A simulation model stitching method, system, and vehicle body surface model stitching method

Abstract

The present invention discloses a simulation model stitching method, a system and a vehicle body surface model stitching method, belonging to the technical field of surface model simulation design. Existing simulation model repair solutions require a great deal of effort and time from engineers and are prone to errors. A simulation model stitching method of the present invention can accurately identify potential gap regions and stitch the gaps of a surface simulation model by constructing a gap recognition unit, a connection relationship generation unit, a gap fitting simulation unit and a gap repair unit, thereby enabling batch and automated solution of gap problems, replacing manual labor to complete cumbersome and repetitive gap processing work, thus efficiently and accurately solving surface gaps, greatly shortening the R & D cycle and being less prone to errors. Furthermore, accurate dynamic characteristic analysis of surface simulation objects can be carried out. The solution is detailed, scientific, reasonable and practical.

Description

Technical Field

[0001] The invention relates to a simulation model stitching method, a system and a vehicle body curved surface model stitching method, belonging to the technical field of curved surface model simulation design. Background Art

[0002] In the computer-aided design (CAD) modeling process, especially when it comes to the design of complex surfaces, designers often divide large surfaces into multiple small blocks for separate modeling and processing. This method can simplify the modeling process, reduce computational complexity, and improve modeling efficiency. However, this division also brings some potential problems, especially when the joints of these small blocks are not precisely docked, leaving tiny gaps in the connection area, which may affect the overall structure and performance of the final model.

[0003] In engineering applications, especially in the fields of body design, aircraft shell design, and shipbuilding, if the gaps between certain surfaces in the simulation model are not repaired, it will not only affect the geometric accuracy of the model, but may also cause errors in subsequent simulation analysis, thereby affecting the product's performance, strength, aerodynamic performance, etc. For example, in body design, if the gaps between certain surfaces are not repaired, it may affect the aerodynamic characteristics of the body, resulting in unnecessary airflow interference and increased resistance.

[0004] To avoid this situation, engineers now generally import the simulation model into pre-processing software, check the gaps in the simulation model one by one, and then repair them manually. This is an extremely tedious process with many repetitive tasks, which will consume a lot of energy and time of engineers, is time-consuming and labor-intensive, and prone to errors. Therefore, it is difficult to obtain high-quality surface simulation objects, which in turn affects the dynamic characteristics analysis of the surface simulation objects.

[0005] The information disclosed in this Background Art is only for understanding the background of the inventive concept and therefore it may include information that does not constitute the prior art. Summary of the invention

[0006] In response to the above problem or one of the above problems, an object of the present invention is to provide a simulation model stitching method and system, which can accurately identify potential gap areas and stitch the gaps of the surface simulation model by constructing a gap identification unit, a connection relationship generation unit, a gap fitting simulation unit, and a gap repair unit to obtain a high-quality surface simulation object; that is, by using multiple gap algorithm units, the gap problem can be solved in a batch and automated manner, thereby replacing manpower to complete tedious and repetitive gap processing work, thereby efficiently and accurately solving surface gaps, realizing rapid stitching of surface models, greatly shortening the R&D cycle, and being less prone to errors.

[0007] In response to the above problem or one of the above problems, the second purpose of the present invention is to provide a method for stitching a car body surface model, which constructs multiple gap algorithm units to form a repair tool to solve the gap problem in a batch and automated manner, thereby greatly improving the stitching efficiency of the car body surface model, and can solve the surface gap problem with high quality, realize rapid stitching of the car body surface, greatly shorten the R&D cycle, and have great significance for the entire automobile R&D process.

[0008] To achieve one of the above purposes, the first technical solution of the present invention is:

[0009] A simulation model stitching method comprises the following steps:

[0010] Step 1: Use the pre-built gap recognition unit to process the surface simulation model and identify the boundary line data with a single connection surface to locate the potential gap area;

[0011] Step 2: Using a pre-built connection relationship generation unit, based on a pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain potential connection relationship information;

[0012] Step 3, using a pre-built gap fitting simulation unit, for potential gap areas, generating fitting surface data according to potential connection relationship information;

[0013] Step 4: Based on the pre-built gap repair unit, a stitching surface is generated according to the fitted surface data, and the gaps of the surface simulation model are stitched to obtain a stitched surface simulation object.

[0014] The present invention identifies potential gap areas and generates potential connection relationship information and fitting surface data by constructing a gap identification unit, a connection relationship generation unit, a gap fitting simulation unit, and a gap repair unit; then the gaps of the surface simulation model are stitched to obtain a high-quality surface simulation object; that is, multiple gap algorithm units are used to perform batch and automatic solutions to gap problems, thereby replacing manpower to complete tedious and repetitive gap processing work, thereby efficiently and accurately solving surface gaps, realizing rapid stitching of surface models, greatly shortening the research and development cycle, and being less prone to errors, and then accurate dynamic characteristic analysis of the surface simulation object can be performed, and the scheme is detailed, scientific, reasonable, and feasible.

[0015] As the preferred technical measures:

[0016] Step 1: Using the pre-built gap recognition unit, the surface simulation model is processed to identify the boundary line data with a single connection surface as follows:

[0017] Obtaining an original surface simulation model, which is a CAD model of a vehicle body, an aircraft shell, or a ship that needs to be processed;

[0018] Collect all geometric lines of the CAD model using the entity collection method and put the geometric lines into a geometric line array;

[0019] Based on the geometry line array, check the number of surfaces connected by each geometry line. If a geometry line only connects one surface, it is a boundary line with a single connected surface.

[0020] All boundary lines are aggregated to obtain boundary line data.

[0021] As the preferred technical measures:

[0022] Step 2: Using the pre-built connection relationship generation unit, based on the pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain the potential connection relationship information as follows:

[0023] Acquire boundary line data having a single connected surface, which includes a plurality of boundary lines;

[0024] Calculate the geometric center of each boundary line to obtain the center value of each boundary line;

[0025] The center value of each boundary line is used as the center of the circle, and based on the preset radius, the local area of ​​each boundary line is set;

[0026] According to the local area of ​​each boundary line, all boundary lines in the local area are determined;

[0027] A number of discrete points are set on the boundary lines in the local area, and connected with the corresponding discrete points on the adjacent boundary lines to generate a number of quadrilateral meshes;

[0028] Calculate the distance between the vertex of the quadrilateral mesh and each boundary line, and obtain the potential connection number of each boundary line based on the pairing judgment mechanism and the vertex distance threshold;

[0029] Based on the number of potential connections, traverse each boundary line, find the corresponding boundary line with the largest number of potential connections with the boundary line, and obtain one-to-one pairing information;

[0030] The one-to-one pairing information is aggregated to obtain potential connection relationship information.

[0031] As the preferred technical measures:

[0032] The method of setting several discrete points on the boundary line in the local area and connecting them with the corresponding discrete points on the adjacent boundary line to generate several quadrilateral meshes is as follows:

[0033] According to the length of each boundary line and the preset discrete step length, a number of discrete points are evenly set on each boundary line so that the distance between adjacent discrete points is not greater than the discrete step length;

[0034] According to the positions of adjacent boundary lines, a distance function is established to calculate the Euclidean distance between discrete points;

[0035] According to the distance function, the distances between discrete points on different boundary lines are calculated to obtain discrete distance data;

[0036] For a discrete point, based on the discrete distance data, find the discrete point closest to the discrete point and obtain the corresponding discrete point;

[0037] Connect the discrete points with the corresponding discrete points and combine them with the corresponding boundary lines to generate several quadrilateral meshes;

[0038] Or / and, the distance between the vertex of the quadrilateral mesh and each boundary line is calculated, and the method of obtaining the potential connection number of each boundary line based on the pairing judgment mechanism and the vertex distance threshold is as follows:

[0039] The pairing judgment mechanism is a voting counting mechanism, which calculates the Euclidean distance between each vertex on the current quadrilateral mesh and all boundary lines in the local area to obtain vertex distance data;

[0040] According to the vertex distance data, find the minimum vertex distance and the corresponding vertex and boundary line;

[0041] When the minimum vertex distance value is less than the vertex distance threshold, it indicates that there is a connection between the vertex and the boundary line, then the count value of the boundary line is increased to obtain the number of connections of the boundary line; when the minimum vertex distance value is greater than or equal to the vertex distance threshold, it indicates that there is no connection between the vertex and the boundary line, then the next minimum vertex distance value is determined;

[0042] The vertex distance threshold is generally set to 0.5, which can be adjusted according to the model size.

[0043] By traversing all vertices of the current quadrilateral mesh, the number of connections between each boundary line and the current quadrilateral mesh vertices is counted to determine the number of potential connections for each boundary line and store it in a global dictionary to represent the number of times the boundary line is connected to other boundary lines through the quadrilateral mesh;

[0044] The global dictionary is a data structure used to record various information related to the boundary line; whenever a potential connection of the boundary line is found, the connection vote count of the boundary line is increased in the corresponding global dictionary.

[0045] As the preferred technical measures:

[0046] Step 3: Use the pre-built gap fitting simulation unit to generate fitting surface data for potential gap areas based on potential connection relationship information as follows:

[0047] Obtaining potential connection relationship information of the boundary line, which includes one-to-one pairing information;

[0048] According to the potential connection relationship information of the boundary lines, a query data structure is established to realize the merging and query of disjoint boundary lines, which can quickly determine whether two boundary lines belong to the same array and merge the two boundary lines into the same array;

[0049] Use the union-find data structure to group boundary lines based on one-to-one pairing information, merge boundary lines that originally belong to different arrays but are paired with each other into the same array, and obtain grouped data;

[0050] According to the grouped data, the boundary lines in the same array are interpolated and connected to create a fitting surface and obtain the fitting surface data.

[0051] As the preferred technical measures:

[0052] According to the grouped data, the boundary lines in the same array are interpolated and connected to create a fitting surface as follows:

[0053] According to the grouped data, get the boundary lines in the same array;

[0054] According to the boundary line characteristics, the spline interpolation algorithm is used to obtain the curve expression of each boundary line;

[0055] According to the curve expression, a two-dimensional spline interpolation algorithm is used to smoothly fit the surface formed by multiple boundary lines to obtain the expression of the two-dimensional spline surface;

[0056] According to the expression of the two-dimensional spline surface, several interpolation points are generated to create a fitting surface.

[0057] As the preferred technical measures:

[0058] According to the boundary line characteristics, the method of using the spline interpolation algorithm to obtain the curve expression of each boundary line is as follows:

[0059] Discretize each boundary line into several control points;

[0060] According to several control points, construct basis functions about the boundary line;

[0061] Based on the basis functions and spline orders, the curve expression of each boundary line is obtained.

[0062] As the preferred technical measures:

[0063] Step 4: Based on the pre-built gap repair unit, according to the fitted surface data, a stitching surface is generated, and the gaps of the surface simulation model are stitched to obtain a stitched surface simulation object as follows:

[0064] Acquire fitting surface data, which includes a number of interpolation points;

[0065] Based on a number of interpolation points, the gaps or vacancies enclosed by the boundary lines are filled to obtain a stitched surface;

[0066] Check the topological structure of the stitched surface to determine whether there are any gaps that have not been stitched;

[0067] When there is a gap that has not been sutured, re-execute steps 1 to 4 to re-suture the sutured surface;

[0068] When the gap has been stitched, it indicates that the simulated stitched surface meets the design requirements, thereby completing the gap stitching of the surface simulation model and finally obtaining the surface simulation object.

[0069] To achieve one of the above purposes, the second technical solution of the present invention is:

[0070] A simulation model suturing system, comprising:

[0071] one or more processors;

[0072] A storage device for storing one or more programs;

[0073] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned simulation model stitching method.

[0074] To achieve one of the above purposes, the third technical solution of the present invention is:

[0075] A method for stitching a car body curved surface model, comprising the following contents:

[0076] Using the pre-built gap recognition unit, the body surface model is processed to identify the boundary line data with a single connection surface to locate the potential gap area;

[0077] Using a pre-built connection relationship generation unit, based on a pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain potential connection relationship information;

[0078] Use the pre-built gap fitting simulation unit to generate fitting surface data for potential gap areas based on potential connection relationship information;

[0079] Based on the pre-built gap repair unit, a stitching surface is generated according to the fitting surface data, and the gaps of the body surface model are stitched to obtain a stitched body surface simulation object.

[0080] The present invention constructs a plurality of gap algorithm units to form a repair tool to solve the gap problem in a batch and automated manner, thereby greatly improving the efficiency of stitching the body surface model, and can solve the surface gap problem with high quality, realize the rapid stitching of the body surface, greatly shorten the research and development cycle, and have a great significance to the entire automobile research and development process.

[0081] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0082] The present invention identifies potential gap areas and generates potential connection relationship information and fitting surface data by constructing a gap identification unit, a connection relationship generation unit, a gap fitting simulation unit, and a gap repair unit; then the gaps of the surface simulation model are stitched to obtain a high-quality surface simulation object; that is, multiple gap algorithm units are used to replace manpower to complete tedious and repetitive gap processing work, thereby efficiently and accurately solving surface gaps, realizing rapid stitching of surface models, greatly shortening the research and development cycle, and being less prone to errors, and then accurate dynamic characteristic analysis of the surface simulation object can be performed, and the scheme is detailed, scientific, reasonable, and feasible.

[0083] The present invention constructs a plurality of gap algorithm units to form a repair tool to solve the gap problem in a batch and automated manner, thereby greatly improving the efficiency of stitching the body surface model, and can solve the surface gap problem with high quality, realize the rapid stitching of the body surface, greatly shorten the research and development cycle, and have a great significance to the entire automobile research and development process. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 A schematic diagram of a flow chart of the simulation model stitching method of the present invention;

[0085] Figure 2 A schematic diagram of the structure of the boundary line of the present invention;

[0086] Figure 3 A schematic diagram showing three boundary lines of the present invention;

[0087] Figure 4 A schematic diagram of grouping boundary lines according to the present invention;

[0088] Figure 5 A schematic diagram of generating a quadrilateral mesh for the present invention;

[0089] Figure 6 A schematic diagram of an existing automobile window model;

[0090] Figure 7 The present invention is used to sew a certain automobile window model. DETAILED DESCRIPTION

[0091] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0092] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the following detailed description of the present invention. Those skilled in the art can fully understand the present invention without the description of these details.

[0093] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0094] like Figure 1 As shown, a specific embodiment of the simulation model stitching method of the present invention:

[0095] A simulation model stitching method comprises the following steps:

[0096] Step 1: Use the pre-built gap recognition unit to process the surface simulation model and identify the boundary line data with a single connection surface to locate the potential gap area;

[0097] Step 2: Using a pre-built connection relationship generation unit, based on a pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain potential connection relationship information;

[0098] Step 3, using a pre-built gap fitting simulation unit, for potential gap areas, generating fitting surface data according to potential connection relationship information;

[0099] Step 4: Based on the pre-built gap repair unit, a stitching surface is generated according to the fitted surface data, and the gaps of the surface simulation model are stitched to obtain a stitched surface simulation object.

[0100] The first specific embodiment of the method for stitching a car body curved surface model of the present invention:

[0101] A method for stitching a car body curved surface model comprises the following steps:

[0102] Step 1: Obtain a body surface model, and use a pre-built gap recognition unit to process the body surface model to identify boundary line data with a single connection surface for locating potential gap areas;

[0103] Step 2: Using a pre-built connection relationship generation unit, based on a pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain potential connection relationship information;

[0104] Step 3, using a pre-built gap fitting simulation unit, for potential gap areas, generating fitting surface data according to potential connection relationship information;

[0105] Step 4: Based on the pre-built gap repair unit, a stitching surface is generated according to the fitted surface data, and the gaps of the body surface model are stitched to obtain a stitched body surface simulation object.

[0106] In this embodiment: Step 1, a method of obtaining a body surface model and processing the body surface model using a pre-built gap recognition unit to recognize boundary line data having a single connection surface is as follows:

[0107] The original body surface model is obtained, which is the body CAD model that needs to be processed; CAD is the abbreviation of Computer Aided Design (Computer Aided Design).

[0108] All geometric lines of the vehicle body CAD model are collected using the entity collection method of the existing pre-processing software, and the geometric lines are placed in a geometric line array;

[0109] Based on the geometry line array, check the number of surfaces connected by each geometry line. If a geometry line only connects one surface, it is a boundary line with a single connected surface.

[0110] All boundary lines are aggregated to obtain boundary line data.

[0111] In this embodiment: Step 2, a method of using a pre-built connection relationship generation unit to process the boundary line data with a single connection surface based on a pairing judgment mechanism to obtain potential connection relationship information is as follows:

[0112] Acquire boundary line data having a single connected surface, which includes a plurality of boundary lines;

[0113] Calculate the geometric center of each boundary line to obtain the center value of each boundary line;

[0114] The center value of each boundary line is used as the center of the circle, and based on the preset radius, the local area of ​​each boundary line is set;

[0115] According to the local area of ​​each boundary line, all boundary lines in the local area are determined;

[0116] A number of discrete points are set on the boundary lines in the local area, and connected with the corresponding discrete points on the adjacent boundary lines to generate a number of quadrilateral meshes;

[0117] Calculate the distance between the vertex of the quadrilateral mesh and each boundary line, and obtain the potential connection number of each boundary line based on the pairing judgment mechanism and the vertex distance threshold;

[0118] Based on the number of potential connections, traverse each boundary line, find the corresponding boundary line with the largest number of potential connections with the boundary line, and obtain one-to-one pairing information;

[0119] The one-to-one pairing information is aggregated to obtain potential connection relationship information.

[0120] In this embodiment, a method of setting a plurality of discrete points on the boundary line in the local area and connecting them with the corresponding discrete points on the adjacent boundary line to generate a plurality of quadrilateral meshes is as follows:

[0121] According to the length of each boundary line and the preset discrete step length, a number of discrete points are evenly set on each boundary line so that the distance between adjacent discrete points is not greater than the discrete step length;

[0122] According to the positions of adjacent boundary lines, a distance function is established to calculate the Euclidean distance between discrete points;

[0123] According to the distance function, the distances between discrete points on different boundary lines are calculated to obtain discrete distance data;

[0124] For a discrete point, based on the discrete distance data, find the discrete point closest to the discrete point and obtain the corresponding discrete point;

[0125] Connect the discrete points with the corresponding discrete points and combine them with the corresponding boundary lines to generate several quadrilateral meshes.

[0126] In this embodiment, the method of calculating the distance between the vertex of the quadrilateral mesh and each boundary line, and obtaining the potential connection number of each boundary line based on the pairing judgment mechanism and the vertex distance threshold is as follows:

[0127] The pairing judgment mechanism is a voting counting mechanism, which calculates the Euclidean distance between each vertex on the current quadrilateral mesh and all boundary lines in the local area to obtain vertex distance data;

[0128] According to the vertex distance data, find the minimum vertex distance and the corresponding vertex and boundary line;

[0129] When the minimum vertex distance value is less than the vertex distance threshold, it indicates that there is a connection between the vertex and the boundary line, then the count value of the boundary line is increased to obtain the number of connections of the boundary line; when the minimum vertex distance value is greater than or equal to the vertex distance threshold, it indicates that there is no connection between the vertex and the boundary line, then the next minimum vertex distance value is determined;

[0130] By traversing all vertices of the current quadrilateral mesh, the number of connections between each boundary line and the current quadrilateral mesh vertices is counted to determine the number of potential connections for each boundary line and store it in a global dictionary to represent the number of times the boundary line is connected to other boundary lines through the quadrilateral mesh;

[0131] The global dictionary is a data structure used to record various information related to the boundary line; whenever a potential connection of the boundary line is found, the connection vote count of the boundary line is increased in the corresponding global dictionary.

[0132] In this embodiment: Step 3, using the pre-built gap fitting simulation unit, for the potential gap area, according to the potential connection relationship information, the method of generating fitting surface data is as follows:

[0133] Obtaining potential connection relationship information of the boundary line, which includes one-to-one pairing information;

[0134] According to the potential connection relationship information of the boundary lines, a query data structure is established to realize the merging and query of disjoint boundary lines, which can quickly determine whether two boundary lines belong to the same array and merge the two boundary lines into the same array;

[0135] Use the union-find data structure to group boundary lines based on one-to-one pairing information, merge boundary lines that originally belong to different arrays but are paired with each other into the same array, and obtain grouped data;

[0136] According to the grouped data, the boundary lines in the same array are interpolated and connected to create a fitting surface and obtain the fitting surface data.

[0137] In this embodiment, according to the grouped data, the boundary lines in the same array are interpolated and connected to create a fitting surface as follows:

[0138] According to the grouped data, get the boundary lines in the same array;

[0139] According to the boundary line characteristics, the spline interpolation algorithm is used to obtain the curve expression of each boundary line;

[0140] According to the curve expression, a two-dimensional spline interpolation algorithm is used to smoothly fit the surface formed by multiple boundary lines to obtain the expression of the two-dimensional spline surface;

[0141] According to the expression of the two-dimensional spline surface, several interpolation points are generated to create a fitting surface.

[0142] In this embodiment, according to the boundary line characteristics, a method of obtaining a curve expression of each boundary line using a spline interpolation algorithm is as follows:

[0143] Discretize each boundary line into several control points;

[0144] According to several control points, construct basis functions about the boundary line;

[0145] Based on the basis functions and spline orders, the curve expression of each boundary line is obtained.

[0146] In this embodiment: Step 4, based on the pre-built gap repair unit, according to the fitting surface data, a stitching surface is generated, and the gap of the body surface model is stitched to obtain a stitched body surface simulation object as follows:

[0147] Acquire fitting surface data, which includes a number of interpolation points;

[0148] Based on a number of interpolation points, the gaps or vacancies enclosed by the boundary lines are filled to obtain a stitched surface;

[0149] Check the topological structure of the stitched surface to determine whether there are any gaps that have not been stitched;

[0150] When there is a gap that has not been sutured, re-execute steps 1 to 4 to re-suture the sutured surface;

[0151] When the gap has been stitched, it indicates that the simulated stitched surface meets the design requirements, thereby completing the gap stitching of the body surface model and finally obtaining the body surface simulation object.

[0152] A second specific embodiment of the method for stitching a car body curved surface model of the present invention:

[0153] A method for stitching a car body surface model is proposed. Aiming at the gaps between the surfaces, a method for stitching the surfaces by means of grid filling is proposed, which includes the following contents:

[0154] First, potential gap areas are located by identifying boundary lines with a single connection surface. Then, the grid filling function and voting mechanism of the pre-processing software ANSA are used to obtain the potential connection relationship between any two pairs. Then, the boundary lines are grouped according to any two pairing relationships, and finally, a fitting surface is created based on the boundary lines in the same group to repair the gaps.

[0155] A third specific embodiment of the method for stitching a car body curved surface model of the present invention:

[0156] A method for stitching a car body curved surface model, comprising the following contents:

[0157] S1, load the CAD model to be processed in the pre-processing software ANSA to complete the import of the original model.

[0158] Then, for each geometry line, check the number of surfaces it is connected to. If only one surface is connected, the geometry line is a boundary line, see Figure 2 , Figure 2 The red lines in the figure represent the boundary lines, and the green areas represent the surfaces.

[0159] If there are potential connections or relationships between these boundary lines, these relationships may constitute the edge of a certain gap area. The gap area here can be understood as an area formed by multiple boundary lines through potential connections.

[0160] In this embodiment, the specific method for identifying potential gaps is as follows:

[0161] Step 11. Collect all geometric lines using the entity collection method and put them into an array.

[0162] Step 12. Call the attribute acquisition module API of the pre-processing software ANSA, traverse each geometric line, and obtain the attribute of the number of connected faces of the geometric line. If the number of connected faces of the geometric line is equal to 2, it means that the geometric line is the common boundary of two faces. If the number of connected faces of the geometric line is equal to 1, it means that the geometric line is the free boundary of the face. The geometric line with the number of connected faces of the geometric line equal to 1 is defined as a boundary edge or boundary line.

[0163] Given any two boundary lines , the maximum distance between them can be calculated , and its calculation formula is as follows:

[0164]

[0165] in, It is a curve Any point on It is a curve Any point on represents the Euclidean distance.

[0166] If this maximum distance is less than a certain tolerance threshold (vertex distance threshold), i.e. , According to the size setting of the model, it is considered There is a potential connection.

[0167] like Figure 3 As shown, there are three boundary lines of different colors, among which the red line represents the boundary line , the blue line indicates the boundary line , the purple line indicates the boundary line ,and , ,therefore , Has potential connection relationship, , There is a potential connection.

[0168] If you create a fitting surface directly based on any two connection relationships, it will cause the surfaces to overlap. The ideal situation is based on , , To create a fitted surface, you need to group the boundary lines, and then create a fitted surface based on the boundary lines in the same group to repair the gap. , , For the same group, see Figure 4 , Figure 4 The red line in the figure indicates the boundary line. , the blue line indicates the boundary line , the purple line indicates the boundary line .

[0169] S2, for each boundary line, voting pairing is performed to find other boundary lines with the greatest possibility of connection with each boundary line, and obtain one-to-one pairing information. The specific method is as follows:

[0170] The expressions for all boundary lines are as follows:

[0171]

[0172] in Indicates A boundary line.

[0173] For any , and define its geometric center as , To ensure that previously processed boundaries are not revisited in subsequent processing, all boundaries are first marked as unvisited. This way, when the algorithm traverses these entities, it knows which ones have been processed, thus avoiding duplication of work.

[0174] Check each boundary line one by one, first determine whether it has been visited. If it has been visited, skip it directly and do not perform subsequent operations. Otherwise, perform the following steps:

[0175] Step 21. Collect local boundary lines, which include the following:

[0176] For each unvisited boundary line , define a is the center and the radius is Local area , which is expressed as follows:

[0177]

[0178] in, is any point in space, For the border line The geometric center of is the radius and can be adjusted according to the model size.

[0179] For each unvisited frontier, collect all The inner boundary , and mark these boundaries as visited, the expression is as follows:

[0180]

[0181] in, It is the border line The geometric center of .

[0182] Step 22. After all the boundary lines in the local area are determined, a grid is generated within the boundary lines with potential connection relationships. The specific steps are as follows:

[0183] For border lines with potential connections ,Right now , first discretize the boundary lines using a series of vertices Based on the length of each boundary line and the discrete step length specified by the user , evenly distribute a number of discrete points on each edge so that the distance between every two adjacent discrete points is no greater than the discrete step length .

[0184] Therefore, for the boundary lines with potential connections There are two discrete point sets, the boundary line The discrete point set is as follows:

[0185] , , …,

[0186] Boundary Line The discrete point set is as follows:

[0187] , , …,

[0188] For border lines with potential connections , construct a distance function , to find each discrete point The nearest discrete point , and its calculation formula is as follows:

[0189]

[0190] in and The boundary lines The discrete point numbers on For discrete points and discrete points The Euclidean distance between them is calculated as follows:

[0191]

[0192] in, , , Is a discrete point The coordinate value on the XYZ axis, , , Is a discrete point The XYZ axis coordinate values.

[0193] For each pair of nearest discrete points and , connect them together to generate a quadrilateral mesh. The mesh generated by this process is as follows Figure 5 shown.

[0194] Step 23. Traverse each grid generated above and perform the following operations:

[0195] (1) Create a counter for each local boundary line, and the initial value of the counter is 0. The purpose of this counter is to store the number of connections between the current mesh vertex and the boundary line.

[0196] (2) For each vertex on the current quadrilateral mesh (A quad mesh has 4 vertices) Calculate the point With all local boundaries The closest distance between , and its calculation formula is as follows:

[0197]

[0198] in, For the border line The discrete point set Any point in for and The Euclidean distance between .

[0199] If a vertex with a boundary line The closest distance Less than 0.5, this 0.5 is a preset threshold, indicating that the two are close enough and can be adjusted according to the model size, so the vertex is considered With the border line If there is a connection between the two vertices, the counter of the boundary line is increased. By traversing all the vertices of the current quadrilateral mesh, the number of connections between each boundary line and the current quadrilateral mesh vertex can be counted.

[0200] (3) Find two boundary lines with a counter value of 2 , since the two boundary lines are connected through the quadrilateral mesh, a voting mechanism is used to record this information. The specific method is as follows:

[0201] First, each boundary line initializes an empty dictionary to store the following information:

[0202] (1) Identification information of other boundary lines connected by quadrilateral meshes;

[0203] (2) The number of connections (votes) of other boundary lines connected through the quadrilateral mesh.

[0204] Whenever two boundary lines with a counter value of 2 are found , that is, the two boundary lines are connected by a quadrilateral mesh, then let Plus one, Plus one. The corresponding dictionary data is { : (4), (5)},{ : (4)},{ (5)}.

[0205] Traverse each boundary line and execute the entire voting pairing process mentioned above until all boundary lines are visited.

[0206] Finally, the dictionary will store the number of times each boundary line is connected to other boundary lines through the grid. The larger the count, the greater the possibility that the boundary line is connected to other boundary lines.

[0207] Traverse each item of the global dictionary and find the boundary line with the highest count in the item. That is, find the other boundary lines with the greatest possibility of connecting with each boundary line, and obtain one-to-one pairing information, as shown in Table 1.

[0208] Table 1

[0209]

[0210] S3, grouping the boundary lines, which includes the following:

[0211] First, we create a boundary line array, the array content represents the parent node of each boundary line. When initializing, the parent node of each boundary line is itself, indicating that it is an independent set, as shown in Table 2.

[0212] Table 2

[0213]

[0214] Then, traverse the boundary line pairing information obtained in the previous step, for each pair of paired boundary lines , determine whether the two boundary lines have the same root node. The specific steps are as follows:

[0215] Finding boundary lines using recursive search The root node:

[0216] If the boundary line The parent node of It is itself, ,So It is its own root node, returning the boundary line If the boundary line The parent node of Not itself, then , and then continue to find the boundary line The parent node of , until the root node is found. Similarly, the boundary line is found by recursive search method. The root node of the boundary line If there is no common root node, use the union-find function to merge the sets they belong to. The specific steps are as follows:

[0217] Finding boundary lines using recursive search The root node . Compare the ranks (heights) of the two root nodes, i.e. the maximum depth of the tree. Set the parent node of the root node with the smaller rank as the root node with the larger rank. Traverse the boundary line pairing information obtained in the previous step, execute the above steps, and update the union-find set, as shown in Table 3.

[0218] Table 3

[0219]

[0220] Finally, initialize a list to store the grouping results, traverse each boundary line, find its root node through the recursive search method, put the boundary lines belonging to the same root node into the same group, and complete the grouping of the boundary lines.

[0221] S4, based on all the boundary lines in the same group, automatically calculates and generates a new fitting surface according to the input information such as the position and shape of the boundary lines, so as to accurately close the gaps or vacant parts surrounded by these boundary lines.

[0222] In this embodiment, the specific method of generating a closed surface is as follows:

[0223] Traverse the grouping results, based on the boundary lines in the same group, and use the spline curve algorithm NURBS to construct a fitting surface. Assume that there are n boundary lines in the same group, where the boundary lines The expression is as follows:

[0224]

[0225] in, It is the border line Coordinate function on the X-axis; It is the border line Coordinate function on the Y axis; It is the border line Coordinate function on the Z axis.

[0226] First, for each boundary line Using spline interpolation, each boundary line is represented as a series of control points Assume that each boundary line Discretized into control points, the basis function is , then the boundary line is expressed as follows:

[0227]

[0228] in It is a curve Discrete control points, is the corresponding spline basis function, Represents the order of the spline basis function.

[0229] Then, a two-dimensional spline interpolation is used to construct a smooth fitting surface. Assume that each curve are discretized into a set of control points , since there are n curves, the expression of the two-dimensional spline surface is:

[0230]

[0231] in , and is a two-dimensional parameter, and They correspond to and The spline basis function of Represents the order of the spline basis function.

[0232] S5, use the CHECK tool of the pre-processing software ANSA to verify whether the topological structure of the surface is correct, that is, check whether the surface has self-intersections, duplications, or incorrect connections. For closed surfaces, ensure that each edge and each face are correctly matched to avoid unconnected faces or isolated points.

[0233] Collect the boundary lines of the model after processing, and check one by one whether there are any gaps that have not been stitched. For unresolved surface gaps, you can iterate the above steps repeatedly, or you can manually solve them through the interactive interface of the pre-processing software.

[0234] A specific embodiment of applying the present invention to sew a certain automobile window model:

[0235] The method for sewing a car body curved surface model of the present invention is used to sew a car window model, which specifically includes the following contents:

[0236] The first step is to import the car window model containing the gap into the pre-processing software ANSA. The car window model can be found in Figure 6 The pre-processing software ANSA will automatically number the geometric entities, and each geometric entity will be assigned a unique identification ID. By using the entity collection function of the pre-processing software to obtain all geometric lines and surfaces, it can be obtained that the entire model contains 34 geometric lines and 7 surfaces.

[0237] In the second step, traverse the 34 geometric lines and call the entity attribute value acquisition function of the pre-processing software to obtain the number of connected faces of each geometric line. If the number of connected faces of a geometric line is equal to 1, it is a boundary line. Finally, 24 boundary lines are collected and regarded as the edges of potential gap areas. The 24 boundary lines are marked as unvisited, and an empty dictionary is created for each of the 24 boundary lines to store the identification IDs and connection times of other boundary lines connected to it through the quadrilateral mesh.

[0238] The third step is to collect the boundary lines in the local area and conduct voting matching, which includes the following:

[0239] Starting from the first boundary line, first determine whether it has been visited. If it has been visited, skip it directly and do not perform subsequent operations. Otherwise, collect all boundary lines in the local area with a radius of 20, and finally get 24 boundary lines, which are marked as visited.

[0240] Then, meshes are generated within the boundary lines with potential connection relationships, resulting in 85 newly generated quadrilateral meshes.

[0241] Based on the quadrilateral grid, the method to obtain the dictionary count is as follows:

[0242] First, create a counter for the 24 boundary lines to store the number of connections between the current mesh vertex and each boundary line.

[0243] Traverse the four vertices of the grid, and for each grid vertex, calculate the distance between it and the 24 local boundary lines. Among them, the distance between two grid vertices and the boundary line with identification ID 23431 is less than 0.5, and they are considered to coincide with the boundary line with identification ID 23431. The other two grid vertices coincide with the boundary line with identification ID 27602. It can be obtained that the counters of identification ID 23431 and identification ID 27602 are 2 respectively.

[0244] Therefore, the boundary lines with identification ID 23431 and identification ID 27602 are considered to be connected, and the count in the boundary line dictionary is updated. At this time, the dictionary content is {23431:27602 (1)}, {27602:23431 (1)}, that is, 23431 and 27602 are connected through a quadrilateral mesh, and the number of connections (number of votes) is 1.

[0245] Traverse the 85 generated quadrilateral meshes and establish the boundary lines , , Connection relationship , which is expressed as follows:

[0246]

[0247] in, For the border line and The number of connections through the quad mesh, For the border line and The number of connections through the quadrilateral mesh is Then explain and The connection possibilities are greater.

[0248] According to the connection relationship , construct the count of all boundary line dictionaries. In this embodiment, the content of the global boundary line dictionary is as follows:

[0249]

[0250]

[0251]

[0252]

[0253] The four digits in the curly brackets represent the ID of the boundary line; the value in the parentheses represents the number of times the boundary line is connected to other boundary lines through the grid. The larger the count in the parentheses, the greater the possibility that the boundary line is connected to other boundary lines.

[0254] Traverse the above boundary line dictionary and find the boundary line with the most counts in each one. The final pairing result is:

[0255]

[0256]

[0257]

[0258] The fourth step is to initialize and query the data structure, traverse the above pairing results, and for each pair of boundary lines , determine whether the root nodes are the same. If the root nodes are the same, they are already in the same set. If there are no identical root nodes, use the union-find function to merge the sets they belong to. After all traversals are completed, traverse all boundary lines starting from the first boundary line and assign boundary lines with the same root node to the same group. The grouping results are as follows:

[0259]

[0260] Step 5: Starting from the first group, traverse all the grouping results, process each group, use all the boundary lines in the same group as input parameters, create a new fitting surface to close the gap, and refer to the specific stitching effect. Figure 7 .

[0261] To sum up, this embodiment adopts secondary development technology based on the pre-processing software ANSA, and proposes a fully automatic stitching method for the body surface model to solve the gaps in the body surface model, thereby efficiently and high-quality solving the surface gaps, realizing rapid stitching of the body surface, greatly shortening the R&D cycle, and having great significance for the entire automobile R&D process.

[0262] An embodiment of a device applying the method of the present invention:

[0263] An electronic device comprising:

[0264] one or more processors;

[0265] A storage device for storing one or more programs;

[0266] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned vehicle body curved surface model stitching method.

[0267] A computer medium embodiment using the method of the present invention:

[0268] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned method for stitching a car body curved surface model.

[0269] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, and computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program codes.

[0270] The present application is described by flowcharts or / and block diagrams of the methods, devices (systems), and computer program products of the embodiments of the present application. It should be understood that each process or / and block in the flowchart or / and block diagram and the combination of the processes or / and blocks in the flowchart or / and block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart or / and block diagram. Figure 1 Process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0271] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 Process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0272] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 Process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0273] The unit in this application is an object that objectively describes the morphological structure with the help of physical or virtual expressions. The object is not equal to the object and is not limited to physical and virtual. It can be a data processing function, software program, processing mode, usage method, operation method, workflow, application process, electronic hardware, circuit module, processing system, system imitation or simulation object.

[0274] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field can still modify or replace the specific implementation methods of the present invention with equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A simulation model suturing method, characterized in that: The following steps are involved: Step 1: Use the pre-built gap recognition unit to process the surface simulation model and identify the boundary line data with a single connection surface to locate the potential gap area; Step 2: Using a pre-built connection relationship generation unit, based on a pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain potential connection relationship information; The method is as follows: Acquire boundary line data having a single connected surface, which includes a plurality of boundary lines; Calculate the geometric center of each boundary line to obtain the center value of each boundary line; The center value of each boundary line is used as the center of the circle, and based on the preset radius, the local area of ​​each boundary line is set; According to the local area of ​​each boundary line, all boundary lines in the local area are determined; A number of discrete points are set on the boundary lines in the local area, and connected with the corresponding discrete points on the adjacent boundary lines to generate a number of quadrilateral meshes; Calculate the distance between the vertex of the quadrilateral mesh and each boundary line, and obtain the potential connection number of each boundary line based on the pairing judgment mechanism and the vertex distance threshold; Based on the number of potential connections, traverse each boundary line, find the corresponding boundary line with the largest number of potential connections with the boundary line, and obtain one-to-one pairing information; Summarize the one-to-one pairing information to obtain potential connection relationship information; Step 3, using a pre-built gap fitting simulation unit, for potential gap areas, generating fitting surface data according to potential connection relationship information; Step 4: Based on the pre-built gap repair unit, a stitching surface is generated according to the fitted surface data, and the gaps of the surface simulation model are stitched to obtain a stitched surface simulation object.

2. A simulation model suturing method as claimed in claim 1, characterized in that: Step 1: Using the pre-built gap recognition unit, the surface simulation model is processed to identify the boundary line data with a single connection surface as follows: Obtaining an original surface simulation model, which is a CAD model of a vehicle body, an aircraft shell, or a ship that needs to be processed; Collect all geometric lines of the CAD model using the entity collection method and put the geometric lines into a geometric line array; Based on the geometry line array, check the number of surfaces connected by each geometry line. If a geometry line only connects one surface, it is a boundary line with a single connected surface. All boundary lines are aggregated to obtain boundary line data.

3. A simulation model suturing method as claimed in claim 1, characterized in that: The method of setting several discrete points on the boundary line in the local area and connecting them with the corresponding discrete points on the adjacent boundary line to generate several quadrilateral meshes is as follows: According to the length of each boundary line and the preset discrete step length, a number of discrete points are evenly set on each boundary line so that the distance between adjacent discrete points is not greater than the discrete step length; According to the positions of adjacent boundary lines, a distance function is established to calculate the Euclidean distance between discrete points; According to the distance function, the distances between discrete points on different boundary lines are calculated to obtain discrete distance data; For a discrete point, based on the discrete distance data, find the discrete point closest to the discrete point and obtain the corresponding discrete point; Connect the discrete points with the corresponding discrete points and combine them with the corresponding boundary lines to generate several quadrilateral meshes; The method of calculating the distance between the vertex of the quadrilateral mesh and each boundary line, and obtaining the potential number of connections for each boundary line based on the pairing judgment mechanism and the vertex distance threshold is as follows: The pairing judgment mechanism is a voting counting mechanism, which calculates the Euclidean distance between each vertex on the current quadrilateral mesh and all boundary lines in the local area to obtain vertex distance data; According to the vertex distance data, find the minimum vertex distance and the corresponding vertex and boundary line; When the minimum vertex distance is less than the vertex distance threshold, it indicates that there is a connection between the vertex and the boundary line, then the count value of the boundary line is increased to obtain the number of connections of the boundary line; When the minimum vertex distance value is greater than or equal to the vertex distance threshold, it indicates that there is no connection between the vertex and the boundary line, and the next minimum vertex distance value is determined; By traversing all vertices of the current quadrilateral mesh, the number of connections between each boundary line and the current quadrilateral mesh vertices is counted to determine the number of potential connections for each boundary line and store it in a global dictionary to represent the number of times the boundary line is connected to other boundary lines through the quadrilateral mesh; The global dictionary is a data structure used to record various information related to the boundary line; whenever a potential connection of the boundary line is found, the connection vote count of the boundary line is increased in the corresponding global dictionary.

4. A simulation model suturing method as claimed in claim 1, characterized in that: Step 3: Use the pre-built gap fitting simulation unit to generate fitting surface data for potential gap areas based on potential connection relationship information as follows: Obtaining potential connection relationship information of the boundary line, which includes one-to-one pairing information; According to the potential connection relationship information of the boundary lines, a query data structure is established to realize the merging and query of disjoint boundary lines, which can quickly determine whether two boundary lines belong to the same array and merge the two boundary lines into the same array; Use the union-find data structure to group boundary lines based on one-to-one pairing information, merge boundary lines that originally belong to different arrays but are paired with each other into the same array, and obtain grouped data; According to the grouped data, the boundary lines in the same array are interpolated and connected to create a fitting surface and obtain the fitting surface data.

5. A simulation model suturing method as claimed in claim 4, characterized in that: According to the grouped data, the boundary lines in the same array are interpolated and connected to create a fitting surface as follows: According to the grouped data, get the boundary lines in the same array; According to the boundary line characteristics, the spline interpolation algorithm is used to obtain the curve expression of each boundary line; According to the curve expression, a two-dimensional spline interpolation algorithm is used to smoothly fit the surface formed by multiple boundary lines to obtain the expression of the two-dimensional spline surface; According to the expression of the two-dimensional spline surface, several interpolation points are generated to create a fitting surface.

6. A simulation model suturing method as claimed in claim 5, characterized in that: According to the boundary line characteristics, the method of using the spline interpolation algorithm to obtain the curve expression of each boundary line is as follows: Discretize each boundary line into several control points; According to several control points, construct basis functions about the boundary line; Based on the basis functions and spline orders, the curve expression of each boundary line is obtained.

7. A simulation model suturing method according to claim 1, characterized in that: Step 4: Based on the pre-built gap repair unit, according to the fitted surface data, a stitching surface is generated, and the gaps of the surface simulation model are stitched to obtain a stitched surface simulation object as follows: Acquire fitting surface data, which includes a number of interpolation points; Based on a number of interpolation points, the gaps or vacancies enclosed by the boundary lines are filled to obtain a stitched surface; Check the topological structure of the stitched surface to determine whether there are any gaps that have not been stitched; When there is a gap that has not been sutured, re-execute steps 1 to 4 to re-suture the sutured surface; When the gap has been stitched, it indicates that the simulated stitched surface meets the design requirements, thereby completing the gap stitching of the surface simulation model and finally obtaining the surface simulation object.

8. A simulation model suturing system, characterized in that: It includes: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement a simulation model stitching method as described in any one of claims 1-7.

9. A method for stitching a car body curved surface model, characterized in that: Includes the following: Using the pre-built gap recognition unit, the body surface model is processed to identify the boundary line data with a single connection surface to locate the potential gap area; Using a pre-built connection relationship generation unit, based on a pairing judgment mechanism, the boundary line data with a single connection surface is processed to obtain potential connection relationship information; The method is as follows: Acquire boundary line data having a single connected surface, which includes a plurality of boundary lines; Calculate the geometric center of each boundary line to obtain the center value of each boundary line; The center value of each boundary line is used as the center of the circle, and based on the preset radius, the local area of ​​each boundary line is set; According to the local area of ​​each boundary line, all boundary lines in the local area are determined; A number of discrete points are set on the boundary lines in the local area, and connected with the corresponding discrete points on the adjacent boundary lines to generate a number of quadrilateral meshes; Calculate the distance between the vertex of the quadrilateral mesh and each boundary line, and obtain the potential connection number of each boundary line based on the pairing judgment mechanism and the vertex distance threshold; Based on the number of potential connections, traverse each boundary line, find the corresponding boundary line with the largest number of potential connections with the boundary line, and obtain one-to-one pairing information; Summarize the one-to-one pairing information to obtain potential connection relationship information; Use the pre-built gap fitting simulation unit to generate fitting surface data for potential gap areas based on potential connection relationship information; Based on the pre-built gap repair unit, a stitching surface is generated according to the fitting surface data, and the gaps of the body surface model are stitched to obtain a stitched body surface simulation object.

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