基于知识的设计流程控制

由于电子ＣＡＤ系统的复杂性不断增加，大量高度专业化的ＶＬＳＩ设计工具使设计的工具选择和启动过程变得十分繁琐和复杂。为了克服上述困难，本文提出一个基于知识推理的方法来解决这一问题。我们采用一种有向图和基于设计上下文的产生式规则来共同构造设计流程的模型。     

Knowledge processing for concurrent engineering: An evolving challenge in CIM research

As technological tasks in CIM environments become more complicated, the level of intelligence required to automate and integrate these tasks also evolves with increasing complexity. This paper classifies CIM tasks and their required intelligence into facility, data and decision levels, and discusses the automation and integration of those knowledge-intensive CIM tasks at their decision level. Since decision-level tasks are often more abstract than those at the facility and data levels, a systematic approach is necessary to build research programs for the automation of these tasks. This paper will use the decision-level task of concurrent engineering as an example to explain the five-step approach that we have adapted to form our research programs in this evolving area of CIM research. These five steps are: (1) perform analysis of the task and its needed decision-level supports, (2) conceptualize these analysis results into a concise framework, (3) propose a software paradigm for the conceptual framework, (4) identify functional requirements from this paradigm to guide software implementations, and (5) correlate implementation results to identify a fundamental technology. More specifically, the analysis of concurrent engineering tasks in CIM can be found in Section 2. Section 3 explains the conceptualization process which views decision making activities as mappings and loops between a control and performance space. In Section 4, concurrent engineering is modeled as a team problem-solving process participated in by multiple cooperating knowledge sources (MCKS) with overlapping expertise to perform those loops. Several functional requirements are identified from this MCKS model of concurrent engineering and example research activities to address these challenges are described in Section 5. The correlations in Section 6 indicate that the knowledge processing technology, evolved from applied artificial intelligence research, is a fundamental technology for building intelligent systems to support various knowledge-intensive CIM tasks at their decision level.     

DEVELOPMENT OF AN INTELLIGENT PRODUCT DESIGN SYSTEM: INTEGRATION STRATEGIES

Conventional computer-aided design (CAD) packages have drastically reduced the workload of the human designer and shortened the product design cycle. However, the degree of effort and volume of information required to use these tools limit their use to the later stages of design. Intelligent computer-aided design (ICAD) systems have sought to provide a more complete design tool to assist the designer in all phases of design. ICAD systems incorporate conventional CAD elements as well as knowledge engineering constructs. The level of integration between different components of an ICAD system determines its usefulness. Most commercial intelligent CAD packages are tied to a specific set of CAD tools, restricting their application domains. This dependence on specific software tools can be reduced by using general purpose modules to interface with available CAD packages. This paper discusses a method of introducing knowledge engineering technology to help develop an advanced intelligent product design system by integrating ICAD's Concept Modeller with SDRC's l-DEAS package for engineering product design. This integration is necessary because neither the Concept Modeller nor the I-DEAS package provides any unified design environment where users can access both symbolic and numerical design tools as needed to carry out design synthesis and analysis activities. Interfacing engineering design and knowledge processing together is not an easy task. The task is further complicated since it needs to be done only by those who have enough knowledge of both technologies, and also because it may result in reorganization of the traditional design process altogether. The proposed intelligent product design system uses artificial intelligence techniques to take care of human experts knowledge and it advocates the use of several commercial software packages that come from a variety of sources (and are proven to be robust) to perform design synthesis in a cost-efficient and timely manner. The technique described here is relatively easy to implement and is well suited to industrial needs.     

多框架CAD环境下的设计数据一致性管理

多框架ＣＡＤ环境下的数据一致性管理要比传统意义上的集成框架内容的数据一致性管理困难得多,因为多框架ＣＡＤ环境管理系统不能直接控制设计工具和管理设计数据。本文给我们在巨型机工程设计多框架环境下的数据一致性管理技术。     

CAD speeds up dinnerware designs

The Pfaltzgraff Company has become America's leading manufacturer and marketer of casual dinnerware and accessories for the home. To compete in this environment, Pfaltzgraff has adopted aggressive product introduction goals that include the design and development of dozens of new shapes every year. The paper considers how the job of designing and fabricating the tooling to mass produce these shapes falls to the computer-aided design (CAD) group of the Engineering Department. Most of the CAD staff have a mechanical engineering background and received their computer training on the job. The entire CAD staff work closely with the process engineering group who is responsible for production efficiency to achieve optimum tool performance     

Designing for operations: Towards a sociotechnical systems and cognitive engineering approach to concurrent engineering

In the practice of concurrent engineering, the factors that are considered early in the product design process include manufacturability, assembly, and cost. A set of issues that are not typically considered revolve around the operational requirements for human workers in the manufacturing system. What tasks will human workers accomplish? How will these tasks be organized and coordinated? What information and resources need to be shared? Will the workers have a coherent set of job responsibilities? How should the manufacturing environment be designed to support effective work practices? How can a manufacturing process be designed that also informs organizational structure and takes into account the quality of working life?

The field of sociotechnical systems theory (STS) focuses on exactly these kinds of issues. Rather than subscribing to the usual view of technological determinism — that a complex human-machine system is designed solely with respect to optimization of technical criteria — the goal of STS is to jointly optimize both human and technological considerations in system design and operation. The spirit of STS has much in common with recent work in cognitive systems engineering that advocates the design of joint cognitive systems in which machines serve as flexible, context-sensitive resources for human problem solving. Furthermore, a focus on design teams necessitates the study of the relationship between group work and technology as studied in the field of computer-supported cooperative work (CSCW). This paper briefly reviews current research in sociotechnical systems theory, computer-supported cooperative work, and cognitive systems engineering and proposes a framework for integrating operational concerns into the concurrent engineering process. Relevance to industry

To be competitive, organizations need to effectively manage human and technological resources. A key issue is the nature of the information and technological infrastructure that both enables and supports ‘best practice’ across the enterprise. This paper describes such an approach in the context of the ‘operational enterprise’ and provides both a philosophical stance as well as specific examples of software support.     

A multi-disciplinary strategy for computer-aided clothing thermal engineering design

The designers and manufactures in apparel industry have urgent needs in designing clothing with superior thermal functions with user-friendly and cost-effective design tools. This paper presents a multi-disciplinary strategy for computer-aided clothing thermal engineering design. It provides a systematical approach to integrate multi-disciplinary knowledge and transfer it into engineering-oriented design tools, thus the designers and manufacturers can easily carry out 1D, 2D and even 3D clothing thermal engineering designs according to the practical design requirements with a short design cycle and low design cost. The research work of this strategy begins from the investigation of the role of the thermal functions of clothing in the thermal comfort of human body. Then the framework is proposed to integrate the multi-disciplinary knowledge and illustrate the process to achieve the thermal engineering design of clothing. The important issues in the realization of computational simulation are addressed, including multi-scale model integration, data availability of characteristic parameters and hierarchical computational scheme. To issue easy-to-use design tools, the thermal functional design of clothing is quantified with important influence parameters, and the user-friendly wizard is designed for the CAD system development. Finally, the design applications of this strategy are discussed in terms of 1D, 2D and 3D thermal engineering designs with versatile CAD systems.     

公开小卫星可复用软件技术研究

小卫星应用领域的不断扩展、功能和结构的日趋复杂以及数量的急剧攀升,使得星载软件的规模和复杂度快速增加,软件可复用性设计变得愈加重要。本文首先分析了面向体系应用的星载软件功能和技术需求,然后对星载软件体系架构进行了分层模块化设计,最后针对星务主机,详细描述了星载软件框架的静态结构,动态结构以及可复用构件的运行模式。在小卫星向体系化应用发展的趋势下,分层模块化软件体系架构和软件框架技术将提高星载软件的可复用性,为实现小卫星快速集成,快速测试和快速生产打下重要基础。     

Decomposition of interdependent task group for concurrent engineering☆

In concurrent engineering, project tasks generally involve the establishment of multifunctional teams in which team members from different functional departments interact in every phase of development tasks to design the products and processes concurrently. However, the increasing complexity of product development and design process often come up with large interdependent task groups due to the nature of the concurrent strategy. The large size of interdependent task groups makes it difficult for team organization and thus delays the project completion. This calls for the intention of this research to develop an effective model to: (1) transform the binary task relationships into the quantifiable task coupling strengths; and (2) to decompose the large interdependent task group into smaller and manageable sub-groups. Design structure matrix (DSM), analytic hierarchy process and cluster analysis are used to represent task relationships, quantify task couplings and decompose large size of task groups. Clustering performance between numerical DSM versus binary DSM is evaluated using a simulation experiment. The experimental results show that the clustering performance of using numerical DSM is better than the use of binary DSM. The effectiveness of this model is then demonstrated by an illustrative example. The result shows that our proposed model is capable of decomposing the large coupling task group that helps team organization for concurrent engineering project.     

面向装配的CAD技术研究

面向装配的设计DFA(Design for Assembly）是并行工程的一个有效工具。本文系统阐述了DFA的发展 、意义及其与传统的考虑装配工艺性的区别;介绍DFA的主要内容和几个典型的DFA分析方法,重点分析Boothroyd-Dewhurst方法和步骤;叙述集成CAD技术的DFA应解决的问题及典型的DFA分析软件;最后总结了DFA的研究特点。     

Collaborative design: Improving efficiency by concurrent execution of Boolean tasks

Computer-Aided Design (CAD) applications provide design and engineering professionals with various computer-based tools to perform design activities. As efficiency is one of the most important requirements in most design tasks, in this article, we contribute a novel collaborative design approach to improving efficiency, where a complex design task can be divided and executed concurrently by multiple collaborative designers. This approach is particularly effective for design tasks where Boolean operations – widely supported by most CAD applications – are heavily used in design activities, such as architecture design, mechanical design and digital media design. We have designed and implemented a prototype system CoAutoCAD to test the approach and to demonstrate a variety of collaborative design activities.     

INTELLIGENT CAD SYSTEM IN CONCURRENT ENGINEERING ENVIRONMENT: A KNOWLEDGE-BASED APPROACH

The objective of this paper is to investigate specific methodologies for conceptual design and to establish a computational framework for an intelligent CAD system in a concurrent engineering environment. The main idea in developing such a system is to help designers in conceiving better design ideas within given sets of design, manufacturing, and assembly constraints. It is, therefore, essential to integrate intelligently diverse knowledge sources from different fields of manufacturing (e.g., design, process planning, assembly, inspection). When an object creation process is complete, the system analyzes the structure in consultation with its intelligent computational modules (“local experts”) to make sure that no functional, geometric design or manufacturing constraints are invalidated and to suggest an alternative better design, whenever possible. The paper also discusses the implementation of a prototype system for automated fixture design in the proposed concurrent engineering environment.     

Management of complex structural engineering objects in a relational framework

To structure the development of an integrated building design environment, the global representation of the design data may best be organized in terms of hierarchies of objects. In structural engineering design we deal with large sets of independent but interrelated objects. These objects are specified by data. For an engineering design data base the system must be able to model the objects composing the design as well as to manage effectively the design data. The data base management system therefore needs to have some knowledge of the intended use of the data, and must provide an abstraction mechanism to represent and manipulate objects. Much recent research in engineering data bases focuses on object management for specific tasks but gives little attention to the shareability of the underlying information. This paper describes an architecture for the management of complex engineering objects in a sharable, relational framework. Potential application of this approach to object management for structural engineering analysis and design is discussed.     

Development of a computer-aided concurrent net shape product and process development environment

This paper presents a systematic approach to developing a collaborative environment for computer-aided concurrent net shape product and process development. This approach includes the steps of (1) conventional development process analysis, (2) development process re-engineering, (3) computer-based system functional requirements analysis, (4) system framework design, and (5) system modeling, integration and implementation. This environment can support concurrent net shape product and process development by providing and integrating functions of product data management, process management and development advisory tools. The results of this research will facilitate the rationalization and automation of net shape product and process development and thus improve the efficiency and quality, and reduce the cost of net shape product development.

IDEF structural analysis methodology was employed to capture the characteristics of net shape product and process development process. The concept of concurrent engineering was used to re-engineer the development process. The technology of system engineering was used to design the computer-aided system framework. Object-oriented analysis, modeling and design methodology, knowledge engineering and data engineering techniques were employed for system modeling and implementation.     

Expert systems in engineering design: an application for injection molding of plastic parts

The rich development environments of expert system shells provide tools for developing knowledge-based expert systems for complex tasks such as engineering design. The diverse knowledge in engineering design combines heuristics with deterministic knowledge, from multiple sources, and involves complicated, interrelated components. The hybrid capabilities in emerging expert system tools effectively address this diverse knowledge, and facilitate the rapid development of design aids by the engineering designer. A prototype expert system for injection-molded plastic parts demonstrates the utility of expert systems for design applications. The prototype is implemented in an object-oriented, rule-based environment, and incorporates solid modeling software and external material databases.     

A workstation approach to IC process and device design

IC designers are turning more and more to CAD tools to develop complex designs and to automate time-consuming tasks. Although there are a variety of integrated tools for many types of VLSI design, very few integrated systems have been built to address process and device design. Recognizing this need, researchers at MIT set out to define the requirements of a process and device design environment, implement a subset of these functions, and integrate the tools into a user-friendly design environment. As part of their work on creating a user-friendly environment, they developed the MASTIF workstation to provide graphic, window-oriented user interaction to process and device designers     

ARCADE — An architecture for CAD in electronics

Ever since the introduction of computers in development and engineering departments, design activities have been supported by computer methods in a growing number of design functions, in the interest of reducing development time and cost, and increasing the quality of the products. Computer Aided Design (CAD) — a generic term for these computerized tools — is recognized as a method for drastically reducing the development time of industrial products.CAD methods are currently being used during each of the various phases in the development activity. The introduction of these CAD tools for the various stages in the development cycle, however, was to a large extent effected in isolation, i.e. not as a “subset” of an overall concept. Lack of such a concept, with its inherent disciplines and compatibility aspects, has given rise to sub-optimal efficiency and effectivity. To remedy this situation, a generalized architecture for CAD has been developed. This architecture drastically reduced the large variety if input methods, combines all product data in one well-structured product file, supports all necessary design functions, assures the proper generation of technical documents, and above all, facilitates maximum efficiency by integrating the processes for various stages in the development cycle.The essentials of ARCADE will be described in this article, together with how the system is designed.The “ARCADE” way and method of working in an organization in which development, engineering, manufacturing, logistic and documentation departments are concerned with technical automation issues will, as such, be discussed.Benefits will, of course, also be elucidated.     

Design parameterization and tool integration for CAD-based mechanism optimization

This paper presents an open and integrated tool environment that enables engineers to effectively search, in a CAD solid model form, for a mechanism design with optimal kinematic and dynamic performance. In order to demonstrate the feasibility of such an environment, design parameterization that supports capturing design intents in product solid models must be available, and advanced modeling, simulation, and optimization technologies implemented in engineering software tools must be incorporated. In this paper, the design parameterization capabilities developed previously have been applied to support design optimization of engineering products, including a High Mobility Multi-purpose Wheeled Vehicle (HMMWV). In the proposed environment, Pro/ENGINEER and SolidWorks are supported for product model representation, DADS (Dynamic Analysis and Design System) is employed for dynamic simulation of mechanical systems including ground vehicles, and DOT (Design Optimization Tool) is included for a batch mode design optimization. In addition to the commercial tools, a number of software modules have been implemented to support the integration; e.g., interface modules for data retrieval, and model update modules for updating CAD and simulation models in accordance with design changes. Note that in this research, the overall finite difference method has been adopted to support design sensitivity analysis.     

A survey of digital design reuse

As integrated circuit technologies advance toward higher performance, greater densities, and increasing system complexity, CAD tools and design methodologies struggle to keep pace. Managing the formidable complexity of the design process is one of the main challenges to IC design. Disseminating design reuse is central to bringing the design effort's complexity back to a manageable size. Effective reuse, though, takes more than just gathering predesigned components in a library. Reuse-oriented policies and strategies must permeate the entire design process, from the methodologies themselves to the final designs. In this article, we provide a brief overview of the state of the art in design reuse for digital systems. We also discuss the challenges posed to this discipline by the recent trend toward integrating processor cores in high-volume application specific integrated circuits