Research on Virtual Prototyping Technology for con

Research on Virtual Prototyping Technology for concurrent design

virtual prototyping technology is an effective means of collaborative simulation and verification of product design information in a virtual realistic environment. It can effectively support concurrent design and shorten the product development cycle After analyzing the relationship between virtual prototyping and concurrent design, a domain object-based virtual prototyping modeling and simulation method is proposed, and the key technologies of the integration framework supporting virtual prototyping are described

1. Introduction

facing the design complexity obstacles of modern high-tech products and fierce market competition, product design and production departments are in great need of new technology support that can effectively improve product design quality, shorten product development cycle, and reduce product development and production costs

in the traditional product design and manufacturing process, in order to verify the overall performance of products, physical prototype method is often used, but this method has long production cycle and high cost After entering the 1990s, with the rapid development of computer technology and CIMS technology, virtual prototype plays an increasingly important role in the process of product design and manufacturing Virtual prototype is a simulatable digital model that is generated according to product design information or product concept and is as similar as the actual product in function, behavior and sensory (visual, auditory, tactile, etc.) characteristics as possible Because virtual prototyping technology is of great significance to promote the development of concurrent engineering and virtual manufacturing technology, many foreign research institutions and software suppliers attach great importance to the research, development and application of virtual prototyping technology, which has been deep into many fields, such as machinery, electronics, aerospace, shipbuilding, automobile and communication

this paper analyzes the relationship between virtual prototyping and concurrent design, proposes a domain object-based virtual prototyping modeling and simulation method, and focuses on the key technologies of the integration framework supporting virtual prototyping

2. Virtual prototype and concurrent design

concurrent design is the integrated and parallel design of products and their related processes It is emphasized that product developers should consider the influence of all relevant factors in the whole life cycle of products from conceptual design to extinction at the beginning, and find and solve all possible errors, contradictions and conflicts as soon as possible, so as to shorten the product development cycle, reduce the product cost and improve the product quality

concurrent design includes two aspects: one is the concurrent design of multi process integration, and the other is the collaborative concurrent design of multiple product development teams (teams)

virtual prototype is an important means to realize concurrent design. It can provide strong support for concurrent design in the above two aspects

2.1 virtual prototype and upstream and downstream concurrent design virtual prototype and upstream density decrease by about 3% downstream concurrent design

while carrying out upstream conceptual design and functional design, carry out downstream physical planning or virtual physical design, plan all relevant factors affecting product quality, cost and cycle in a parallel and comprehensive manner, generate reasonable constraints, drive design with constraints, and pay attention to the full verification of upstream design

Figure 1 is a schematic diagram of product concurrent design process using virtual prototype After the upstream structure function design and verification, the virtual prototype of the product is generated according to the product function structure information, library component information and some empirical data; The virtual prototype contains the required system structure behavior, structure and physical design information Based on the virtual prototype, concurrent design planning comprehensively considers various constraints, simulates and tests the virtual prototype, especially the temperature measurement and sampling process of steelmaking, analyzes and plans the physical parameter information, judges whether the performance indicators can be met, and whether the design scheme is reasonable, and gives the engineering realizability evaluation of the product If it is found that the performance index and various constraints cannot be met, corresponding modification suggestions are put forward to regenerate the virtual prototype or modify the design scheme; Otherwise, design optimization constraint rules are planned to drive downstream design

Figure 1 Schematic diagram of concurrent design process of products using virtual prototype

2.2 virtual prototype and collaborative design

the design space of products can be regarded as a multidimensional space, and each dimension represents a constraint that affects the product life cycle, such as performance, cost, manufacturability, maintainability, etc., and these constraints affect each other For a certain dimension, the design scheme of a product may be very good, but due to the constraints of other dimensions, it may become an infeasible scheme In the design, experts in every field will always consider the indicators of a certain aspect of the product too much and ignore the comprehensive indicators of the product due to the restriction of knowledge and subjective desire For complex products, collaborative design by multiple experts is inevitable The evaluation in product design is mostly an uncertainty problem, which cannot be solved by traditional methods Using virtual prototype is an effective way to solve multi expert collaborative design

in the collaborative design environment of multiple product development groups, professionals in different places and departments focus on the realistic virtual prototype, test, simulate and evaluate the virtual prototype from different angles and different needs, and improve and perfect it They can also communicate and share information with each other through virtual prototypes This can ensure the elimination of design hidden dangers in the early stage of product design and development, improve product design quality and shorten product development time

3. Virtual prototype modeling and simulation based on domain object

3.1 domain object and domain entity object

domain object is to realize the sharing of heterogeneous data between different tools or domains, encapsulate the corresponding tools, models, data and methods in the domain, and form an entity with the functional characteristics of real product components Domain object is composed of intelligent interface, design data and simulation tools Intelligent interfaces are intelligent agents between domain objects and the external world The design data inside domain objects are generated by the same design tool, while there is great heterogeneity between different domain objects Outside the domain object, the product component can be regarded as an entity with certain functions, which only cares about its excitation and response characteristics, without considering its internal details Thus, it is convenient to eliminate the differences between tools and realize heterogeneous integration

for each type of domain object, there is a domain entity object corresponding to it on the virtual prototype server The domain entity object contains the attribute information related to the design entity, which is created by the designer in the overall design stage For design entities in different fields, the system provides some predefined templates for the creation of domain entity objects. Users can select and customize their own domain entity objects according to design needs At the same time, the structural relationship between entity objects in various fields can be defined graphically, and the system can automatically generate interface relationship information according to the interconnection relationship and the definition of entity objects in various fields

3.2 virtual prototype modeling and simulation framework based on domain objects virtual prototype modeling and simulation framework based on domain objects

virtual prototype simulation is carried out on the basis of the functions of domain objects Its model is logically a network composed of multiple domain objects, which is managed by a server Users participating in the virtual prototype simulation connect to the level server of the adjusted experimental machine through the client node, as shown in figure 2 The core of the server node is the object manager, which centrally reflects the overall structure information of the product through the management of a group of domain entity objects The client node is composed of view object, simulation client agent and collaborative virtual prototype simulation interface The view object is dynamically generated by the object manager according to the user's simulation requirements, and records the content and form of the information the user wants. Its main function is to cooperate with the simulation customer agent to provide the user with the required product simulation view, so as to reduce information redundancy Designers in different fields care about different contents and different angles of understanding problems The simulation client agent looks up the information needed by the user in the simulation output results generated by the objects in various fields, and sends it to the virtual prototype interface after a certain transformation to generate visual output After being perceived by the virtual prototype interface, the user's operation on the virtual prototype interface is also transformed into a recognizable incentive form of domain objects through the simulation client agent, and sent to each domain object through the virtual prototype server

Figure 2. Heterogeneous modeling framework based on domain objects

4. Integration framework supporting virtual prototype

the implementation of virtual prototype requires the support of simulation tools, domain design tools, and open integration framework platform The integration framework integrates the data management ability of the database, the communication ability of the network and the control ability of the process. It can not only realize the unified management of product data in the distributed environment, but also well support the virtual prototype

4.1 structure of integration framework supporting virtual prototype structure of integration framework supporting virtual prototype

the integration framework supporting virtual prototype is based on client/server structure, and the communication between client and server objects is connected through CORBA based client/server middleware. Its structure is shown in Figure 3

Figure 3 integration framework supporting virtual prototyping

from the perspective of software, it is a hierarchical structure, with the upper layer being the user server, which reflects the main functions supported by the virtual prototyping system. Users use the high-level user services provided by the service provider through the client user interface, and do not need to care about the underlying implementation structure Each type of service is composed of multiple agents, which communicate and interoperate in a flexible way User services are divided into four categories: data services, integration services, interactive services, and application services Among them:

● data service stores and manages domain data and prototype data, and is responsible for generating virtual data It uses object-oriented method to model data, and uses appropriate model to connect component description and behavior

● integrated services support tool integration and team integration It includes shared electronic notepad for communication among people in multidisciplinary design teams, as well as tool integration and packaging mechanisms

● interactive services provide 3D virtual environment, support the visualization and interaction of product data, and create a sense of immersion for users

● application services manage relatively static applications (mostly commercialized tools), which perform specific functions for virtual prototype users Application services include some tools related to virtual prototype design verification, such as virtual prototype generation tools, virtual prototype simulation tools, as well as some specific services, such as process management, project management, tool scheduling, concurrent design planning, etc

under these user services is the underlying support structure, which is invisible to users The main purpose of this structure is to support the communication requirements between high-level agents, which includes three levels:

(1) information sharing layer: related to the high-level communication requirements between entities in the system

(2) object management layer: hide communication details from users and applications in a distributed heterogeneous computing environment

(3) high performance computing and communication network interface layer: separate the underlying hardware of the network level from the communication and object management layer and other high-level agents

in the above structure, data service is the core and difficulty of realizing the integration framework supporting virtual prototyping, which is described in Section 4.2

4.2 data services data services

Figure 4 shows the structure of virtual prototype data services based on domain objects The domain is stored in the discipline database (DDB)