Science Letters:Dynamic concision for three-dimensional reconstruction of human organ built with virtual reality modelling language (VRML)

This research studies the process of 3D reconstruction and dynamic concision based on 2D medical digital images using virtual reality modelling language (VRML) and JavaScript language, with a focus on how to realize the dynamic concision of 3D medical model with script node and sensor node in VRML. The 3D reconstruction and concision of body internal organs can be built with such high quality that they are better than those obtained from the traditional methods. With the function of dynamic concision, the VRML browser can offer better windows for man-computer interaction in real-time environment than ever before. 3D reconstruction and dynamic concision with VRML can be used to meet the requirement for the medical observation of 3D reconstruction and have a promising prospect in the fields of medical imaging.

A Virtual Assembly System for Aero-engines Based on VR

In this paper,a synthesized technique is explored through design of a virtual experiment system for main aero-engine based on VR,which attempts to integrate some VR techniques,such as 3D stereo simulation and modeling,3D scene management and human-computer virtual assembly based on data glove and collision detection.The geometry modeling and instantiation technique,virtual hand modeling and data glove interaction technique are discussed chiefly.Finally,taking aim at assembling and dismantling experiment system of a certain aero-engine,interface technology is expounded also.

Analysis and Design of Open Remote Monitor and Control System Based on Virtual Reality

Introduced a Web-based real-time network monitoring and control system design methods, the 3-D VR was applied in a remote monitor system based on browser/server structure, and a VRML and Java based 3-D remote monitor system was realized. Meanwhile, give possible solutions of the real-time data transmission and the stability of the system.

Virtual Reality Toolkit for the Assembly of Nanotube-based Nano-electro-mechanical Systems

Nano assembly and manipulation technologies are the basis for nano-electro-mechanical systems（NEMS）. Atomic force microscope（AFM） is widely used to manipulate nanotubes to assemble NEMS. Manipulating nanotubes with AFM is a challenging and difficult task. One of the major reasons is the deficiency of visual information during the manipulation process. To address these difficulties, this research aims to put forward novel virtual tools and assembly strategies to improve the efficiency, accuracy and ease of the assembly process of NEMS. This paper begins by the discussion of the principles and implementation of a virtual nano-assembly simulator, which serves as a benchmark to test the proposed NEMS assembly techniques and virtual tools. Then, a general framework of nanotube-based NEMS assembly is proposed. Several nano-assembly strategies and virtual tools, such as automated path planning for NEMS assembly, a four-step scheme of nanotube manipulation, virtual fixtures for assembly finalization and safe manipulation, are introduced. These virtual tools and methods are experimented for justification. An assembly task of moderate complexity was performed in our virtual nano-assembly simulator with and without the help of the proposed toolkit. Experimental results suggest that the proposed methods tend to greatly enhance the efficiency and accuracy of nanotube-based NEMS assembly. In general, the proposed virtual reality toolkit not only ensures the safety, but also enhances the accuracy and efficiency of the assembly of nanotube-based NEMS.

RESEARCH OF GUIDANCE TECHNOLOGY FOR ASSEMBLY MODELING IN VIRTUAL ENVIRONMENT

Technology of movement and knowledge guidance in virtual assembly is presented The designer can move the mechanical part precisely under the movement guidance The movement guidance is implemented based on constraint recognition and assembly degree of freedom analysis A multi hierarchy knowledge base is built to represent the assembly knowledge and information The virtual assembly system judges the requirement of the designer based on the context of design task and searches for the useful knowledge and information, which can be provided to the designer in a natural way

Cable Harness Assembly Planning in Virtual Environment

Based on the analysis of characteristic of cable harness planning in virtual environment,a discrete control node modeling (DCNM) method of cable harness in virtual environment and the cable harness assembly routing technique based on it are proposed. DCNM converts a cable harness into continuous flexed line segments connected by a series of section center points,and the design can realize cable harness planning through controlling those control nodes. This method of cable harness routing in the virtual environment breaks the status that virtual assembly process planning is just suitable for the rigid components at present,and impulse the virtual assembly process planning to be more practical. Relation algorithms have been verified in a self-developed system named virtual cable harness assembly planning (VCHAP) system,and this VCHAP system has been applied in assembly process planning of aerospace-related products.

Approach to Modeling and Virtual-reality-based Simulation for Plant Canopy Lighting

Over the past 20 years, significant progress has been made in virtual plant modeling corresponding to the rapid advances in information technology. Virtual plant research has broad applications in agronomy, forestry, ecol- ogy and remote sensing. As many biological processes are driven by light, it is the key for virtual plant to estimate the light absorbed by each organ. This paper presents the radiance equation suitable for calculating sun and sky light intercepted by plant organs based on the principles of the interaction between light and plant canopy firstly; analyzes the process principles of plant canopy primary lighting based on ray casting and projection secondly; describes the multiple scattering of plant lighting based on Monte Carlo ray tracing method and on the radiosity method thirdly; and confirms the research with 3D visualization based on Virtual Reality Modeling Language (VRML) finally. The research is the primary work of digital agriculture, and important for monitoring and estimating corn growth in Northeast China.

Virtual Reality with Haptic Application

Virtual reality (VR) is the use of advanced technologies, including computers and various multimedia peripherals (such as haptic), to produce a simulated environment that users perceive as comparable to real world objects and events. With the aid of specially designed transducers and sensors, users interact with displayed images, moving and manipulating virtual objects, and performing other actions in a way that engenders a feeling of actual presence (immersion) in the simulated environment. Haptic interfaces provide carefully controlled force feedback to the fingers of the user so that they feel as though they are touching objects in the virtual landscape. This article presented an overview to the concepts of VR focusing on haptics in a variety of interfaces and applications.

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.

WEB-BASED VIRTUAL CNC MACHINE MODELING AND OPERATION

A CNC simulation system based on intemet for operation training of manufacturing facility and manufacturing process simulation is proposed. Firstly, the system framework and a rapid modeling method of CNC machine tool are studied under the virtual environment based on PolyTrans and CAD software. Then, a new method is proposed to enhance and expand the interactive ability of virtual reality modeling language（VRML） by attaining communication among VRML, JavaApplet, JavaScript and Html so as to realize the virtual operation for CNC machine tool. Moreover, the algorithm of material removed simulation based on VRML Z-map is presented. The advantages of this algorithm include less memory requirement and much higher computation. Lastly, the CNC milling machine is taken as an illustrative example for the prototype development in order to validate the feasibility of the proposed approach.

Digital assembly technology based on augmented reality and digital twins: a review

Product assembly simulation is considered as one of the key technologies in the process of complex product design and manufacturing.Virtual assembly realizes the assembly process design,verification,and optimization of complex products in the virtual environment,which plays an active and effective role in improving the assembly quality and efficiency of complex products.In recent years,augmented reality(AR)and digital twin(DT)technology have brought new opportunities and challenges to the digital assembly of complex products owing to their characteristics of virtual reality fusion and interactive control.This paper expounds the concept and connotation of AR,enumerates a typical AR assembly system structure,analyzes the key technologies and applications of AR in digital assembly,and notes that DT technology is the future development trend of intelligent assembly research.

基于VRML的虚拟环境生成工具的研究

虚拟现实建模语言ＶＲＭＬ可应用Ｉｎｔｅｒｎｅｔ网上构造第二代ＷＷＷ。但由于自身的繁杂性，直接构造三维虚拟空间较为困难，若能设计ＶＲＭＬ生成工具，这就大大提高工作效率。本文主要讨论创建ＶＲＭＬ生成工具的基本方法，最后我们利用生成工具完成一个应用实例。

VRML环境下基于语义的产品装配设计技术研究

装配语义是零件间装配约束的抽象与概括 ,研究基于语义的产品装配设计可有效地提高装配设计的直观性与装配效率 .文中给出了基于语义的产品装配设计系统的总体框架结构 ,将装配语义分为常用语义与特殊语义 ,并建立了装配语义的层次表达 ;通过装配语义与几何约束的映射 ,形成几何约束的代数表达 ;借助零部件间的运动自由度的求解 ,实现了装配语义的驱动 。

基于VRML和JAVA的虚拟现实协同系统研究与设计

该文在讨论了基于 ＶＲＭＬ的虚拟现实协同系统是 ＣＳＣＷ未来的发展方向的基础上，分析了 ＶＲＭＬ在构造虚拟现实ＣＳＣＷ系统的局限性。接着，探讨了如何将ＶＲＭＬ与 ＪＡＶＡ等技术结合起来，提高 Ｉｎｔｅｒｎｅｔ上协同环境的可感知性和交互性。在此基础上，提出了一种基于Ｉｎｔｅｒｎｅｔ虚拟现实的协同应用结构。

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

基于VRML的可视化工具的研究

随着网络技术和硬件设施的飞速发展,虚拟现实建模语言(VRML)被广泛用于在因特网上构建虚拟境界。由于VRML语言自身的特点,虚拟现实的制作十分繁琐。如何使用辅助工具来提高开发的效率,具有很重要的意义。本文分析和讨论了几种基于VRML的可视化工具。

VRML在三维地质曲面动态显示中的应用

简要介绍了虚拟现实和 VRML的基本概念。根据地质曲面的实际情况 ,提出采用网格化数据文件与 Elevation Grid节点相结合方法建立虚拟空间 ,动态显示三维地质曲面。将该方法应用到煤田地质曲面上 。

基于VRML的三维地质体可视化研究

论文根据地学领域的实际情况,提出了一种在VRML环境下实现地质体三维可视化的方法。该方法采用双层高程格网分别模拟地质体上下表面,用普通三角网连接两层表面的边界,从而构成一个视觉上的三维地质体。最后,笔者综合运用VRML语言中IndexedFaceSet节点和ElevationGrid节点中的coord、color、coordIndex以及normal等字段构造了一个能够在网络上运行的三维地质体,取得了良好的视觉效果。

基于VRML和VRMLScript的虚拟现实仿真研究

提出了一种使用VRMLScript构建仿真器直接驱动VRML场景的新机制,较好地解决了以往仿真控制中存在的场景抖动、易产生仿真逻辑错误的问题。给出了利用基本三维实体实现场景仿真建模的新方法,使得场景更易于控制和修改,开发了基于VRML的飞机部件装配虚拟现实仿真系统,验证了机制的有效性。

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。