基于事例推理的汽车覆盖件CAPP系统中的事例表达模型

为基于事例推理的汽车覆盖件CAPP系统提出了一种面向对象的事例表达模型。在面向对象建模方法中的传统对象模型的基础上添加关系对象集合R和约束对象集合C以构成扩展对象模型，在此基础上进一步扩展构成事例对象模型，作为事例表达模型的直接基础。事例表达模型分为四层，并包含三种关键类：事例类、索引类和答案类，不同类别的事例信息由上述三种类的对象表达。以某型轿车翼子板为例，建立了轿车翼子板事例中的零件类。简要介绍了该系统的事例检索与改写方法。     

工艺设计中支持事例推理的扩展对象模型

建立一个基于事例推理的CAPP系统的事例表达模型。对传统的对象模型进行了扩展，并在此基础上给出了支持事例推理的事例表达模型，该模型具有表达零件工艺知识和复杂事例的能力，以及支持在事例推理全过程中对信息的需求，为相似零件检索和零件事例的自动修改打下了基础。     

工艺设计中的事例表达与相似计算

介绍了基于事例推理的CAPP系统的面向对象零件事例表达模型和零件相似计算方法，该模型适用于各种类型的零件，具有表达零件工艺知识和复杂事例的能力，以及支持在事例推理全过程中对信息的需求。可以对具有复杂层次结构的事例进行表示并计算相似度。     

三维定量化工艺设计的关键技术研究

定量化和智能化工艺设计是CAPP发展的主要趋势。综合已有的有效工艺知识表达方法,基于Un igraph ics的知识融合模块UG/KF(Know ledge Fusion),提出以基于规则的面向对象表示方法(主要是intent!语言)和基于规则的过程表示(Java Expert System Shell,JESS)为基础,以开放式知识库连接协议(Open Know ledge Base Connection,OKBC)为核心模型的工艺知识表达方法和工艺知识推理机制等关键技术。最后给出原型系统的实现方法。     

基于事例的工艺设计中形状相似性计算方法

面向对象的零件事例的表示、形状相似性计算方法适用于各种类型的零件,可以表示具有复杂层次结构的事例并计算其相似度。该方法可以在具有不同属性结构的事例之间进行相似性计算,解决了相似零件的检索和异构事例的相似性比较的问题。     

流程工业生产计划与调度系统的对象建模方法

为解决流程工业生产计划与渊度系统丌发的各类问题,提出了一种对象分析建模方法。该方法通过建江线长度属性进行数据抽象和封装,设计出具有通用性的流程工业生产计划与调度系统的对象类,并应用于流程工业中冷轧薄板生产过程。实践表明,建立的对象类与现实生产能高度吻合,大大提高了系统开发效率。     

An effective integration approach toward assembly sequence planning and evaluation

An integration strategy for assembly sequence planning and sequence scheme evaluation is proposed. This strategy can be used to plan a reasonable assembly sequence, to optimize a sequence scheme, and to predict whether a collision will occur between the assembly tool and assembled components by considering factors like target components and assembly resources. A hybrid method is presented for assembly sequence modeling that combines human-computer interactive operations to manually build a hierarchical assembly sequence main model and a hybrid graph method to automatically generate sub-assembly sequence schemes of the main model. An optimization algorithm based on time-cost is introduced to handle a best candidate components selection. This relieves the problem of limited capability found when handling large size assembly models with traditional methods. The essential issues involved in system implementation are discussed as well; these include a representation method for the assembly consequence model, an optimization model of assembly sequence planning, and an object-oriented system architecture model employed with multi-agent technology for visually evaluating the assembling process. This system, KM computer-aided assembly process planning, KMCAAPP, has been developed on the basis of our previous work, KMCAD3; KMCAAPP uses the presented approach. KMCAAPP can be integrated with CAD model from KMCAD3D. A case study shows that the presented approach can use large CAD assembly models and delivers a feasible and effective way to integrate the assembly sequence planning process with scheme evaluation by visually evaluating the assembling process. This allows the identification of design errors in a timely manner and mitigates economic loss.     

Performance Modelling and Evaluation of Dynamic Tool Allocation in Flexible Manufacturing Systems using Coloured Petri Nets: An Object-Oriented Approach

Manufacturing systems are faced with ever-increasing customisation and unstable demand. The traditional hierarchical control structures for shop floor (pre-release planning, scheduling, dispatching and activity control) are often inflexible in responding to unexpected scenario changes and are thus not robust to system disturbances. In this paper, an object-oriented approach to modelling of FMS dynamic tool allocation and control under a non-hierarchical shop floor control scheme using coloured Petri nets is presented. A client–server paradigm is used in the proposed modelling method. The complete FMS model is partitioned into individual classes (machines, magazines, tool transport system, SGVs, tool storage, etc.) thereby significantly reducing the complexity of the model to a tractable size. The system performance under different tool request selection rules is also evaluated using coloured Petri net simulation. The proposed method can provide the designer of a tool management system with a high-level and structured representation of the tool-sharing control. It also provides an effective method for prototyping and evaluating performance of object-oriented shop floor control software.     

面向对象的模块化柔性生产线并行设计研究

针对模块化柔性生产线方案设计系统的复杂性,研究了面向对象的并行设计系统。通过把设计过程分解为对系统若干对象的设计,提出了面向对象的模块化柔性生产线并行设计过程模型。在此基础上建立统一的全局数据模型,开发了箱体类零件柔性生产线并行设计原型系统,以支持加工对象的特征设计、工艺规划、系统配置结构设计、模块化机床、刀具等设计的并行运行,并进行了实例验证。     

冷挤压工艺设计系统模糊知识表示和推理机制的研究

研究了冷挤压工艺设计领域的知识表示以及冷挤压工艺设计系统的模糊推理机制。利用面向对象表示法、模糊产生式表示法以及模糊框架表示法等知识表示方法,实现了基于模糊的面向对象的异构知识混合表示,该方法利用面向对象的思想构建领域知识的基类,利用模糊产生式规则表示领域知识库中的模糊知识规则。在此基础上构建了冷挤压工艺设计领域知识库。提出了广义可信度的概念和一种基于广义可信度的模糊推理方法,该方法通过对知识库中的知识设置可信度和构建隶属函数,用隶属度来定量表示冷挤压工艺设计领域知识的不确定性,实现领域知识的不确定性匹配,用广义可信度来表示不确定性匹配的程度,并利用不确定性传递算法计算最终结论的可信度值。通过典型实例进行了验证。     

基于偏差流分析法（SOVA）的二维多工位装配顺序规划的研究

针对目前产品装配顺序通常从装配时间和装配成本角度来考虑而难以保证装配质量的情形,应用偏差流分析法,以提高装配质量为目标,提出一种新的二维多工位装配顺序优化方法。以多工位装配过程为研究对象,分析影响装配质量的偏差源,建立偏差及其传递的数学模型,应用装配稳健度概念来评价装配工艺流程方案的优劣。以汽车侧围的4个零件装配为例,运用装配稳健度分析、比较了三种不同的装配顺序,得到了较优的装配方案。实例分析和仿真表明,应用装配稳健度可以分析选择装配顺序方案,为优化设计多工位装配工艺流程提供了新的途径。     

基于分层实例推理的混合型行业工艺设计系统研究

混合流程型生产行业的生产周期长、工艺过程复杂多变,工艺设计知识的提取和表达比较困难,若采用传统的单一大型实例推理系统表示其工艺设计方案,将造成实例库的庞大和冗余,求解效率低下。针对该问题,提出了基于分层实例推理的混合型行业的工艺设计策略。通过设计问题的逐步分解以及不同层次的多实例重用,既充分利用了实例推理方法的优点,又降低了搜索空间,提高了实例检索效率;研究了不同层次下工艺实例的知识表达、实例库的组织结构,以及实例的分层检索匹配算法,并以某钢铁产品订单的工艺设计问题为例加以说明;最后,给出了基于分层实例推理的混合型生产行业的智能工艺设计系统的总体框架,并总结了该方案的优点。     

CAPP系统面向对象工艺信息建模体系研究

以对象类树、对象关系图、对象类(属性、方法)描述表为基础,分析CAPP面向对象工艺信息模型的建立过程,提出进行企业工艺分析与信息建模的规范化方法,形成企业面向对象工艺信息建模体系.     

KBE-based stamping process paths generated for automobile panels

As automobile body panels are one kind of sheet metal part with groups of free form surfaces, the process planning is more complicated than common sheet metal stamping to implode effectively and practically. Based on KBE, new frameworks have been presented as intelligent master model at the system level and as procedure model at the activity level. In accordance with these frameworks, an intelligent CAPP system has been specifically developed. Based on feature technology, features have been extracted and represented by the object-oriented method. Stamping features and their parameters have been defined and extracted based on feature technology and stamping process rules. The whole product knowledge has been represented by frames which directly map to objects (or features) in the object-oriented sense. Relevant appropriate operations features have been assigned to stamping features of a product based on feature-operation criteria, parameters of the stamping feature and their correlativity. This assignment is a decision-making activity using a set of rules with a decision-making tree and model-based reasoning methods. With knowledge between operations, such as operations order constraint (do-after) and operations combination constraint, process paths have been improved based on relevant intelligent reasoning methods. Based on the relationships (preferred-to) between processes and machines/dies, the structure of die and machine for each process can be identified, since the process route has been determined. In this stamping process planning, the procedure and information have been controlled by a process control structure that is associative and integrated.     

汽车覆盖件成形性集成分析技术研究

提出在汽车覆盖件早期设计阶段将基于成形工艺知识的定性分析与基于一步模拟法的定量分析相结合进行覆盖件特征模型的成形性分析。在基于知识的覆盖件成形性定性分析中提出一种自动识别与交互定义相结合的覆盖件形状特征识别方法 ,提出汽车覆盖件集成信息模型和CBR/RBR集成的推理方法。在此基础上提出基于知识的汽车覆盖件冲压工艺设计系统的总体结构和系统的冲压工艺设计流程     

Representation and similarity assessment in case-based process planning and die design for manufacturing automotive panels

This work improves process planning and die design in automotive panel manufacturing using a novel case-based reasoning (CBR) methodology. An innovative indexing representation and retrieval approach are also addressed. The flat-bend graph, which is utilized to represent a panel model with a B-rep structure, retains geometric and topological data in the Standard for the Exchange of Product model data format. Flat-type faces collected into several groups are represented by graph nodes, and bend-type faces are represented by graph arcs. Based on the topological information between bend-type faces and flat-type faces, a graph is constructed. Additionally, the holes detected are considered another graph node types. Geometric information and stamping parameters are utilized as graph attributes. To retrieve an appropriate case for a potentially huge search space, independent maximal cliques detection is applied. All independent maximal cliques that represent the maximum number of features shared by models are identified. Based on the retrieval result, previous process plans and die sets can be acquired for use by new cases. Experimental results obtained using the CBR system integrated with the product data management system demonstrate the practicality of reusing previous designs to accelerate stamping process planning and die design.     

基于工业机器人的汽车覆盖件柔性冲孔系统

针对汽车覆盖件个性化制孔的需求,提出并实现了一种基于工业六轴机器人和专用冲孔钳的柔性冲孔系统。为了得到准确无干涉的冲孔轨迹,根据冲孔钳的形状特征,提出了一种在二维平面内交互冲孔的路径生成方法。该系统具有较高的灵活性,能够方便调整冲孔的位置和种类。     

PRODUCT GENE REPRESENTATION AND ACQUISITION METHOD BASED ON POPULATION OF PRODUCT CASES

The representation and acquisition of a product gene is a crucial problem in product evolutionary design. A new methodology of product gene representation and acquisition from a population of product cases is proposed, and the methodology for product evolutionary design based on a population of product cases is realized. By properly classifying product cases according to its product species, the populations of product cases are divided and a model is established. Knowledge of the scheme design is extracted and formulated as the function base, principle base, and structure base, which are then combined to form a product gene. Subsequently, the product gene tree is created and represented by object-oriented method. Then combining this method with the evolutionary reasoning technology, an intelligent and automatic evolutionary scheme design of product based on the population of product cases is realized. This design method will be helpful in the processing of knowledge formulation, accumulation, and reuse, and in addressing the difficulty of acquiring design knowledge in traditional design. In addition, the disadvantages of manual case adaptation and update in case-based reasoning can be eliminated. Moreover, by optimizing the design scheme in multiple levels and aspects of product function, principle, and structure etc., the level of creativity in the scheme design can be improved.