虚拟拆卸中多方式交互技术的应用

通过分析虚拟环境下不同人-机交互方式的特点，结合对产品装配体进行人工拆卸的操作活动，提出面向虚拟拆卸的人-机-零件间的多方式交互操作方法，在虚拟环境下研究和利用手抓取操作、手势操作、语音命令和3D虚拟菜单等多种交互方式对产品零部件进行自然、直观的人工拆卸，人机结合进行产品的装配／拆卸序列规划。     

虚拟环境中基于约束动态解除的产品拆卸技术研究

虚拟拆卸是验证产品可拆卸性与可维护性、确定产品装配序列的有效手段．提出虚拟拆卸过程中配合约束的自动解除方法．随着拆卸过程的递进，根据设计者的交互意图，适时取消零件所受的配合约束．实现了虚拟拆卸过程中零件的约束运动，将运动传感器检测到的设计者手的实际运动映射到虚拟环境中零件的可自由运动空间，以有效地支持虚拟环境中交互拆卸的完成．相关方法在虚拟设计与装配原型系统的研究与开发中得到实现．     

虚拟拆卸环境中工具的操作技术

在虚拟拆卸环境中借助工具拆除紧固零件，能够使虚拟环境下的拆卸活动更加真实，有利于获得符合工程实际的拆卸序列．提出工具定位约束的概念，对虚拟拆卸环境中工具的操作技术进行了深入研究．首先分析工具的拆卸操作过程；然后对常用工具的工具定位约束进行研究，并论述了虚拟环境中工具精确定位的实现方式；最后以Bell-roller产品装配体模型为例，在沉浸式虚拟环境中基于工具定位约束、操作螺钉起子和扳手完成紧固零件的拆除。     

基于矩阵运算的虚拟装配体拆卸过程建模方法

现有装配体建模方法在描述虚拟维修训练中装配体拆卸过程时,存在的信息冗余大、建模过程复杂等缺点,在研究现有装配体建模方法和分析装配过程与拆卸过程差异的基础上,提出了一种面向虚拟维修拆卸过程的建模方法。该方法以矩阵描述装配体模型,用矩阵运算描述零部件拆卸过程,简化了建模过程,减少了模型数据量,为虚拟维修训练系统的快速构建提供了一种思路和方法。     

虚拟装配环境支持下的产品可装配性评估

为了解决传统的产品可装配性评估研究需要结合实物模型或样机进行反复试验造成的评估周期长且成本高的问题,提出虚拟装配环境(VA)下的产品可装配性评估方法.从CAD模型及产品虚拟装配操作过程中分别得到产品装配中各零件的基本属性信息及主观属型信息,建立零件属性信息模型,通过Boothroyd-Dewhurst方法中的装配操作时间表计算得到产品装配效率,对产品可装配性进行评估.以减速箱产品装配为研究实例在虚拟环境下对产品可装配性进行了评估,验证了该方法的有效性和实用性.     

基于装配约束动态管理的虚拟拆卸

装配约束是虚拟拆卸环境下必须考虑的装配体的重要信息，提出虚拟拆卸过程中装配约束的动态管理机制，并实现了基于装配约束导航的虚拟拆卸。装配约束的动态管理包括虚拟环境下装配约束的获取、表达以及拆卸过程中装配约束的动态维护，即装配约束的动态解除和产生，文中用装配约束图表达零件间的装配约束，提出装配约束的间接解除方法，并实现了基于装配约束推理的零件可拆卸方向的推导。最后，通过一个简单装配体的拆卸实例，对文中方法进行了验证。     

基于协同虚拟环境的装配设计系统

针对分布式环境中复杂产品协同开发的装配设计需求,研究基于协同虚拟环境的装配设计系统的体系结构和关键技术,提出分布式条件下支持多用户实时交互操作的协同虚拟装配方法,包括复杂场景高分辨率实时渲染和多通道沉浸输出方案。以此为基础开发分布式协同虚拟装配环境,并通过面向汽车整车的多用户协同虚拟装配实例验证了系统的有效性。结果证明,用户可在该系统中完成复杂产品的协同虚拟装配设计工作。     

面向虚拟装配的产品层次信息表达研究

提出了将虚拟装配中的产品属性与行为信息分为产品层、特征层、几何拓扑层以及显示层。通过产品层次信息模型中的数据映射与约束映射,实现产品信息的层次间关联。面向虚拟装配的产品层次信息模型在满足虚拟现实实时性要求的同时,不仅保持了CAD静态设计信息的完整性,还表达了零件在虚拟环境中的动态行为信息。     

交互式拆卸引导装配路径规划方法研究

在分析研究虚拟装配中的装配路径生成办法的基础上,根据实际需要提出了以交互式拆卸引导的装配路径规划方法的装配路径规划优化算法.算法主要通过人机交互的方式,记录零部件在拆卸过程中不同状态下每一步关键点的位置姿态信息.根据装配过程是拆卸过程反演的原则,通过“拆卸引导”形成零部件的装配路径,经过多次人机交互调试最终实现装配的最优路径.该算法的目的是生成无碰撞、无干涉的优化装配路径,从而实现虚拟环境中零部件更快捷、有效地装配.     

虚拟环境中装配设计语义的表达、传递与转化研究

研究了虚拟环境产品装配建模过程中装配语义的表达、装配语义与装配约束的转化技术,提出了采用语义－约束图对装配设计语义与约束进行维护。通过语义－约束图可以从语义层次和约束层次对产品装配模型进行编辑和维护。提出了采用模糊参量表达和处理产品装配设计中的模糊语义。基于模糊参量的语义表达不仅为设计信息输入提供了更大的自由度,而且扩展了计算机对模糊信息的处理能力,有利于产品设计意图的维护。通过产品装配信息从抽象到具体、从模糊到精确的转化,实现了虚拟装配设计系统对抽象、模糊设计信息的表达、传递与处理。     

并行工程中的装配仿真系统及其关键技术研究

传统的图表分析型ＤＦＡ虽然对改进产品的可装配性有显著作用,但其可视化程度较差。为弥补这一不足,提出了一种装配仿真系统,可在产品设计阶段生动直观地进行预装配,验证了改进产品的装置工艺。着重介绍了系统的２个关键技术：装／拆运动的１１元组表示及变换可实现装配元件任意运动的模拟,闱配路径有效性检查的递进算法能较大程度地提高运算效率。该系统已在商用ＣＡＤ软件Ｐｒｏ／Ｅｎｇｉｎｅｅｒ 的基础上用 Ｃ和Ｐｒｏ／Ｄ     

Quantitative measurement of component accessibility and product assemblability for design for assembly application

One of the important issues about product assemblability (PA) is to design a product configuration that will facilitate assembly operations. The product configuration in this paper means the arrangement of components within a product. When a product is assembled, every component has to be handled by an assembly agent from the feeding position to the composing position. During this action, the product configuration plays a critical role in the planning and execution of the handling task of each component. The influence of the product configuration on the accessible range of a component can be investigated by considering the accessibility of the component. With an assembly oriented product configuration a product can achieve maximal assemblability in terms of the accessibility of each component.A quantitative rating, referred to as component accessibility (CA), has been developed to measure the accessibility of a component of a product during the conceptual and preliminary design stages. The CA is defined as the reciprocal of the information required for an ideal assembly agent to manipulate the component to have collision-free straight-line destination approaching in the presence of other assembled components. This CA has not previously been quantified and thus designers have only been able to rely on their own experience in arranging the components of a product. With the help of CA, a designer can select an optimal arrangement of components for assembly operations, and the best method for joining mating components can be chosen accordingly. As a result of the provision of CA, traditional DFA evaluation methodologies can be reinforced and many DFA-related applications can be further explored.Another quantitative measure, referred to as PA, has been developed accordingly to quantify the assemblability of a product on the basis of accessibility of each component. The relationship between the information content of assembling a product and the information content associated with each component has been derived. It has been found that the relationship between PA and CA of each component is similar to the relationship between the resistance of an equivalent resistor and the resistance of parallel resistors in electricity.     

A framework for automatic DFA system development

Deisgn for assembly (DFA) evaluation has proved to be a systematic approach is determining how well a product is designed from an assembly point of view. Proposed here is a framework for automating DFA evaluation procedure, a key step in achieving a concurrent design environment. Five modules required for this development are: assembly sequence generation; assembly features extraction; assembly code and other necessary operations generation; data manipulation and computation; and re-design suggestion. Partial implementation (linking DFA evaluation procedure with a feature based CAD system) of the framework is also presented.     

Integration of the STEP-based assembly model and XML schema with the fuzzy analytic hierarchy process (FAHP) for muti-agent based assembly evaluation

Assemblability analysis and evaluation plays a key role in assembly design, operation analysis and planning. In this paper, we propose an integrated intelligent approach and framework for evaluation of assemblability and assembly sequence for electro-mechanical assemblies (EMAs). The approach integrates the STEP (STandard for the Exchange of Product model data, officially ISO 10303)-based assembly model and XML schema with the fuzzy analytic hierarchy process for assembly evaluation. The evaluation structure covers not only the geometric and physical characteristics of the assembly parts but also the assembly operation data necessary to assemble the parts. The realization of the integration system is implemented through a multi-agent framework. Through integration with the STEP-based product modeling agent system, CAD agent system and assembly planning agent system, the developed assembly evaluation agent system can effectively incorporate, exchange, and share concurrent engineering knowledge into the preliminary design process so as to provide users with suggestions for improving a design and also helping obtain better design ideas. The applications show that the proposed approach and system are feasible. Received: July 2004 / Accepted: January 2006     

The design and development of an automated DFA system

This paper presents the design and development of an automated system to assist with Design for Assembly (DFA) analysis. The system is designed to accept information on alternative assemblies using DFA metaphors. Statistics are calculated for these assemblies so as to evaluate their assemblability. The alternative assemblies and improvements in any assembly design are evaluated using these statistics.

A binary tree data structure is used in the DFA system to represent the design data. This structure is implemented by a linked method with three links in each tree node. This allows any arbitrary tree to be represented efficiently, and it also allows for unpredictable tree growth and easy tree manipulation. The user interface of the DFA system is managed by the “User Interface Management System”, that achieves direct and fast control of the screen by directly accessing the video memory.     

基于上下文的分布式协同过滤推荐技术

针对传统协同过滤推荐技术应用于大规模动态数据集时难以兼顾准确度和效率的问题,提出一种基于上下文的分布式协同过滤推荐技术,引入推荐上下文的概念,并在此基础上充分考虑用户的即时兴趣以提高推荐的准确度,采用评分矩阵的分布式存储和计算以提高推荐的效率。实验结果表明,该分布式协同过滤技术能同时保证推荐的准确度和效率,使其在大规模动态数据集上的应用更具优势。     

雷达高功率铰链装配工艺规划系统的开发

面向并行工程的需求,提出并设计了雷达高功率铰链三维装配工艺规划系统（HPH-CAAP）。系统利用微软的Microsoft Visual C++ 6.0作为开发语言,UG/OPEN API作为开发工具,用来验证和改进产品可装配性的仿真系统。阐述了HPH-CAAP的体系结构以及虚拟装配模型的定义、交互式装配工艺规划、装配仿真、干涉检验和模型的参数化重构关键技术模块。研究了HPH-CAAP各模块的实现全流程。最后给出了系统的应用实例。