Bolt through hole rate calculation method based on laser point cloud measured value

Abstract

The invention provides a bolt through hole rate calculation method based on a laser point cloud measured value, and the method comprises the steps: obtaining plane projection point clouds of a first screw hole and a second screw hole on an intersecting 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 a current screw hole group; obtaining a binary image based on the plane 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 a comparison result; repeating the steps to obtain a comparison result of other screw hole groups; and then the ratio of the number of the screw hole groups through which the bolts can pass to the number of all the screw hole groups is used as the bolt through hole rate. Through the method, the structural feature information in the screw hole group can be reflected on the plane projection point cloud obtained through projection, a more accurate screw hole group model is introduced, the parameter calibration process is optimized, and the problem of errors caused by neglecting the roundness and the structural feature information of the screw hole in the prior art is effectively solved.

Description

Technical Field

[0001] The present application relates to the technical field of bolt assembly, and in particular to a method for calculating bolt through-hole rate based on actual measured values ​​of laser point cloud. Background Art

[0002] Laser scanning technology and point cloud data are increasingly used in the industrial field, especially in precision assembly and quality control. In the construction of large buildings such as bridges, especially steel structures, bolt connection is one of the most common connection methods. The correct installation of bolts is essential to ensure 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] Traditionally, manual inspection is required to determine the alignment of bolt holes. This method is not only inefficient, but also subject to human error. With the continuous advancement of laser scanning technology, laser point clouds can be used to quickly and accurately obtain the geometric information of components. By analyzing these point cloud data, automated algorithms can be developed to evaluate the penetration rate of bolt holes, that is, the proportion of pre-assembled screws that can pass through the holes smoothly.

[0004] An efficient bolt through-hole rate calculation method based on laser point cloud can provide engineers with real-time quality feedback, help them make decisions quickly, ensure construction quality, and ultimately reduce costs and improve construction efficiency. However, in the current digital pre-assembly process, the through-hole rate calculation method used is often based on the circular holes after point cloud fitting, and the distance between the circular holes is calculated for simplified calculation, ignoring the roundness of the screw holes and the error of circular hole fitting, resulting in the final result often being too large or too small. The present invention abandons the shortcomings of the traditional method, uses the measured point cloud value for deviation calculation, and converts the three-dimensional point cloud into an image, solving the problem of solving the maximum inscribed circle of the irregular image, and improving the accuracy of the bolt through-hole rate. Summary of the invention

[0005] The present application provides a method for calculating the bolt through-hole rate based on the actual measured value of the laser point cloud, which can solve the technical problem that when calculating the bolt through-hole rate by the existing technology, only the distance between the circular holes is simplified and the errors caused by the roundness and structural characteristics of the screw holes are ignored, resulting in the final result often being too large or too small.

[0006] In a first aspect, an embodiment of the present application provides a method for calculating the bolt through-hole rate based on the actual measured value of the laser point cloud, comprising: obtaining a plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane therebetween 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 plane 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 taking the ratio of the number of screw hole groups through which the bolt can pass to the number of all screw hole groups as the bolt through-hole rate.

[0007] In combination 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 larger than the bolt radius, the output result is passed and is marked as a screw hole group that can pass; when the maximum inscribed circle radius is less than or equal to the bolt radius, the output result is failed to pass.

[0008] In combination with the first aspect, 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, a plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane therebetween is obtained, including the following steps: based on the circular feature information of the first screw hole, first point cloud data is obtained, and according to the first point cloud data, a first plane projection point cloud along a direction perpendicular to the intersecting plane is obtained; based on the circular hole feature information of the second screw hole, second point cloud data is obtained; according to the second point cloud data, a second plane projection point cloud along a direction perpendicular to the intersecting plane is obtained; and the first plane projection point cloud and the second plane projection point cloud are used as plane projection point clouds.

[0009] In combination with the first aspect, in one embodiment, based on the plane projection point cloud of the current screw hole group, the maximum inscribed circle radius of the current screw hole group is obtained, and the specific steps are as follows: based on the plane projection point cloud, the closest projection point cloud of the current screw hole group is obtained; according to the closest projection point cloud, a first polygon outline and a second polygon outline and a grayscale image corresponding thereto are obtained; the first polygon outline and the second polygon outline are overlapped to obtain the intersecting polygon outline of the current screw hole group; based on the intersecting polygon outline, the binary image of the current screw hole group is obtained; based on the binary image, a 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.

[0010] In combination with the first aspect, in one embodiment, based on the plane projection point cloud of the current screw hole group, the nearest projection point cloud of the current screw hole group is obtained, and the steps are as follows: obtain the coordinates of the center of the first screw hole projected on the intersecting plane and the coordinates of all projection points of the plane projection point cloud; set an angle threshold to divide the intersecting plane into multiple center angle ranges based on the center of the circle; based on the center coordinates and the coordinates of the projection point, obtain the projection point closest to the center of the circle in the first center angle range as the target point of the first center angle range, repeat the above steps to obtain the target point in each center 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. The first nearest projection point cloud and the second nearest projection point cloud are used as the nearest projection point clouds.

[0011] In combination with the first aspect, in one embodiment, a first polygon outline and a second polygon outline are obtained based on the nearest projection point cloud, and the specific steps are as follows: connect the target points within the adjacent central angle range on the first nearest projection point to obtain the first polygon outline; connect the target points within the adjacent central angle range on the second nearest projection point to obtain the second polygon outline.

[0012] In combination with the first aspect, in one implementation, the first polygon outline and the second polygon outline are overlapped to obtain an intersecting polygon outline, and the specific steps are as follows: in a grayscale image corresponding to the first polygon outline, the pixel value of the area within the outline is set to 255, and the remaining area is set to 0; in a grayscale image corresponding to the second polygon outline, the pixel value of the area within the outline is set to 255, and the remaining area is set to 0; a set of pixel points whose pixel values ​​are all 255 is taken, and the set is processed to obtain a binary image of the intersecting polygon outline; the overlapping area in the binary image is white, and the remaining area is black;

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

[0014] In combination with the first aspect, 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: traverse all pixel values ​​in the distance output image, obtain the maximum value of the pixel values ​​corresponding to all pixel points, and use it as the radius of the maximum inscribed circle of the current screw hole group.

[0015] In the second aspect, an embodiment of the present application provides a bolt through-hole rate calculation system based on the actual measured value of the laser point cloud, which includes: a three-dimensional laser scanning system, which is used to obtain the circular feature information of the first screw hole and the second screw hole of the current screw hole group; a point cloud processing system, which is used to obtain the plane projection point cloud and the nearest projection point cloud on the intersecting plane of the current screw hole group; an image processing system, which is used to obtain the polygonal contour of the current screw hole group and process the eight-bit image, binary image and distance output image, and to make statistics on the output results of all screw hole groups and output the bolt through-hole rate.

[0016] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0017] A method for calculating the bolt through-hole rate based on the measured value of laser point cloud is adopted, wherein, by obtaining the circular feature information of the first screw hole and the second screw hole in the current screw hole group, and obtaining the plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane between them, the structural feature information inside the screw hole can be reflected on the obtained plane projection point cloud; and based on the feature conversion into a binary image, the maximum inscribed circle radius of the current screw hole group can be accurately obtained by using the binary image, that is, the radius requirement of the maximum bolt that can pass through the current screw hole group can be obtained, so the output result of the current screw hole group can be obtained by comparing the obtained maximum inscribed circle radius with the bolt radius, repeating this step to obtain the output result after comparison of all screw hole groups, and according to the ratio of the number of screw hole groups that the bolt can pass through to the number of all screw hole groups, as the bolt through-hole rate. Through this method, the technical problem that when calculating the bolt through-hole rate by the existing technology, only the distance between the circular holes is simplified, and the error caused by the roundness and structural characteristics of the screw holes is ignored, resulting in the final result often being too large or too small is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of the bolt through-hole rate calculation method based on the laser point cloud measured value of this application;

[0019] Figure 2 A schematic diagram of circular feature information of a bolt hole group in a bolt through-hole rate calculation method based on laser point cloud measured values ​​in this application;

[0020] Figure 3 This is a schematic diagram of a plane projection point cloud of a bolt hole group in the bolt through-hole rate calculation method based on the laser point cloud measured value of this application;

[0021] Figure 4 This is a schematic diagram of the nearest projection point cloud of the bolt hole group of the bolt through-hole rate calculation method based on the laser point cloud measured value of this application;

[0022] Figure 5This is a schematic diagram of a binary image and a distance conversion image of a bolt hole group in the bolt through-hole rate calculation method based on the actual measured value of the laser point cloud in this application. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] First, some technical terms in the present application are explained to facilitate those skilled in the art to understand the present application.

[0025] Regarding the reasons for the invention of this application: Regarding the method of judging whether a bolt can pass through a screw hole group, in the prior art, only the distance between the circular holes is calculated for simplified calculation, ignoring the roundness of the screw hole and the error of the circular hole fitting, resulting in the final result often being too large or too small. This application proposes a method for calculating the bolt through-hole rate based on the measured value of the laser point cloud, which can obtain a plane projection point cloud based on the circular feature information of the screw hole group and project it perpendicular to the intersecting plane, reflecting the internal structural characteristics of the screw hole group, and further screen the plane projection point cloud to reduce the error, and finally obtain the maximum bolt radius that can pass through the screw hole group that meets the requirements. Based on the obtained maximum inscribed circle radius of each screw hole group, compared with the bolt radius, the bolt through-hole rate can be obtained by ratioing the number of screw hole groups that the bolt can pass through to the number of all screw hole groups.

[0026] The method is applied in scenarios such as the construction of large buildings such as bridges, where the penetration rate of pre-assembled bolts can be known to ensure the stability and safety of the installation structure.

[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0028] In the first aspect, the present application embodiment provides a method for calculating the bolt through-hole rate based on the actual measured value of the laser point cloud, referring to Figure 1-5 , Figure 1 FIG. 1 is a flow chart of a method for calculating bolt through-hole rate based on actual measured values ​​of laser point cloud in this application. Figure 1 As shown in FIG. 1 , the bolt through-hole rate calculation method based on the laser point cloud measured value 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 a plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane therebetween;

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

[0031] Step 102, based on the plane projection point cloud, a binary image is obtained; the maximum inscribed circle radius in the binary image is calculated, the maximum inscribed circle radius is compared with the bolt radius and the comparison result is output;

[0032] After obtaining the plane projection point cloud, a binary image can be obtained by processing. The binary image can be further converted into a distance to obtain the maximum inscribed circle radius of the plane projection point cloud, that is, the maximum bolt radius that can smoothly pass through the first screw hole and the second screw hole. The 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 comparison results of the remaining screw hole groups, and then take the ratio of the number of screw hole groups through which the bolts can pass to the number of all screw hole groups as the bolt through-hole rate.

[0034] The above steps are calculated and compared for the remaining screw hole groups in turn to obtain the comparison results of each screw hole group. Finally, the number of screw hole groups that the bolt can pass through is ratioed to the number of all screw hole groups to obtain the bolt through-hole rate, which is the proportion of screw hole groups that the bolt can successfully pass through to all screw hole groups.

[0035] This calculation method can evaluate the bolt through-hole rate more comprehensively and accurately through comprehensive analysis of multiple steps. It solves the technical problem that when calculating the bolt through-hole rate by the existing technology, only the distance between the circular holes is simplified, and the roundness of the bolt hole and the errors caused by the structural characteristics are ignored, resulting in the final result being too large or too small.

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

[0037] When the maximum inscribed circle radius is greater than the bolt radius, the output result is passed and marked as a screw hole group that can pass; when the maximum inscribed circle radius is less than or equal to the bolt radius, the output result is failed.

[0038] Compare the radius of the maximum inscribed circle of the current screw hole group with the bolt radius. According to this judgment rule, after comparing the maximum inscribed circle radius of the screw hole group and the bolt radius, it is possible to accurately determine whether the screw hole group can pass. And mark the screw hole group as a screw hole group that can pass, so that the system can efficiently count the number of screw hole groups that can pass and accurately obtain the bolt through-hole rate.

[0039] Further, in one embodiment, the intersecting plane is a 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, obtaining the plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane therebetween includes the following steps:

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

[0041] The above steps can help realize the processing process of obtaining plane projection point cloud data based on the circular feature information of the screw hole of the current screw hole group. The structural feature information inside the screw hole can be reflected on the obtained plane projection point cloud, helping to obtain the required maximum bolt radius that can pass through the current screw hole group.

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

[0043] Based on the plane 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 polygon outline and a second polygon outline and a grayscale image corresponding thereto are obtained; the first polygon outline and the second polygon outline are overlapped to obtain the intersecting polygon outline of the current screw hole group; based on the intersecting polygon outline, a binary image of the current screw hole group is obtained; based on the binary image, a distance output image of the current screw hole group is obtained; based on the distance output image, a maximum inscribed circle radius of the current screw hole group is obtained.

[0044] Through the above steps, the process of obtaining the maximum inscribed circle radius of the current bolt hole group step by step based on the plane projection point cloud is explained. This calculation method can evaluate the bolt through-hole rate more comprehensively and accurately through the comprehensive analysis of multiple steps. The following will gradually summarize how each process is achieved.

[0045] Further, in one embodiment, based on the plane projection point cloud of the current screw hole group, the nearest projection 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 on the intersecting plane and the coordinates of all projection points of the plane projection point cloud; set an angle threshold to divide the intersecting plane into multiple center angle ranges based on the center of the circle; based on the center coordinates and the coordinates of the projection points, obtain the projection point closest to the center of the circle in the first center angle range as the target point of the first center angle range, repeat the above steps to obtain the target point in each center angle range, and the set of all target points is the first closest projection point cloud; repeat the above steps to obtain the second closest projection point cloud of the second screw hole. The first closest projection point cloud and the second closest projection point cloud are used as the closest projection point cloud.

[0047] Through this step, the projection points of the plane projection point cloud are screened, and the angle threshold is set to 0.5°, so that 720 target points can be obtained. The target points obtained within the range of all center angles are combined together to form the first closest projection point cloud of the first screw hole. Similarly, the second closest projection point cloud of the second screw hole is obtained, that is, the closest projection points within each angle range are obtained according to the center of the second screw hole, and then summarized as the second closest projection point cloud of the second screw hole. These closest projection point clouds can best reflect whether it affects the smooth passage of the bolt through the screw hole group.

[0048] Furthermore, in one embodiment, the first polygon outline and the second polygon outline are obtained according to the nearest projected point cloud, and the specific steps are as follows:

[0049] The target points within the adjacent central angle range of the first closest projection point are connected to obtain the first polygonal outline; the target points within the adjacent central angle range of the second closest projection point are connected to obtain the second polygonal outline.

[0050] Through this step, a set of adjacent target points is found according to the angle range of the nearest projection point, and these target points are connected in order of increasing angles to form a first polygonal outline and a second polygonal outline.

[0051] Furthermore, in one embodiment, the first polygon outline and the second polygon outline are overlapped to obtain an intersecting polygon outline, and the specific steps are as follows:

[0052] In the grayscale image corresponding to the first polygonal outline, the pixel value of the area within the outline is set to 255, and the remaining area is set to 0; in the grayscale image corresponding to the second polygonal outline, the pixel value of the area within the outline is set to 255, and the remaining area is set to 0; take a set of pixel points whose pixel values ​​are all 255, and process the set to obtain a binary image of the intersecting polygonal outlines; the overlapping area in the binary image is white, and the remaining area is black;

[0053] Through logical operations, only when the pixel values ​​of the corresponding positions of the two operands are both 255, the pixel value of the corresponding position of the result image is 255, otherwise it is 0. Through this step, the binary image of the intersecting polygon outline can be obtained, that is, the area where the two polygon outlines overlap. Through the above steps, the intersection area can be obtained based on the polygon outline of the current screw hole group, and the intersection between the screw hole groups can be further explored.

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

[0055] Get the minimum value of the distance from any pixel point in the white area of ​​the binary image to the edge pixel point of the white area, and assign the minimum value to the pixel point; repeat the above steps to get the minimum value of the distance from the remaining pixel points in the white area to the edge pixel points of the white area, assign the minimum value to the corresponding pixel point, and obtain the distance output image.

[0056] Through this step, the shortest distance from each pixel point in the white area to the edge pixel point of the white area is calculated as a candidate value, and different distance measurement methods can be used. For each pixel point in the white area, the candidate value calculated is replaced as the new value of the pixel value. Through the above steps, a distance output image can be generated based on the binary image of the intersecting polygon outline of the current screw hole group. Such a distance output image can provide the value of the maximum inscribed circle radius.

[0057] Further, in one embodiment, the maximum inscribed circle radius of the current screw hole group is obtained according to the distance output image, and the specific steps are as follows:

[0058] All pixel values ​​in the distance output image are traversed, and the maximum value among the pixel values ​​corresponding to all pixel points is obtained, and is used as the radius of the maximum inscribed circle of the current screw hole group.

[0059] Through this step, each pixel in the distance output image is traversed, and the pixel value corresponding to each pixel is recorded. The maximum value is found from the recorded pixel values, and the maximum value is the maximum inscribed circle radius of the current screw hole group.

[0060] In the second aspect, an embodiment of the present application also provides a bolt through-hole rate calculation system based on the actual measured value of the laser point cloud, which includes a three-dimensional laser scanning system, which is used to obtain the circular feature information of the first screw hole and the second screw hole of the current screw hole group; a point cloud processing system, which is used to obtain the plane projection point cloud and the nearest projection point cloud on the intersecting plane of the current screw hole group; an image processing system, which is used to obtain 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 make statistics on the output results of all screw hole groups and output the bolt through-hole rate.

[0061] Among them, the three-dimensional laser scanning system: obtains the circular feature information of the first and second screw holes in the current screw hole group, that is, converts the geometric features of the screw holes into point cloud data. Point cloud processing system: processes the point cloud data based on the current screw hole group, obtains the plane projection point cloud and the nearest projection point cloud for subsequent analysis and calculation. Image processing system: obtains the polygonal contour of the current screw hole group, and processes the eight-bit image, binary image and distance output image to provide the necessary image data support for the calculation of the screw hole penetration rate, and comprehensively processes the output comparison results of all screw hole groups, statistically calculates the bolt penetration rate, and outputs the results. The system integrates a variety of technologies to achieve accurate calculation of the screw hole penetration rate, which is of great significance for quality control and process optimization in the field of engineering manufacturing.

[0062] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0063] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0064] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0065] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0066] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the 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 in sequence or in parallel, and these operations or steps may be combined.

[0067] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0068] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for calculating bolt through-hole rate based on laser point cloud measured values, characterized in that: The bolt through-hole rate calculation method based on the laser point cloud measured value includes: Based on the circular feature information of the first screw hole and the second screw hole in the current screw hole group, a plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane therebetween is obtained; Based on the plane projection point cloud, a binary image is obtained; a maximum inscribed circle radius in the binary image is calculated, the maximum inscribed circle radius is compared with the bolt radius and a comparison result is output; Repeat the above steps to obtain comparison results of the remaining screw hole groups; then take the ratio of the number of screw hole groups through which the bolts can pass to the number of all screw hole groups as the bolt through-hole rate.

2. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 1, characterized in that: Compare the maximum inscribed circle radius with the bolt radius and output the comparison result: When the maximum inscribed circle radius is greater than the bolt radius, the output result is passed and marked as a screw hole group that can pass; When the maximum inscribed circle radius is less than or equal to the bolt radius, the output result is "failed to pass".

3. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 1, characterized in that: 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 plane projection point cloud of the first screw hole and the second screw hole on the intersecting plane therebetween is obtained, including the following steps: Based on the circular feature information of the first screw hole, first point cloud data is obtained, and according to the first point cloud data, a first plane projection point cloud along a direction perpendicular to the intersecting plane is obtained; Based on the circular hole feature information of the second screw hole, second point cloud data is obtained; and according to the second point cloud data, a second plane projection point cloud along a direction perpendicular to the intersecting plane is obtained; The first plane projection point cloud and the second plane projection point cloud are used as the plane projection point cloud.

4. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 3, characterized in that: Based on the plane projection point cloud of the current screw hole group, the maximum inscribed circle radius of the current screw hole group is obtained, and the specific steps are as follows: Based on the plane projection point cloud, the nearest projection point cloud of the current screw hole group is obtained; According to the nearest projected point cloud, a first polygon outline and a second polygon outline and a grayscale image corresponding thereto are obtained; Overlapping the first polygonal outline and the second polygonal outline to obtain an intersecting polygonal outline of the current screw hole group; Based on the intersecting polygonal contours, acquiring the binary image of the current screw hole group; Based on the binary image, obtaining a distance output image of the current screw hole group; The image is output according to the distance to obtain the maximum inscribed circle radius of the current screw hole group.

5. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 4, characterized in that: Based on the plane projection point cloud of the current screw hole group, the nearest projection point cloud of the current screw hole group is obtained. The steps are as follows: Obtaining the coordinates of the center of the first screw hole projected on the intersecting plane and the coordinates of all projection points of the plane projection point cloud; Setting an angle threshold to divide the intersecting plane into a plurality of central angle ranges based on the center of the circle; Based on the coordinates of the center of the circle and the coordinates of the projection point, obtain the projection point closest to the center of the circle within the first center angle range as the target point within the first center angle range, repeat the above steps to obtain the target point within each center angle range, and the set of all the target points is the first closest projection point cloud; Repeat the above steps to obtain the second closest projection point cloud of the second screw hole. The first closest projected point cloud and the second closest projected point cloud are used as the closest projected point clouds.

6. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 5, characterized in that: The first polygon outline and the second polygon outline are obtained according to the nearest projected point cloud, and the specific steps are as follows: Connect the target points within the range of the circle center angle adjacent to the first closest projection point to obtain the first polygon outline; The target points within the range of the circle center angle adjacent to the second closest projection point are connected to obtain the second polygonal outline.

7. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 6, characterized in that: The first polygon outline and the second polygon outline are overlapped to obtain the intersecting polygon outline, and the specific steps are as follows: In the grayscale image corresponding to the first polygon outline, the pixel value of the area within the outline is set to 255, and the pixel value of the remaining area is set to 0; in the grayscale image corresponding to the second polygon outline, the pixel value of the area within the outline is set to 255, and the pixel value of the remaining area is set to 0; Taking a set of pixel points whose pixel values ​​are all 255, and processing the set to obtain a binary image of the outline of the intersecting polygon; The overlapping area in the binary image is white, and the remaining area is black.

8. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 7, characterized in that: Based on the binary image, the distance output image of the current screw hole group is obtained, and the specific steps are as follows: Obtaining the minimum value of the distance between any pixel point in the white area of ​​the binary image and the edge pixel point of the white area, and assigning the minimum value to the pixel point; Repeat the above steps to obtain the minimum value of the distances from the remaining pixels in the white area to the edge pixels of the white area, assign the minimum value to the corresponding pixel points, and obtain a distance output image.

9. The method for calculating bolt through-hole rate based on laser point cloud measured values ​​according to claim 8, characterized in that: According to the distance output image, the maximum inscribed circle radius of the current screw hole group is obtained. The specific steps are as follows: All pixel values ​​in the distance output image are traversed, and the maximum value among the pixel values ​​corresponding to all pixel points is obtained, and is used as the radius of the maximum inscribed circle of the current screw hole group.

10. A bolt through-hole rate calculation system based on laser point cloud measured values, characterized in that: The bolt through-hole rate calculation system based on the laser point cloud measured value includes: A three-dimensional laser scanning system, used for acquiring the circular feature information of the first screw hole and the second screw hole of the current screw hole group; A point cloud processing system, which is used to obtain the plane projection point cloud and the closest projection point cloud on the intersecting plane of the current screw hole group; The image processing system is used to obtain the polygonal outline of the current screw hole group and process the eight-bit image, the binary image and the distance output image, and to make statistics on the output results of all screw hole groups and output the bolt through-hole rate.

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