Micropositioning of a weakly calibrated microassembly system usingcoarse-to-fine visual servoing strategies

This paper presents a novel visual servoing framework for micropositioning in three dimensions for assembly and packaging of hybrid microelectromechanical systems (MEMS). The framework incorporates a supervisory logic-based controller that selects feedback from multiple visual sensors in order to execute a microassembly task. The introduction of a visual sensor array allows the motion of microassembly tasks to be controlled globally with a wide angle view at the beginning of the task. Then a high precision view is used for fine motion control at the end of the task. In addition, a depth-from-focus technique is used to visually servo along the optical axis, providing the ability to perform full three-dimensional (3-D) micropositioning under visual control. The supervisory logic-based controller selects the relevant sensor and tracking strategy to be used at a particular stage in the assembly process, allowing the system to take full advantage of the individual sensor's attributes such as field-of-view, resolution, and depth-of-field. The combination of robust visual tracking and depth estimation within a supervisory control architecture is used to perform high-speed, automatic microinsertions in three dimensions. Experimental results are presented for a micro insertion task performed under this framework in order to demonstrate the feasibility of the approach in high precision assembly of MEMS. Results demonstrate that a relative parts placement repeatable to 2 μm in XY and 10 μm in Z is possible without the use of costly vibration isolation equipment and thermal management systems     

微装配中变焦变倍视觉系统标定及自动聚焦

在微装配中,采用变焦变倍视觉系统可以有效解决测量范围与精度的矛盾,但同时也引入了动态标定和实时自动聚焦的新问题。为此,对变焦变倍显微视觉系统的标定和自动聚焦技术展开研究。在标定方面,首先通过变倍率法完成图像主点的标定。基于平面靶标定法,采用单视图单应矩阵分解对固定倍率下相机内外参数进行线性标定,再引入畸变模型,并由量子行为粒子群优化算法对标定结果进行非线性优化,优化之后的最大反投影误差约为0.13 pixel,平均反投影误差约为0.1 pixel。此外,通过高斯曲线拟合完成对任意工作状态下视觉系统放大倍数的校准。在自动聚焦方面,针对传统灰度梯度函数只考虑固定梯度方向且易受噪声影响的问题,采用八邻域最大梯度阈值的自动调焦算法,通过梯度阈值提高算法的抗噪性。与其他几种灰度梯度调焦函数相比,该算法的单峰性好,抗噪性强。     

Behind the scenes of virtual reality: vision and motion

The phrase “Concealing Telecommunications Networks” is first introduced as an ultimate philosophical concept in human-to-human or physically evolving “multimedia” communications by employing the same face-to-face mode that is used in natural communications. Then virtual reality (VR) technologies and their current applications are introduced, followed by an introduction of cutting-edge research on “Teleconferencing with Realistic Sensations”, which is a communications system that conceals the existence of telecommunications networks. Next, research activities on “vision” and “motion”, the most important underlying human functions supporting technologies such as VR, are presented. These activities consist of 1) a perception model that explains how human beings mentally reconstruct 3-D shapes from 2-D information projected on the retina, and 2) research on the close relationship between the senses, i.e., auditory and visual perception, visual information, and muscular motion stimuli. As a practical application, an example of measuring eye movements for early detection of Alzheimer's disease is briefly introduced. Finally, some fundamental problems with stereoscopic 3-D displays on 2-D screens, which can make them more fatiguing than the natural environment, are discussed     

基于三维视觉的室内设计虚拟现实方法研究

针对传统基于辐射度算法的室内场景三维虚拟现实方法存在耗时高、建模效果差的弊端,研究基于三维视觉的室内设计虚拟现实方法,采用主动式、全方位立体视觉传感器采集室内场景的三维点云数据,基于点云数据进行室内场景内的物体几何关系以及摆放位置分布,完成室内三维场景的自主合成,对物体摆放位置分布实施训练,通过三维场景点云数据集获取相同类型支撑物中物体产生的位置,对数据实施归一化操作,采用高斯混合模型拟合这些数据,训练出三维室内场景中物件在支撑面中的位置分布模型。采用基于深度信息场景重构方法实现室内三维场景的虚拟实现。实验结果说明,所提方法重构的室内场景直观、视觉效果好,并且具有较高的重构效率和精度。     

虚拟现实系统中人的头部运动与跟踪研究

为了克服虚拟现实系统中的视觉延迟现象,在对各种头部运动规律测试结果分析研究的基础上,提出人的头部运动是具有高斯-马尔可夫特性的随机过程,建立了头部运动的随机数学模型,设计了基于卡尔曼滤波和测量数据预处理技术的头部未来位置预测算法.理论分析和仿真检验都表明,该算法明显地提高了预测精度,减缓了图像的抖动和对操作者头部运动的限制,有效地减少了视觉延迟.     

Research on virtual reality system design for body and psychological rehabilitation

There are many people in China who suffered from physical and mental diseases and need physical and psychological rehabilitation. Traditional treatments can work in rehabilitation, but will take much money and labor. In recent years, virtual reality (VR) technology has become a new direction to innovate rehabilitation. This paper summarizes the research results of VR technology in rehabilitation for stroke, anxiety, depression and autism. Based on these results, we propose a framework for VR rehabilitation system with virtual agents. A prototype system is developed to corroborate the proposed design guidelines. With the prototype rehabilitation system, autistic children can train their life skills in different scenarios. Preliminary test results show the proposed framework can push users to take the rehabilitation training actively and can be a new method for rehabilitation training.     

基于双目视觉的增强现实模型系统设计

本文的研究旨在改善目前以单目增强现实设备存在着视场小、成像不逼真、单目观察、适应人群窄等问题。模型系统选用高分辨率、宽色域、高集成度OLED微显示器作为成像像源,大尺寸的半透射半反射BS棱镜和凹面镜作为成像元件,通过光路建模,控制图像放大倍率,以提高视场;利用CAD设计模型结构,采用3D打印技术制作模型组件。该系统具有多维的可调节度,包括调节放大倍数、眼距和双目图像合成角度等。该模型系统可以实现高清晰稳定的单目及双目成像效果,色彩及图像还原度高,与外景能够自然融合,系统的用户普适性强。     

基于虚拟现实技术的水体虚拟仿真替代式建模方法研究

本文简述了水体仿真的应用领域、特性及建模方法,并以虚拟系统中的瀑布仿真为例,为满足虚拟场景对真实性和实时性的需求,提出替代式的建模方式。文中阐述了替代式仿真构建的全过程,并通过多案例对比证实替代式建模方式的可行性和优越性。以替代式建模方法作为构建瀑布场景的主要方式,即用简单模型结合纹理贴图、粒子效果等形式替代复杂模型,在确保仿真效果的同时将复杂模型用最简化的方式表现出来,使虚拟场景在真实性和实时性两个方面都得到很好地表现。     

面向工业培训应用的虚拟现实装配系统研究

将虚拟现实技术运用到工业培训中可以弥补传统工业培训指导性不强、耗费资源度大等缺点。文中以工业模具装配为例,利用改进后的预分割OBB碰撞检测算法结合Petri网对模具的装配序列和装配实现方法进行了研究,描述了基于HTC Vive虚拟现实头盔和Unity3d,3ds MAX等软件开发的虚拟现实模具装配系统。最后,通过装配系统训练模块对面向工业培训中的虚拟现实交互训练功能的研究和实现进行详细的描述,结果表明虚拟现实装配系统的研究对工业培训指导有着很大的意义。     

基于虚拟现实的下肢主动康复训练系统

针对传统下肢康复训练中病人参与度低、主动运动意图逐渐丧失的问题,设计一种基于虚拟现实的下肢主动康复训练系统。该系统采用惯性检测单元(IMU)获取并解算下肢关节活动度,作为虚拟场景中的运动控制信号,并建立无线蓝牙通信机制,把患者下肢运动与运动功能康复训练游戏结合在一起。基于鞋内置多点足底力传感器(FSR)获取患肢足底力参数,识别步态相周期,作为康复评估的数据基础。实验验证了康复数据获取的准确性、交互通信的实时性与康复场景运行的流畅性。     

基于虚拟现实技术在教育系统中的运用

虚拟现实技术是一种高端的综合性信息技术,从诞生到现在已经经历了50多年的历史,从最开始的这种技术集中运用于军事、科研等领域,到后来逐渐应用于军事、医学、娱乐等各个领域。虚拟现实技术在教育系统中的应用也有非常大的现实意义,本文将对这方面进行深入研究分析。     

基于虚拟现实的三维户型展示系统

通过3DStudio MAX结合Cosmo World、VrmlPad和Java语言制作虚拟场景,嵌入网页来展示小区户型及其周边环境,在二维导航图中实现视点跳转、实时导航,在虚拟环境中进行交互操作,使人们对三维小区户型和其周边环境具有强烈的身临其境感,增强了宣传效果。     

基于虚拟现实的三维户型展示系统

通过3D Studio MAX结合Cosmo World、VrmlPad和Java语言制作虚拟场景,嵌入网页来展示小区户型及其周边环境,在二维导航图中实现视点跳转、实时导航,在虚拟环境中进行交互操作,使人们对三维小区户型和其周边环境具有强烈的身临其境感,增强了宣传效果.     

Haptics in virtual reality and multimedia

Imagine that you're chatting with a good friend who tells you about her new cashmere pullover, and that you're able to touch it and appreciate the soft sensation of the cashmere wool - remotely over the Web in your virtual chatroom! In this article, the authors present their work on haptic sensing of virtual textiles. This is work done in the context of the Haptex research project that aims at integrating the human sense of touch into multimodal user interfaces. Being able to support haptic perception in the user interface will be a great step toward next-generation immersive multimedia experiences.     

融合虚拟现实技术的桥梁监测系统设计与实现

针对桥梁健康监测系统直观、高效的业务需求,研究当前的工业监测系统模式,提出了融合虚拟现实技术的桥梁监测系统的设计方案。该系统能够应用开源框架Three.js对桥梁信息进行三维可视化监测显示,全方位展现桥梁内外部结构,并结合传感器的实时数据实时反映其当前健康状态;为优化Web系统实时访问监测数据的速度,提出实时和历史数据分离的二层数据存储结构。实践应用结果表明,以Web3D模型为主,多层数据分离存储为辅的监测系统,可以对桥梁监测数据高效地、直观地呈现以及预警,对桥梁管养单位分析、维护桥梁健康情况具有重要意义。     

结构工程领域对系统仿真和虚拟现实技术的应用研究

本文着重阐述了将系统仿真与虚拟现实技术相结合后,在工程结构分析、岩土工程、防灾工程及模拟施工等结构工程领域中应用的基本思路和发展前景.     

3D augmented reality teleoperated robot system based on dual vision

A 3D augmented reality navigation system using stereoscopic images is developed for teleoperated robot systems.The accurate matching between the simulated model and the video image of the actual robot can be realized,which helps the operator to accomplish the remote control task correctly and reliably.The system introduces the disparity map translation transformation method to take parallax images for stereoscopic displays,providing the operator an immersive 3D experience.Meanwhile,a fast and accurate registration method of dynamic stereo video is proposed,and effective integration of a virtual robot and the real stereo scene can be achieved.Preliminary experiments show that operation error of the system is maintained at less than 2.2 mm and the average error is 0.854 7,0.909 3 and 0.697 2 mm at x,y,z direction respectively.Lots of experiments such as pressing the button,pulling the drawer and so on are also conducted to evaluate the performance of the system.The feasibility studies show that the depth information of structure can be rapidly and recognized in remote environment site.The augmented reality of the image overlay system could increase the operating accuracy and reduce the procedure time as a result of intuitive 3D viewing.     

基于虚拟现实技术的模拟驾驶实验数据采集系统

针对传统开发型模拟驾驶系统存在成本高、教学型模拟驾驶系统不能采集数据的问题,利用软件和硬件设计并实现对模拟驾驶实验数据的采集。硬件部分的Logitech G29方向盘、汽车踏板作为模拟驾驶的输入,计算机作为数据的处理中心,采用Visual C++6.0与OpenGL联合开发实现对输入模块、汽车力学分析模块、虚拟现实驾驶环境生成模块、车辆运行状态参数记录模块、接口模块的构建。经实例验证所设计的模拟驾驶实验数据采集系统运行稳定可靠,能够为汽车操纵动力学特性研究提供数据来源,并完成了数据的采集功能。     

基于BIM技术的绿色公共建筑虚拟现实系统设计研究

针对传统虚拟现实系统生成的绿色公共建筑三维图像与实际场景相似度较低这一问题,基于BIM技术研究一种新的绿色公共建筑虚拟现实系统。系统硬件主要选取中央处理器、存储器、建模设备和交互设备,处理器内部选用的芯片为美国Intel公司生产的型号为TUSA852的新型处理芯片,存储器分为主存储器和外存储器,建模设备主要有3D扫描仪和声音设备,交互设备主要选取三维鼠标和数据手套。采用C++语言编写了三维场景编辑程序和数字建筑程序。对比实验结果表明,基于该文系统构建的模型与实体建筑的相似度逼近于100%,比传统二维平面图20%的相似度、基于物理构建的模型50%左右的相似度更高,优势突出。