基于语义的虚拟装配仿真模型研究及应用

针对虚拟装配中装配模型的信息完备性与虚拟仿真系统的交互效率之间的矛盾,提出一种轻量化的基于树-图分离结构的虚拟装配模型,该模型包括装配树模型和语义关系图模型。装配树模型以二叉树的形式表达虚拟产品的层次结构以及零部件间的装配顺序,语义关系图以二分图的形式表达零件之间的装配关系。将该模型应用于水轮机组虚拟装配仿真系统中,不仅满足了虚拟仿真过程对装配模型信息表达的要求,而且减少了系统存储负担,提高了交互效率。     

基于特征的飞机框肋件参数化设计与装配

针对飞机框肋件设计中存在的重复工作量大、设计模型柔性差、缺乏对后续CAPP所需信息的衔接等问题,提出采用基于特征的参数化建模方法,利用visual Basic6.0对三维建模软件SolidWorks进行二次开发,建立飞机框肋件的交互式设计与装配系统。通过某歼击机典型框肋件实例说明具体设计方法,最终实现模型的尺寸驱动以及零件间的智能装配,达到缩短设计周期,提高零件生产效率,提升设计柔性目的。     

装配仿真关键技术的研究和实现

装配顺序规划和装配路径规划 ,是进行模型预装配的两项关键技术。本文提出了实施装配顺序规划的优先关系约束半角矩阵法 ,并利用Pro/TOOLKIT提供的动画功能 ,基于Pro/E建立了一种装配仿真系统。该系统能够形象、直观地进行产品预装配 ,验证和改进产品的装配工艺。     

复杂约束条件下的分层装配模型

为在装配建模过程中保证信息的完整性,提出基于装配对象属性的分层约束装配模型。以需求块的概念为基础,对装配对象采用先分块再分层的方法进行分组,分析各块、各层之间复杂的约束关系,构建分层约束装配图,完成装配顺序算法的设计。实验结果表明,该模型能有效表达装配形成过程的顺序,实现装配关系的分解和时序化,对象之间的交互过程简单真实且便于操作。     

虚拟装配仿真系统相关技术的研究

研究了一种等离子体增强化学气相沉积(PECVD)装备虚拟装配仿真系统,介绍了系统的装配模型以及装配顺序和路径的规划.建立了虚拟装配仿真场景结构图,并采用细节层次技术对仿真场景进行优化.为了能够实时、方便地修改装配序列和装配路径,准确地描述零部件在装配或拆卸过程中的位置姿态信息,提出了一种虚拟装配的描述语言代码(V代码)和虚拟装配函数(V函数).最后采用基于包围盒逐层分解的干涉检验方法,实现装配过程的干涉检验.该仿真系统有助于缩短产品开发周期、提高设计质量、降低装配成本.     

协同装配信息集成建模及装配顺序规划研究

研究了装配的参照元素、装配方式、装配关系，并总结出三大装配类型．针对协同装配活动的需求，提出包含设计技术决策和产品社会属性信息在内的广义装配建模思想；在引人装配结和装配链概念的基础上，构建了适合协同装配的装配信息模型．通过搜索模型，容易获得产品装配关系图，再经过界定装配导元属性，依据自定义修剪规则，形成具有装配层次和顺序属性的同心圆图，从而能够有效地获得可行的产品装配顺序．     

基于激光跟踪的数字化装配定位系统实时仿真

定位是飞机装配中的一个重要环节,运用基于激光跟踪的数字化装配定位系统进行定位能够提高定位精度,减少定位型架,对降低成本、提高装配质量和效率有重要意义;使用激光跟踪测量仪函数库开发数据采集模块控制测量仪采集数据,在实时测量数据与产品工程数据集的基础上计算装配模型的位姿,基于Open CASCADE图形软件平台开发实时仿真可视化模块,该模块实现了对系统工作过程的实时仿真与显示。     

工装夹具增强装配技术研究应用

为了减少装配操作步骤和提高装配准确度和效率,在现有CAD软件装配功能的基础上提出一种基于装配特征识别的增强装配算法,利用特征识别以及定义的特征之间的装配关系实现增强装配功能,进而能实现装配的自动化。基于该算法实现的增强装配系统具有良好的扩充性,在实际装配应用中提高CAD软件装配功能的效率。     

面向虚拟装配的装配建模及其重构

装配建模是进行虚拟装配的前提和基础,决定着虚拟装配实施的质量和效率。针对虚拟装配中装配建模问题,介绍一种多视图层次化的装配模型,给出了模型的信息组成和信息来源,并很好地解决了在此模型基础上的重构问题。     

面向装配序列规划的装配本体设计*

为提高装配序列规划的自动化程度,实现装配相关活动间信息的共享、重用和顺畅传递,实现装配序列规划系统与其它异构系统之间的无缝集成和互操作,将本体技术引入到装配建模中.针对装配序列规划建模需求,构建面向装配序列规划且基于装配对象的装配本体(OWL-ASP).OWL-ASP由Properties本体、AssemblyInfo本体和AssemblySeq本体组成,分别描述装配对象的装配属性、装配信息、装配顺序等.在OWL-ASP的基础上,利用语义Web规则语言刻画装配规则,形成统一的装配知识表示层次体系,实现对装配知识的严格刻画和自动推理.通过球阀装配的实例说明装配本体和装配规则的有效性.     

Interference checking approach with tolerance based on assembly dimension chain

CAD model with nominal dimension is implemented in interference checking of assembly simulation of aircraft complex parts at present,which causes inadequate availability.In order to address this challenging issue,interference checking method with tolerance based on assembly dimension chain was proposed.Worst case and maximum error probability of tolerance of composing loop were used,and CAD models were respectively re-constructed and inserted into simulation system.Before dynamic interference checking,engineering semantic interference condition was set to assembly requirements.Finally,the interface checking result was a basis for reasonability of assembly process and tolerance.A prototype system was developed based on the above research.     

Automatic generation of assembly dimension chain based on tolerance cell

In the process of generating assembly dimension chain automatically,there are many problems such as complex assembly relationship,variety of constraints of components and complex dimension and tolerance relations of components.These problems lead to many difficulties in search process and need lots of man-machine interaction.Because of these difficulties,this paper presents a method of automatic generation of assembly dimension chain based on tolerance cell.This method is realized through obtaining assembly tolerance cell and part tolerance cell first.These two types of tolerance cell are extracted and expressed in the form of linked list structure in computer further.Then assembly dimension chain is searched automatically based on obtained tolerance cell,and the correct assembly dimension chain is extracted finally.A system of generating assembly dimension chain automatically has been developed based on DELMIA and successfully deployed in aircraft assembly simulation in the engineering practice.     

A hierarchical assembly knowledge representation framework and microdevice assembly ontology

Microdevice assembly knowledge is dispersed in different product development phases, such as assembly design, assembly simulation and assembly process, and a lot of essential knowledge is implicit and heterogeneous. It is difficult for researchers and computer-aided systems to share and reuse different assembly knowledge quickly and accurately, leading to inefficient and inaccurate assembly process planning. To integrate and structurally represent the assembly design knowledge, assembly simulation knowledge and assembly process knowledge of microdevice, this paper proposes a hierarchical assembly knowledge representation framework and develops a microdevice assembly ontology. There are four layers in the framework, including the organizational structure, the structural relationship, the assembly accuracy, and the process characteristics. The assembly design knowledge that is integrated involves the basic properties of the assembly object as well as the spatial, mating, and assembly relationship, etc. Assembly simulation knowledge refers to the permissible range of assembly force and contact force. Knowledge of assembly processes comprises assembly sequence and operating method of the part. The microdevice assembly ontology is developed based on METHONTOLOGY, and implemented with Protégé. The corresponding SWRL rules have been established to inference the implicit knowledge in assembly design. An ignition target assembly knowledge model based on the microdevice assembly ontology is constructed. In the assembly task of the ignition target, engineers can quickly and accurately access the required assembly knowledge from the ignition target assembly knowledge model, thus verifying the integrity and validity of the microdevice assembly ontology.     

Using requirement-functional-logical-physical models to support early assembly process planning for complex aircraft systems integration

The assembly line process planning connects product design and manufacturing through translating design information to assembly integration sequence. The assembly integration sequence defines the aircraft system components installation and test precedence of an assembly process. This activity is part of the complex systems integration and verification process from a systems engineering view. In this paper, the complexity of modern aircraft is defined by classifying aircraft system interactions in terms of energy flow, information data, control signals and physical connections. At the early conceptual design phase of assembly line planning, the priority task is to understand these product complexities, and generate the installation and test sequence that satisfies the designed system function and meet design requirements. This research proposes a novel method for initial assembly process planning that accounts for both physical and functional integrations. The method defines aircraft system interactions by using systems engineering concepts based on traceable RFLP (Requirement, Functional, Logical and Physical) models and generate the assembly integration sequence through a structured approach. The proposed method is implemented in an industrial software environment, and tested in a case study. The result shows the feasibility and potential benefits of the proposed method.     

面向航空发动机装配线的知识化制造系统重调度和自重构

为了解决航空发动机装配过程中存在的不确定返工问题,建立了面向航空发动机装配线的知识化制造系统(knowledgeable manufacturing system,KMS)重调度和班组自重构优化模型,提出装配线重调度及自重构集成优化算法.在算法调度层,证明了以加权完工成本为优化目标的工序排序性质,并对工序进行初始排序.定义了3种邻域结构,用变邻域搜索(variable neighborhood search,VNS)对工序在并行装配组上的指派问题和调度问题进行优化.在重构层,在不违背装配组装配技能约束的前提下利用装配线负载平衡原则对装配班组进行配置,并采用禁忌搜索(tabu search,TS)对班组配置进行优化.仿真实验结果表明了模型与算法的有效性.     

A physically based approach with human–machine cooperation concept to generate assembly sequences

Assembly plan is considered one of the important stages to minimize the cost of manufacturer and to ensure the safety of assembly operation, the main problem of assembly sequence planning approach is how to reduce the deviation from the real manufacture conditions. In this paper, we have extensively investigated a novel approach to automatically generate the assembly sequences for industrial field, which is especially applied to other large-scale structures. A physically based assembly representation model includes not only the pre-determined basic assembly information, such as precedence relations between parts or subassemblies, geometric constraints, different assembly types, and also the dynamic real-time physical properties, such as the center position of gravity, the force strength of the part, et al. This representation model considered the influences on optimum sequences by assembly operations will be modified by the feedback from interactive virtual environment. Then, we select the safety, efficiency and complexity as the optimization objectives. A hybrid search approach may be used to find the optimum assembly sequence, which will be integrated into an interactive assembly virtual environment (IAVE). It means that the results of assembly interaction can be provided to update the assembly planning model as a feedback, by which the approach will take advantages of the immune memory for local optimum search. The user can adjust the assembly sequences with obvious good objective by interaction with IAVE to improve the performance of the search algorithm. We describe human–machine cooperation (HMC) method for ASP in this work, by which human also can play a pivotal role instead of pure soft-computing. A series of numerical experiments are done to validate the performance of the physically based approach (PBA) to generate assembly sequence, which shows the efficiency and the operability to guide the assembly work.     

基于图论的飞机典型装配工艺数据挖掘方法

为实现飞机装配指令编制的快速化、智能化,提出基于图论的飞机典型装配工艺数据挖掘方法。该方法将停用词表和分隔数组两个约束引入语义分词法完成装配工艺指令的分词处理,并以装配工艺特征向量结构化地表达分词后的装配工艺指令。将装配工艺特征向量映射为单向有序链,以此构建装配工艺图。通过定义装配工艺图的节点支持度和边支持度,给出了典型装配工艺挖掘方法。以某型飞机的平尾装配工艺为例,在多个支持度下验证了方法的有效性。     

异构装配信息的统一表达方法研究

异构平台三维模型的装配序列规划和运动仿真需将模型统一到同一平台。针对这一需求,提出了一种装配模型的统一表达方法,将不同CAD模型统一到相同结构的三维模型中,利用零部件层次模型和关系模型混合表达记录零部件的层次结构、装配关系、运动关系以及相关属性等,构建了统一的装配信息表达方法。同时,为了提高模型信息交换和显示的效率,采用轻量化方法来构建和表达零部件模型。     

Integrated knowledge-based Petri net intelligent flexible assembly planning

Automatic assembly planning is recognized as an important tool for reducing manufacturing costs in concurrent product and process development. A novel knowledge-based Petri net (KBPN) is defined, based on the incorporation of expert systems into the usual Petri nets, and used for a unified assembly knowledge representation scheme. A KBPN-approach integrated with a sequence generation algorithm is proposed for the modeling, planning, simulation, analysis and evaluation of the flexible assembly system (FAS). The developed KBPN-based assembly planning system (KAPS) can automatically adjust the deviations between the theoretical planning parameters and the process parameters of real assembly operations to guarantee the best strategies and plans (sequences) for flexible assembly. The research findings are exemplified with a simple assembly to show the effectiveness of the method.     

Data driven production modeling and simulation of complex automobile general assembly plant

Flexible manufacturing and customization has long been a topic in modern manufacturing society. However, challenges still remain on the responsiveness of production system to the fluctuation of market demand. In this paper, we developed a data driven simulation methodology to automatically model a production system and rapidly modify the model corresponding to dynamic requirements and real time information. This methodology provides a “rapid prototyping” capability for production system modeling and enables a quick analyzing and remodeling capability to respond to the fluctuation of demands. The approach is developed and applied to an automotive general assembly plant with an online material handling system. A complete information model based on IDEF1X is constructed for this domain specific modeling and simulation. The main simulation modules for assembly line and material handling system of the plant floor are analyzed and a simulator is implemented in ARENA by SIMAN/VBA program. The case study of an automotive assembly plant shows that the data driven approach enables the modeling and simulation of the complex assembly plant in a “real-time” fashion and therefore effectively improve the responsiveness and flexibility of the production line.