Efficient interference checking method for CAD model with complex structure

Abstract

The invention belongs to the technical field of CAD (computer-aided design) manufacturing informatization, and relates to an efficient interference checking method for a CAD (computer-aided design) model with a complex structure, which is implemented by adopting a hierarchical bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm and comprises the following steps of: 1, establishing a quantitative evaluation index; 2, optimizing a hierarchical bounding box assembly tree algorithm; 3, recursively using the result of the optimized hierarchical bounding box assembly tree algorithm through a synchronous recursive descent algorithm; according to the method, the collision detection optimization algorithm of the hierarchical bounding box assembly tree and the synchronous recursive descent is adopted, and the nodes needing to be compared are calculated by using the synchronous recursive descent, so that the problems that the method in the prior art is high in time complexity and cannot balance the efficiency and the precision well are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of CAD manufacturing informationization, and relates to an efficient interference inspection method for a complex structure CAD model in CAD manufacturing. Background Art

[0002] At present, the 3D design software CATIA has been widely used in the design of the appearance structure and system of aircraft equipment. In the design process of aircraft production, interference often occurs between various parts. If the interference position cannot be checked and the error cannot be eliminated in time, serious consequences may occur. However, the efficiency and accuracy of collision detection directly affect the efficiency of interference detection, and are also important indicators that affect the user interaction experience. How to balance the efficiency and accuracy of collision detection is a problem that needs to be studied.

[0003] Bounding box is an algorithm for obtaining the optimal bounding space of a model. The basic idea is to use larger but simple geometric shapes such as spheres and cuboids to approximate objects with complex geometric shapes. General bounding box algorithms include bounding sphere, aligned axis bounding box (AABB), oriented bounding box (OBB), etc., which are widely used in the field of collision detection.

[0004] (1) Among these popular bounding box algorithms, the bounding sphere algorithm is more efficient but less accurate and is usually used for the initial processing of objects in collision detection.

[0005] (2) The rectangular bounding box algorithm is used for subsequent processing because of its high accuracy.

[0006] a) In the rectangular bounding box algorithm, the AABB algorithm is relatively simple. It is a bounding box whose faces are parallel to the three planes of the space absolute coordinate system. Therefore, it cannot be used as the optimal minimum bounding box.

[0007] b) OBB is a bounding box with higher precision compared to bounding sphere and AABB. It can be rotated arbitrarily according to the first moment of the object, so OBB with a proper orientation matrix can be regarded as the best minimum bounding box of the geometric object.

[0008] However, although the complex bounding box has low collision detection cost, its construction time is long, so it is necessary to combine the bounding box with the tree structure through the hierarchical bounding box tree algorithm. In a complex structure CAD model, when the objects composed of m geometric shapes are tested in pairs, CATIA's own interference check directly performs two-by-two interference on each part. This method takes a long time to perform interference check. By traversing the bounding box constructed at each level of the tree structure, the time complexity is reduced from O(n2) to O(logn), thereby realizing bounding box traversal detection and reducing the complexity of detection.

[0009] Although the hierarchical bounding box tree detection algorithm has reduced time complexity, it has a certain impact on the efficiency and accuracy of the algorithm, and it is difficult to meet the requirements of efficient interference detection methods for complex structural CAD models. In addition, the hierarchical bounding box tree algorithm needs to re-divide the parts into space and generate a new tree structure. It cannot use the original assembly tree structure of the parts, nor can it quickly and reasonably design bounding boxes for the assembly tree of complex structures, and it cannot make good use of CATIA's CAA related interfaces.

[0010] Therefore, it is necessary to consider designing a collision detection optimization algorithm using a hierarchical bounding box assembly tree and synchronous recursive descent for complex structure CAD assembly trees to optimize the overall efficiency of interference checking in CATIA. Summary of the invention

[0011] Purpose of the invention: The present invention proposes an efficient interference checking method for complex structure CAD models, adopts a collision detection optimization algorithm of a hierarchical bounding box assembly tree and synchronous recursive descent, and uses synchronous recursive descent to calculate the nodes that need to be compared, thereby solving the problem that the prior art method has high time complexity and cannot strike a good balance between efficiency and accuracy.

[0012] Technical Solution

[0013] An efficient interference checking method for complex structural CAD models is implemented by using a hierarchical bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm, including the following steps:

[0014] Step 1: Establish quantitative evaluation indicators;

[0015] Step 2: Optimize the hierarchical bounding box assembly tree algorithm;

[0016] Step 3: Recursively use the results of the optimized hierarchical bounding box assembly tree algorithm through a synchronous recursive descent algorithm.

[0017] Furthermore, step 1 is specifically: recursively download the digital models of the parts of the two complex structures that need to be compared, establish a total cost formula for quantitative evaluation indicators to measure the overall performance of the algorithm, and at the same time count the average depth of the assembly tree during the recursive downloading process.

[0018] Furthermore, the component assembly trees of two complex structures to be compared are recursively downloaded respectively. During the recursive downloading process, the average depth n of the tree is calculated according to the average path length formula recursively to the leaf node.

[0019] Furthermore, the total cost formula of the quantitative evaluation index is Tcd=NpCp×NqCq, where Tcd refers to the overall performance of the algorithm; Np refers to the time of bounding box connection detection; Cp refers to the consumption of bounding box collision detection, Nq refers to the number of geometric object collision detection; Cq refers to the consumption of geometric object collision detection.

[0020] Further, step 2 is specifically as follows: according to the average depth n of the assembly tree, the assembly tree is divided into four layers, ABCD. A spherical bounding box needs to be constructed for layer A, an AABB bounding box needs to be constructed for layer B, an OBB bounding box needs to be constructed for layer C, and no bounding box is constructed for layer D. The nodes are directly traversed to call the interference check interface of CATIA CAA. Among them, layer A is the first n / 3-1 layers of the assembly tree, layer B is from layer n / 3 to layer 2n / 3-1 of the assembly tree, layer C is from layer 2n / 3 to layer n-1 of the assembly tree, and layer D is the nth layer and below of the assembly tree.

[0021] Furthermore, for step 2, if the average depth of the assembly tree is 3, the assembly tree is divided into three layers, ABC. A spherical bounding box needs to be constructed for layer A, an AABB bounding box needs to be constructed for layer B, and no bounding box is constructed for layer C. The nodes are directly traversed to call the interference check interface of CATIA CAA. At this time, layer A is the first layer of the assembly tree, layer B is the second layer of the assembly tree, and layer C is the third layer and below of the assembly tree.

[0022] Further, for step 2, if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree does not exceed 3, directly traverse the nodes and call the interference check interface of CATIA CAA; if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree exceeds 3, the assembly tree is divided into three layers AB, and an AABB bounding box needs to be constructed for layer A, and a bounding box is not constructed for layer B. Directly traverse the nodes and call the interference check interface of CATIA CAA. At this time, layer A is the first layer of the assembly tree, and layer B is the second layer and below of the assembly tree.

[0023] Further, step 3 specifically includes:

[0024] Step 3.1 calculates the spherical bounding box of the assembly tree root node of the two complex structure assemblies to be compared;

[0025] Step 3.2: Determine whether the spherical bounding boxes of the root nodes of the two complex structure assemblies intersect. If so, execute step 3.3. If not, the process ends.

[0026] Step 3.3: Use the optimization result based on the hierarchical bounding box assembly tree algorithm, traverse the algorithm recursively layer by layer through the synchronous descent rule, synchronously calculate the corresponding bounding boxes level by level, and detect the intersection status of the child nodes.

[0027] Furthermore, in step 3.3, if the corresponding lower-level node that needs to be judged for interference is recursively traversed at a level where a bounding box does not need to be constructed, there are three cases: 1) When both nodes are leaf nodes, interference check is performed directly; 2) When either of the two nodes is leaf node A, recursively traverse the other node B, find all the leaf nodes obtained by traversal and perform interference check with leaf node A; 3) When neither node is a leaf node, recursively traverse the two nodes AB, find all the leaf nodes obtained by traversal of node A and all the leaf nodes obtained by traversal of node B and perform interference check;

[0028] If the recursive traversal reaches the corresponding lower-level node that needs to be judged for interference at the level where the bounding box needs to be built, but any node is a leaf node C, then build an OBB bounding box for the leaf node, calculate the bounding box of the other node, and determine whether they intersect. If they intersect, recursively traverse the node and synchronously construct the bounding box of the corresponding level to determine whether they intersect with the leaf node C. This process continues until the recursive traversal reaches the level where the bounding box does not need to be built. Then recursively traverse the nodes that need to be compared at this level to find all the leaf nodes obtained through the traversal and perform interference checks with the leaf node C.

[0029] Beneficial Effects

[0030] The present invention proposes an efficient interference inspection method for a complex structure CAD model, which adopts a hierarchical bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm. The principle of the hierarchical bounding box tree algorithm is to combine the bounding box with the tree structure. When performing a pairwise test on an object composed of m geometric shapes, the hierarchical bounding box tree algorithm is used without reconstructing the assembly tree to reduce the time complexity from O(n2) to O(logn) order of magnitude, thereby realizing bounding box traversal detection and reducing the complexity of detection.

[0031] The method of the present invention establishes a total cost formula of quantitative evaluation index to measure the overall performance of the algorithm. In the recursive process, the average depth of the tree and the spatial weight of the parts of each node are counted to determine the appropriate algorithm parameters. The present invention also uses a synchronous descent rule for the assembly tree to traverse the nodes, thereby improving the efficiency and accuracy of collision detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a traditional binary hierarchical bounding box tree provided by an embodiment of the present invention.

[0033] FIG. 2( a ) and FIG. 2( b ) are schematic diagrams of an original assembly tree and a hierarchical enclosing tree based on the assembly tree provided in an embodiment of the present invention.

[0034] Figure 3 A schematic diagram of an example of a layered bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] Embodiment 1:

[0038] An efficient interference checking method for a complex structure CAD model is provided, which adopts a hierarchical bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm, and includes the following steps:

[0039] Step 1: Establish quantitative evaluation indicators; this step is specifically: recursively download the digital models of the components of the two complex structures that need to be compared, establish the total cost formula of the quantitative evaluation indicators to measure the overall performance of the algorithm, and at the same time count the average depth of the assembly tree during the recursive downloading process.

[0040] The two component assembly trees of complex structures to be compared are recursively downloaded respectively, and during the recursive downloading process, the average depth n of the tree is calculated according to the average path length formula recursively to the leaf node.

[0041] Among them, the total cost formula of the quantitative evaluation index is Tcd=NpCp×NqCq, where Tcd refers to the overall performance of the algorithm; Np refers to the time of bounding box connection detection; Cp refers to the consumption of bounding box collision detection, Nq refers to the number of geometric object collision detection; Cq refers to the consumption of geometric object collision detection.

[0042] Step 2: Optimize the hierarchical bounding box assembly tree algorithm;

[0043] Step 2 is as follows: according to the average depth n of the assembly tree, the assembly tree is divided into four layers, ABCD. A spherical bounding box needs to be constructed for layer A, an AABB bounding box needs to be constructed for layer B, an OBB bounding box needs to be constructed for layer C, and no bounding box is constructed for layer D. The nodes are directly traversed to call the interference check interface of CATIA CAA. Among them, layer A is the first n / 3-1 layers of the assembly tree, layer B is from layer n / 3 to layer 2n / 3-1 of the assembly tree, layer C is from layer 2n / 3 to layer n-1 of the assembly tree, and layer D is the nth layer and below of the assembly tree.

[0044] Among them, if the average depth of the assembly tree is 3, the assembly tree is divided into three layers of ABC. A spherical bounding box needs to be constructed for layer A, and an AABB bounding box needs to be constructed for layer B. No bounding box is constructed for layer C. The nodes are directly traversed to call the interference check interface of CATIA CAA. At this time, layer A is the first layer of the assembly tree, layer B is the second layer of the assembly tree, and layer C is the third layer and below of the assembly tree.

[0045] Among them, for step 2, if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree does not exceed 3, directly traverse the nodes to call the interference check interface of CATIA CAA; if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree exceeds 3, the assembly tree is divided into three layers AB, and an AABB bounding box needs to be constructed for layer A, and no bounding box is constructed for layer B. Directly traverse the nodes to call the interference check interface of CATIA CAA, at this time, layer A is the first layer of the assembly tree, and layer B is the second layer and below of the assembly tree.

[0046] Step 3: Recursively use the results of the optimized hierarchical bounding box assembly tree algorithm through a synchronous recursive descent algorithm, including:

[0047] Step 3.1 calculates the spherical bounding box of the assembly tree root node of the two complex structure assemblies to be compared;

[0048] Step 3.2: Determine whether the spherical bounding boxes of the root nodes of the two complex structure assemblies intersect. If so, execute step 3.3. If not, the process ends.

[0049] Step 3.3: Use the optimization result of the hierarchical bounding box assembly tree algorithm, traverse the algorithm recursively through the nodes layer by layer through the synchronous descent rule, calculate the corresponding bounding boxes synchronously and step by step, and detect the intersection status of the child nodes. In this step, if the recursive traversal reaches the corresponding lower-level node that needs to be judged for interference at a level where the bounding box does not need to be constructed, it is divided into three cases: 1) When both nodes are leaf nodes, interference check is performed directly; 2) When any of the two nodes is leaf node A, recursively traverse the other node B, find all the traversed leaf nodes and perform interference check with leaf node A; 3) When neither of the two nodes is a leaf node, recursively traverse the two nodes AB, find all the traversed leaf nodes of node A and all the traversed leaf nodes of node B, and perform interference check;

[0050] If the recursive traversal reaches the corresponding lower-level node that needs to be judged for interference at the level where the bounding box needs to be built, but any node is a leaf node C, then build an OBB bounding box for the leaf node, calculate the bounding box of the other node, and determine whether they intersect. If they intersect, recursively traverse the node and synchronously construct the bounding box of the corresponding level to determine whether they intersect with the leaf node C. This process continues until the recursive traversal reaches the level where the bounding box does not need to be built. Then recursively traverse the nodes that need to be compared at this level to find all the leaf nodes obtained through the traversal and perform interference checks with the leaf node C.

[0051] Embodiment 2:

[0052] An efficient interference checking method for a complex structure CAD model is provided, comprising the following steps:

[0053] Step S1: recursively compare the component assembly trees of two complex structures to be compared respectively, and in the recursive process, calculate the average depth n of the tree according to the average path length formula of the recursive to leaf nodes.

[0054] Step S2: According to the average depth n of the tree, the tree is divided into four layers, ABCD. A spherical bounding box needs to be constructed for the A layer (the first n / 3-1 layers), an AABB bounding box needs to be constructed for the B layer (n / 3 layers to 2n / 3-1 layers), an OBB bounding box needs to be constructed for the C layer (2n / 3 layers to n-1 layers), and no bounding box is constructed for the D layer (nth layer and below), and the interference check interface of CATIA CAA is directly called by traversing the nodes. In particular, if the average depth of the tree is 3, the tree is divided into three layers, ABC, and a spherical bounding box needs to be constructed for the A layer (the first layer), an AABB bounding box needs to be constructed for the B layer (the second layer), and no bounding box is constructed for the C layer (the third layer and below), and the interference check interface of CATIA CAA is directly called by traversing the nodes. If the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree does not exceed 3, directly traverse the nodes and call the interference check interface of CATIA CAA; if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree exceeds 3, the assembly tree is divided into three layers, AB, and an AABB bounding box needs to be built for layer A (layer 1), and no bounding box is built for layer B (layer 2 and below), and directly traverse the nodes and call the interference check interface of CATIA CAA.

[0055] Step S3: Calculate the spherical bounding box of the assembly tree root node of the two complex structure assemblies to be compared.

[0056] Step S4: Determine whether the spherical bounding boxes of the root nodes of the two complex structure assemblies intersect. If not, end. If so, go to step S5.

[0057] Step S5: Calculate the bounding boxes that need to be constructed corresponding to the subordinate nodes of the root nodes of the two complex structure assemblies, and determine whether they intersect with each other. If not, end. If any of them intersect, continue traversing the intersecting nodes and go to step S6.

[0058] Step S6: Calculate the bounding boxes that need to be constructed for the subordinate nodes corresponding to the intersection nodes in the two complex structure assemblies S5, and determine whether they intersect. If not, end; if intersecting, repeat step S6.

[0059] Furthermore, for step S1, a total cost formula of quantitative evaluation index Tcd = NpCp × NqCq is established. Tcd refers to the overall performance of the algorithm. Np refers to the time for bounding box connection detection. Cp refers to the consumption of bounding box collision detection, and Nq refers to the number of geometric object collision detection. Cq refers to the consumption of geometric object collision detection. According to the average depth of the assembly tree and the complexity of the parts, it is proposed to construct bounding boxes of different degrees of rigor to reduce the number of bounding box collision detection and the time of bounding box construction when performing collision detection, and to achieve efficient collision detection testing by reducing the number of geometric object collision detection and the consumption of geometric object collision detection. However, these parameters affect each other, so a reasonable NpCpNqCq value is calculated based on the average depth of the tree and the balance factor of the assembly tree structure.

[0060] Furthermore, for step S6, if the recursive traversal reaches the corresponding lower-level node that needs to be judged for interference at a level where a bounding box does not need to be constructed, it is divided into three cases: 1) When both nodes are leaf nodes, perform interference check directly; 2) When either of the two nodes is leaf node A, recursively traverse the other node B, find all the traversed leaf nodes and perform interference check with leaf node A; 3) When neither node is a leaf node, recursively traverse the two nodes AB, find all the traversed leaf nodes of node A and all the traversed leaf nodes of node B and perform interference check.

[0061] Further, for step S6, if the recursive traversal reaches the corresponding lower-level node that needs to be judged for interference at the level where a bounding box needs to be constructed, but any node is a leaf node C, then an OBB bounding box is constructed for the leaf node, the bounding box of the other node is calculated, and a determination is made as to whether they intersect; if they do intersect, the node is recursively traversed, and a bounding box of the corresponding level is synchronously constructed to determine whether it intersects with the leaf node C, until the level is recursively reached where a bounding box does not need to be constructed, then the nodes that need to be compared at that level are recursively traversed, and all the leaf nodes obtained by the traversal are found to perform interference check with the leaf node C.

[0062] Figure 1 A schematic diagram of a traditional binary hierarchical bounding box tree provided by an embodiment of the present invention. Figure 1 As shown in the figure, the traditional binary hierarchical bounding box tree algorithm needs to re-divide the parts into space and generate a new tree structure. Although it has an advantage in efficiency, the overhead of spatial division and generation of a new tree structure is obviously higher than that of directly using the original assembly tree structure of the parts for fast and reasonable bounding box design.

[0063] Fig. 2 is a schematic diagram of an assembly tree and a hierarchical bounding tree model applicable to the present invention provided by an embodiment of the present invention. As shown in Fig. 2(a), the assembly tree of complex structure is a complex multi-branch tree, and the traversal of the complex multi-branch tree needs to consider the time complexity of the traversal. As shown in Fig. 2(b), the complex multi-branch tree is divided into corresponding bounding boxes by the partitioning algorithm of the hierarchical bounding box assembly tree.

[0064] Figure 3 The following is a schematic diagram of an example of a hierarchical bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm provided by an embodiment of the present invention. Figure 3 As shown, the time for quickly traversing and eliminating non-intersecting objects using a detection system that adopts a hybrid hierarchical bounding box collision detection optimization algorithm structure is greatly reduced compared to the time for recursively traversing each part leaf node, that is, the number of geometric object collision detections Nq and the consumption Cq of geometric object collision detection are reduced.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. An efficient interference checking method for complex structural CAD models, using a hierarchical bounding box assembly tree and a synchronous recursive descent collision detection optimization algorithm, characterized in that: The following steps are involved: Step 1: Establish quantitative evaluation indicators; Step 2: Optimize the hierarchical bounding box assembly tree algorithm; Step 3: Recursively use the results of the optimized hierarchical bounding box assembly tree algorithm through a synchronous recursive descent algorithm.

2. The complex structure CAD model efficient interference checking method according to claim 1 is characterized in that: Step 1 is as follows: recursively download the digital models of the components of the two complex structures that need to be compared, establish a total cost formula for quantitative evaluation indicators to measure the overall performance of the algorithm, and at the same time count the average depth of the assembly tree during the recursive downloading process.

3. The complex structure CAD model efficient interference checking method according to claim 2 is characterized in that: The component assembly trees of two complex structures to be compared are recursively downloaded respectively. During the recursive downloading process, the average depth n of the tree is calculated according to the average path length formula recursively to the leaf node.

4. The complex structure CAD model efficient interference checking method according to claim 2 is characterized in that: The total cost formula of the quantitative evaluation index is Tcd=NpCp×NqCq, where Tcd refers to the overall performance of the algorithm; Np refers to the time of bounding box connection detection; Cp refers to the consumption of bounding box collision detection, Nq refers to the number of geometric object collision detection; Cq refers to the consumption of geometric object collision detection.

5. The complex structure CAD model efficient interference checking method according to claim 3 is characterized in that: Step 2 is as follows: according to the average depth n of the assembly tree, the assembly tree is divided into four layers, ABCD. A spherical bounding box needs to be constructed for layer A, an AABB bounding box needs to be constructed for layer B, an OBB bounding box needs to be constructed for layer C, and no bounding box is constructed for layer D. The nodes are directly traversed to call the interference check interface of CATIA CAA. Among them, layer A is the first n / 3-1 layers of the assembly tree, layer B is from layer n / 3 to layer 2n / 3-1 of the assembly tree, layer C is from layer 2n / 3 to layer n-1 of the assembly tree, and layer D is the nth layer and below of the assembly tree.

6. The complex structure CAD model efficient interference checking method according to claim 5 is characterized in that: For step 2, if the average depth of the assembly tree is 3, the assembly tree is divided into three layers, ABC. A spherical bounding box needs to be built for layer A, and an AABB bounding box needs to be built for layer B. No bounding box is built for layer C. The nodes are directly traversed to call the interference check interface of CATIA CAA. At this time, layer A is the first layer of the assembly tree, layer B is the second layer of the assembly tree, and layer C is the third layer and below of the assembly tree.

7. The complex structure CAD model efficient interference checking method according to claim 6 is characterized in that: For step 2, if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree does not exceed 3, directly traverse the nodes and call the interference check interface of CATIACAA; if the average depth of the assembly tree does not exceed 2, and the maximum depth of the assembly tree exceeds 3, the assembly tree is divided into three layers AB, and an AABB bounding box needs to be built for layer A, and no bounding box is built for layer B. Directly traverse the nodes and call the interference check interface of CATIACAA. At this time, layer A is the first layer of the assembly tree, and layer B is the second layer and below of the assembly tree.

8. The complex structure CAD model efficient interference checking method according to claim 5 is characterized in that: Step 3 specifically includes: Step 3.1 calculates the spherical bounding box of the assembly tree root node of the two complex structure assemblies to be compared; Step 3.2: Determine whether the spherical bounding boxes of the root nodes of the two complex structure assemblies intersect. If so, execute step 3.

3. If not, the process ends. Step 3.3: Use the optimization result based on the hierarchical bounding box assembly tree algorithm, traverse the algorithm recursively layer by layer through the synchronous descent rule, synchronously calculate the corresponding bounding boxes level by level, and detect the intersection status of the child nodes.

9. The complex structure CAD model efficient interference checking method according to claim 8, characterized in that: In step 3.3, if the corresponding lower-level node that needs to be judged for interference is recursively traversed at a level where a bounding box does not need to be constructed, there are three cases: 1) When both nodes are leaf nodes, interference check is performed directly; 2) When either of the two nodes is leaf node A, recursively traverse the other node B, find all the leaf nodes obtained by traversal and perform interference check with leaf node A; 3) When neither node is a leaf node, recursively traverse the two nodes AB, find all the leaf nodes obtained by traversal of node A and all the leaf nodes obtained by traversal of node B and perform interference check; If the recursive traversal reaches the corresponding lower-level node that needs to be judged for interference at the level where the bounding box needs to be built, but any node is a leaf node C, then build an OBB bounding box for the leaf node, calculate the bounding box of the other node, and determine whether they intersect. If they intersect, recursively traverse the node and synchronously construct the bounding box of the corresponding level to determine whether they intersect with the leaf node C. This process continues until the recursive traversal reaches the level where the bounding box does not need to be built. Then recursively traverse the nodes that need to be compared at this level to find all the leaf nodes obtained through the traversal and perform interference checks with the leaf node C.

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