Method for automatically generating thin coating based on target ontology triangular facet data

Abstract

This invention discloses an automatic generation method for thin-coated targets based on target body triangular facet metadata, enabling rapid modeling and accurate electromagnetic analysis of thin-coated targets. The method comprises the following steps: First, reading the triangular facet metadata from the target body mesh file to obtain the unit normal vector of each triangular facet and the number of triangular facets containing each vertex; then, looping through all vertices and storing the unit normal vectors of each triangular facet containing the i-th vertex sequentially as matrix A. i The column vectors of matrix A i Perform linear correlation analysis based on matrix A i The number of linearly independent column vectors is used to determine the outward extension vector required for each vertex during coating; finally, the new vertices are used to generate triangular face metadata about the coating. The coating model generated by this invention is more general and accurate.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic scattering characteristic calculation technology of coating targets, and in particular, it is a method for automatically generating thin coatings based on the target body triangular facet metadata. Background Technology

[0002] The study of target electromagnetic scattering characteristics is a crucial topic in computational electromagnetics. Accurate calculation of a target's electromagnetic scattering characteristics requires precise target modeling. In engineering electromagnetic scattering analysis, the model typically obtained is a CAD (Computer-Aided Design) model of the target's structure or a model with a triangular mesh. However, when analyzing the impact of thin layers of protective paint or stealth materials on electromagnetic scattering, modeling the thin coating is necessary. While commercial modeling software can quickly model thin coatings for simple targets, it presents challenges for complex targets. Therefore, the technology for automatically generating thin coatings is extremely important in addressing this issue. Existing TDS algorithms, when applying a coating, extend each triangular facet along its normal to obtain the required thickness of the coating data. For planar targets, the extended facets have the same shape and area as the original facets, except that each vertex is translated along its normal to a plane parallel to the target surface. However, for curved targets, the vertices of a facet are not necessarily extended along its normal direction. Therefore, some have proposed summing the unit normal vectors of several adjacent facets containing a vertex; this sum approximates the normal vector at that vertex before extension. However, these coating algorithms produce coatings that are neither universal nor accurate. Therefore, a universal and accurate automatic thin-coating generation method is needed to address the shortcomings of existing thin-coating modeling and analysis methods. Summary of the Invention

[0003] The purpose of this invention is to provide an automatic thin-coating generation method based on target body triangular facet metadata, enabling rapid modeling and accurate electromagnetic analysis of thin-coating targets.

[0004] The technical solution to achieve the purpose of this invention is: an automatic thin coating generation method based on target ontology triangular face metadata, comprising the following steps:

[0005] Step 1: Read the triangular face metadata from the target body mesh file;

[0006] Step 2: Calculate the unit normal vector of each triangular facet and the number of triangular facets containing each vertex based on the triangular facet data.

[0007] Step 3: Loop through all vertices and store the unit normal vectors of each triangle containing the i-th vertex as a matrix A.i Column vectors;

[0008] Step 4: For matrix A i Perform linear correlation analysis to find the number of linearly independent column vectors and their corresponding column vectors, based on matrix A. i Depending on the number of linearly independent column vectors, the corresponding method is used to determine the outward extension vector required for coating each vertex;

[0009] Step 5: Use the new vertices to generate triangular metadata about the coating.

[0010] In a second aspect, the present invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method described in the first aspect.

[0011] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0012] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention improves upon the shortcomings of existing thin-coating modeling and analysis methods, points out the accuracy problems of thin-coating generation algorithms and electromagnetic analysis algorithms for thin-coating structures, and discloses a general and highly accurate thin-coating modeling and analysis method. Compared with existing automatic thin-coating generation methods based on target ontology triangular facet metadata, the coating model generated by this invention is more general and accurate, and the analysis results of the coating model obtained based on this method are also more accurate than the results of existing publicly reported thin-coating scattering approximation analysis techniques. Attached Figure Description

[0013] Figure 1 This is a flowchart of an automatic thin coating generation method based on target ontology triangular face metadata in this invention.

[0014] Figure 2 This is a schematic diagram of the target body in this invention (taking a cube as an example), wherein (a) is a schematic diagram of the target body (taking a cube as an example) model, and (b) is a schematic diagram of the triangular facets of the target body (taking a cube as an example).

[0015] Figure 3 This is a schematic diagram of the triangular facet subdivision file of the target body (taking a cube as an example) in this invention (taking Nastran format as an example).

[0016] Figure 4 This is a schematic diagram illustrating three scenarios encountered when coating the target body (taking a cube as an example) outwards in this invention.

[0017] Figure 5This is a schematic diagram illustrating the generation of triangular facet metadata about the coating in this invention.

[0018] Figure 6 Figure (a) is a schematic diagram of the coating of the target body (taking a cube as an example) generated by the TDS algorithm, and Figure (b) is a schematic diagram of the coating of the target body (taking a cube as an example) generated by the method of the present invention.

[0019] Figure 7 This is a comparative schematic diagram of the bistationary RCS of the coating of the target ontology (taking a cube as an example) generated by the TDS algorithm, the bistationary RCS of the coating of the target ontology (taking a cube as an example) verified by FEKO for the correctness of the TDS algorithm, and the bistationary RCS of the coating of the target ontology (taking a cube as an example) generated by the method of this invention.

[0020] Figure 8 Figure (a) is a schematic diagram of the coating of the target body (taking a cube as an example) by the existing thin coating modeling method, and Figure (b) is a schematic diagram of the coating of the target body (taking a cube as an example) by the method of the present invention.

[0021] Figures 9-12 These are schematic diagrams illustrating the coating process of the present invention on the warhead, frustum, prism, and missile model. Detailed Implementation

[0022] This invention proposes an automatic thin-coating generation method based on target body triangular facet metadata, enabling rapid modeling and accurate electromagnetic analysis of thin-coated targets. In engineering electromagnetic scattering analysis, the model typically obtained is a computer-aided design model of the target body structure or a model after triangular mesh partitioning. When analyzing the impact of thin layers such as protective paint or stealth materials on electromagnetic scattering, it is necessary to model the thin coating before analysis. This invention addresses the shortcomings of existing thin-coating modeling and analysis methods, identifies issues with the accuracy of thin-coating generation algorithms and electromagnetic analysis algorithms for thin-coating structures, and publishes a general and highly accurate thin-coating modeling and analysis method.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The methods and means used in the description of the specific embodiments of the present invention are merely for the purpose of fully and clearly explaining the invention and are not intended to limit the invention.

[0024] Combination Figure 1 The present invention discloses an automatic thin coating generation method based on target ontology triangular facet metadata, comprising the following steps:

[0025] Step 1: Read the triangular face metadata from the target body mesh file, as follows:

[0026] Combination Figure 2 and Figure 3 Taking a cube as an example, the first step is to model it in commercial software and perform triangular face subdivision, such as... Figure 2 As shown, export the triangular mesh file. As an example, export the triangular mesh in Nastran format. Typical Nastran format information is as follows: Figure 3 As shown, the nodes of the triangles are arranged in a right-hand rule pointing outwards. The triangular face metadata in the triangle mesh file is read, including the number of triangular face elements M, the number of triangular face element vertices N, and the coordinates of the triangular face element vertices.

[0027] Step 2: Calculate the unit normal vector of each triangular facet and the number of triangular facets containing each vertex based on the triangular facet data.

[0028] The ontology triangle data read in step 1 contains the vertex numbers of the three vertices of the ontology triangle and the coordinate information of N vertices. Let the three vertices of the triangle be numbered a1, b1, and c1. Using the coordinate information of vertices a1, b1, and c1, the edge vectors are calculated. and Then, the unit normal vector of the triangular element is calculated.

[0029] Combination Figure 3 The unit normal vectors of each triangular element are obtained:

[0030] For example, in the first triangular element, the three vertices are 1, 2, and 3. The coordinates of vertex 1 are (0.5, 0.3, 0.5), the coordinates of vertex 2 are (0.5, 0.2, 0.5), and the coordinates of vertex 3 are (0.3924, 0.2505, 0.5). Subtracting vertex 1 from vertex 2 gives vector V1 (0, -0.1, 0), and subtracting vertex 1 from vertex 3 gives vector V2 (-0.1076, -0.0495, 0). From vectors V1 and V2, we obtain the normal vector of this triangular element. After normalization, the unit normal vector (0,0,-1) is obtained. Similarly, the unit normal vectors of all triangular facets can be calculated in the same way.

[0031] Combination Figure 3 The number of triangle vertices is 158, which is read from the mesh file. All vertices are looped through in turn to obtain the number of triangles containing each vertex.

[0032] Step 3: Loop through all vertices and store the unit normal vectors of each triangle containing the i-th vertex as a matrix A. i The column vector is specifically:

[0033] There are N triangular facet vertices. By iterating through these vertices, we find the number M of triangular facets containing the i-th vertex according to step 2.i And to find M i The unit normal vectors of each triangular element are stored sequentially in matrix A. i column vectors, matrix A i The size is 3×M i .

[0034] Combination Figure 3 There are 158 triangular facet vertices. By iterating through these vertices, we find the number M of triangular facets containing the i-th vertex according to step 2. i And to find M i The unit normal vectors of each triangular element are stored sequentially in matrix A. i column vectors, matrix A i The size is 3×M i .

[0035] Step 4: For matrix A i Perform linear correlation analysis to find the number of linearly independent column vectors and their corresponding column vectors, based on matrix A. i The number of linearly independent column vectors is used to determine the outward extension vector required for coating each vertex using appropriate methods, combined with... Figure 4 The details are as follows:

[0036] For matrix A i Linear correlation analysis can be performed using corresponding matrix decomposition methods. This invention takes QR decomposition as an example, that is, decomposing matrix A... i Perform a pivot-selective QR decomposition to find the number of linearly independent column vectors and their corresponding column vectors, resulting in AP = QR. The P matrix is ​​a permutation matrix. This operation will decompose the resulting A... i Move the linearly independent vectors in the matrix to the first few columns, and then find the decomposed A. i Find the maximum value on the diagonal of the matrix, and then compare each value on the diagonal with the maximum value. The absolute value of the division of each value must be greater than 1 × 10. -5 The column vector containing this value is a linearly independent column vector. When counting the number of linearly independent column vectors (Number), three cases will occur:

[0037] The fact that Number = 1 indicates that the unit normal vectors of all triangle elements containing vertex i are the same, and the unit movement vector of this vertex is the unit normal vector of the triangle element.

[0038] The fact that Number = 2 indicates that the unit normal vector of each triangular facet containing vertex i has two different directions. Figure 4 In, for example and It is the unit normal vector of the surface formed by these two different direction unit normal vectors, that is...

[0039] Find the unit movement vector of this vertex. Need to meet exist and The projection on is 1. exist The projection onto the surface is 0. Based on this condition, construct a matrix equation and solve the system of equations:

[0040]

[0041] ·Number = 3 indicates the unit normal vector of each triangle element containing vertex i. There are 3 or more different directions, with the subscript M. i Let be the number of triangle elements containing that vertex, and Figure 4 The unit normal vectors of the six triangular facets containing this vertex have three different directions.

[0042] Then the unit movement vector of that vertex Need to meet the following conditions The projection on the surface is 1. Based on this condition, construct an overdetermined system of equations:

[0043]

[0044] Solving this system of equations using the least squares method yields the unit movement vector of the vertex.

[0045] Step 5: Generate triangular face metadata about the coating using the new vertices, as follows:

[0046] Combination Figure 5 Based on the required coating thickness, the coordinates of the coating element vertices corresponding to each vertex of the body triangle are determined. For example, vertex i is labeled D, and its coordinates are (x... D ,y D ,z D The coating thickness is d0. Vertex D is moved along the unit movement vector. Move to D', so that Then the coordinates (x) of the newly added vertex (i+N) labeled D' are... D' ,y D' ,z D' )for:

[0047] x D' =x D +d0q ix ,y D' =y D +d0q iy ,z D' =zD +d0q iz (3)

[0048] Find the unit movement vector of each vertex i = 1, 2, ..., N. After moving the coordinates of the thickness d0, construct new triangular elements according to the vertex numbers (a1, b1, c1) of the original triangular elements. The vertex numbers are (a1+N, b1+N, c1+N). Combine this information with the original triangular element information to generate new triangular element metadata, and you will get the triangular element metadata containing the coating.

[0049] The accuracy of the method of the present invention will be illustrated below using a metal cube coating as an example. The versatility of the method of the present invention will be demonstrated through calculation examples of coatings for various models.

[0050] Example 1

[0051] Combination Figure 6 This embodiment performs electromagnetic scattering calculations on a 0.2m metal cube coating at a computational frequency of 1GHz. This embodiment is implemented on a computing platform with a 12th Gen Intel(R) Core(TM) i5-12400F CPU @ 2.50GHz and 32GB of memory. The incident angle of the uniform plane wave is θ = 0°. Polarization angle α = 0°, observation angle is θ = 0°~360°, with a layer of lossless medium with a thickness of 0.016m and ε = 3.4. Figure 6 (a) represents the coating generated by TDS. Figure 6 (b) represents the coating generated by the method of this invention. The bistationary RCS of metal cube coatings obtained by the TDS algorithm and the method of this invention were compared. The correctness of the TDS algorithm was verified using FEKO, and the bistationary RCS of the cube coating generated by the method of this invention was calculated using CST. The calculation results are as follows: Figure 7 The results of the two methods are significantly different, indicating that the analysis results of the coating model obtained by the method of this invention are more accurate than the results of the existing publicly reported TDS analysis technology. Only accurate modeling can correctly calculate the electromagnetic scattering characteristics of the target.

[0052] Example 2

[0053] Combination Figure 6 and Figure 8 Taking cubic coatings as an example, this paper compares existing thin coating modeling methods. Figure 6 (a) and Figure 8 (a) and the coating of the method of the present invention ( Figure 6 (b) and Figure 8(b) Regarding the coating effect, existing thin-coating modeling methods cannot accurately achieve the coating effect required by the actual situation. The method of this invention can achieve a coating effect that is highly consistent with the actual requirements, demonstrating the accuracy of the method. Combined with... Figures 9 to 12 In this embodiment, coatings were applied to the warhead, frustum, prism, and missile model. Using the method of this invention, the triangular element model of the entire model can be calculated when a coating with a thickness of 0.016 μm is applied to the surface of these models, demonstrating the versatility of the method.

[0054] In summary, the present invention provides an automatic thin coating generation method based on target body triangular facet metadata, which can coat any model, perform coating more accurately, and achieve coating effects consistent with actual requirements, thereby correctly calculating the electromagnetic scattering characteristics of the target.

Claims

1. A method for automatically generating thin coatings based on target ontology triangular face metadata, characterized in that, Includes the following steps: Step 1: Read the triangular face metadata from the target body mesh file; Step 2: Calculate the unit normal vector of each triangular facet and the number of triangular facets containing each vertex based on the triangular facet data. Step 3: Loop through all vertices and store the unit normal vectors of each triangle containing the i-th vertex as matrices. Column vectors; Step 4: For the matrix Perform linear correlation analysis to find the number of linearly independent column vectors and their corresponding column vectors, based on the matrix. The number of linearly independent column vectors is used to determine the outward extension vector required for coating each vertex, as follows: Using matrix decomposition method, the matrix is... Perform linear correlation analysis and count the number of linearly independent column vectors. : This means that the unit normal vectors of all triangle elements containing vertex i are the same, and the unit movement vector of this vertex is the unit normal vector of the triangle element. This indicates that the unit normal vector of each triangular facet containing vertex i has two different directions. and , It is the unit normal vector of the surface formed by these two different direction unit normal vectors, that is... Then the unit movement vector of the vertex to be determined. Satisfies the system of equations: (1) Explain the unit normal vectors of each triangle containing vertex i. , ... If there are three or more different directions, then the unit movement vector of that vertex is... Need to meet the following conditions , ... The projection on is 1, and the subscript is 1. Given the number of triangular facets containing the vertex, construct an overdetermined system of equations based on this condition: (2) Solving this system of equations using the least squares method yields the unit movement vector of the vertex. ; Step 5: Use the new vertices to generate triangular metadata about the coating.

2. The method for automatically generating thin coatings based on target ontological triangular facet metadata according to claim 1, characterized in that, The method for calculating the unit normal vector of each triangular facet in step 2 is as follows: the data of the body triangular facet read in step 1 contains the vertex numbering information of the three vertices of the body triangular facet and... The coordinates of the three vertices of the triangle are given. , , ,use , , Using the coordinates of the vertices, calculate the edge vectors. and Then, the unit normal vector of the triangular facet element is calculated. .

3. The method for automatically generating thin coatings based on target ontological triangular facet metadata according to claim 2, characterized in that, In step 3, iterate through all vertices, and store the unit normal vectors of each triangle containing the i-th vertex as matrices. The column vectors are as follows: There exist Given a set of vertices of a triangle, iterate through these vertices and, according to step 2, find the number of triangles containing the i-th vertex. and to obtain The unit normal vectors of each triangular element are stored sequentially as matrices. column vectors, matrices The size is .

4. The method for automatically generating thin coatings based on target ontological triangular facet metadata according to claim 1, characterized in that, In step 5, the new vertices are used to generate triangular face metadata about the coating, as follows: Based on the required coating thickness, the coordinates of the vertices of the coating element corresponding to each vertex of the body triangle are obtained; let vertex i be labeled as... The coordinates are The coating thickness is Move vertex D along the unit movement vector Move to Then add a new vertex (i+ ) label coordinates for: (3) We find i = 1, 2, ... Unit movement vector of each vertex Moving thickness The coordinates are determined according to the vertex index of the body triangle element. , , Construct a new triangular element, whose vertices are numbered as ( , , This information, along with the original triangular element information, generates new triangular element metadata, resulting in triangular element metadata containing the coating.

5. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method as described in any one of claims 1-4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-4.

Images