基于实例的计算机辅助装配过程设计

为了简化装配过程设计,使过于依赖人类经验的装配过程设计自动化,提出了基于实例推理技术的计算机辅助装配过程设计方法.提出装配线设计系统体系结构,研究如何确定装配过程设计系统的输入信息,利用基于实例的推理技术将装配功能树映射为装配过程机制树,以实现装配过程设计.将装配实例分解为装配过程功能需求、装配过程行为和装配过程机制三个层次,根据输入零件类型和装配过程类型计算装配实例的相似性系数,并基于模糊评价方法从多个可行相似实例中选择最优的装配过程实例,通过机床修改、单元操作修改和工艺编程修改三步对实例进行修改,以满足给定的装配功能需求.运用具体实例验证了所提方法的正确性.     

多对称机械系统的功能设计研究*

多对称在机械系统中普遍存在,而且对系统满足设计需求起着重要的作用。系统分析国际、国内机械设计学发展的思路,阐明机械概念设计与详细设计,功能设计与原理设计,需求对称性、功能对称性、原理对称性与结构对称性的内涵,认为功能结构是功能设计的结果,功能结构体现了系统解的原理和结构布局。提出多对称机械系统的分类体系。通过对一千多个机械实例的分析,探索各种多对称在功能结构中的存在方式和在机械中的效用,发现多对称机械系统的功能结构主要由功能并联分解和组合,功能串联分解和组合,功能交叉串并联,功能并联复合,功能循环,功能选择和决策等基本模式组成。进而获取机械系统功能-载体配置原理与多对称类型之间的关联性知识和应用多对称性进行系统功能设计的规律性知识。最后利用上述知识发明一个具有多对称特征的海浪发电装置,并给出其功能结构。     

特征设计方法在方案设计中的应用初探

本文基于特征设计的基本思想,初步研究了以原型特征为设计单元的方案设计实现方法,重点讨论了原型特征的基本定义及其功能和几何表达方式,给出了方案设计的特征模型构成、设计过程的形式化表示及基本设计算法。所提出的方法为计算机辅助方案设计的实现提供了初步框架。     

基于生长型设计的产品反求

当前的反求工程研究大多集中于三维重构和快速成型方面,而针对产品的反求设计理论与系统研究较少.文中引入了产品功能结构分解重构原理与广义定位原理的生长型设计理论,在此基础上开发了支持后续创新设计的产品反求系统.从已有产品的实体模型出发,应用生长型设计理论对产品设计过程进行回溯,将产品分解为由功能元组成的功能原型,然后通过功能元之间的耦合作用实现对需求原型的反求,支持基于产品功能结构进行的产品结构方案的创新设计.     

基于功能单元的产品自适应设计系统研究

将“自适应控制”理念引入产品设计系统中,通过建立功能需求模型,使设计者的设计行为始终自动适应功能需求和产品工程规范,从而显著减少设计迭代次数,缩短设计周期,主要介绍了基于功能单元产品自适应设计的概念,功能特征及约束模型和自适应设计机制。     

基于多粒度共进化功能能推理的机械运动方案设计新方法

提出了基于多粒度共进化功能推理的机械运动方案设计方法.首先分析了共进化功能推理模型和多粒度设计模型的特点,并结合二者的优点构造了一种多粒度的共进化功能推理模型;然后将该推理模型应用于机械运动方案设计,提出了一种面向机械运动方案设计的共进化功能推理方法,该方法采用分类功能来描述机构单元及机械系统的运动特征信息,将机构单元和机械系统都采用运动功能变换函数进行抽象表达,通过功能推理来生成机械运动变换单元的串联组合方案;随即给出了相应的功能推理算法流程,通过与已有算法的比较详细分析了该算法的特性,并讨论说明了该算法所具有的效率高、可精确描述运动功能变换特性等优点;最后通过电线进给机构运动方案设计实例验证了该方法的有效性.     

机床协同设计中基于实例的冲突消解

将实例推理应用于机床产品协同设计的冲突消解中,研究了基于框架结构的冲突消解实例知识的描述方法,将用框架表达的知识转换成关系数据库表的存储结构,提出了基于冲突主特征和辅特征的冲突检索模型,并利用模糊综合评价原理对检索到的多个冲突消解实例进行优化和评估.详细研究了基于实例的冲突消解方法的实现过程,并开发了相应的原型系统.     

基于产品功能树的实例推理研究

以功能树为基础,在产品改型设计中实施实例推理的全过程.研究在推理过程中功能矩阵的提取与抽象、功能树相似度的计算和功能树的修改等问题.以功能树为基础,实现对产品结构树和零部件实例的修改,使产品达到设计需求功能.结合实例,给出了基于功能树实例推理的流程.该流程尽量保持装配关系的不变,避免了多个零部件的重新组合,减少对实例的修改程度.     

基于本体的公理化系统设计语义建模与推理规则

使得计算机理解系统设计的语义并完成自动推理是实现智能制造和基于模型的系统工程的两个重要特征,但现有系统建模语言对语义表达和自动推理的支持有限.第一,为了满足复杂产品系统建模的语义表达要求,在前期工作—基于模型的公理化系统设计(Axiomatic model-based systems engineering,A-MBSD)的基础上,构建对应的本体模型 A-MBSD Ontology;通过网络本体语言(Web ontology language 2,OWL2),明确定义系统设计的语义及其之间的关系.第二,为了满足系统建模的推理要求,使用语义网规则语言(Semantic web rule language,SWRL)对设计公理和规则进行定义,支持功能耦合性的判断和最优设计方案的选择.最后,以卫星太阳翼的系统设计为例,证明所构建的本体模型能够明确表达系统设计语义,相应的规则可以自动推理出设计参数所影响的功能需求、功能需求之间的耦合等,避免在试验阶段才发现耦合问题而导致的设计返工,提高系统设计的效率.     

定性推理在产品概念设计中的应用研究

概念设计是产品开发中的一个重要阶段 ,利用定性推理在信息不完全情况下所具有的定性行为预测功能 ,能够部分提高概念设计阶段的计算机辅助设计的水平。文中结合重心稳定问题 ,介绍了一个定性推理原型系统 ,并讨论了其在概念设计中的作用     

Computer-aided structural design of drawing dies for stamping processes based on functional features

This paper describes a structural design system for 3D drawing dies based on functional features using a minimum set of initial information. In addition, it is also applicable to assign the functional features flexibly before accomplishing the design of a solid model for the main parts of a drawing die, such as upper die, lower die, and blank holder. The initial information includes blank sizes, work strokes, die faces, punch open lines, and press data. The proposed system integrated the design knowledge of drawing die into functions of 3D computer-aided design (CAD) software to automate design and to shorten design time. This design system is constructed on a PC and integrated with a Pro/ENGINEER CAD system including feature selector, shape calculator, model generator, design coordinator, and user interface. The proposed system is demonstrated using the example of designing a drawing die for the roof panel of a vehicle within 1 h. The results reveal that it can dramatically improve the design quality and can save both time and costs with excellent design quality.     

产品设计意图的建模研究

一个完善的CAD系统应该提供产品设计意图的有关信息 ,以使得设计意图能在设计者之间共享。给出一个设计意图的模型 ,可供产品再设计时参考。     

Knowledge-based configuration design of a train bogie

The configuration design of a mechanical product can be performed efficiently when it is based on a functional model. There are some function-based design methodologies that decompose functions from the abstract level to the concrete level by matching the functions to physical parts. However, executing innovative design is difficult when the function is matched only to pre-defined parts. This paper describes the configuration design process of a train bogie with a design expert system that uses function taxonomy and TRIZ. The design expert system can propose a functional model of a new part that is not on the existing parts list of train bogies. Levels of design knowledge which describe the operations of the mechanical product at different levels of abstraction are introduced. This is the theoretical basis for using TRIZ with the function taxonomy for configuration design. The design expert system is adequate for controlling the design knowledge, which is expressed as knowledge of parts, functional modeling, mapping rules between functions and parts, and TRIZ. The functional model of a new brake system in the bogie is introduced with the design expert system.     

基于设计特征的特征转换技术研究

分析特征和特征转换技术,并建立一个基于产品设计特征模型的特征转换系统,实现产品特征模型由设计域到加工域的转变.同时,对实现系统通用性的关键技术--设计特征信息的获取进行了研究.     

Assembly design system based on engineering connection

An assembly design system is an important part of computer-aided design systems, which are important tools for realizing product concept design. The traditional assembly design system does not record the connection information of production on the engineering layer; consequently, the upstream design idea cannot be fully used in the downstream design. An assembly design model based on the relationship of engineering connection is presented. In this model, all nodes are divided into two categories: The component and the connection. Moreover, the product is constructed on the basis of the connection relationship of the components. The model is an And/Or graph and has the ability to record all assembly schemes. This model records only the connection information that has engineering application value in the product design. In addition, this model can significantly reduce the number of combinations, and is very favorable for the assembly sequence planning in the downstream. The system contains a connection knowledge system that can be mapped to the connection node, and the connection knowledge obtained in practice can be returned to the knowledge system. Finally, VC++6.0 is used to develop a prototype system called Connect-based Assembly Planning (CAP). The relationship between the CAP system and the commercial assembly design system is also established.     

A design representation scheme for collaborative product development

Design is an integral component of product development, which includes manufacturing. In order to avoid costly reworks and delays, and to reduce the lead-time in product development, effective communication of design concepts among the various stakeholders such as customers, designers and engineers is of utmost importance. In this respect, functional representations provide a methodology, which can be used to describe a design or product effectively. However, function is not the only type of information that needs to be communicated among the various stakeholders during a design process. Other types of information such as design specifications and constraints, which are non-functional, also need to be taken into account. This non-functional information cannot be adequately expressed using existing functional representations. Accordingly, in this work, a novel purpose-behaviour-structure (PBS) representation scheme to capture vital design knowledge for collaborative product development is proposed. The proposed PBS representation scheme can be used by designers working in a collaborative environment for product development. A case study on the design of a vacuum cleaner is used to illustrate the functionality of the PBS representation scheme. The details of the representation scheme are presented in this paper.     

Extraction/conversion of geometric dimensions and tolerances for machining features

It is important for a feature-based system to preserve feature integrity during feature operation, especially when feature interaction occurs. The paper presents a feature conversion approach to convert design features used in a design model into machining features for the downstream applications. This process includes both form features (geometric information) and non-geometric features conversion. Most researchers have concentrated on geometric information extraction and conversion without tackling the important problem of non-geometric feature information. This paper focuses on the extraction and conversion of feature geometric dimensions and tolerances (GD&T) for downstream machining application.The main barrier to the integration of a feature-based CAD/CAPP/CAM system – feature interaction – is discussed in this paper, which alters design features in their geometries and non-geometric information. How to identify and validate these feature dimensions and tolerances is one of the key issues in feature interaction conversion. The development of robust methodologies for preserving feature integrity for use in process planning application is the main thrust of the work reported in this paper.     

基于知识的电气综合方案设计系统研究

电气综合系统设计是对现有知识继承、重用、再创新的过程.在分析设计过程特点的基础上,提出了基于知识的电气综合方案设计系统框架结构,基于混合知识表示构建了多层次知识库,结合基于实例推理和基于规则推理方法设计了混合推理机,开发了原型系统IESDS(Integrated Eletrical Scheme Design System)对上述研究的进行了可行性验证.     

Automatic recognition of design and machining features from prismatic parts

Prismatic parts usually comprise basic features, such as slots, steps, holes, bosses, which may intersect with one another. In general, automatic recognition of intersecting features is difficult and may present bottlenecks when automating the design procedures which make use of features for downstream operations.This paper presents a novel approach to recognising intersecting features and auxiliary features due to tool movements and cutter radii. Since no cutting edges can be perfectly sharp, corner fillets on machined features are invariably created by end mills and other cutters. Fillets, on the other hand, could very well be features which have been designed to increase strength and reduce stress concentration of certain features. A feature recognition system is proposed to recognise features having fillets which may be either design or manufacturing features. This information will be useful to the product designer as it would be possible to distinguish between the intended and unintended features of a part. The developed system has been implemented on an HP-ME30 Solid Modeler.