Shulou(Shulou.com)06/02 Report--

Architecture of distributed virtual design platform based on PDM

The distributed virtual design platform based on PDM can be divided into four layers, which are interface layer, application tool layer, object management layer and supporting environment layer from high to low, as shown in figure 3.1.

Figure 3.1 Architecture of PDM-based distributed virtual design platform

(1) Interface layer: all users operate on a unified user interface, and users can customize the interface according to their own application needs.

(2) Application tool layer: provide a variety of application tools for realizing various functions of visual virtual design platform, including design modeling tools, simulation analysis tools, collaborative design support tools, comprehensive function modeling and simulation tools and design, analysis and decision-making systems, etc.; integrate with the integrated tools of PDM, and provide various services to users through the interface layer.

(3) object management: the workflow and product design of product development process are managed by PDM software, and the product development process is controlled comprehensively by establishing project management, process management and task scheduling mechanism. Various applications access data through the standard data access interface of PDM, and the management function of PDM ensures the consistency, integrity and continuity of data.

(4) supporting environment layer: database is the supporting platform of PDM, which supports the management of underlying data by PDM system objects through the operation data function provided by database. The database includes global shared database, local shared database and private database. Network and computer systems provide the necessary software and hardware environment for system operation.

The information transmission between various CAx systems of CAD, CBD and CAE becomes the information transmission between them and PDM, that is, all kinds of CAx systems extract the information they need from the PDM system, and their respective results are also put into the PDM. Thus it can be seen that PDM is the integration platform of various CAx systems, which integrates the information of product design, analysis, manufacturing, process planning and quality management. And then realize the unified management of the data in the whole product life cycle.

CAD system is the source of information, including graphic files and attribute information. The graphic file includes the 3D model of the assembly, the 3D model of the parts and the 2D engineering view, and the attribute information includes the attribute information of the graphics and the attribute information of the parts (such as material, cost, etc.). CAD system gives the information it produces to PDM system to manage. CBD system, CAE system and other systems all extract product feature attribute parameters and graphic files from PDM system, and hand over all kinds of graphic files and document data generated by them to PDM to manage, so as to achieve unified management and sharing of product data.

3.2 characteristics of distributed virtual design platform based on PDM

The distributed virtual design platform based on PDM has the following characteristics:

The main contents are as follows: (1) distributed distribution is a main feature of distributed virtual design platform based on PDM, which is multi-node distributed. Each subsystem is in the node unit system of the whole system, joins the system as elements, and becomes a member of the system under the unified system of PDM module. The whole system runs in a distributed environment supported by computer network and database management system (central database and local database). The central database acts as a data warehouse in the system, and the final data information generated by each module in the system is stored in the central database system through the PDM subsystem. On the contrary, the data sharing of each module is based on the central database.

(2) Integration is another main feature of PDM-based distributed virtual design platform. The distributed virtual design platform uses PDM technology to realize the integration of product data, process and application in the process of virtual design. On the basis of information integration, it emphasizes process integration. Process integration needs to optimize and reorganize the product development process, organize multi-department personnel to complete design tasks in a coordinated working environment.

(3) parallelism the distributed virtual design platform based on PDM regards the whole design process as an integrated parallel process, and realizes parallel design from the point of view of global optimization. It is embodied in: on the one hand, realize the reorganization of the design process, eliminate the errors and deficiencies of product design, and improve the success rate of product development. On the other hand, PDM provides the basic environment for concurrent design. It integrates the data management ability of database, the communication ability of network and the control ability of process. it can realize the information sharing and exchange of design activities in distributed environment and dynamically adjust the design and manufacturing process.

And monitoring, but also can well support the coordination of various subsystems, support the optimal allocation of resources. In order to realize the support of concurrent engineering.

(4) Fast and intelligent distributed virtual design platform based on PDM uses case-based rapid intelligent design method to develop products, and uses PDM system as the supporting environment of distributed virtual design platform. The use of case-based design can greatly improve the efficiency of product development, improve the speed of product development, improve the intelligence and practicability of uncoiler design, and can reuse a large number of mature product resources.

(5) openness is an important feature of PDM-based distributed virtual design platform, which is reflected in four aspects: adaptability to basic environment, connection with underlying environment through different interfaces; openness of PDM kernel, using object-oriented modeling method and technology, establishing system management model and information model, and providing object management mechanism to realize product information management. Realize plug-in function, tool encapsulation and integration.

(6) highly flexible PDM-based distributed virtual design platform is based on flexibility, market-oriented, user-oriented, and pays attention to flexibility in organization and implementation.

3.3.Rapid variant design system based on PDM

With the globalization of market competition, users have more choices. The diversification and personalization of user needs has led to the widespread implementation of multi-variety, small batch (and even single-piece) orders in many machinery manufacturing enterprises. Compared with the traditional mode of production with few varieties and large quantities, in order-to-order production, due to the increase of varieties and the decrease of batches, the types of product information are more diverse and the quantity is more large, resulting in an unprecedented complex situation. But on the other hand, if enterprises want to win in the competition, they must respond to the needs of users with faster delivery time, lower cost, better quality and better service than their peers. In order to achieve this goal, enterprises can only use the existing product information resources in a scientific and orderly manner to respond to user orders quickly and reasonably with variant design.

Product design is usually divided into novelty / innovative design and adaptive / variant design. Innovative design has few reusable information resources, the product quality and delivery time are difficult to guarantee, and the cost is difficult to control, which makes the enterprise lack of competitiveness. Variant design is to reorganize the information and structure according to the market demand on the basis of the original products, maximize the reuse of the existing mature product resources of the enterprise, have strong flexibility and adaptability, and improve the speed and quality of the design. in the fierce market competition, enterprises can produce new products with high efficiency, high quality and low cost to meet the requirements of users. The rapid response variant design of products is an important means for enterprises to achieve rapid response to the market.

In the mechanical manufacturing industry, innovative design is rare after all, and a large number of them are always variant designs. In fact, many designers do often use variant design to respond to user orders, but the traditional variant design can not automatically guarantee fast delivery, low cost and high quality of the ordered products. The fundamental reason is that a large number of complicated product information and design knowledge are involved in the process of variant design, and at present, the retrieval and management of these information and knowledge are mainly realized by designers manually and spontaneously. Therefore, it seriously affects the speed and rationality of the design. In order to overcome this obstacle, it is necessary to use advanced information theory and computer technology to reorganize the product information resources of enterprises.

In the long-term production activities, enterprises have accumulated a large number of extremely valuable product information (drawings, documents, data, experience, standards, norms, etc.), which are fully excavated and scientifically reorganized. make it useful and easy to reuse product information resources, and store them in the database, coupled with the information resources accumulated in the previous development, it is enough to effectively support the rapid response to the market. In the face of the rapidly changing market environment, enterprises are required to respond quickly to market demand, quickly develop new products, and change passive adaptation to users to actively guide the market. Therefore, it is the need of the times to implement the "rapid response project" to adapt to the changes of the market environment and the transfer of users' needs.

The variant design strategy takes the relational product model, the corresponding product information management system and the intelligent technology based on case-based reasoning as the main means, with special emphasis on the standardization and reorganization of enterprise product information. through the variant redesign of the enterprise's existing mature products, the valuable information resources of the enterprise can be reused as much as possible. In order to achieve the goal of winning the market with the rapid response competition strategy of fast delivery, high quality, low cost and heavy environmental protection. The main points of the variant design strategy are:

(1) reorganize the enterprise workflow and respond to the market demand quickly with variant design.

(2) reorganize the product information of enterprises, so that the rich technical data accumulated by enterprises in the field of design and development can be transformed into useful and useful valuable information resources, with a view to using as few new design parts as possible to form as many variant series of new products as possible.

(3) the integrated relational product model and cross-functional parallel working environment are established, and the intelligent technology of case-based reasoning is adopted to support rapid variant design through the reorganization of product structure. In short, it is business process reengineering, information resource reengineering and product restructuring.

3.3.1 Information reorganization and variant design based on relational product model

To reuse enterprise product information resources and carry out rapid variant design, the information should be reorganized according to the relational product model based on the reasonable definition and expression of product resources. Product model is a kind of digital information model, which abstracts, defines and expresses information about products in the product life cycle with certain data, including data, structure and relations.

In the process of product development, that is, from abstract concept to concrete structural materialization, there is a lot of information contained in the materialization process. Many kinds of relations can be obtained by abstracting and summarizing these implicit information. the existence and discovery of these relations ensure the correctness and speed of variant design. Relational product model takes various relationships in the process of variant product development as the core, supports rapid variant design through the reorganization of product structure, and can make maximum use of the existing product resources of the enterprise. it is a powerful tool for rapid product design.

3.3.2 take the product data management system as the data platform for Shaanxi rapid variant design

Product data management integrates all product-related information and product development process to create a highly transparent virtual environment that can meet the needs of complex and changeable variant design. under the condition of consistent definition of product data throughout the product life cycle, product design data management and process control is an important weapon for the integration of computer-aided tools. Become a data platform that can support rapid variant design based on relational product model.

In the global and increasingly competitive market environment, enterprises must fundamentally restructure their business process in order to maintain competitive advantage in the time to market, quality, cost and service (i.e. TQCS), which is called Enterprise restructuring (Enterprise Reengineering). The enterprise reorganization system is composed of business process reengineering, production process reengineering and information technology reengineering. Information technology reorganization refers to the use of advanced product data management PDM system to establish an intelligent product model, so that designers and developers can have a clear and comprehensive understanding of the production process of the whole enterprise when carrying out new product design and variant design. Product data management system is the enabler to realize these philosophies and the core of computer tool integration. It has gradually become a strategic weapon for enterprises to effectively manage, make use of product resources and win market competition.

The PDM system which supports rapid variant design is mainly composed of object characteristic table management, classification and coding system management and so on. The characteristics of things are the characteristics that describe objects that are not affected by their surroundings. The thing characteristic table is a kind of thing and relation characteristic table that combines and arranges a group of objects, which can be used to describe, restrict and select standard, non-standard, material and non-material objects and similar objects to each other. When it is used in CAD, it can normalize the archiving, storage and exchange of CAD data, each column of the table represents the characteristics of related components, and each row of the table represents an instance of the related component class.

The combination of thing characteristic technology and relational CAD system can establish an intelligent relational product model and ensure the reasonable variation of parts and components through the definition of relationship. The relationship is established between the shape model and the thing characteristic table, which can realize the rapid variant design driven by the thing characteristic table. In order to exchange product information and realize the rationalization of high-level technical management, it is necessary to choose appropriate classification standards. The classification and coding system can uniformly classify and manage the part layer, component layer and product layer of product resources, and form the product resource library of the enterprise. establish the relationship between products, components, parts and their documents, drawing paper and suppliers, and establish product structure information.

3.3.3 using CBR as an intelligent reasoning tool for rapid variant design

CBR (Case based Reasoning) technology, that is, case-based reasoning technology, is a new and important reasoning technology in artificial intelligence. Its core idea is to make full use of human successful experience in problem solving, and to take human experience in dealing with certain kinds of problems as a reference to deal with similar problems. To apply it to the design field is to directly refer to the previous examples of similar products and generate new products through necessary modifications. This reasoning technology accords with the traditional habits and thinking mode of designers, and is especially suitable for intelligent reasoning of large-scale structural variant design. It is an intelligent reasoning tool for rapid variant design.

In the operation of case-based reasoning, the most important operations are the retrieval of related cases, the selection of the best cases and the modification of cases. The introduction of CBR reasoning technology into the design field is to overcome the shortcomings of traditional rule-based expert systems and model-based reasoning systems. It can not only alleviate the difficulties of knowledge acquisition in expert systems, but also greatly improve the reasoning efficiency of the system. At the same time, it can enhance the ability of artificial intelligence to deal with heterogeneous knowledge, which can deal with both process knowledge and empirical knowledge. It can also deal with case knowledge, which has the following advantages:

(1) CBR reasoning does not require an accurate domain model, so knowledge extraction becomes a process of collecting the real side.

(2) the execution process of CBR reasoning is simplified to determine the typical characteristics of the description example, which is much easier than generating an accurate model or numerous rules.

(3) the application of database technology can solve the problem of managing a large amount of information.

(4) the CBR system can realize self-learning by transforming new knowledge into examples, which makes the maintenance of the system easy.

Therefore, it is feasible to apply CBR technology to solve variant design problems. CBR is an effective intelligent system development tool for a problem domain that does not have a clear model or is not fully understood.

3.4 system Integration based on Virtual Product Model

The establishment of a distributed virtual design platform based on PDM requires a structured representation of all product data. But these data are stored in different application systems. In order to make the virtual product model transparent to all users, these decentralized systems must be integrated into a whole. These systems mainly include CAx, PDM, and some application systems developed by users.

In the process of system integration such as CAx/PDM, the following issues need to be considered:

(1) the same information is described differently in different systems, and how to describe the data uniformly.

(2) the problem of data control, that is, who generates the data and controls the jointly owned information is the core of this problem:

(3) the direction and content of data transmission.

(4) organizational obstacles, it is difficult for the departments of the integrated system to accept each other's ideas, which is also a problem that can not be ignored in system integration.

According to the different ways to solve the above problems, different integration strategies can be adopted in the integration of CAx/PDM systems. When enterprises integrate the system, they not only consider the technical factors, but also consider the organizational structure, personnel and integration costs that the enterprise can bear.

According to the compactness of system integration, it can be divided into three integration modes: encapsulation, interface and full integration: encapsulation is the simplest integration mode, which costs less to implement, and because there are few changes to the original system, it is easier to be accepted by people in different departments. OLE technology is integrated at this level. At this time, the two integrated systems can not manipulate each other's internal data, such as embedding AutoCAD documents in Word documents, and it is impossible to change the data in AuotCAD documents directly in Word documents. This integration is limited.

The interface is programmed according to the API function provided by the two integrated systems, and the information they need is extracted through the API function, and then converted into a mutually acceptable format for information exchange. In this integration mode, the system accesses the internal data through the API function, while the API function is generally limited, which becomes a bottleneck of the integration. At the same time, we must fully understand the data structure of the parameters in each API function when integrating. This integration mode requires more investment (compared with the encapsulation integration mode), and it is a more common integration mode at present.

Fully integrated in the fully integrated mode, the two systems have a unified description format in the original data and function-oriented data definition. The transmission of these data does not have to go through the transformation of API functions, and the integration efficiency is high. This kind of integration requires the strong participation of software vendors, and at the same time costs a lot of manpower, material resources and time.

Integration of 3.4.1PDM system and CAD system

(1) basic function description of PDM/CAD system integration the core task of PDM/CAD system integration is to build the work results of CAD users together with related business objects and data objects in the PDM data model, so that all business objects, data objects and data describing component views, models, drawings and so on in the virtual product model can be integrated. The integration functions of the following four aspects are mainly completed in the PDM/CAD system integration interface, as shown in figure 3.2.

Figure data exchange between 3.2PDM and CAD system integration

A. Manipulating the view and model of the part the view and model of the part are first generated in the CAD system. In order to manage the view and model, the basic record of the model is generated in the PDM system accordingly. If there is no corresponding basic record of the part at this time, the basic record of the part must be generated first, which forms the connection chain of the basic record of the part-the basic record of the model-the model and the view. After this process is completed, the information of the view and model of the part can be transferred between PDM and CAD system.

The view and model information transferred from the CAD system to the PDM system mainly includes the weight and volume of the part, which forms a part of the basic record of the part model. The information transferred from the PDM system to the CAD system is mainly the description information of the part model and view, such as item number, mark, display level and classification index key, as well as the storage path and file name of the CAD view and model. The process is the same for components.

B. manipulating the main drawing of a part is composed of a 2D view or a detail view generated from the main 3D model plus corresponding working information (such as tolerances, etc.). All variant drawings of parts and assemblies can be derived from the main drawing. The operation on the main drawing of the part is similar to that on the part view / model.

C. The operation of part drawings between PDM/CAD systems mainly includes the registration, browsing, loading and editing of drawings. If a piece of information such as scale, page number and number of pages are recorded in the CAD side with borders and engineering annotations, these information can be transmitted to the basic records of the corresponding engineering drawings in the PDM system during the registration process. In the process of browsing, loading and modifying in PDM system, the attributes such as drawing number, name, material and weight can be dynamically transferred from the basic records of parts and drawings to the standard bar of engineering drawings in CAD system.

D. The first task to operate the component structure is to automatically reconstruct a complete product structure in the PDM system using the information obtained from the component drawing or component model, or to expand the existing basic structure to form a complete product structure; the second task is to use the product data structure in the PDM system to assemble into a corresponding component in the CAD system.

(2) PDM,CAD system integration data structure description above describes the main functions that need to be completed in the integration of PDM/CAD systems, and the completion of these functions requires the support of the corresponding data structure. The following describes the expression of the product data structure during PDM/CAD system integration.

In PDM system, parts are classified and organized through part clusters. Both the main graph and the main model are connected with the corresponding classification elements through the contact objects, and the parameters in the main graph and the main model are expressed by the table of characteristics of things associated with the classification elements. Each row in the table of the characteristics of things is associated with a corresponding basic record of the part, so that the model and engineering drawings of the parts can be derived from the parameters, the main drawing and the main model in the table of the characteristics of things corresponding to the basic record of the part.

In the process of deriving part model and part engineering drawing from the main drawing and the main model, it is necessary to make use of the corresponding relationship between the thing characteristic table and the parameter table. The characteristic table of things is generally managed as an object in the PDM system, but the description of the main graph and the main model in the CAD system is carried out by using the main model and the parameter table of the main graph, so it is necessary to establish the corresponding relationship between the characteristic table of things and the parameter table. In the CAD system, the corresponding models and engineering drawings can be generated in the CAD system through each row in the parameter table and the corresponding main model and master drawing.

In the process of deriving engineering drawings and models from the main drawing and the main model between PDM/CAD, the main data is transferred through the parameter tables of the main drawing and the model. When generating an engineering drawing or model from the PDM system, first map the corresponding parameter table data from the thing characteristic table, and then generate the corresponding engineering drawing and model through the parameter table data in the CAD system; after a model is generated in the CAD system, the corresponding parameter table data can be proposed and transmitted to the corresponding thing characteristic table in the PDM system, and a new basic record of the part can be generated in the PDM system.

Integration of 3.4.2PDM system and CAx system

(1) PDM/CAx system integration basic function description PDM/CAx system integration mainly refers to the integration with the CAx system that produces general product documents. The CAx system here mainly refers to the comparison with the CAD system, because the integration between PDM/CAD systems needs to deal with the internal information of the documents about CAD, while when integrating with the general CAx system, it only needs to deal with the relevant documents in these systems as an information unit. This integration method is relatively simple.

More.

When a document is treated as an information unit in PDM/CAx system integration, they have some common characteristics, on the basis of which a general integration interface can be constructed, which mainly performs the following functions, as shown in figure 3.3.

A. Register the CAx document in the PDM system

B. Load / view CAx documents through the PDM system:

C. Load / edit CAx documents through the PDM system:

Figure data Exchange between 3.3PDM/CAx system Integration

(2) the general interface description of PDM/CAx system integration can be seen from the above description that similar functions need to be completed when PDM is integrated with some CAx systems, so that the interface between PDM/CAx systems can be constructed with the same structure to reduce the difficulty and cost of integration. The main function of this general interface is to register, browse and edit documents in the PDM system. This generic interface can be described in figure 3.4.

In the process of PDM/CAx system integration, as long as a general message calling module and pre-and post-processing module are developed on the PDM system side, it can be integrated with a variety of CAx systems. The pre-and post-processing module mainly realizes the conversion of the neutral format of the basic document records. In the CAx system side, in addition to the pre-and post-processing module, we also need a special interface for CAx, which is mainly used to realize the integration of CAx system and other systems.

Figure A general interface for 3.4PDM/CAx system integration to process general documents

This chapter analyzes the architecture and characteristics of the distributed virtual design platform based on PDM, and discusses the key technologies of building a rapid variant design system based on PDM. Finally, it analyzes the system integration based on virtual product model. This article is from Qingsoft Yingtai Yuyun software. for more details, please click www.plmpdm.cn, or search for Qingrou Yingtai on Baidu.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.