基于案例的产品设计系统中程序型知识检索研究及实现

基于Internet的计算机辅助工业设计系统,基于案例的计算机辅助工业设计系统研究基础上,结合Case-based Reasoning CBR技术,采用语义隶属度分析的方法,提出了基于设计问题的程序型知识获取模型以及基于相似度计算的程序型知识检索算法,为计算机辅助工业设计提供了一个新的思维方式,并在CBID系统构建中得到实践与验证.     

A case-based reasoning approach toward developing a belief about the cost of concept

It is generally acknowledged that product development involves a sequence of decision making under uncertainty, including setting target requirements for a new product, selecting product concept, and developing conceptual and detailed design of a chosen concept. To select a product concept, engineers need to assess the uncertainty of a future market share, market size, and a cost of concept (cost of the final product developed from a concept). This paper proposes a case-based reasoning (CBR) approach to model beliefs about the uncertainty of a cost of concept. The proposed CBR approach consists of storing information about various products in a knowledge-base, defining a new product concept, retrieving a cluster of products in the knowledge-base that are highly similar to the concept, and adapting the cost of the retrieved product to construct a distribution of the cost of concept. This paper illustrates the proposed approach using printers as an example.     

案例推理技术在包装设计系统中的应用

鉴于包装设计的复杂性和不确定性,基于案例推理技术及其应用特点,将CBR技术应用到包装设计系统中,提出了一种以CBR为基础的包装设计系统的功能模型。详细探讨了系统的关键技术。对构造更加高效的包装设计系统有一定的实用价值。     

Study on Case—Based Fixture Design

Fixture is an important manufacturing activity.Afixture design system based on case-based reasoning(CBR) is proposed in this paper.A nwe method of case representation on the basis of fixture function is presented,where the case representation is constituted of workpiece knowledge,processing feature knowledge,and fixture feature knowledge.Running the prototype system shows that the knowl-edge representation method ,using cases,is a better way to transform and explain the design knowl-edge.     

Development and evaluation of a tree-indexing approach to improve case-based reasoning: illustrated using the due date assignment problem

In this study a novel case indexing approach is proposed for case-based reasoning (CBR). This new approach, called the tree-indexing approach, is a modified form of the inductive learning-indexing (IL-indexing) approach and is especially applied to assist CBR in numeric prediction. The tree-indexing approach organizes the cases in the memory by inducting a tree-shaped structure, in order to improve the efficiency and effectiveness of case retrieval. The experiments, using three real world problems from the UCI repository, show that the CBR with the tree-indexing approach (T-CBR) is superior to the conventional CBR. This study also applies T-CBR for solving the due date assignment problem in a dynamic job shop environment in order to investigate whether T-CBR's expected benefits can be observed in practice. The results of the experiments show that our proposed T-CBR can indeed more accurately predict the job due date than the other methods presently in use.     

约束对象的产品族模型知识表示及配置方法

针对目前产品族模型存在冗余、配置效率低、不易更新的问题,研究了基于约束对象的产品族模型的知识表示方法,有效地降低了产品结构冗余以及配置的复杂度,实现模型知识的有效封装.在此基础上研究了基于约束和实例的配置推理方法,给出了具体的配置推理过程.最后,给出了一个摩托车产品族建模的案例.该模型及其推理方法能够方便地利用计算机实现,可用于建立一个高效的产品族配置系统.     

Group-based product scheme-screening decision method based on fuzzy AHP and evidential reasoning theory

Selecting the favourable product scheme is the first step to successful new product development (NPD). There are usually large numbers of uncertainties in product scheme evaluation and screening process of NPD due to lack of or incomplete reliable information. Considering fully the uncertainties and then conducting correct reasoning could guarantee reliability and rationality of scheme-screening results. As an extension of analytic hierarchy process (AHP), fuzzy AHP inherits multi-merits of the AHP approach and is capable of dealing with fuzzy information effectively, but it still has two weaknesses. One is the well-known ranking reversal problem. Although several researchers have analysed the reasons, we think the root cause for ranking reversal problem is due to the fact that AHP treats weights of attribute criteria and performance scores of alternatives in the same way. Therefore, we intend to deal with attribute weights and performance scores of alternatives separately and introduce evidential reasoning (ER) theory, which is good at uncertain reasoning, into fuzzy AHP to calculate the performance scores of alternatives. On the other hand, in view of the difficulty in resolution for fuzzy weights from fuzzy comparison matrix, a linear goal-programming model is proposed to calculate fuzzy weights, whose objective is to minimise the inconsistency degree of comparison matrix. By combining fuzzy AHP with ER, a group-based hybrid decision model FAHP-ER is developed. The hybrid model not only gets a great improvement in the capability of dealing with uncertainty, but also reflects the most real decision scenario and thinking process of the decision maker. Finally, a case study for schemes screening of the rotor and bearing system in the turbine generator is presented to demonstrate the application of the hybrid decision method.     

实例基集成推理技术及其在产品协同设计支持系统中的实现

介绍了一种基于实例和规则的集成推理模型,并给出其在机械产品协同设计支持系统中的应用。重点讨论了集成系统中的设计实例表示及其结构组织,并给出系统方案设计结果。最后对系统进行了分析与评价,实践证明其运行结果良好。     

A scheme for functional reasoning in conceptual design

An ideal functional reasoning environment should support designs of any nature, routine or innovative, at any level of detail, as well as through varying levels of detail. In this paper, three existing functional reasoning models are reviewed in this perspective. It has been found that none of these models support all of these requirements. It has been shown that a functional reasoning approach cannot guarantee the generation of solution concepts, which are combinations of known solutions, unless guided by the knowledge of existing solutions. A new model which can support design both across a level of detail and down through levels of detail has been proposed, which, using a divide and rule approach and using recursive problem redefinition while incorporating existing solutions, could support conceptual design. It is also shown that, although the generation of completely new solutions is not supported by the model, the model, when aided by a framework allowing a sustained progress of its knowledge base by transfer of knowledge from existing designs in the form of basic structures and rules of combination, could support generation of designs which otherwise would be considered unsupportable in a systematic way (innovative).     

数控编程KBE系统的基础性使能技术研究

针对数控编程领域知识的特点,对KBE系统实现的基础性使能技术进行了研究,介绍了基于实例和规则的数控编程领域知识表示方法和知识获取的概念、途径及过程,阐述了CBR在复杂零件数控编程中的应用,提出了以人工知识获取为主、机器学习为辅的数控编程领域知识获取方式和基于双向混合推理控制策略的CBR／RBR集成数控编程领域知识推理方法,研究成果在开发的原型系统中得到了应用,证明方法可行．     

CAQFD概念设计专家系统模式的研究

质量功能配置(QFD）对满足用户需求的产品概念设计提供了一种切实可行的方法。探讨了计算机辅助QFD概念设计专家系统的设计模型和计算机实现的关键技术。对用户需求信息的获取方法进行了研究,构建了用户需求知识表达的拓扑结构。从知识工程的角度,提出了基于数据库的知识表达模式和推理方式,设计了专家系统的知识推理过程。最后以高速专用磨床的主轴前支承轴承的概念设计为例,进行了系统的应用验证,取得了满意的效果。     

A fuzzy logic based approach to reliability improvement estimation during product development

During early stages of product development process, a vast amount of knowledge and information is generated. However, most of it is subjective (imprecise) in nature and remains unutilized. This paper presents a formal structure for capturing this information and knowledge and utilizing it in reliability improvement estimation. The information is extracted as improvement indices from various design tools, experiments, and design review records and treated as fuzzy numbers or linguistic variables. Fuzzy reasoning method is used to combine and quantify the subjective information to map their impact on product reliability. The crisp output of the fuzzy reasoning process is treated as new evidence and incorporated into a Bayesian framework to update the reliability estimates. A case example is presented to demonstrate the proposed approach.     

An optimisation support for the design of hybrid production lines including assembly and disassembly tasks

The optimisation problems related to the assignment of tasks to workstations in assembly and disassembly lines have been largely discussed in the literature. They are known, respectively, as Assembly Line Balancing and Disassembly Line Balancing Problems. In this study, both types of task performed on the identical product are integrated in a common hybrid production system. Therefore, the logistic process is simplified and disassembly tasks can supply easier the assembly tasks with the required components. The considered production system has the layout of two parallel lines with common workstations. The product flow is conventional in the assembly line and reverse in the disassembly line. The paper provides a new mathematical model for designing such a hybrid system and an approximate approach based on ant colony optimisation for solving large-scale instances. The solution method is tested in a case study. The obtained results are compared with the solution provided by the design of two independent lines. The analysis of the results highlights the potential benefits of the hybrid production system.     

Process-oriented tolerancing for multi-station assembly systems

In multi-station manufacturing systems, the quality of final products is significantly affected by both product design as well as process variables. Historically, however, tolerance research has primarily focused on allocating tolerances based on the product design characteristics of each component. Currently, there are no analytical approaches to optimally allocate tolerances to integrate product and process variables in multi-station manufacturing processes at minimum costs. The concept of process-oriented tolerancing expands the current tolerancing practices, which bound errors related to product variables, to explicitly include process variables. The resulting methodology extends the concept of “part interchangeability” into “process interchangeability,” which is critical due to increasing requirements related to the selection of suppliers and benchmarking. The proposed methodology is based on the development and integration of three models: (i) the tolerance-variation relation; (ii) variation propagation; and (iii) process degradation. The tolerance-variation model is based on a pin-hole fixture mechanism in multi-station assembly processes. The variation propagation model utilizes a state space representation but uses a station index instead of a time index. Dynamic process effects such as tool wear are also incorporated into the framework of process-oriented tolerancing, which provides the capability to design tolerances for the whole life-cycle of a production system. The tolerances of process variables are optimally allocated through solving a nonlinear constrained optimization problem. An industry case study is used to illustrate the proposed approach.     

基于事例推理的自由曲面型汽车前照灯方案设计方法

 快速地确定满足配光要求的自由曲面型前照灯的设计方案,是车身造型的要求.采用基于事例推理的方法,首先研究了面向对象的前照灯事例表达模型,然后根据最近邻事例检索方法,利用车灯包围盒和布置坐标系等预处理工具,建立了前照灯事例索引模型和匹配算法,提出了约束满足和尺寸驱动求解相结合的前照灯事例修改算法.应用实例表明,所提出的方法能在前照灯方案设计中引入工程设计要求,快速产生符合要求的设计方案,能够有效地克服工程要求与造型设计的冲突,减少设计过程的反复.     

物质-场情景分解法在工业设计中的应用研究

市场经济带来的竞争性压力促使企业不断进行产品创新设计.为了提高产品创新设计的效率和成功率,系统化的产品创新设计方法显得尤为重要.物质-场情景分解法,是以情景分解法为基础分析产品全生命周期过程,结合TRIZ理论体系中的物质-场分析法将情景分解法中的问题转化为功能模型,并应用标准解对问题进行求解,为产品创新设计提供一种系统化创新设计方法.最后以轮椅设计为例,验证该方法的有效性和实用性.     

融合TRIZ理论和FBS模型的担架车创新设计

目的 提出TRIZ理论和FBS模型融合的创新设计模式,以更充分地发挥两者在产品创新设计上的特点,形成优势互补,基于该模式设计一款代替救护车通过狭小路段实施救援的新型担架车。方法 基于现有担架车产品,运用FBS模型挖掘医护人员和伤者的用户需求,并由用户需求推导分析用户行为,进而得到担架车创新结构特征。之后,应用TRIZ理论矛盾冲突矩阵对担架车结构及功能设计中出现的矛盾冲突进行分析,找到问题解决的思路并形成方案。结果 根据产品创新设计模式设计出一款带有动力系统、可快速转移伤员、携带一定数量的救援物资,并能够通过狭窄空间、可承载多人的新型担架车。结论 融合TRIZ理论和FBS模型的产品创新设计模式,为产品创新设计过程中的问题挖掘与问题解决,提供了一套系统且有效的设计思路与工具。     

基于科学文献计量的概念设计知识图谱研究

目的 探究概念设计研究的知识结构关系及谱系特征。方法 在我国科学基金资助的文献基础上,借助Citespace软件可视化,构建概念设计研究的知识图谱。结论 首先,通过作者共被引分析法,剖析概念设计领域的代表性学者及概念设计过程模型、产品信息建模、概念设计推理技术、计算机辅助概念设计等研究主题;其次,运用共词分析和聚类分析法,阐释研究领域涵盖的设计结构矩阵、设计认知、产品配置、产品进化等知识聚类;最后,利用引文分析法,探测概念设计在不同发展阶段的图谱特征,从而为基于科学文献的研究提供新视角和新思路。     

Module-based similarity measurement for commercial aircraft tooling design

Similarity measurement (SM) between pairs of features plays an essential role in the tooling retrieval. However, the number of tooling is usually large and difficult to retrieve. What’s more, the most similar tooling model is not always optimal in the case-based reasoning (CBR). To refine this situation, we propose a novel module-based similarity measurement method. Through dividing each tooling model into different modules, a new similarity is obtained by integrating all the most similar modules (MSMs) from existing tooling models. As a result, the new similarity is superior or at least equal to the result which is derived from previous methods. With the proposed method in this paper, feature similarities of modules between a new tooling ontology and each similar tooling ontology are calculated by fuzzy similarity measurement, and the MSMs are restructured to form a new tooling model after conflict resolution. A case study on forming mould is provided to illustrate the applications and prove the higher similarity by comparing with CBR. The proposed method has been adopted in an aircraft manufacturing company.     

Modelling functional design information for injection mould design

Injection mould design is a complex process incorporating various aspects of design information and a variety of design activities. Specific requirements such as undercut mould design add difficulties to the problem because they often require innovation, which involves the conceptual stage of design problem solving. Modelling injection mould design from a functional perspective enables a higher level of design abstraction, thus facilitating a wider range of conceptual variants selection. In this paper, the authors discuss the essential aspects of functional design information in injection mould design and how they can be modelled. Functional design knowledge supporting the modelling process is also discussed and formalized, and a number of knowledge libraries are implemented. A side core mechanism design is used as an example to illustrate the proposed method and its usefulness.