A part curved surface measurement process planning method, device, equipment and medium

Abstract

The application discloses a part curved surface measurement process planning method, device, equipment and medium, and the method comprises the following steps: establishing a curved surface model of a part to be measured; the curved surface model is pretreated to obtain a geometric curved surface; the geometric curved surface is divided into a triangular mesh to obtain a curved surface mesh with multiple triangular facets; the vertex coordinates and normal vector of each triangular facet are obtained to obtain a measurement point list; the optimal theoretical position of the measurement equipment is obtained according to the normal vector information of the triangular facet; the coordinate system of the optimal theoretical position is unified with the actual measurement coordinate system to obtain a reference coordinate system; the optimal actual position of the measurement equipment is obtained according to the reference coordinate system; the measurement equipment is based on the optimal actual position, and measurement work is performed according to the measurement point list; the application has the advantages of realizing fast process planning of complex curved surface measurement, reducing measurement and data processing time, and improving measurement efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of part curved surface measurement, and particularly to a part curved surface measurement process planning method, device, equipment and medium. BACKGROUND

[0002] With the improvement of stealth requirements and aerodynamic requirements, the aircraft body is increasingly changing to streamline, resulting in various cabin doors, cabin covers and other structures being complex curved surfaces. In order to ensure the shape accuracy of the aircraft, the shape of these structures, especially the curved surface edge profile, needs to be measured, because the edge line determines the step gap between structures, which has a great influence on the stealth performance.

[0003] Usually, a laser radar or a handheld laser scanner and other measurement equipment are used to scan the part curved surface shape. Process planning needs to be performed before measurement to determine the relevant measurement parameters. However, the existing process planning method for part curved surface measurement has the disadvantage of long measurement and data processing period, large workload, and low subsequent measurement efficiency. SUMMARY

[0004] The main purpose of the present application is to provide a part curved surface measurement process planning method, device, equipment and medium, which aims to solve the technical problem of low subsequent measurement efficiency caused by the existing process planning method for part curved surface measurement.

[0005] To achieve the above purpose, the present application provides a part curved surface measurement process planning method, comprising the following steps:

[0006] establishing a curved surface model of a part to be measured;

[0007] preprocessing the curved surface model to obtain a geometric curved surface;

[0008] triangular mesh division is performed on the geometric curved surface to obtain a curved surface mesh with a plurality of triangular facets;

[0009] obtaining the vertex coordinates and normal vector of each triangular facet to obtain a measurement point list;

[0010] obtaining the optimal layout theoretical position of the measurement equipment according to the normal vector information of the triangular facet;

[0011] unifying the coordinate system of the optimal layout theoretical position with the actual measurement coordinate system to obtain a reference coordinate system;

[0012] obtaining the optimal layout actual position of the measurement equipment according to the reference coordinate system;

[0013] making the measurement equipment based on the optimal layout actual position and performing measurement work according to the measurement point list.

[0014] Optionally, the pre-processing of the curved surface model to obtain a geometric curved surface comprises:

[0015] extracting a plurality of sub-curves of the curved surface model;

[0016] merging adjacent sub-curves to obtain a geometric curved surface;

[0017] independently cutting out a key area of the geometric curved surface, and the remaining part of the geometric curved surface is a non-key area; wherein the key area includes a region with large deformation or a region that needs to be analyzed in detail.

[0018] Optionally, the triangular meshing of the geometric curved surface to convert it into a curved surface mesh with a plurality of triangular facets comprises:

[0019] point cloud triangulation processing of the geometric curved surface in point cloud processing software;

[0020] grid refinement of the key area of the processed geometric curved surface;

[0021] grid simplification of the non-key area of the processed geometric curved surface;

[0022] finally obtaining a curved surface mesh with a plurality of triangular facets.

[0023] Optionally, the acquisition of the vertex coordinates and normal vector of each triangular facet to obtain a measurement point list comprises:

[0024] exporting the curved surface mesh as an STL format file, which stores the vertex coordinates and normal vector of each triangular facet;

[0025] saving the STL format file as a txt format, storing the vertex coordinate data and normal vector data into an Excel table using the string matching function of the VBA program of Excel, and then exporting the vertex coordinate data as an ASCII format measurement point file;

[0026] importing the measurement point file into laser radar measurement software to form a measurement point list.

[0027] Optionally, the constraint condition of the optimal layout theoretical position of the measurement device is:

[0028] the angle between the laser incidence direction vector of the measurement device and the normal vector of the triangular facet should be less than 45°, that is, the number of points with an angle greater than 45° between the laser incidence direction vector and the normal vector of the triangular facet is minimized, and the angle optimization objective function is constructed as:

[0029]

[0030] wherein, t n represents the angle between the normal vector of the triangular facet to which the nth measurement point belongs and the laser incidence direction vector; The purpose of the transformation is to make the angle less than 45° as small as possible and the angle greater than 45° as large as possible to the influence of the objective function;

[0031] The total distance from the measurement device to all measurement points is minimized, and the distance optimization objective function is constructed as:

[0032] wherein, L n is the distance from the measurement device layout position to the nth measurement point;

[0033] According to the angle optimization objective function and the distance optimization objective function, the overall optimization objective function is constructed as:

[0034]

[0035] wherein, k1 represents the weight value of the angle optimization, and k2 represents the weight value of the distance optimization.

[0036] Optionally, the coordinate system of the optimal layout theoretical position is unified with the actual measurement coordinate system to obtain a reference coordinate system, comprising:

[0037] The assembly positioning feature of the part is measured by the measurement device;

[0038] The actual measurement value of the assembly positioning feature is aligned with the theoretical value of the assembly positioning feature to obtain the reference coordinate system.

[0039] Optionally, the optimal layout actual position of the measurement device is obtained according to the reference coordinate system, comprising:

[0040] Based on the reference coordinate system, the laser of the measurement device is directed to the optimal layout theoretical position direction;

[0041] The laser beam is intercepted by the baffle, the baffle position is adjusted, the coordinates of the light spot on the baffle are continuously measured, until the distance from the measurement point position on the baffle to the optimal layout theoretical position is less than a specified value, and the current baffle position is the optimal layout actual position of the measurement device.

[0042] A part curved surface measurement process planning device, comprising:

[0043] A model establishing module is configured to establish a curved surface model of a part to be measured;

[0044] A model processing module is configured to pre-process the curved surface model to obtain a geometric curved surface;

[0045] a mesh division module configured to perform triangular mesh division on the geometric curved surface to convert the geometric curved surface into a curved surface mesh having a plurality of triangular facets;

[0046] a measurement point list acquisition module configured to acquire vertex coordinates and normal vector of each triangular facet to obtain a measurement point list;

[0047] a theoretical position acquisition module configured to obtain an optimal arrangement theoretical position of a measurement device according to the normal vector information of the triangular facet;

[0048] a coordinate unification module configured to unify a coordinate system of the optimal arrangement theoretical position with an actual measurement coordinate system to obtain a reference coordinate system;

[0049] an actual position acquisition module configured to obtain an optimal arrangement actual position of the measurement device according to the reference coordinate system;

[0050] a measurement execution module configured to cause the measurement device to perform a measurement work according to the measurement point list based on the optimal arrangement actual position.

[0051] A computer device includes a memory and a processor, the memory stores a computer program, and the processor executes the computer program to implement the method described above.

[0052] A computer readable storage medium stores a computer program, and a processor executes the computer program to implement the method described above.

[0053] The beneficial effects that can be achieved by the present application are as follows:

[0054] The present application can quickly provide a key measurement point list according to a curved surface model of a part, and determine an optimal arrangement theoretical position of a measurement device based on a measurement point determined by a triangular facet region and an optimal arrangement theoretical position calculated by optimization, so that part complex curved surface shape measurement no longer depends on a large amount of point cloud scanning, but only needs to perform accurate point measurement, improves the efficiency and scientificity of complex curved surface measurement process planning, and after unifying the theoretical and actual coordinates, the optimal arrangement actual position of the measurement device can be obtained by station matching, and the subsequent measurement device can perform point automatic measurement according to the key measurement point list. Therefore, the present application realizes rapid process planning for complex curved surface measurement, improves the scientificity of process parameter design, and changes the measurement mode from point cloud scanning to single point measurement, improves the measurement accuracy and greatly reduces the measurement and data processing time, thereby improving the efficiency of subsequent measurement of the measurement device. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference signs. In the drawings, the elements or parts are not necessarily drawn according to the actual proportions.

[0056] Figure 1 A flowchart of a part curved surface measurement process planning method in an embodiment of the present application;

[0057] Figure 2 A schematic diagram of a curved surface model of a part to be measured established in an embodiment of the present application;

[0058] Figure 3 A schematic diagram of a merged geometric curved surface in an embodiment of the present application;

[0059] Figure 4 A schematic diagram of a key attention area cut out from a geometric curved surface in an embodiment of the present application;

[0060] Figure 5 A schematic diagram of a geometric curved surface imported into a point cloud processing software in an embodiment of the present application;

[0061] Figure 6 A schematic diagram of a curved surface after a point cloud triangulation processing is performed on a geometric curved surface in an embodiment of the present application;

[0062] Figure 7 A schematic diagram of a curved surface mesh after a refinement and simplification are performed on a processed geometric curved surface in an embodiment of the present application.

[0063] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0065] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directionality indications also change accordingly.

[0066] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the technical features indicated or implicitly indicating the number of technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. For example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the scope of protection claimed by the present application.

[0067] Embodiment 1

[0068] Referring to Figures 1-7 The embodiment provides a part curved surface measurement process planning method, comprising the following steps:

[0069] Establishing a curved surface model of a part to be measured;

[0070] Pretreating the curved surface model to obtain a geometric curved surface;

[0071] Triangular meshing the geometric curved surface to obtain a curved surface mesh with a plurality of triangular facets;

[0072] Obtaining vertex coordinates and normal vector of each triangular facet to obtain a measurement point list;

[0073] Obtaining the optimal layout theoretical position of a measurement device according to the normal vector information of the triangular facet;

[0074] Unifying the coordinate system of the optimal layout theoretical position with an actual measurement coordinate system to obtain a reference coordinate system;

[0075] Obtaining the optimal layout actual position of the measurement device according to the reference coordinate system;

[0076] Making the measurement device based on the optimal layout actual position and performing measurement work according to the measurement point list.

[0077] In the prior art, when determining relevant measurement parameters in process planning before measurement, for example, for a laser radar, a scanning path and a sampling interval need to be given, different sampling rates are set according to accuracy requirements, and a layout position of the laser radar is selected. The above parameters are usually planned according to experience. The scanning path and the sampling interval are set too conservatively, resulting in a large sampling density and a large number of overlapping areas in measurement, and a low measurement efficiency. The layout position of the laser radar is usually tested at multiple stations in the field, and a station with the best measurement visibility is selected, which can only meet the basic requirement of measurement and cannot guarantee the measurement accuracy of global points. In addition, a lot of time is wasted in the testing process, which is not conducive to the sudden troubleshooting of field production. Therefore, in the process of laser radar measurement on a complex curved surface, the following problems exist:

[0078] (1) The measurement path and the measurement parameter need to be given manually according to experience, lacking scientificity and guidance;

[0079] (2) The measurement position can only be determined through multiple tests, and the accuracy of the position cannot be guaranteed to be optimal;

[0080] (3) Generally, point cloud scanning mode is used for measurement on a complex curved surface, and the measurement accuracy is not as good as single-point measurement. Moreover, millions of points are measured, resulting in a long measurement and data processing period.

[0081] Therefore, in the present embodiment, a list of key measurement points can be quickly given according to a curved surface model of a part, and the optimal layout theoretical position of a measurement device is determined based on the measurement points determined by a triangular facet region and the optimal layout theoretical position of the measurement device calculated by optimization, so that the measurement of the complex curved surface of the part is no longer dependent on a large number of point cloud scans, but only needs to be measured at accurate points, improving the efficiency and scientificity of the process planning for complex curved surface measurement. After the theoretical and actual coordinates are unified, the optimal layout actual position of the measurement device can be obtained by station matching. The subsequent measurement device can perform automatic measurement at points according to the list of key measurement points. Therefore, the present application realizes the process planning for automatic measurement of a complex curved surface without relying on experience and field testing, can quickly form a list of measurement points and an optimal layout theoretical position of a measurement device, improves the efficiency and scientificity of complex curved surface measurement, realizes rapid process planning for complex curved surface measurement, improves the scientificity of process parameter design, changes the measurement mode from point cloud scanning to single-point measurement, improves the measurement accuracy, and greatly reduces the measurement and data processing time, thereby improving the efficiency of subsequent measurement of the measurement device.

[0082] As an optional implementation, the pre-processing of the curved surface model to obtain a geometric curved surface comprises:

[0083] extracting a plurality of sub-curves of the curved surface model;

[0084] merging adjacent sub-curves to obtain a geometric curved surface;

[0085] The key attention area of the geometric curved surface is independently divided, and the remaining part of the geometric curved surface is a non-key attention area; wherein the key attention area includes a region with large deformation or a region that needs to be analyzed in detail.

[0086] In the embodiment, the complex curved surface is often composed of multiple sub-surfaces during design (as shown in Figure 2 To avoid the formation of redundant grid points at the connection of the curved surface, it is necessary to combine multiple sub-surfaces into one curved surface in the three-dimensional design software (as shown in Figure 3 For the key attention area, the outer shape at the edge line is taken as an example, and the area needs to be independently divided (as shown in Figure 4 to facilitate subsequent grid densification in each area.

[0087] As an optional embodiment, the triangular mesh division of the geometric curved surface to convert the curved surface into a mesh with multiple triangular facets includes:

[0088] The geometric curved surface is processed by point cloud triangulation in the point cloud processing software;

[0089] The key attention area of the processed geometric curved surface is refined;

[0090] The non-key attention area of the processed geometric curved surface is simplified;

[0091] Finally, the curved surface mesh with multiple triangular facets is obtained.

[0092] In the embodiment, the divided geometric curved surface can be saved as an STP format in the three-dimensional processing software, and the file is imported into the point cloud processing software (as shown in Figure 5 Selecting the conversion of the curved surface into a polygon, the curved surface is converted into a triangular mesh according to the default parameters, which is equivalent to a coarse division of the triangular mesh (as shown in Figure 6The curved surface is converted into a triangular mesh, and the mesh density is automatically adapted according to the curvature of the curved surface. The greater the curvature change, the greater the mesh density, so as to ensure that the mesh accuracy is controlled within a certain range. In addition, for different areas on the same surface, the mesh number is coordinated. The smaller the area, the greater the mesh density. The above characteristics determine that when the curved surface is converted from geometry to triangular mesh, the more complex the structure on the curved surface, the denser the mesh points. The maximum geometric deviation between the physical object and the model is generally in millimeter level. In the key attention area, the mesh can be refined, so that the deviation between the surface formed by the point cloud measured according to the model and the shape of the physical object is controlled within 0.1 mm (affected by the measurement equipment accuracy, the laser radar MV331 can guarantee the accuracy at 2 m), so the mesh points can be directly set as the measurement object. In the measurement, the density of the measurement points is automatically adjusted according to the change of the curved surface structure and the area, so as to realize the comprehensive optimization of the accuracy and the efficiency. For the non-key attention area, the mesh can be simplified to reduce the point cloud points to improve the measurement speed. For the key attention area, the mesh can be refined to improve the sampling density and increase the measurement accuracy. The refined and simplified curved surface is as shown in FIG. 8. Figure 7

[0093] Therefore, the embodiment based on the merging, cutting and simplification and refinement of different areas of the curved surface can quickly and scientifically adjust the density of the measurement points, and can well control the measurement accuracy of the key attention area and the measurement efficiency of the non-key attention area.

[0094] It should be noted that the basic flow of point cloud triangulation processing is as follows: reading point cloud: reading the original point cloud. As can be seen from the figure, the point cloud resolution is very high, which will make the calculation amount very large, and there are many outliers and noises; point cloud downsampling: sparsifying the original point cloud to reduce the calculation amount; removing outliers: the triangulation algorithm is sensitive to outliers; point cloud smoothing: due to the measurement noise of the sensor itself, the obtained point cloud will fluctuate, and the point cloud is smoothed by calculating the normal vector (similar to the image smoothing operation in image processing); finally, the point cloud is triangulated.

[0095] As an optional embodiment, the vertex coordinates and normal vector of each triangular facet are obtained to obtain a measurement point list, including:

[0096] The curved surface mesh is exported as an STL format file, and the STL format file stores the vertex coordinates and normal vector of each triangular facet;

[0097] ​The STL format file is saved as a txt format, the vertex coordinate data and the normal vector data are stored into an Excel table by using a string matching function of a VBA program of the Excel, and the vertex coordinate data is exported as a measurement point file in an ASCII format;

[0098] The measurement point file is imported into a laser radar measurement software to form a measurement point list.

[0099] In the embodiment, the STL file describes original unstructured triangular meshes by surface unit normals and vertices sorted by the right-hand rule in a three-dimensional triangular Cartesian coordinate system, and the STL can only be used to represent a closed surface or body. The STL file has two types: one is an ASCII plain code format, and the other is a binary format. The measurement point file exported in the ASCII format is the measurement point list. The step is a data conversion process, and is convenient for subsequent automatic measurement instructions of the measurement device through the measurement point list.

[0100] As an optional embodiment, the constraint condition of the optimal arrangement theoretical position of the measurement device is that:

[0101] The included angle between the laser incidence direction vector of the measurement device and the normal vector of the triangular facet should be less than 45°, that is, the number of points with the included angle between the laser incidence direction vector and the normal vector of the triangular facet greater than 45° is minimum, and an angle optimization objective function is constructed as:

[0102]

[0103] Wherein, t n represents the included angle between the normal vector of the triangular facet to which the nth measurement point belongs and the laser incidence direction vector; The purpose of the transformation is to make the influence of the angle with the included angle less than 45° on the objective function as small as possible and the influence of the angle with the included angle greater than 45° on the objective function as large as possible;

[0104] The total distance of the measurement device to all the measurement points is minimum, and a distance optimization objective function is constructed as:

[0105] Wherein, L n is the distance from the arrangement position of the measurement device to the nth measurement point;

[0106] According to the angle optimization objective function and the distance optimization objective function, a total optimization objective function is constructed as:

[0107]

[0108] Wherein, k1 represents the weight value of the angle optimization, and k2 represents the weight value of the distance optimization.

[0109] In this embodiment, a lidar is used as an example of a measuring device. After the list of measuring points is determined, the optimal placement of the measuring device needs to be calculated to ensure that all measuring points can be measured and that the accuracy is as high as possible. The constraint is that all measuring points can be measured, that is, the angle between the incident direction vector of the measuring laser and the normal vector of the triangular facet should be less than 45°. According to engineering practice, the probability of lidar measurement failure increases sharply when the angle is greater than 45°. Therefore, this constraint can be expressed as minimizing the number of points where the angle between the incident direction vector of the laser and the normal vector of the triangular facet is greater than 45°, thus constructing the above-mentioned angle optimization objective function. In addition, to ensure the accuracy is as high as possible, that is, to minimize the total distance from the measuring device to all measuring points, the above-mentioned distance optimization objective function is constructed. Finally, for multi-objective optimization problems, the above-mentioned overall optimization objective function can be constructed. Generally, the influence of the two (i.e., angle and distance) is made equal, that is, transformed to the same order of magnitude for calculation. Each sub-objective function needs to be divided by the width of its respective value interval to achieve consistency of order of magnitude.

[0110] Therefore, this implementation constructs an objective function based on angle constraints and distance constraints to optimize the deployment location of the measuring equipment, so that the measuring equipment can satisfy the measurability of as many points as possible during deployment, and can also take into account the goal of minimizing the total measurement distance, i.e., maximizing the measurement accuracy.

[0111] For example, if there are 8000 points to be measured, and the measurement distance range is 2m-8m, then the value range of g(x) is [16000, 64000], and its interval width is 48000; if there are 8000 points to be measured, and the incident angle range is [0, 180], then the objective function range for angle optimization is [0.28, 12.39], and its interval width is 12.2.

[0112] To make the two have the same magnitude, therefore K 1: K 2 = 48000: 12.2;

[0113] Can make K 1 = 3934; K 2=1, in order to measure as many points as possible, we can... K 1. Magnify to 10000;

[0114] The overall optimization objective function is: ;

[0115] Let the measurement point be ( x n , y n , z n The direction of the normal vector of the triangular facet it contains is (u n , v n , w n ), the position of the measuring device is (x, y, z) x p , y p , z p ); wherein:

[0116]

[0117] The least square method is used in MATLAB to find the (x, y, z) that satisfies the objective function. x p , y p , z p The optimal layout theoretical position of the measuring device can be obtained by least square method, and details are not repeated.

[0118] As an optional implementation, the coordinate system of the optimal layout theoretical position is unified with the actual measurement coordinate system to obtain a reference coordinate system, comprising:

[0119] The assembly positioning feature of the part is measured by the measuring device;

[0120] The actual measurement value of the assembly positioning feature is aligned with the theoretical value of the assembly positioning feature to obtain the reference coordinate system.

[0121] The actual measurement coordinate system is used in actual measurement, and the coordinate system of the optimal layout theoretical position needs to be aligned with the actual measurement coordinate system, so that the measurement point list and the optimal device layout position can be used. Therefore, the assembly positioning feature of the curved surface part is measured by the measuring device (i.e. laser radar), and the measurement value is aligned with the theoretical value of the assembly positioning feature in the measurement software, so that the coordinate system of the optimal layout theoretical position is unified with the actual measurement coordinate system.

[0122] It should be noted that the curved surface part usually has assembly features such as pin holes, positioning shoulders and other assembly structures. First, the feature points of the solid assembly structure such as hole axis and matching plane are measured, and then the theoretical geometry of the above features is imported into the measurement software. Generally, the measurement software has the best fitting registration function, and the measured features and the theoretical features are best fitted and registered, so that the actual measurement coordinate system is unified with the coordinate system of the optimal layout theoretical position.

[0123] As an optional implementation, the optimal layout actual position of the measuring device is obtained according to the reference coordinate system, comprising:

[0124] pointing the laser of the measuring device to the direction of the optimal arrangement theoretical position based on the reference coordinate system;

[0125] intercepting the laser beam with a baffle, adjusting the position of the baffle, and continuously measuring the coordinates of the light spot on the baffle until the distance between the measuring point position on the baffle and the optimal arrangement theoretical position is less than a specified value, and the current baffle position is the optimal arrangement actual position of the measuring device.

[0126] In the embodiment, under the unified reference coordinate system, the laser of the measuring device is pointed to the direction of the optimal arrangement theoretical position, the laser beam is intercepted with a baffle, the position of the baffle is adjusted, the coordinates of the light spot on the baffle are continuously measured, until the distance between the measuring point position on the baffle and the optimal arrangement theoretical position is less than a specified value (an empirical value less than 100 mm), and then a mark is made at the position (i.e. the optimal arrangement actual position of the measuring device). After the mark is made, the laser radar can be transferred to the position, and then the automatic measurement function built in the measurement software can be used to import the above-mentioned ASCII text into the measurement point list of the software, and the automatic measurement function is started, and the software automatically measures the point position.

[0127] Embodiment 2

[0128] The embodiment provides a part curved surface measurement process planning device, which comprises:

[0129] a model establishing module, configured to establish a curved surface model of a part to be measured;

[0130] a model processing module, configured to pre-process the curved surface model to obtain a geometric curved surface;

[0131] a mesh division module, configured to perform triangular mesh division on the geometric curved surface to convert the geometric curved surface into a curved surface mesh comprising a plurality of triangular facets;

[0132] a measurement point list acquisition module, configured to acquire the vertex coordinates and normal vector of each triangular facet to obtain a measurement point list;

[0133] a theoretical position acquisition module, configured to acquire an optimal arrangement theoretical position of a measuring device according to the normal vector information of the triangular facet;

[0134] a coordinate unification module, configured to unify the coordinate system of the optimal arrangement theoretical position with an actual measurement coordinate system to obtain a reference coordinate system;

[0135] an actual position acquisition module, configured to acquire an optimal arrangement actual position of the measuring device according to the reference coordinate system;

[0136] a measurement execution module, configured to make the measuring device perform measurement work based on the optimal arrangement actual position and according to the measurement point list.

[0137] Embodiment 3

[0138] The embodiment provides a computer device, which comprises a memory and a processor, the memory stores a computer program, and the processor executes the computer program to realize the method in the embodiment 1.

[0139] Embodiment 4

[0140] The embodiment provides a computer readable storage medium, which stores a computer program, and a processor executes the computer program to realize the method in the embodiment 1.

[0141] The above merely describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method of part surface measurement process planning, characterized by, The method comprises the following steps: a curved surface model of a part to be measured is established; the curved surface model is preprocessed to obtain a geometric curved surface; the geometric curved surface is divided into a triangular mesh to obtain a curved surface mesh having a plurality of triangular facets; vertex coordinates and normal vector of each triangular facet are obtained to obtain a measurement point list; an optimal theoretical position of a measuring device is obtained according to the normal vector of the triangular facet; the optimal theoretical position of the measuring device is subject to the following constraint condition: an angle between a laser incidence direction vector of the measuring device and the normal vector of the triangular facet should be less than 45°, that is, the number of points at which the angle between the laser incidence direction vector and the normal vector of the triangular facet is greater than 45° should be minimized, and an angle optimization objective function is constructed as follows: wherein, t n represents the angle between the normal vector of the triangular facet to which the nth measurement point belongs and the laser incidence direction vector; The purpose of the transformation is to make the angle smaller than 45° have a small influence on the objective function, and the angle larger than 45° have a large influence on the objective function. a total distance from the measuring device to all measurement points should be minimized, and a distance optimization objective function is constructed as follows: wherein, L n to measure the distance from the device deployment location to the nth measurement point; a total optimization objective function is constructed according to the angle optimization objective function and the distance optimization objective function as follows: wherein k1 represents a weight value of the angle optimization, and k2 represents a weight value of the distance optimization; a coordinate system of the optimal theoretical position is unified with an actual measurement coordinate system to obtain a reference coordinate system; an optimal actual position of the measuring device is obtained according to the reference coordinate system; the measuring device is caused to perform measurement work based on the optimal actual position and according to the measurement point list.

2. A method of process planning for part surface measurement as claimed in claim 1, wherein, The preprocessing of the curved surface model to obtain the geometric curved surface comprises the following steps: a plurality of sub-curved surfaces of the curved surface model are extracted; adjacent sub-curved surfaces are merged to obtain the geometric curved surface; a key attention area of the geometric curved surface is independently segmented out, and a remaining part of the geometric curved surface is a non-key attention area; wherein the key attention area includes a region with large deformation or a region that needs to be analyzed in priority.

3. A method of process planning for part surface measurement as claimed in claim 2, wherein, The triangular mesh division of the geometric curved surface to convert into the curved surface mesh having a plurality of triangular facets comprises the following steps: the geometric curved surface is subjected to point cloud triangulation processing in a point cloud processing software; the key attention area of the processed geometric curved surface is subjected to mesh refinement; the non-key attention area of the processed geometric curved surface is subjected to mesh simplification; finally, the curved surface mesh having a plurality of triangular facets is obtained.

4. A method of process planning for part surface measurement as claimed in claim 3, wherein, The obtaining of the vertex coordinates and the normal vector of each triangular facet to obtain the measurement point list comprises the following steps: the curved surface mesh is exported as an STL format file, and the STL format file stores the vertex coordinates and the normal vector of each triangular facet; the STL format file is saved as a txt format, vertex coordinate data and normal vector data are stored into an Excel table by using a string matching function of a VBA program of the Excel, and the vertex coordinate data is exported as a measurement point position file in ASCII format; the measurement point position file is imported into a laser radar measurement software to form the measurement point list.

5. A method of process planning for part surface measurement as recited in claim 1, wherein, The unification of the coordinate system of the optimal theoretical position with the actual measurement coordinate system to obtain the reference coordinate system comprises the following steps: an assembly positioning feature of the part is measured by the measuring device; an actual measurement value of the assembly positioning feature is aligned with a theoretical value of the assembly positioning feature to obtain the reference coordinate system.

6. A method of process planning for part surface measurement as claimed in claim 5, wherein, The optimal arrangement actual position of the measuring device is obtained according to the reference coordinate system, and the optimal arrangement actual position of the measuring device is obtained according to the reference coordinate system, comprising: The laser of the measuring device is pointed to the optimal arrangement theoretical position direction based on the reference coordinate system; The laser beam is intercepted by the baffle, the position of the baffle is adjusted, the coordinates of the light spot on the baffle are measured continuously, until the distance between the measuring point position on the baffle and the optimal arrangement theoretical position is less than a specified value, and the current baffle position is the optimal arrangement actual position of the measuring device.

7. A part surface measurement process planning apparatus characterized by comprising: Comprise: The model establishing module is used for establishing a curved surface model of a part to be measured; The model processing module is used for pre-processing the curved surface model to obtain a geometric curved surface; The grid division module is used for triangular mesh division of the geometric curved surface to obtain a curved surface grid with multiple triangular facets; The measuring point list acquisition module acquires the vertex coordinates and normal vector of each triangular facet to obtain a measuring point list; The theoretical position acquisition module is used for acquiring the optimal arrangement theoretical position of the measuring device according to the normal vector information of the triangular facet; the constraint condition of the optimal arrangement theoretical position of the measuring device is that the included angle between the laser incidence direction vector of the measuring device and the normal vector of the triangular facet should be less than 45°, that is, the number of points at which the included angle between the laser incidence direction vector and the normal vector of the triangular facet is greater than 45° is minimized, and an angle optimization objective function is constructed as follows: The total distance of the measuring device to all measuring points is minimized, and a distance optimization objective function is constructed as follows: wherein, t n represents the angle between the normal vector of the triangular facet to which the nth measurement point belongs and the laser incidence direction vector; The purpose of the transformation is to make the angle smaller than 45° have a small influence on the objective function, and the angle larger than 45° have a large influence on the objective function. According to the angle optimization objective function and the distance optimization objective function, a total optimization objective function is constructed as follows: wherein, L n is the distance from the device placement position to the nth measurement point; Wherein, k1 represents the weight value of the angle optimization, and k2 represents the weight value of the distance optimization; The coordinate unification module is used for unifying the coordinate system of the optimal arrangement theoretical position with an actual measurement coordinate system to obtain a reference coordinate system; The actual position acquisition module acquires the optimal arrangement actual position of the measuring device according to the reference coordinate system; The measurement execution module is used for enabling the measuring device to perform measurement work according to the measuring point list based on the optimal arrangement actual position. The computer device comprises a memory and a processor, the memory stores a computer program, and the processor executes the computer program to realize the method in any one of claims 1-6.

8. A computer device, comprising: The computer readable storage medium stores a computer program, and the processor executes the computer program to realize the method in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, ​

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