hole groups; and then using the ratio of the number of screw hole groups through which the bolt can pass to the total number of screw hole groups as the bolt through-hole rate.

[0007] In conjunction with the first aspect, in one embodiment, the maximum inscribed circle radius is compared with the bolt radius and the comparison result is output: when the maximum inscribed circle radius is greater than the bolt radius, the output result is "passed" and it is marked as a passable bolt hole group; when the maximum inscribed circle radius is less than or equal to the bolt radius, the output result is "cannot pass".

[0008] In conjunction with the first aspect, in one embodiment, the intersecting plane is the plane where the interface of two screw holes in the screw hole group is located; based on the circular feature information of the first screw hole and the second screw hole in the current screw hole group, a planar projection point cloud on the intersecting plane between the first screw hole and the second screw hole is obtained, including the following steps: based on the circular feature information of the first screw hole, a first point cloud data is obtained; based on the first point cloud data, a first planar projection point cloud is obtained along a direction perpendicular to the intersecting plane; based on the circular hole feature information of the second screw hole, a second point cloud data is obtained; based on the second point cloud data, a second planar projection point cloud is obtained along a direction perpendicular to the intersecting plane; the first planar projection point cloud and the second planar projection point cloud are used as a planar projection point cloud.

[0009] In conjunction with the first aspect, in one embodiment, the maximum inscribed circle radius of the current screw hole group is obtained based on the planar projection point cloud of the current screw hole group. The specific steps are as follows: Based on the planar projection point cloud, the nearest projection point cloud of the current screw hole group is obtained; based on the nearest projection point cloud, a first polygonal contour and a second polygonal contour, as well as their corresponding grayscale images, are obtained; the first polygonal contour and the second polygonal contour are overlapped to obtain the intersecting polygonal contour of the current screw hole group; based on the intersecting polygonal contour, the binary image of the current screw hole group is obtained; based on the binary image, the distance output image of the current screw hole group is obtained; based on the distance output image, the maximum inscribed circle radius of the current screw hole group is obtained.

[0010] In conjunction with the first aspect, in one implementation, based on the planar projection point cloud of the current screw hole group, the nearest projection point cloud of the current screw hole group is obtained, with the following steps: obtaining the coordinates of the center of the first screw hole projected onto the intersecting plane and the coordinates of all projection points of the planar projection point cloud; setting an angle threshold to divide the intersecting plane into multiple central angle ranges based on the center; based on the center coordinates and the coordinates of the projection points, obtaining the projection point closest to the center within the first central angle range as the target point of the first central angle range, repeating the above steps to obtain the target point within each central angle range, and the set of all target points is the first nearest projection point cloud; repeating the above steps to obtain the second nearest projection point cloud of the second screw hole. The first and second nearest projection point clouds are used as the nearest projection point cloud.

[0011] In conjunction with the first aspect, in one embodiment, a first polygonal contour and a second polygonal contour are obtained based on the nearest projected point cloud. The specific steps are as follows: connect the target points within the range of adjacent central angles on the first nearest projected point to obtain the first polygonal contour; connect the target points within the range of adjacent central angles on the second nearest projected point to obtain the second polygonal contour.

[0012] In conjunction with the first aspect, in one embodiment, the first polygonal contour and the second polygonal contour are overlapped to obtain an intersecting polygonal contour. The specific steps are as follows: in the grayscale image corresponding to the first polygonal contour, the pixel value of the region within the contour is set to 255, and the other regions are set to 0; in the grayscale image corresponding to the second polygonal contour, the pixel value of the region within the contour is set to 255, and the other regions are set to 0; a set of pixels with a pixel value of 255 is taken, and the set is processed to obtain a binary image of the intersecting polygonal contour; in the binary image, the overlapping region is white, and the other regions are black.

[0013] In conjunction with the first aspect, in one implementation, a distance output image of the current screw hole group is obtained based on a binary image. The specific steps are as follows: obtain the minimum distance from any pixel in the white area of ​​the binary image to the edge pixel of the white area, and assign the minimum value to the pixel; repeat the above steps to obtain the minimum distance from the remaining pixels in the white area to the edge pixel of the white area, and assign the minimum value to the corresponding pixel to obtain the distance output image.

[0014] In conjunction with the first aspect, in one implementation, the maximum inscribed circle radius of the current screw hole group is obtained based on the distance output image. The specific steps are as follows: traverse all pixel values ​​in the distance output image, obtain the maximum value among all pixel values, and use it as the radius of the maximum inscribed circle of the current screw hole group.

[0015] Secondly, embodiments of this application provide a bolt through-hole rate calculation system based on measured laser point cloud values, comprising: a three-dimensional laser scanning system for acquiring the circular feature information of the first and second bolt holes in the current bolt hole group; a point cloud processing system for acquiring the planar projection point cloud and the nearest projection point cloud on the intersecting plane of the current bolt hole group; and an image processing system for acquiring the polygonal contour of the current bolt hole group and processing eight-bit images, binary images, and distance output images, and statistically analyzing the output results of all bolt hole groups and outputting the bolt through-hole rate.

[0016] The beneficial effects of the technical solutions provided in this application include:

[0017] A method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​is proposed. This method involves acquiring the circular feature information of the first and second screw holes in the current screw hole group and obtaining a planar projection point cloud on the intersecting plane between them. This allows the structural features of the screw holes to be represented in the resulting planar projection point cloud. This feature is then converted into a binary image, which accurately determines the maximum inscribed circle radius of the current screw hole group. This indicates the radius requirement of the largest bolt that can pass through the current screw hole group. The output result for the current screw hole group is obtained by comparing the calculated maximum inscribed circle radius with the bolt radius. This process is repeated to obtain the output results for all screw hole groups. The bolt through-hole ratio is calculated as the ratio of the number of screw hole groups through which the bolt can pass to the total number of screw hole groups. This method solves the problem of existing techniques that simplify the calculation of bolt through-hole ratio by only considering the distance between the circular holes, neglecting the roundness and structural features of the screw holes, leading to results that are often too high or too low. Attached Figure Description

[0018] Figure 1 This is a flowchart of the bolt through-hole ratio calculation method based on measured laser point cloud values ​​in this application;

[0019] Figure 2 This is a schematic diagram of the circular feature information of the bolt hole group in the bolt hole rate calculation method based on measured laser point cloud values ​​of this application.

[0020] Figure 3 This is a schematic diagram of the planar projection point cloud of the bolt hole group based on the bolt through-hole ratio calculation method based on measured laser point cloud values ​​in this application.

[0021] Figure 4 This is a schematic diagram of the nearest projection point cloud of the bolt hole group based on the bolt through-hole ratio calculation method based on measured laser point cloud values ​​in this application.

[0022] Figure 5This is a schematic diagram of the binary image and distance-converted image of the bolt hole group based on the bolt hole rate calculation method based on measured values ​​of laser point cloud in this application. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0024] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0025] The reason for the invention of this application is as follows: In existing technologies, methods for determining whether a bolt can pass through a set of screw holes only simplify the calculation by calculating the distance between the holes, neglecting the roundness of the screw holes and the error in fitting the holes, leading to results that are often too large or too small. This application proposes a method for calculating the bolt through-hole rate based on measured laser point cloud values. This method uses the circular feature information of the screw hole set and projects it perpendicularly to the intersecting plane to obtain a planar projection point cloud, reflecting the internal structural characteristics of the screw hole set. This planar projection point cloud is further filtered to reduce errors, ultimately yielding the maximum bolt radius that can pass through the screw hole set. Based on the obtained maximum inscribed circle radius of each screw hole set, it is compared with the bolt radius. The bolt through-hole rate is obtained by comparing the number of screw hole sets that the bolt can pass through to the total number of screw hole sets.

[0026] This method can be applied in the construction of large buildings such as bridges, where the through-hole ratio of pre-assembled bolts can be determined to ensure the stability and safety of the installation structure.

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0028] In a first aspect, embodiments of this application provide a method for calculating the bolt through-hole ratio based on measured laser point cloud values, referring to... Figure 1-5 , Figure 1 This is a flowchart illustrating the bolt through-hole ratio calculation method based on measured laser point cloud values ​​used in this application. Figure 1 As shown, the method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​includes:

[0029] Step 101: Based on the circular feature information of the first screw hole and the second screw hole in the current screw hole group, obtain the planar projection point cloud on the intersecting plane between the first screw hole and the second screw hole;

[0030] By acquiring the circular feature information of the first and second screw holes in the current screw hole group, and obtaining the planar projection point cloud of the first and second screw holes on the intersecting plane between them, the structural features inside the screw holes can be reflected in the obtained planar projection point cloud; wherein, the intersecting plane is the plane where the interface of the first and second screw holes intersects.

[0031] Step 102: Obtain a binary image based on the planar projection point cloud; calculate the maximum inscribed circle radius in the binary image, compare the maximum inscribed circle radius with the bolt radius, and output the comparison result;

[0032] After obtaining the planar projection point cloud, processing it will yield a binary image. By performing distance transformation on the binary image, the maximum inscribed circle radius of the planar projection point cloud can be obtained, which is the maximum bolt radius that can pass smoothly through the first and second screw holes. The obtained maximum inscribed circle radius of the current screw hole group is compared with the bolt radius, and the comparison result is output to determine whether the bolt can pass through the current screw hole group.

[0033] Step 103: Repeat the above steps to obtain the comparison results of the remaining screw hole groups, and then use the ratio of the number of screw hole groups that the bolt can pass through to the total number of screw hole groups as the bolt through hole rate.

[0034] The above steps are repeated for the remaining screw hole groups to obtain the comparison results for each screw hole group. Finally, the ratio of the number of screw hole groups through which the bolt can pass to the total number of screw hole groups is used to obtain the bolt through hole rate, which represents the proportion of screw hole groups through which the bolt can successfully pass out to the total number of screw hole groups.

[0035] This calculation method, through a comprehensive analysis of multiple steps, can more fully and accurately assess the bolt through-hole ratio. It solves the technical problem that existing technologies, when calculating the bolt through-hole ratio, often simplify the calculation by only considering the distance between the holes, neglecting errors caused by the roundness and structural characteristics of the bolt holes, resulting in final results that are either too high or too low.

[0036] Furthermore, in one embodiment, the maximum inscribed circle radius is compared with the bolt radius, and the comparison result is output:

[0037] If the maximum inscribed circle radius is greater than the bolt radius, the output result is "passed" and it is marked as a passable bolt hole group; if the maximum inscribed circle radius is less than or equal to the bolt radius, the output result is "cannot pass".

[0038] The radius of the largest inscribed circle of the current threaded hole group is compared with the bolt radius. Based on this rule, after comparing the radius of the largest inscribed circle of the threaded hole group and the bolt radius, it can be accurately determined whether the threaded hole group can pass through. This threaded hole group is then marked as a passable group, enabling the system to efficiently count the number of passable threaded hole groups and accurately obtain the bolt through-hole rate.

[0039] Further, in one embodiment, the intersecting plane is the plane where the interface of the two screw holes in the screw hole group is located; based on the circular feature information of the first screw hole and the second screw hole in the current screw hole group, the planar projection point cloud of the first screw hole and the second screw hole on the intersecting plane between them is obtained, including the following steps:

[0040] Based on the circular feature information of the first screw hole, a first point cloud data is obtained. Based on the first point cloud data, a first planar projection point cloud is obtained along the direction perpendicular to the intersecting plane. Based on the circular feature information of the second screw hole, a second point cloud data is obtained. Based on the second point cloud data, a second planar projection point cloud is obtained along the direction perpendicular to the intersecting plane. The first planar projection point cloud and the second planar projection point cloud are used as a planar projection point cloud.

[0041] The above steps help to process the planar projection point cloud data based on the circular feature information of the screw holes in the current screw hole group. This allows the internal structural features of the screw holes to be reflected in the obtained planar projection point cloud, helping to determine the radius of the largest bolt that can pass through the current screw hole group.

[0042] Furthermore, in one embodiment, the maximum inscribed circle radius of the current screw hole group is obtained based on the planar projection point cloud of the current screw hole group. The specific steps are as follows:

[0043] Based on the planar projection point cloud, the nearest projection point cloud of the current screw hole group is obtained; based on the nearest projection point cloud, the first polygonal contour and the second polygonal contour, as well as their corresponding grayscale images, are obtained; the first polygonal contour and the second polygonal contour are overlapped to obtain the intersecting polygonal contour of the current screw hole group; based on the intersecting polygonal contour, the binary image of the current screw hole group is obtained; based on the binary image, the distance output image of the current screw hole group is obtained; based on the distance output image, the maximum inscribed circle radius of the current screw hole group is obtained.

[0044] The above steps explain how to obtain the maximum inscribed circle radius of the current bolt hole group step by step based on the planar projection point cloud. This calculation method, through the comprehensive analysis of multiple steps, can more comprehensively and accurately evaluate the bolt through hole rate. The following will summarize how each process is implemented.

[0045] Furthermore, in one embodiment, based on the current planar projection point cloud of the screw hole group, the most recently projected point cloud of the current screw hole group is obtained, and the steps are as follows:

[0046] Obtain the coordinates of the center of the first screw hole projected onto the intersecting plane and the coordinates of all projected points in the planar projection point cloud; set an angle threshold to divide the intersecting plane into multiple central angle ranges based on the center of the circle; based on the center coordinates and the coordinates of the projected points, obtain the projection point closest to the center within the first central angle range as the target point within the first central angle range; repeat the above steps to obtain the target point within each central angle range, and the set of all target points is the first nearest projection point cloud; repeat the above steps to obtain the second nearest projection point cloud of the second screw hole. Use the first nearest projection point cloud and the second nearest projection point cloud as the nearest projection point cloud.

[0047] This process filters the projected points of the planar projection point cloud, setting the angle threshold to 0.5°, resulting in 720 target points. These target points within all central angle ranges are then grouped together to form the first nearest projected point cloud for the first screw hole. Similarly, the second nearest projected point cloud for the second screw hole is obtained by acquiring the nearest projected points within each angle range around the center of the second screw hole and summing them up. These nearest projected point clouds best reflect whether they affect the smooth passage of the bolt through the screw hole group.

[0048] Furthermore, in one embodiment, the first polygonal contour and the second polygonal contour are obtained based on the most recently projected point cloud, and the specific steps are as follows:

[0049] Connect the target points within the range of adjacent central angles on the first nearest projection point to obtain the first polygonal outline; connect the target points within the range of adjacent central angles on the second nearest projection point to obtain the second polygonal outline.

[0050] This process involves finding a set of adjacent target points based on the angular range of the nearest projection point. These target points are then connected in ascending order of angle to form a first polygonal profile and a second polygonal profile.

[0051] Furthermore, in one embodiment, the first polygonal contour and the second polygonal contour are overlapped to obtain an intersecting polygonal contour. The specific steps are as follows:

[0052] In the grayscale image corresponding to the first polygonal contour, the pixel value of the region within the contour is set to 255, and the pixel value of the remaining region is set to 0. In the grayscale image corresponding to the second polygonal contour, the pixel value of the region within the contour is set to 255, and the pixel value of the remaining region is set to 0. Take the set of pixels with a pixel value of 255, process the set to obtain the binary image of the intersecting polygonal contours. In the binary image, the overlapping region is white, and the remaining region is black.

[0053] Through logical operations, the pixel value at the corresponding position in the resulting image is 255 only if the pixel values ​​at the corresponding positions of the two operands are both 255; otherwise, it is 0. This step allows us to obtain a binary image of the intersecting polygon contours, i.e., the area where the two polygon contours overlap. Using these steps, we can obtain the intersecting region based on the polygon contours of the current screw hole group, further exploring the intersection situation between screw hole groups.

[0054] Furthermore, in one embodiment, the distance output image of the current screw hole group is obtained based on the binary image, and the specific steps are as follows:

[0055] Obtain the minimum distance from any pixel within the white region of the binary image to the edge pixel of the white region, and assign the minimum value to that pixel; repeat the above steps to obtain the minimum distance from the remaining pixels within the white region to the edge pixel of the white region, and assign the minimum value to the corresponding pixel to obtain the distance output image.

[0056] This step calculates the nearest distance from each pixel within the white area to the edge pixels of the white area, using these distances as candidate values. Different distance metrics can be employed. For each pixel within the white area, its calculated candidate value is replaced with its new pixel value. Through these steps, a distance output image can be generated based on the binary image of the intersecting polygonal contours of the current screw hole group. This distance output image can provide the value of the maximum inscribed circle radius.

[0057] Furthermore, in one embodiment, the maximum inscribed circle radius of the current screw hole group is obtained based on the distance output image. The specific steps are as follows:

[0058] Iterate through all pixel values ​​in the distance output image, obtain the maximum value among all pixel values, and use it as the radius of the largest inscribed circle of the current screw hole group.

[0059] This process involves iterating through each pixel in the output image and recording the pixel value for each point. The maximum value is then found among the recorded pixel values, and this maximum value is the maximum inscribed circle radius of the current screw hole group.

[0060] Secondly, embodiments of this application also provide a bolt through-hole rate calculation system based on measured laser point cloud values, comprising a three-dimensional laser scanning system for acquiring the circular feature information of the first and second bolt holes in the current bolt hole group; a point cloud processing system for acquiring the planar projection point cloud and the nearest projection point cloud on the intersecting plane of the current bolt hole group; and an image processing system for acquiring the polygonal contour of the current bolt hole group and processing the eight-bit image, the binary image, and the distance output image, and statistically analyzing the output results of all bolt hole groups and outputting the bolt through-hole rate.

[0061] The system comprises several components: a 3D laser scanning system, which acquires the circular feature information of the first and second screw holes in the current screw hole group, converting the geometric features of the screw holes into point cloud data; a point cloud processing system, which processes the point cloud data based on the acquired screw hole group, obtaining planar projection point clouds and nearest-nearest projection point clouds for subsequent analysis and calculation; and an image processing system, which acquires the polygonal contour of the current screw hole group and processes 8-bit images, binary images, and distance output images, providing necessary image data support for calculating the screw hole penetration rate. It also comprehensively processes and compares the output results of all screw hole groups, statistically calculates the bolt penetration rate, and outputs the results. This system integrates multiple technologies, enabling accurate calculation of the screw hole penetration rate, which is of great significance for quality control and process optimization in the engineering manufacturing field.

[0062] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0063] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0064] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0065] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0066] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0067] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0068] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for calculating the bolt through-hole ratio based on measured laser point cloud values, characterized in that, The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​includes: Based on the circular feature information of the first and second screw holes in the current screw hole group, the planar projection point cloud of the first and second screw holes on the intersecting plane between them is obtained; Based on the planar projection point cloud, a binary image is obtained; the radius of the largest inscribed circle in the binary image is calculated, and the radius of the largest inscribed circle is compared with the bolt radius and the comparison result is output. Repeat the above steps to obtain the comparison results of the remaining screw hole groups; then, the ratio of the number of screw hole groups through which the bolt can pass to the total number of screw hole groups is taken as the bolt through hole rate. The intersecting plane is the plane where the interface between two screw holes in the screw hole group is located; based on the circular feature information of the first screw hole and the second screw hole in the current screw hole group, the planar projection point cloud of the first screw hole and the second screw hole on the intersecting plane between them is obtained, including the following steps: Based on the circular feature information of the first screw hole, a first point cloud data is obtained; based on the first point cloud data, a first planar projection point cloud is obtained along a direction perpendicular to the intersecting plane; based on the circular feature information of the second screw hole, a second point cloud data is obtained; based on the second point cloud data, a second planar projection point cloud is obtained along a direction perpendicular to the intersecting plane; the first planar projection point cloud and the second planar projection point cloud are used as the planar projection point cloud. Based on the planar projection point cloud of the current screw hole group, the maximum inscribed circle radius of the current screw hole group is obtained. The specific steps are as follows: Based on the planar projection point cloud, the nearest projection point cloud of the current screw hole group is obtained; according to the nearest projection point cloud, the first polygonal contour and the second polygonal contour, as well as their corresponding grayscale images, are obtained; the first polygonal contour and the second polygonal contour are overlapped to obtain the intersecting polygonal contour of the current screw hole group; based on the intersecting polygonal contour, the binary image of the current screw hole group is obtained; based on the binary image, the distance output image of the current screw hole group is obtained; according to the distance output image, the maximum inscribed circle radius of the current screw hole group is obtained. Based on the planar projection point cloud of the current screw hole group, obtain the most recent projection point cloud of the current screw hole group. The steps are as follows: Obtain the coordinates of the center of the first screw hole projected onto the intersecting plane and the coordinates of all projected points of the planar projection point cloud; set an angle threshold to divide the intersecting plane into multiple central angle ranges based on the center; based on the center coordinates and the coordinates of the projected points, obtain the projection point closest to the center within the first central angle range as the target point within the first central angle range, repeat the above steps to obtain the target point within each central angle range, and the set of all the target points is the first nearest projection point cloud; repeat the above steps to obtain the second nearest projection point cloud of the second screw hole; use the first nearest projection point cloud and the second nearest projection point cloud as the nearest projection point cloud.

2. The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​as described in claim 1, characterized in that: Compare the maximum inscribed circle radius with the bolt radius and output the comparison result: If the maximum inscribed circle radius is greater than the bolt radius, the output result is "passed" and it is marked as a passable bolt hole group; If the maximum inscribed circle radius is less than or equal to the bolt radius, the output result is "cannot pass".

3. The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​as described in claim 1, characterized in that: Based on the most recently projected point cloud, the first polygonal contour and the second polygonal contour are obtained, and the specific steps are as follows: Connect the target points within the range of the adjacent central angles on the first nearest projection point to obtain the first polygonal outline; Connect the target points within the range of the adjacent central angles on the second nearest projection point to obtain the second polygonal outline.

4. The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​as described in claim 3, characterized in that: The first polygonal contour and the second polygonal contour are overlapped to obtain the intersecting polygonal contour. The specific steps are as follows: In the grayscale image corresponding to the first polygonal outline, the pixel value of the region within the outline is set to 255, and the pixel value of the other region is set to 0. In the grayscale image corresponding to the second polygonal outline, the pixel value of the region within the outline is set to 255, and the pixel value of the other region is set to 0. Take a set of pixels with a pixel value of 255, and process the set to obtain a binary image of the intersecting polygon contour; In the binary image, the overlapping areas are white, and the remaining areas are black.

5. The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​as described in claim 4, characterized in that: Based on the binary image, the distance output image of the current screw hole group is obtained. The specific steps are as follows: Obtain the minimum distance from any pixel within the white region of the binary image to the edge pixel of the white region, and assign the minimum value to that pixel. Repeat the above steps to obtain the minimum distance from the remaining pixels within the white area to the edge pixels of the white area, and assign the minimum value to the corresponding pixel to obtain the distance output image.

6. The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​as described in claim 5, characterized in that: Based on the distance output image, the maximum inscribed circle radius of the current screw hole group is obtained. The specific steps are as follows: Iterate through all pixel values ​​in the distance output image, obtain the maximum value among all pixel values, and use it as the radius of the largest inscribed circle of the current screw hole group.

7. A bolt through-hole ratio calculation system based on measured laser point cloud values, characterized in that, The method for calculating the bolt through-hole ratio based on measured laser point cloud values ​​as described in claim 1 is provided; the bolt through-hole ratio calculation system based on measured laser point cloud values ​​includes: A three-dimensional laser scanning system is used to acquire the circular feature information of the first screw hole and the second screw hole in the current screw hole group; A point cloud processing system for acquiring the planar projection point cloud and the most recently projected point cloud on the intersecting plane of the current screw hole group; An image processing system is used to acquire the polygonal contour of the current screw hole group and process the eight-bit image, the binary image and the distance output image, and to perform statistics on the output results of all screw hole groups and output the bolt through hole rate.

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