面向过程的虚拟环境中产品装配建模研究

提出了面向过程的虚拟装配建模方法,在虚拟环境中将装配建模与装配仿真相结合,建立装配关系模型的同时,实现了对装配过程的创建与仿真,从而,在虚拟环境中将面向结果的装配建模发展为面向过程的装配建模.设计者采用直接三维交互进行装配建模操作的同时,系统通过装配关系识别自动捕捉设计者的装配设计意图,通过装配约束运动确定零件的装配路径,通过虚拟装配建模过程信息重用为装配规划提供有效的支持.开发了面向过程的虚拟装配建模原型系统.实践表明,面向过程的虚拟环境中产品装配建模方法有效地提高了产品装配设计的质量与效率.     

雷达结构交互式虚拟装配系统研究

文中针对雷达结构传统装配设计中存在的效率低、一次装配成功率不高等问题,提出了一种基于虚拟现实技术的交互式虚拟装配系统构建方案。该系统集成交互式外设在不需要任何雷达实物的情况下,完全在虚拟环境下通过用户的自然操作,实现雷达结构装配的全过程。文中介绍了系统中虚拟装配功能模型的构建方法,重点分析了虚拟手在系统中的动作实现过程,阐述了雷达结构装配仿真规划的方法,最后还介绍了原型系统的开发过程和系统功能的实现。     

Feature-Based Component Models for Virtual Prototyping of Hydraulic Systems

This paper proposes a feature-based approach for the virtual prototyping of hydraulic systems. It presents a framework which allows the designer to develop a virtual hydraulic system prototype in a more intuitive manner, i.e. through assembly of virtual components with engineering data. The approach is based on identifying the data required for the development of the virtual prototypes, and separating the information into behaviour, structural, and product attributes. Suitable representations of these attributes are presented, and the framework for the feature-based virtual prototyping approach is established, based on the hierarchical structure of components in a hydraulic system. The proposed framework not only provides a precise model of the hydraulic prototype but also offers the possibility of designing variation classes of prototypes whose members are derived by changing certain virtual components with different features.     

柴油机虚拟装配的研究

虚拟装配是近几年来出现的先进制造技术,它是在虚拟环境中,利用虚拟现实技术将设计的柴油机整机或部件三维模型进行预装配,在满足产品性能与功能的条件下,通过分析、评价、规划、仿真等改进产品的设计和装配结构,实现产品可装配性和经济性。本文主要介绍虚拟装配研究的现状、柴油机虚拟装配系统的总体结构及柴油机虚拟装配的关键技术。柴油机虚拟装配的关键技术包括虚拟装配建模技术、虚拟装配仿真技术、虚拟装配控制技术和虚拟装配支撑技术等。     

Mixed Reality-based Interactive Technology for Aircraft Cabin Assembly

Due to the narrowness of space and the complexity of structure, the assembly of aircraft cabin has become one of the major bottlenecks in the whole manufacturing process. To solve the problem, at the beginning of aircraft design, the different stages of the lifecycle of aircraft must be thought about, which include the trial manufacture, assembly, maintenance, recycling and destruction of the product. Recently, thanks to the development of the virtual reality and augmented reality, some low-cost and fast solutions are found for the product assembly. This paper presents a mixed reality-based interactive technology for the aircraft cabin assembly, which can enhance the efficiency of the assemblage in a virtual environment in terms of vision, information and operation. In the mixed reality-based assembly environment, the physical scene can be obtained by a camera and then generated by a computer. The virtual parts, the features of visual assembly, the navigation information, the physical parts and the physical assembly environment will be mixed and presented in the same assembly scene. The mixed or the augmented information will provide some assembling information as a detailed assembly instruction in the mixed reality-based assembly environment. Constraint proxy and its match rules help to reconstruct and visualize the restriction relationship among different parts, and to avoid the complex calculation of constraint's match. Finally, a desktop prototype system of virtual assembly has been built to assist the assembly verification and training with the virtual hand.     

A pragmatic system to support interactive assembly planning and training in an immersive virtual environment (I-VAPTS)

Assembly planning for complex products is a difficult task requiring both intensive knowledge and experience. Computer aided assembly planning (CAAP) systems have been the subject of considerable research in recent years without achieving a wide application in manufacturing industry. In this paper an alternative approach to the generation of an optimal assembly planning scheme is presented based on the adoption of immersive virtual reality. A product is assembled from CAD models by providing a CAD interface to transfer assembly constraint information from the CAD system to a virtual environment. In the virtual environment an efficient dynamic recognition and management method based on surface geometry is employed, and a process-oriented assembly task model is established to support interactive assembly planning and evaluation. The system is implemented using an object oriented methodology, and has been successfully applied to train and guide the assembly workers in a pump assembly process.     

基于VRML的数控机床的虚拟操作研究

虚拟环境下加工设备虚拟操作和虚拟加工是虚拟制造的一个重要研究内容。本文通过对数控机床的虚拟操作的研究,阐述了在VRML的虚拟现实应用平台上建立数控机床的虚拟操作系统的方法,提出了利用VRMLJavaAppletJavaScriptHtml多方相互通信的办法对VRML人机交互功能进行增强与扩展,从而满足数控机床虚拟操作的功能要求。实验结果表明,这种增强办法不仅使VRML原有的人机交互能力得到进一步的增强,并且为VRML添加了接收与处理文本信息以及读写文件等交互能力。此外,文中还提出了一种利用SolidWork与PolyTrans相互结合而实现的在虚拟环境下的数控机床的快速建模方法,并取得令人满意的效果。本系统不但可应用于异地制造、数控机床加工仿真,还可应用于基于WEB的数控机床操作、编程与加工培训等方面。     

Multi-User NC Machining Simulation over the WWW

The realisation of a virtual manufacturing system requires an open network environment to perform 3D graphics simulation or virtual reality information processing among multiple users. This paper introduces a prototype system that employs Java, the virtual reality modelling language (VRML) and the external authoring interface (EAI) to perform NC machining simulation. A client/server paradigm is adopted to construct a multi-user enabled interactive environment. A novel method is presented to update dynamically the geometry of a workpiece being cut in a VRML-based scene. In addition, the prototype system is analysed in terms of functionality and performance.     

Interactive assembly tool planning based on assembly semantics in virtual environment

Assembly tool planning in virtual environment remains to be a challenge because of the complexity and variety in tools configuration and manipulation. In order to solve the problem, an interactive assembly tool planning based on assembly semantic model is proposed. After detailed analysis on assembly tool planning in virtual environment, an improved assembly semantic model is represented, and a new assembly tool model is developed based on assembly semantic model. With the help of assembly semantic processing method, such as recognition, solving, navigation and so on, a series methods including assembly tool selection, orientation, manipulation are proposed for interactive assembly tool planning in virtual environment. Finally, tightening tool planning for connecting rod caps of auto engine assembly line demonstrates the feasibility and validity of presented methods.     

虚拟装配工艺设计技术研究与应用

阐述虚拟装配工艺设计技术内涵及其体系结构,深入分析其所涉及的CAD系统与虚拟现实系统间的数据转换、碰撞检测技术、装配规划与仿真以及装配运动导航与准确定位等关键技术,并应用该技术,以商品化CAD系统Pro/E为建模工具,在VC与WTK平台及ORACLE数据库的支持下开发了一个虚拟装配工艺设计原型系统HIT-VAPD,实现了虚拟现实环境下的产品装配工艺规划与设计.实际应用表明,该系统可显著提高装配工艺设计效率,减少设计缺陷.     

Shape Representation and Interoperability for Virtual Prototyping in a Distributed Design Environment

Internet technology opens up another domain for building a future CAD/CAM environment. The environment will be global, network-centric, and spatially distributed. In this paper, we present an approach to network-centric virtual prototyping (NetVP) in a distributed design environment. The presented approach combines the current virtual assembly modelling and analysis technique with distributed computing and communication technology for supporting virtual prototyping activities over the network. This paper focuses on shape representation and interoperability of product models for distributed virtual prototyping. STEP standard and CORBA-based interfaces allow bi-directional communication between the CAD model and the virtual prototyping model, which makes it possible to solve the problems of interoperability, heterogeneity of platforms, and data sharing. STEP AP203 is used as a means of transferring and sharing product models. In addition, Attributed Abstracted B-rep (AAB) is introduced as 3D shape abstraction for trans-parent transmission of 3D models and for the maintenance of naming consistency between CAD models and virtual prototyping models over the network.     

A new type haptics-based virtual environment system for assembly training of complex products

Virtual reality (VR)-based assembly training has been an interesting topic for the last decades. Generally, there are two shortcomings for nowadays virtual assembly training systems. One is that the operators cannot move around the virtual environment in a natural way as people activity in the real world: they are constrained in a fixed position or can only move in a limited space. The other is that most of the virtual assembly training systems are based on geometry constraint modeling only, which lacks haptics feedback. A new type haptics-based virtual environment system for assembly training of complex products is described in this paper. A new low-cost motion simulator is designed and integrated with the virtual environment to realize free walking by human. An automatic data integration interface is developed to transfer geometry, topology, assembly, and physics information from a computer-aided design system to a VR application, and a hierarchical constraint-based data model is rebuilt to construct the virtual assembly environment. Physics-based modeling and haptics feedback are undertaken to simulate the realistic assembly operations. The application examples and evaluation experiments demonstrate that both motion simulator and haptics have great value for training of assembly processes.     

RESEARCH OF MOVEMENT NAVIGATION BASED ON ASSEMBLY CONSTRAINT RECOGNITION

0 INTRODUCTIONThe traditional assembly design stresses the final result of assembly modeling, but pays little attention to the process of assembly simulation. Nonetheless, the procedure of assembly is a cardinal element that determines the quality of assembly modeling. These drawbacks hinder the advancement of the speed and quality of assembly design. Moreover, in the traditional mode of product development, designers make prototypes to evaluate the function and appearances of products. P…     

Augmented reality aided interactive manual assembly design

Augmented reality (AR) is a novel technology which overlays computer-generated information seamlessly on the real-world environment. AR technologies have opened up a powerful set of tools for computer-aided assembly planning. This paper presents a manual assembly design system using AR technologies. An assembly data structure is devised for assembly information management. Algorithms for assembly constraint recognition and assembly location refinement have also been proposed. A hybrid approach based on these methods has been formulated and implemented to allow the users to simulate a manual assembly without the need for auxiliary computer-aided design information in assembly design. This would result in enhanced user experience and reduced preparation time. A methodology for 3D bare-hand interaction is integrated with this interactive manual assembly design system for the users to manipulate the virtual components in a natural and effective manner. A prototype system for interactive manual assembly design has been developed. An example has been provided to demonstrate the developed prototype system.     

基于Delphi和VRML的虚拟装配平台的实现

针对目前 CAD软件只生成静态三维装配体 VRML 文件的问题 ,分析了交互式虚拟装配 VRML 文件的事件流程和虚拟产品的顺序装配的机理 ,提取其中可赋值变量 ,利用可视化编程语言 Delphi开发一个实现复杂虚拟装配的平台 ,完成静态 V RML文件到动态交互式虚拟装配文件的自动转换     

面向虚拟装配的装配信息自动提取技术的研究与实现

针对商品化CAD系统与虚拟装配系统之间装配信息的转换问题,根据CAD系统中装配信息的表达形式,提出了一种获取装配信息的算法,实现了Pro/E中装配信息的自动提取,并依据Pro/E中装配信息的数据结构和虚拟装配系统的功能要求,设计了一种适用于虚拟装配系统的装配数据结构,较好解决了Pro/E与虚拟装配系统之间的装配信息集成问题,提高了虚拟装配的效率。     

基于虚拟现实和仿生算法的装配序列优化

针对自动装配规划和交互式规划都存在不足,将虚拟现实和仿生算法结合起来,提出一种生成优化装配序列的新方法.建立基于几何约束的虚拟装配环境,在该环境中根据经验和知识进行交互式拆卸,定义优先约束表来表达零件间的优先约束关系.应用蚁群算法规划出初始优化的装配顺序,再在虚拟环境下进行仿真、评价和优化,考虑装配位置可达性和工具操作等因素,识别新的优先约束和评价准则,重新规划出更优的装配顺序,不断反复和完善,直到得到满意的最佳装配顺序为止.通过实例验证该方法有效性.     

虚拟装配技术在自动引导车转向系统中的应用

阐述了虚拟装配技术基本原理、过程和方法,提出了基于SolidWorks三维建模软件,以自动引导车转向系统为设计对象,进行三维建模和虚拟装配设计.先通过虚拟装配关系识别捕捉设计者的意图,然后利用装配约束条件确定零件的装配路径,并完成其装配,最后对自动引导车转向系统进行相应的干涉检验,并进行动画制作,进一步检测虚拟装配的可靠性.实践表明,利用虚拟装配技术可有效地缩短产品研发周期,节约成本和提高产品装配质量.     

基于虚拟现实的装配工艺规划研究

对虚拟现实(Virtual reality, VR)环境下的产品装配规划进行了研究,分析了系统的功能结构,建立了系统的面向对象的UML(Unified modeling language,统一建模语言)模型,给出了虚拟环境下装配约束关系的识别方法,实现了零部件基于约束的三维空间运动,建立了原型系统,为虚拟环境下的装配工艺规划奠定了基础。     

基于装配工艺规程的产品虚拟装配技术

描述了VPD环境下的产品装配模型，建立了产品装配模型的数据结构，定义了产品装配模型系统的结构组成及模块功能；参照加工工艺规程，提出了虚拟产品装配工艺规程的概念；结合挤塑模和轻型客车的虚拟装配、活塞连杆机构及发动机的运动过程，实现了基于真实动画感的VPD环境下的产品虚拟装配及虚拟工作过程仿真。