Product CAD model-oriented agent model automatic construction method

Abstract

The invention provides an automatic agent model construction method for a product CAD (computer-aided design) model, which comprises the following steps of: defining a part CAD model of a product form and a size and a dependency relationship of a logic relationship and a constraint between different parts; according to a mapping rule for converting an assembling CAD model into Sysml-based model elements based on a plurality of parts and relative positions and connection modes among the plurality of parts, realizing standardized proxy model expression of the product CAD model; and realizing automatic conversion from a native model to a Sysm l-based proxy model based on ATL, and realizing automatic construction of the whole process of the proxy model. A mechanical arm product CAD model serves as an example, an agent model of the mechanical arm product CAD model is constructed, and the abstraction and expression process of the product CAD model is displayed. According to the method, the CAD model of the product can be effectively supported to be incorporated into a digital main line, rapid transmission and feedback of information in the whole life cycle process of the product are promoted, and information cross-domain integration and collaboration are promoted.

Description

Technical Field

[0001] The present invention belongs to the field of product digital design and manufacturing technology. The present invention is directly applied to the construction of digital thread in product life cycle management (PLM), especially the automatic conversion technology of CAD models of complex mechanical products (such as industrial robots, aerospace equipment, etc.) to standardized system modeling language (SysML) proxy models. By defining the mapping rules between CAD model elements and SysML model elements, combined with the model conversion engine (such as ATL), the structured abstraction and cross-domain expression of design data such as product geometric information, physical properties, and assembly constraints are realized. This technical field covers computer-aided design systems, multidisciplinary system modeling, model-driven engineering (MDE), and data integration and collaborative optimization in the industrial Internet, aiming to solve the cross-departmental (design, manufacturing, operation and maintenance) information transmission barriers caused by data redundancy and format heterogeneity in traditional CAD models in digital threads, and improve the design change response efficiency and multi-domain collaborative capabilities within the product life cycle. Background Art

[0002] With the deepening of digital transformation in the manufacturing industry, technologies such as computer-aided design (CAD), product lifecycle management (PLM), and virtual prototypes have become core tools for product development. However, existing technologies still face the following bottlenecks:

[0003] 1. Data silo problem: Traditional CAD models have heterogeneous data formats (such as different software formats such as SolidWorks and CATIA), which leads to information fragmentation in the design, manufacturing, and operation and maintenance links;

[0004] 2. Redundancy and inefficiency: CAD models contain too many geometric details (such as surface topology and assembly constraints), which require manual simplification when transferred across fields, which can easily lead to information loss and is time-consuming;

[0005] 3. Lack of system-level analysis capabilities: Existing PLM systems focus on data management, but lack standardized descriptions of system attributes such as product functions and performance, making it difficult to support multidisciplinary collaborative optimization (MDO).

[0006] Although integration technologies represented by the Digital Thread attempt to open up data flows throughout the entire life cycle, existing implementations rely heavily on the conversion of intermediate file formats (such as STEP and IGES), resulting in loss of semantic information and an inability to dynamically respond to design changes.

[0007] The main shortcomings of the heterogeneous CAD model data integration device and integration method for network collaborative design in the specific implementation can be summarized as follows:

[0008] 1. The cross-system adaptation is complex due to the reliance on plugins and interfaces. In the existing solutions, the data integration between different CAD systems often relies on their respective plugins and interfaces such as Component Object Model (COM). Due to the significant differences in the kernel, data structure, and API design of CAD software, when it is necessary to be compatible with more types of CAD systems or higher versions of systems, separate adaptation and plugin development must be carried out for each system. This "point-to-point" adaptation mode makes system expansion complex and costly. In addition, if the CAD system itself lacks open interfaces or the interface encapsulation is imperfect, it is often difficult for plugins to obtain complete geometric and feature data, resulting in the risk of information loss or accuracy degradation during the data conversion process.

[0009] 2. The geometric data representation based on discrete grids is prone to the loss of model features and associated information. Existing methods usually discretize the geometric shapes of parts and assembly models into grid data, and then combine a small number of topological elements (such as faces, edges, vertices) for proxy representation. Although this method can achieve cross-platform geometric expression at the visualization level, high-level information such as parametric features, sketch associations, and equation-driven geometric relationships relied on in CAD feature modeling systems is difficult to retain after discrete meshing. Key data such as materials, processes, and design constraints are easily overlooked. Subsequent virtual assembly, collaborative annotation, or design verification can only be carried out at the grid level, lacking direct access to CAD parameters and feature relationships, and it is difficult to support complex secondary modeling and fine analysis.

[0010] 3. The mechanisms for real-time synchronization and version management are relatively weak. Although this method manages and transmits proxy models through a network collaborative design server, it focuses more on "file-level" or "model-level" upload / download. Once a CAD source model is updated, it still needs to be re-exported through a plugin on the client, and then the server notifies other clients to update the proxy model. The real-time and automation levels of this process are not ideal in the scenario of large-scale collaborative projects. When the update frequency is high, users need to perform repetitive conversion and upload operations frequently, resulting in a decline in collaborative efficiency; when multiple people modify in parallel, it is impossible to manage or merge different design branches at a fine-grained level, and version conflicts or data overwrite problems are likely to occur. Summary of the Invention

[0011] In the prior art, the cross-system adaptation is difficult and the expansion cost is high. Different CAD software usually has obvious differences in kernel, data structure, and API design. When relying on plugins and various COM interfaces for data conversion, if it is necessary to be compatible with more types of CAD systems or higher versions, corresponding adaptation modules must be developed one by one, resulting in an increasing development and maintenance cost and complexity; if the interface encapsulation is imperfect, high-level geometric and feature information cannot be obtained completely.

[0012] Features, parameters, and associated information are missing. Some existing methods rely on grid-based or discrete topology data structures to represent surrogate models, which can only retain geometric contours; high-level information such as parametric features, equation constraints, and sketch associations often cannot be retained at the grid level, leading to increased difficulty in subsequent design reuse and fine-grained collaborative analysis.

[0013] To address the above problems, the present invention proposes an automatic construction method for a surrogate model for a product CAD model, which includes the following steps:

[0014] Step 1: Surrogate model construction mechanism based on multi-level abstraction

[0015] The present invention realizes hierarchical abstraction of multi-dimensional elements by defining a set of mapping rule libraries between the CAD model and the system modeling language (such as SysML). Specifically, it includes:

[0016] Mapping of parts and related attributes: Map the native geometric features, material properties, and physical quantities (such as mass, inertia matrix) of CAD to elements such as Block, Property, and Value in the surrogate model, and explicitly identify them through custom stereotypes to ensure high-fidelity retention of high-level geometric and process data.

[0017] Mapping of dependencies between parts: Analyze the key role of dependencies between parts in product function realization and system design optimization, introduce a method to abstract dependencies as interfaces, and realize the construction of a surrogate model for dependencies between parts.

[0018] Mapping of assemblies and dependencies: Introduce an interface-based publish-reference mechanism, so that the constraints and reference features of upper-level assembly parts can be directly called by downstream parts or subsystems in the surrogate model; use ontology or semantic rule methods to ensure that when the geometry of the parent part is updated, the child parts can be automatically notified to update, thereby overcoming the problem that traditional "point-to-point" plugins are difficult to completely obtain associated information.

[0019] Step 2: Automatic conversion and toolchain integration

[0020] The present invention realizes automatic conversion from the CAD model to the Sysml surrogate model by extracting key information from the product CAD model and using the ATL language for efficient model conversion and construction, specifically as follows:

[0021] Method for Extracting Key Information from Product CAD Models: By means of the product CAD model data parsing method, information such as physical attributes and assembly relationships in the product CAD model is captured. At the part level, parameters such as dimensions and materials are extracted, and a standard parameter information table is output and converted into XML; at the assembly level, the part connection relationships and assembly constraints are sorted out, the parameters are recursively read, and a standard assembly parameter information table is output and converted into XML to ensure the integrity and standardization of the information.

[0022] Rule-driven Transformation Engine: Using ATL (Atlas Transformation Language) or a similar transformation language, the XML data generated after parsing the CAD model is automatically mapped to the SysML proxy model. By means of a set of general rules for the product CAD model to the Sysml-based proxy model, the dependence on specific CAD system plug-ins is greatly reduced; when the CAD system is upgraded or replaced, only limited maintenance needs to be done for the parsing process, rather than writing new interface codes.

[0023] Support for Visual Reuse of High-fidelity Geometry and Feature Information: In the proxy model, the core design intent is retained in the form of attributes and behavior abstractions (such as functions or formulas), which can not only be used for lightweight browsing and analysis at the system level, but also support tracing back to the native CAD model for geometric or process-level operations, taking into account both abstraction and traceability.

[0024] Multi-domain Sharing Oriented to the Digital Thread: Through the interface-based and Sysml semantic association-based method, the proxy model is embedded in the enterprise's digital thread platform in the present invention, enabling different professional fields such as design, process planning, simulation, and operation and maintenance to carry out collaboration based on the same standardized data source. Compared with the traditional manual or only meshed data exchange method, it can effectively reduce model redundancy and distortion.

[0025] Inertial Thinking and Prejudice: It is usually considered that "using discrete grids is sufficient for cross-platform visualization" or "relying on external plug-ins can quickly complete data exchange", ignoring the requirements for advanced features and parametric associations, or believing that the high-fidelity abstraction of the proxy model has no obvious economic value.

[0026] Concerns about Complex Implementation and High Maintenance Difficulty: If a large number of plug-ins are directly written for each CAD system, the maintenance cost will inevitably increase sharply. The present invention adopts a unified extraction script and transformation rules, and establishes an adaptive publish-reference mechanism in the proxy model, thereby reducing the dependence on the "point-to-point" interfaces of each system.

[0027] Doubts about Insignificant Effect Improvement: In local or small-scale applications, strong collaborative pain points may not be reflected. However, through strengthening real-time synchronization and version management, the present invention can achieve unexpected efficiency improvement in the environment of multi-party parallel design of large projects.

[0028] Advantages of the present invention compared with the prior art:

[0029] At the technical level: Reduce data loss: Avoid the loss of high-level geometry, features, and process information caused by simply relying on discrete meshes or simple plug-ins, and retain the complete design intent and constraint logic within the surrogate model.

[0030] Improve cross-platform expansion ability: There is no need to write "point-to-point" adaptation plug-ins for each CAD system. Only the core parsing and conversion rules need to be maintained, which is faster and more economical when the system is upgraded or new software is added for compatibility.

[0031] Strengthen real-time synchronization and version control: It can achieve automatic merging and difference tracking for multi-user parallel editing and multi-person multi-branch collaboration, significantly improving collaboration efficiency and accuracy.

[0032] At the economic level: Reduce development and maintenance costs: Significantly reduce the dependence on plug-ins and interfaces, greatly saving the manpower for repeated development; at the same time, reduce design rework or quality risks caused by model inconsistencies or information loss.

[0033] Improve product R & D efficiency: In large projects, cross-departmental collaboration can significantly shorten the iteration cycle, improve the response speed to market demand changes, and bring obvious competitive advantages to the enterprise.

[0034] At the social level: Promote knowledge accumulation and sharing: Based on the abstraction and semantic expression of the surrogate model, the design knowledge and experience within the enterprise can be better precipitated and reused, which is conducive to the technological progress and innovation of the industry. Brief Description of the Drawings

[0035] Figure 1 Is the standardized expression of the surrogate model class and instance of rod-like parts.

[0036] Figure 2 Is the standardized expression of the surrogate model of the slider-base dependency relationship.

[0037] Figure 3 Is the standardized expression of the surrogate model of the crank-slider assembly model.

[0038] Figure 4 Is the introduction of non-specific class implementation assembly classification in SysML.

[0039] Figure 5 Is the standardized formal expression of the mapping interface of the published elements of the crank-slider class in the assembly surrogate model.

[0040] Figure 6 Is the part information extraction process.

[0041] Figure 7 Is the assembly information extraction process.

[0042] Figure 8 It is the model information conversion principle based on the ATL language.

[0043] Figure 9 It is a schematic diagram of the CAD model of the robotic arm product.

[0044] Figure 10 It is an example diagram of the standard XML file of the robotic arm model information.

[0045] Figure 11 It is a definition diagram of the robotic arm proxy model block.

[0046] Figure 12 It is an internal block diagram of the robotic arm proxy model. Detailed implementation manners

[0047] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail in combination with the accompanying drawings and technical solutions.

[0048] The present invention provides an automatic construction method for a proxy model for a product CAD model, and the method specifically includes:

[0049] Model conversion mapping rules

[0050] Mapping of parts and related attributes

[0051] Parts and their parameters play a fundamental role in the product CAD model. They define the geometric shape, physical properties and related features of the product and are the basic units that make up the whole product. In system design, especially in the context of multidisciplinary collaboration and cross-domain integration, the proxy model of a part needs to be simplified into certain key geometric parameters and physical characteristics through formal expression to support system-level design, optimization and analysis.

[0052] The geometric information of a part, as the core content of the product CAD model, defines the shape and size of the product. The CAD model expresses the shape and structure of the part through various geometric features (such as holes, grooves, chamfers, curved surfaces, etc.). Under the proxy model modeling framework based on SysML, the conversion of part geometric information is carried out by simplifying complex geometric shapes into basic parameters (such as length, width, height, etc.) for the formal expression of key geometric features.

[0053] The physical properties of a part, including information such as the material, mass, and inertia matrix of the part, not only affect the manufacturing and performance of the product, but also directly affect the functional performance of the product in system-level design. By using the SysML language to create new stereotypes and storing them through attribute fields, the formal expression of the physical properties of the proxy model is carried out.

[0054] The detailed mapping relationships between the geometric information and physical properties of the key model elements of the CAD model of the parts and the model elements based on SysML are shown in Table 1. Among them, the Part element in the CAD model and the Block element in SysML are regarded as modular units for describing and organizing complex systems or products in their respective fields, so a mapping relationship is established between them. The Annotation element in the CAD model and the Comment element in SysML can both provide additional text information, so a mapping relationship is established between them during the model conversion process.

[0055] Table 1: Mapping Table of CAD Model Elements of Parts to Agent Model Elements

[0056]

[0057]

[0058] Referring to the concept of classes in object-oriented modeling, the model class of parts of the same type is expressed by extending the class construct stereotype 《CADPart》 of SysML. The key parameters of the CAD model of parts are mapped to the attributes of the 《CADPart》 class and marked with the 《CADPar》 stereotype. Among them, the data type of the attribute corresponds to the parameter unit, and the data type of the reference is predefined in the package containing all the SI value types. Similarly, the material information of the parts is expressed by the 《CADMaterial》 stereotype, and the mass information of the parts is expressed by the 《CADMass》 stereotype, etc.

[0059] Each part in the product is an instance of the part class. For example, the rod part instances with different parameter values are as Figure 1 shown. When a design change is made to a certain part class, all part instances are automatically updated.

[0060] Mapping of Dependencies between Parts

[0061] The dependencies between parts describe the logical relationships and constraints between different parts, manifested as the mating, reference geometries, shared geometric features, or relative motions between parts. It defines how different parts in the product work together to complete specific functions and is the key information for realizing cross-domain integration and collaboration in the process of system design analysis and optimization.

[0062] The dependencies between parts include geometric constraints (such as alignment, parallelism, coaxiality, etc.) and features shared through references or geometric relationships. The dependencies between parts ensure the structural integrity and functional correctness of the product. Especially in complex products, the mutual dependencies between multiple parts determine the performance and functional performance of the product.

[0063] Construct a proxy model of the dependency relationship by abstracting the dependency relationship between parts into interfaces. Among them, the interface defines the indirect interaction between parts through shared geometric bodies or reference geometries. For example, the coaxial relationship between two parts in the product CAD model is mapped to an interface representing the dependency relationship in the proxy model, and the interface implementation means retaining the logical relationship and constraints of the two parts having coaxiality in the CAD model in the proxy model.

[0064] The dependency relationships between parts are complex and tight. In the constructed proxy model of the dependency relationship, the dependent parts are called sub-components, and the referenced parts are called parent components. Define that the parent component explicitly declares the elements available for other parts to use through the interface of the 《CADPublication》 stereotype, and the sub-component expresses the dependency relationship by referencing the published elements. Define that the 《CADPart》 base class of the parent component has the interface implementation of 《CADPublication》. Mark the dependency relationship of the set entity of parts through the 《CADCCPLink》 stereotype. Establish the dependency between parts in the form of published elements, and finally achieve the accurate retention and standardized description of the dependency relationship in the proxy model of the dependency relationship.

[0065] The publishing mechanism makes the geometric entity replacement process more transparent and concise. When the parent component changes, the sub-component is updated accordingly. As Figure 2 shown, it is an example of constructing a proxy model of the dependency relationship by publishing sketch elements between the slider and the base. The bottom shape of the slider part (sub-component) depends on the guide rail contour shape of the base part in the sketch (parent component). The instance of the part class base has the interface implementation of 《CADPublication》 "base-slider" and has the published element "guide rail contour" of the type of sketch.

[0066] Assembly and Dependency Relationship Mapping

[0067] The assembly of part instances is called a product. The assembly relationship is one of the core information in the product CAD model, which defines the relative positions and connection methods among multiple parts in the product. The correct assembly relationship ensures the operability and stability of the product during actual assembly. In the construction of the proxy model of the assembly CAD model, key attention is paid to the constraint relationships and connections among parts or assembly units, as well as the part decomposition of the assembly proxy model, so as to make full use of the key information of the assembly proxy model for services such as design and manufacturing during the analysis and optimization process of the product's entire life cycle. The detailed mapping relationship between the key model elements of the assembly CAD model and the model elements of SysML is shown in Table 2. Among them, both the Product in the assembly CAD model and the Package in SysML play a role in organizing and managing complex structures. The Product in the assembly CAD model is a complex structure composed of multiple parts, components, or assemblies, and the Package in SysML is a container for organizing and managing related model elements. Therefore, a mapping relationship is established between the two.

[0068] Table 2: Mapping Table of Assembly CAD Model Elements to Proxy Model Elements

[0069]

[0070] The assembly proxy model refers to the concept of classes in object-oriented modeling and extends the class construction stereotype 《CADProduct》 of SysML to express the model class of the assembly. Parts or assembly units in the assembly CAD model are described as attributes in the assembly proxy model, and their types are the proxy model classes of the parts. For example, Figure 3 The standardized expression of the proxy model of the crank-slider assembly model is shown. The attribute types of the assembly proxy model of the crank-slider mechanism class are respectively the skeleton class, base class, crank class, rod class, and slider class, marked with the 《CADPart》 construction stereotype.

[0071] The assembly proxy model introduces new classes according to the characteristics of the assembly CAD model to achieve a higher-level hierarchical classification of parts or assembly units in the assembly proxy model. The new non-specific classes introduced are connected to the 《CADPart》 class in the form of generalization. The instance of the 《CADProduct》 class references the part instances it owns through the slots of the new non-specific classes. For example, Figure 4 As shown, the parts of the crank-slider mechanism product can introduce new non-specific classes through their mobility, namely the fixed part and moving part classes. The assembly class of the crank-slider mechanism references the part classes such as the rod, crank, and base of the parts it owns through the non-specific classes of the moving part and fixed part through slots.

[0072] The constraint relationships in the assembly CAD model ensure the correct position and orientation of parts or assembly units. Assembly constraints limit the relative movement between entities. For example, in the assembly model instance of a rod and a slider, their rotation axes need to coincide to ensure that when one part moves, the other part can move synchronously accordingly. The establishment of constraint relationships in the assembly agent model is achieved by referencing the published elements of parts or assembly units. Analyze the functions and intentions of the published elements based on their different roles, map the published elements to interfaces that clearly describe the services or dependency relationships between classes, and more intuitively express the different functions and uses of the published elements through the interface partitioning method. As Figure 5 It is the formalized expression of the mapped interface standard for the published elements of the crank-slider class in the assembly agent model. The base part publishes the "guide rail profile" sketch of the slider by implementing the "base-slider" interface, and at the same time publishes other assembly-related geometric entities through the "base-assembly" interface.

[0073] Automatic construction of the product agent model

[0074] Key information extraction of the product CAD model

[0075] The product CAD model contains a large amount of detailed information about geometric shapes, physical properties, and assembly relationships, etc. To integrate this information into the SysML system-level agent model, these key information are structured through multiple levels of extraction processes to ensure the integrity of the information and abstract unnecessary details for efficient representation in the system model.

[0076] The information extraction process of the product CAD model is analyzed and processed from two aspects: part information and assembly information. Part information extraction mainly focuses on the detailed description of a single component, such as dimensions, materials, etc., while assembly information extraction focuses on the mutual relationships between multiple parts and the constraint relationships between assembly units.

[0077] The part information extraction process is as Figure 6 shown. First, locate the position of the key parameter information of the model according to the CAD model of the part, call the interface to read the key parameter information of the part name, mass, material, dimensions, and finally output a standard format part parameter information table. Finally, convert the output part parameter information table into a corresponding XML file.

[0078] The assembly information extraction process is as Figure 7 shown. Obtain the model document pointer according to the CAD model document of the assembly, read the parameter information of the parts under its root directory node in turn and judge whether the component composed of multiple parts is an assembly, and recursively loop in turn until the bottom-level assembly information is obtained, output as a standard format assembly parameter information table, and finally convert the assembly parameter information table into a corresponding XML file.

[0079] Rule-based Model Information Transformation

[0080] Model information transformation is rule-driven. By predefined a series of transformation rules, various elements in the source model are mapped to the target model. Each transformation rule defines how elements in the source model are converted into corresponding elements in the target model, ensuring the accuracy and consistency of data during the model transformation process. Atlas Transformation Language (ATL) is a rule language designed specifically for model transformation. By defining mapping rules between the source model and the target model, the ATL tool can achieve automatic transformation between complex models.

[0081] In step two, the mapping relationship between the product CAD model and the SysML model is discussed, that is, how to map parts, geometric elements, attributes, and assembly constraints in the product CAD model to Block modules, attributes, and constraints in the SysML-based proxy model, so that the details of the product CAD model can be abstractly expressed at the system design level and provide support for systems engineering. These mapping relationships lay the foundation for writing rules based on the ATL language and accurately describe the mapping from the product CAD model to the proxy model.

[0082] The process of model information transformation based on the ATL language is as Figure 8 shown. First, ATL-related tools load and parse the source model (the standardized XML structure information extracted from the product CAD model). Based on the mapping relationship rules defined in step two, the ATL engine matches each element in the source model with elements in the target model. The target model can be directly parsed and used by system modeling tools (such as MagicDraw) to automatically construct a Sysml-based proxy model, which is used for subsequent system-level design analysis and optimization.

[0083] The following takes the construction example of the proxy model of the robotic arm CAD model to illustrate specifically:

[0084] The transformation from the product CAD model to the Sysml-based proxy model helps to grasp the key information of the product to achieve system-level design and optimization. The following takes a robotic arm product CAD model as an example to show the process of transforming the product CAD model into a Sysml-based proxy model.

[0085] The product robotic arm consists of a part base, robotic arm 1, robotic arm 2, joint 1, and joint 2. Among them, the base, robotic arm 1, and robotic arm 2 are connected together through joints 1 and 2. The specific geometric parameters of the robotic arm are shown in Table 3, and its CAD model is as Figure 9 shown.

[0086] Table 3: Geometric Parameter Table of Robotic Arm Parts

[0087] Part Type Part Parameters (mm) Arm Length = 80, R = 20, Width = 40, Height = 10 Joint R = 10, Height = 10 Base R = 10, Depth = 10

[0088] According to the model information extraction method described in Section 2.1, the key parameter information of the robotic arm is extracted and the corresponding standard format parameter information is generated as shown in Table 4, and the robotic arm constraint information extracted and generated based on the constraint information of geometric features is shown in Table 5.

[0089] Table 4: Key Parameter Information Table of Robotic Arm Parts

[0090] Key Parameter Name Key Parameter Value ‘Length of arm’ 80 ‘Width of arm’ 40 ‘Thickness of arm’ 10 ‘Bore diameter of arm’ 10 ‘Outer circle radius’ 20 ‘Bore diameter of base’ 10 ‘Density’ 2710 ‘Radius of joint’ 10 ‘Thickness of joint’ 20

[0091] Table 5: Robotic Arm Constraint Information Table

[0092] Constraints Part 1 Part 2 ‘Constraint\Coincidence.1\Coincidence.1 joint2 arm1 ‘Constraint\Coincidence.2\Coincidence.2 base arm1 ‘Constraint\Surface Contact.3\Surface Contact.3 base arm1 ‘Constraint\Surface Contact.4\Surface Contact.4 Joint2 arm1 ‘Constraint\Coincidence.5\Coincidence.5 arm2 arm1 ‘Constraint\Surface Contact.6\Surface Contact.6 arm1 arm2 ‘Constraint\Coincidence.7\Coincidence.7 joint1 arm2

[0093] After reading the key parameters and constraint information of the robotic arm CAD model, an XML document corresponding to the specific geometric parameter information is generated, as Figure 10 shown.

[0094] Through the constructed proxy model conversion rule library, the XML file generated by converting the CAD product model information is converted into an XML document that can be parsed by the system engineering modeling software based on the Sysml language, and the corresponding product proxy model is generated. The proxy model representation of the robotic arm based on Sysml is as Figure 11 , Figure 12 shown. The block definition diagram mainly describes the specific geometric parameter information and density information of each part of the robotic arm, and the internal block diagram describes the constraint relationship between each geometric feature.

[0095] By constructing a proxy model of the robotic arm CAD model to achieve an abstract expression of the model, it supports the design analysis and optimization of the system where the robotic arm is located, and realizes the integration and collaboration of information across domains.

[0096] Conclusion

[0097] This invention conducts research on the automatic construction method of the proxy model for the product CAD model, defines the model conversion mapping rules from the product CAD model to the proxy model based on Sysml, and details the mapping conversion of the part CAD model, the dependency relationship between different parts, and each model element of the assembly CAD model; by extracting the key information of the product CAD model into a standard XML file, based on the mapping conversion rules, with the help of the ATL model transformation design language, the automatic construction of the proxy model is realized. Finally, taking the CAD model of the robotic arm product as an example, the abstract information expression of the robotic arm product in the form of an internal block diagram and a block definition diagram is realized, demonstrating the process of the automatic conversion of the product CAD model to the proxy model based on Sysml.

[0098] This method can incorporate the native CAD model of the product as an authoritative data source in the form of a proxy model into the digital thread to support data integration and information sharing throughout the product life cycle and improve the collaborative efficiency in product design, manufacturing, maintenance, etc. At the same time, this method can also effectively reduce the model complexity, enhance the system analysis and optimization capabilities, and provide strong support for the digital transformation and intelligent manufacturing of enterprises.

Claims

1. An automatic construction method for proxy models oriented to product CAD models, characterized in that, It includes the following steps: Step 1: Agent model construction mechanism based on multi-level abstraction By defining a set of mapping rule libraries between the CAD model and the system modeling language, hierarchical abstraction of multi-dimensional elements is realized; specifically including: Mapping of parts and related attributes: Map the native geometric features, material properties, and physical quantities of the CAD to the Block, Property, and Value elements in the agent model, and explicitly identify them through the custom stereotype Stereotype; Mapping of dependencies between parts: Analyze the key role of dependencies between parts in product function realization and system design optimization, introduce a method to abstract dependencies as interfaces, and realize the construction of an agent model for dependencies between parts; Mapping of assembly and dependencies: Introduce an interface-based publish-reference mechanism, so that the constraints and reference features of upper-level assembly parts can be directly called by downstream parts or subsystems in the agent model; Use ontology or semantic rule methods to ensure that child parts are automatically notified of updates when the geometry of the parent part is updated; Step 2: Automatic conversion and toolchain integration Through the extraction of key information from the product CAD model and the use of the ATL language for efficient model conversion and construction, automatic conversion from the CAD model to the Sysml agent model is realized, specifically as follows: Method for extracting key information from the product CAD model: With the help of the product CAD model data parsing method, capture the physical attributes and assembly relationship information in the product CAD model; For the part level, extract dimensions and material parameters, output a standard parameter information table and convert it to XML; At the assembly level, sort out the part connection relationships and assembly constraints, recursively read the parameters, output a standard assembly parameter information table and convert it to XML to ensure the integrity and standardization of the information.

2. The automatic construction method of an agent model for a product CAD model according to claim 1, characterized in that: In Step 1, the mapping of parts and related attributes includes: The geometric information of parts, as the core content of the product CAD model, defines the shape and size of the product. The CAD model expresses the shape and structure of parts through various geometric features. Under the modeling framework of the agent model based on SysML, the conversion of part geometric information is achieved by formalizing key geometric features by simplifying complex geometric shapes into basic parameters.

3. The automatic construction method of the proxy model for the product CAD model according to claim 1 or 2, characterized in that: The physical attributes of parts include the material, mass, and inertia matrix information of parts. The formal expression of the physical attributes of the agent model is achieved by creating a new stereotype using the sysml language and storing it through the attribute field.

4. The automatic construction method of an agent model for a product CAD model according to claim 1, wherein: The Part element in the CAD model and the Block element in SysML are both regarded as modular units for describing and organizing complex systems or products in their respective fields. Therefore, a mapping relationship is established between the two; The Annotation element in the CAD model and the Comment element in SysML both provide additional text information. Therefore, a mapping relationship is established between the two during the model conversion process.

5. The automatic construction method of an agent model for a product CAD model according to claim 1, characterized in that: Referring to the concept of classes in object-oriented modeling, the model classes of parts of the same type are expressed by extending the SysML class construction stereotype 《CADPart》. The key parameters of the part CAD model are mapped to the attributes of the 《CADPart》 class and marked with the 《CADPar》 stereotype. The data type of the attribute corresponds to the parameter unit, and the data type of the reference is predefined in the package containing all SI value types of the International System of Units. The material information of the part is expressed by the 《CADMaterial》 stereotype, and the mass information of the part is expressed by the 《CADMass》 stereotype.

6. The automatic construction method of an agent model for a product CAD model according to claim 1, characterized in that: In step one, the mapping of dependencies between parts includes: abstracting the dependencies between parts into interfaces to construct a proxy model of the dependencies; among them, the interface defines the indirect interaction between parts through shared geometries or reference geometries; the coaxial relationship between two parts in the product CAD model is mapped to the interface representing the dependencies in the proxy model, and the interface implementation means that the logical relationship and constraints of the two parts being coaxial in the CAD model are retained in the proxy model.

7. The automatic construction method of the proxy model for the product CAD model according to claim 1 or 6, characterized in that: The dependencies between parts are complex and tight. In the constructed proxy model of dependencies, the dependent parts are called sub-components, and the referenced parts are called parent components; it is defined that the parent component explicitly declares the elements for use by other parts through the interface of the 《CADPublication》 stereotype, and the sub-component expresses the dependencies by referencing the published elements; it is defined that the 《CADPart》 base class of the parent component has the interface implementation of 《CADPublication》; the dependencies of the set entity of parts are marked by the 《CADCCPLink》 stereotype; the dependencies between parts are established in the form of published elements, and finally the accurate retention and standardized description of the dependencies in the proxy model of dependencies are realized.

8. The automatic construction method of an agent model for a product CAD model according to the claim, characterized in that: In step one, the mapping of assembly and dependencies includes: both the Product in the assembly CAD model and the Package in SysML play a role in organizing and managing complex structures. The Product in the assembly CAD model is a complex structure composed of multiple parts, components or assemblies, and the Package in SysML is a container for organizing and managing related model elements. Therefore, a mapping relationship is established between the two. The assembly proxy model refers to the concept of classes in object-oriented modeling and extends the SysML class construction stereotype 《CADProduct》 to express the model class of the assembly. The parts or assembly units in the assembly CAD model are described as attributes in the assembly proxy model, and their types are the proxy model classes of the parts.

9. The automatic construction method of an agent model for a product CAD model according to claim 1, characterized in that: In step two, the extraction of key information from the product CAD model includes: The process of extracting information from the product CAD model is analyzed and processed from two aspects: part information and assembly information; the extraction of part information focuses on the detailed description of a single part, including dimensions and materials, and the extraction of assembly information focuses on the mutual relationships between multiple parts and the constraint relationships between assembly units. For the part information extraction process, first locate the positions of the key parameter information of the model according to the CAD model of the part, call the interface to read the key parameter information of the part name, mass, material, and dimensions, and finally output a part parameter information table in a standard format. Finally, convert the output part parameter information table into a corresponding XML file; For the assembly information extraction process, obtain the model document pointer according to the CAD model document of the assembly, sequentially read the parameter information of the parts under the root directory node and determine whether the component composed of multiple parts is an assembly. Recursively loop sequentially until the bottom-level assembly information is obtained, and output it as an assembly parameter information table in a standard format. Finally, convert the assembly parameter information table into a corresponding XML file.

10. A method for automatically constructing an agent model for a product CAD model according to claim 1 or 9, characterized in that: In step two, for the process of converting model information based on the ATL language model, first load the source model, that is, the standardized XML structure information extracted from the product CAD model, and parse it; based on the defined mapping relationship rules, the ATL engine matches each element in the source model with the elements in the target model; the target model is directly parsed and used by the system modeling tool to automatically construct a proxy model based on Sysml and is used for subsequent system-level design analysis and optimization.

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