Peltier Haptic Interface (PHI) for improved sensation of touch in virtual environments

In this report we describe an advanced virtual reality glove that we are developing, called the Peltier Haptic Interface (PHI), which will provide improved sensation of touch in virtual environments. PHI will provide force/pressure feedback that can be varied independently on each finger, as well as temperature sensation that can be varied non-uniformly over the whole hand. The combination of these sensations will provide a more realistic sense of touch and significantly increase the realism of virtual environments. PHI will find extensive applications in biomedical simulations, teaching, industrial line training, and many other areas.     

Haptic modeling in the conceptual phases of product design

The paper presents the results of a research project aimed at developing an innovative system for modeling industrial products based on haptic technology. The system consists of a Computer Aided Design (CAD) system enhanced with intuitive designer-oriented interaction tools and modalities. The system integrates innovative six degrees of freedom (DOF) haptic tools for modeling digital shapes, with sweep operators applied to class-A surfaces and force computation models based on chip formation models. The system aims at exploiting designers’ existing skills in modeling products, improving the products design process by reducing the necessity of building several physical models for evaluating and testing the product designs. The system requirements have been defined observing designers during their daily work and translating the way they model shapes using hands and craft tools into specifications for the modeling system and the haptic tool. The system prototype has been tested by designers who have found it intuitive and effective to use.     

A Novel Seven Degree of Freedom Haptic Device for Engineering Design

In this paper, the authors intend to demonstrate a new intuitive force-feedback device that is ideally suited for engineering design. Force feedback for the device is tension-based and is characterised by 7 degrees of freedom (3DOF for translation, 3DOF for rotation, and 1DOF for grasp). The SPIDAR-G (SPace Interface Device for Artificial Reality with Grip) allows users to interact with virtual objects naturally by manipulating two hemispherical grips located in the centre of a device frame. Force feedback is achieved by controlling tension in cables that are connected between a grip and motors located at the corners of a frame. Methodologies will be discussed for displaying force and calculating translation, orientation and grasp using the length of 8 connecting cables. The SPIDAR-G is characterised by smooth force feedback, minimised inertia, no backlash, scalability and safety. Such features are attributed to strategic cable arrangement and control that results in stable haptic rendering. Experimental results validate the feasibility of the proposed device and example applications are described.     

The impact of haptic augmentation on middle school students’ conceptions of the animal cell

Of the five sensory channels—sight, sound, taste, smell, and touch, it is only our sense of touch that enables us to modify and manipulate the world around us. This article reports the preliminary findings of a systematic study investigating the efficacy of adding haptic feedback to a desktop virtual reality program for use in middle school science instruction. Current technology allows for the simulation of tactile and kinesthetic sensations via sophisticated haptic devices and a computer interface. This research, conducted with 80 middle school students, examined the cognitive and affective impact of this technology on students’ understandings of the structure and function of an animal cell. The results of this work offer valuable insights into the theoretical and practical considerations involved in the development and implementation of haptically augmented virtual reality instructional programs.     

Smoothing haptic interaction using molecular force calculations

This paper presents a new method for smoothing haptic interaction with molecular force calculations that uses Lennard-Jones forcefield. The gradient of the forcefield is used unaltered when the distance between two atoms is greater than the sum of their van der Waals radii. However, when they are smaller, a hard-surface wall implemented using a spring model is used to repel two atoms. This eliminates the instability when two atoms are in contact in the presence of forcefields that have strong gradients. This method is tested on rigid hydrocarbon molecules with no bond creation or breaking.     

虚拟体空间中的触觉雕刻

目前，在虚拟环境中大多数的信息获取是通过视觉、听觉等非接触感觉获得的。然而缺乏触觉反馈的信息减少了很大一部分的信息源。在看和听之外，能够触摸、感觉和操纵物体，在很大程度上提高了虚拟环境的真实性。该文研究了触觉绘制的基本模型，提出了采用虚平面作为中介实现体数据的实时触觉绘制。并在此基础上探讨了体的局部变形及结合触觉反馈模型，实现了具有触觉反馈的虚拟雕刻交互系统。该系统可应用于融化、燃烧、印记、构造和着色实时交互操作。     

基于光学映射虚物体的并行绘制

尽管当前基于全局光照模型的图形绘制方法可以渲染出高质量的图象 ,但因为其计算量巨大 ,难以适用于诸如建筑物漫游、虚拟现实等对绘制速度有严格要求的场合 .为此引入光学映射虚物体的概念 ,利用构建在联网PC机上的集群系统 ,并行创建反射和折射虚物体 ,然后利用集群中各节点的图形加速硬件 ,像处理实际三维物体一样绘制这些虚物体 ,可以快速地绘制出反射 /折射效果的图象 .实验结果证明 ,该方法利用 CU P的计算能力和图形硬件的加速特性实现了真实感图形的高性能绘制 ,特别适用于诸如建筑物漫游、计算机动画和虚拟现实等要求交互式绘制的场合     

力／触觉再现设备的研究现状与应用

力/触觉再现技术作为一种新兴的人机交互模式在虚拟现实系统得到较多应用。力/触觉再现设备是力/触觉再现系统实现过程中必不可少的环节,受到广泛的重视和研究。讨论了力/触觉再现设备的种类和特点,分类介绍了国内外力/触觉再现设备的研究现状,并作了分析比较。最后讨论了力/触觉再现设备在不同领域的应用,并探讨了其未来的研究发展趋势。     

基于游戏引擎的三维虚拟漫游系统实现

三维虚拟环境漫游是虚拟现实技术应用的基本方向之一,具有重要的研究意义与应用价值。基于成熟的游戏引擎技术,提出一个具有较强通用性和可扩展性的三维虚拟漫游系统开发框架,并从3D场景快速构建、3D场景实时绘制、高级视觉特效生成和基于物理的场景模拟等四个方面详细介绍了该框架的关键技术实现。通过对系统原型的测试表明,采用该开发框架所构建的三维虚拟漫游系统可在一般的普通主流PC机上达到较好的性能和表现效果。     

The development of an integrated haptic VR machining environment for the automatic generation of process plans

In modern manufacturing it is crucial to be able to produce a product right first time, as efficiently as possible. Virtual prototyping can play a key part in fulfilling this requirement, allowing the simulation of production in advance without the need for unnecessary downtime, material waste or increased lead times. This makes virtual reality (VR) potentially an ideal planning tool since, with each simulation, a better understanding of requirements can be reached and a more effective solution found.     

A novel approach to documenting artifacts at the Gold Museum in Bogota

We present our work on novel digitizing techniques to create virtual exhibitions in the context of the Gold Museum in Bogotá, Colombia, a world renown space for precious pre-Colombian gold artifacts. In order to solve issues related to high specular reflection in gold artifacts, we developed a multi-spectral approach that solves some of the shortfalls of many commercial scanners. We also integrated commercial haptic devices into a new virtual installation that allows visitors to touch, hear, and see virtual approximations of the real objects. As an evaluation methodology, we compare the results of a scanner with normal light with our approach, and we also present results from user studies on our virtual installation.     

Physically touching and tasting virtual objects enhances the realism of virtual experiences

Experiment 1 explored the impact of physically touching a virtual object on how realistic the virtual environment (VE) seemed to the user. Subjects in a no touch group picked up a 3D virtual image of a kitchen plate in a VE, using a traditional 3D wand. See and touch subjects physically picked up a virtual plate possessing solidity and weight, using a technique called tactile augmentation. Afterwards, subjects made predictions about the properties of other virtual objects they saw but did not interact with in the VE. See and touch subjects predicted these objects would be more solid, heavier, and more likely to obey gravity than the no touch group. In Experiment 2 (a pilot study), subjects physically bit a chocolate bar in one condition, and imagined biting a chocolate bar in another condition. Subjects rated the event more fun and realistic when allowed to physically bite the chocolate bar. Results of the two experiments converge with a growing literature showing the value of adding physical qualities to virtual objects. This study is the first to empirically demonstrate the effectiveness of tactile augmentation as a simple, safe, inexpensive technique with large freedom of motion for adding physical texture, force feedback cues, smell and taste to virtual objects. Examples of practical applications are discussed.Based in part on Physically touching virtual objects using tactile augmentation enhances the realism of virtual environments' by Hunter Hoffman which appeared in the Proceedings of the IEEE Virtual Reality Annual International Symposium '98, Atlanta GA, pp 59–63. ¢ 1998 IEEE.     

真实感图形绘制技术研究

随着虚拟现实技术的发展,对各种图形绘制技术提出了越来越高的要求。好的图形绘制技术是虚拟现实、动态仿真、实时可视化、高品质动画等越来越多的图像、图形应用技术的实现基础。本文主要介绍了基于图像的绘制技术、基于点的绘制技术,以及基于图形与图像的混合绘制技术在原理和应用。     

增强现实技术在虚拟演播室系统中的应用

虚拟演播室是虚拟现实技术和视频合成技术相结合的产物,其场景是计算机生成的三维场景,由于人们对虚拟场景和复杂度的无限要求,使得场景的实时显示十分困难,使用基于图像的绘制技术构造虚拟空间能够较好地解决这个问题。在虚拟演播室中,演员需要与三维运动虚拟物体进行交互,运用增强现实技术,可以将三维虚拟物体与基于图象绘制的虚拟场景融合在一起。     

基于图像绘制的虚拟环境构建与漫游技术研究

虚拟现实是一个重要目标是用计算机构建逼真的视觉世界,使参与者漫游虚拟世界。传统上,其实现是用3D图形学进行几何建模和绘制,但有诸多不足,而基于图像绘制的实现虚拟实现系统的新方法,它克服了3D图形方法的缺点,本文提出了一个实现基于图像绘制的虚拟环境的构建与漫游系统框架模型。     

Haptics-based virtual reality periodontal training simulator

This paper focuses upon the research and development of a prototype dental simulator for training of periodontal procedures. By the use of virtual reality and haptics technology, the periodontal simulator allows trainees to learn performing diagnosis and treatment of periodontal diseases by visualizing a three-dimensional virtual human mouth and feeling real tactile sensations while touching the surface of teeth, gingiva, and calculi with virtual dental instruments. Since periodontics requires dentists to depend primarily on tactile sensations to perform diagnostic and surgical procedures, the use of haptics is unquestionably crucial for a realistic periodontal simulator. The haptics-based virtual reality periodontal training simulator has been validated by a experiment conducted by the College of Dentistry at University of Illinois at Chicago (UIC) with faculty members and dental students, which demonstrates the scientific contribution and usefulness of the simulator as a vital part of the curriculum of the Department of Periodontics at UIC.

An Image-Based Virtual Reality Prototype System

The most important goal of virtual reality is to create a virtual world computers where users are allowed to view the environment and control the virtual objects interactively.Traditionally,virtual reality systems use 3D computer graphics to model and render a virtual environment in real time.However,this approach usually requires laborious modeling and expensive special-purpose rendering hardware.Image-based rendering is a new approach in composing a virtual environment in which a set of panoramic images is used to compose the virtual environment and walking in the space is accomplished by “hopping”to different panoramic points.This paper introduces an experimental image-based VR system.The techniques utilized in the system,in particular the authoring and interactive control tools of the system,are described in detail.     

虚拟环境下石墨微观表面的力感知技术研究

介绍了虚拟环境下基于物理模型的触觉渲染技术和算法.提出了利用在物体表面上的点仿真物体对其静态摩擦约束,逐渐增大施加在该点上的力,直到由静态摩擦变为动态摩擦,由于在动摩擦和静摩擦转换之间计算模型没有发生变化,因此该模型可以在状态转换时稳定地计算出摩擦力的大小.最后描述了该模型在石墨微观表面的力感知中的应用.     

实时虚拟舞台系统灯光效果的实现

在舞台排练系统中,经常有上百盏不同式样的灯同时照亮场景的情况发生,但是目前图形处理器硬件只支持8盏灯同时点亮,而且大多数渲染引擎只提供点光源、聚光源和方向光源三种灯光模型.为了实时模拟真实的效果,使用了一个称为超级椭圆的光源模型,它可以把各种不同形状的灯的式样预先计算出并保存在纹理贴图中,这样后期计算光强度时只要从纹理中获得即可.此外,还提出如何进行光照优化,减少不必要计算,使所有灯都能发挥作用的方法.通过测试,系统达到了令人满意的实时帧数和效果.     

速度驱动的复杂场景多层级力觉交互算法

触/力觉交互技术应用环境的复杂化,对复杂触/力觉场景的研究提出了新的挑战.文中以虚拟现实牙科手术训练系统为背景,研究基于速度驱动的复杂场景多层级力觉交互算法.文中采用CATIA对下牙列大量数据进行网格简化,建立了下牙列场景的层次细节(Levels Of Detail,LOD)模型;基于人类触觉感知的精度随交互速度的变化规律,设计了速度驱动的LOD模型触发机制;提出了虚拟工具化身SCP(Surface Contact Point)层级映射算法,保证了力觉交互设备的稳定性,并发现了映射约束线段的长度是保证力觉逼真性及实时性协调的关键变量;最后,设计了针对一般儿何体和复杂曲面的实验,量化评价文中算法的逼真性及实时性,证明了将人手运动速度作为场景模型复杂度切换驱动条件的有效性.