一种虚拟环境温度触觉再现仿真系统设计

分析了温度触觉感知特性,提出了手指和物体接触时各自表面的温度变化过程,结合单热源温度触觉再现装置设计了一种基于三维力反馈手控器的虚拟环境温度触觉再现仿真系统。手控器可控制虚拟手的动作,对虚拟物体进行温度和力的感知。仿真系统中能再现手指与不同热属性物体接触时的温度变化和力变化,且视觉效果逼真,体现了温度触觉再现的实时性和有效性。     

基于力反馈的虚拟拆卸系统关键技术研究

在虚拟拆装系统的研制过程中,一般要求设计的系统具有尽可能好的“沉 浸感”,除了给用户良好的视觉感受外,应尽可能多的增加其它感官感受,例如触觉等。因 此,对于力/触觉反馈的研究就变得尤为重要。该文在对PHANTOM Omni 力反馈装置工作 原理分析的基础上,运用VC++与OSG 相结合,实现了虚拟物体的拾取和交互式移动,针 对典型机械装备,开发了基于力反馈的交互式虚拟拆卸系统。使维修人员对机械产品和维修 场景产生最直接的感受与真实的操作体验,提高维修人员的维修质量和效率,降低训练成本。     

气动力反馈数据手套设计与验证

针对目前面向大型复杂机电产品的虚拟装配环境中力反馈装置所能提供的触觉力偏小的问题,提出一种基于微型低摩擦气缸的内置式力反馈数据手套.首先介绍了手套结构及其工作原理;然后搭建了实验系统,基于牛顿迭代法进行运动学方程组求解,验证了手套的角度测量和力反馈功能;最后开发了手套的人机交互控制系统,采用D-H理论来描述虚拟手的空间位置,基于虚拟墙的弹簧-质点模型计算虚拟力.实验结果表明,所设计的数据手套可实现大触觉力的反馈,满足虚拟装配系统虚拟抓取的需求.     

一种基于物理意义的快速力反馈形变模型及实时力觉响应算法

虚拟物体在受力作用时的形变建模是虚拟环境中力/触觉人机交互的关键.文中提出了一种新的基于物理意义的形变建模方法,不仅计算速度快,满足力反馈的实时性要求,而且能够同时保证接触力和形变的计算具有较高的精度,适用于具有较大变形量的柔性物体的力反馈计算,满足精细作业对虚拟现实系统的要求.     

用于触摸屏交互的可穿戴指端力反馈系统设计

力触觉再现技术在增强用户与触摸屏交互的真实感和沉浸感方面发挥着越来越重要的作用,设计了一种面向触摸屏图像信息感知的可穿戴指端力反馈装置。设计基于线绳牵引驱动的指端力反馈机构,将装置分为驱动和可穿戴部分,使其具备小巧、轻便、易佩戴的特点。设计测控系统,实现了输出反馈力的检测和控制。研究图像信息提取和力触觉建模算法,获取图像中物体的三维特征信息,配合力反馈装置和测控系统实现图像纹理高度、外形轮廓信息再现反馈。实验结果表明,该装置最大可以提供5.3 N的反馈力,能够帮助用户感知触摸屏中图像的高度和形状信息。     

计算机触觉:虚拟现实环境的力触觉建模和生成

触觉是人类5种感觉通道之一,在日常生活中发挥着不可缺少的作用.在虚拟现实和增强现实系统中,力触觉反馈的引入有望显著提高人机交互的沉浸感和交互性.文中综述了虚拟现实环境中力触觉感受的建模和生成方法,从力触觉生成与视觉生成的差异性出发,回顾了计算机触觉的发展历史和国内外研究现状,重点分析了虚拟物体建模、碰撞检测、碰撞响应、变形计算等关键技术,并提出了力触觉生成技术的未来发展趋势和技术挑战.     

面向虚拟介入手术的电磁力反馈模型的设计与仿真

为满足虚拟血管介入手术中力触觉反馈的实时性和精准性,采用磁悬浮原理设计一种力反馈模型生成虚拟介入手术中的周向旋转力触觉.通过分析通电线圈磁场特性和介入手术操作模式,首先设计电磁线圈阵列的拓扑结构和手术器械模型;随后针对线圈阵列提出最优电流分配策略并进行仿真验证;最后通过模型融合方法构建力矩-电流预测模型.实验结果表明,该模型能以3％的误差、40 Hz的频率预测出电流,结合最优电流分配策略可对介入手术中的关键力反馈进行实时、精确还原.     

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。     

一种提高基于线绳的力反馈设备显示阻抗范围的方法

提出一种通过动态调整线绳预紧力提高基于线绳的力反馈设备显示阻抗范围的方法．介绍了基于线绳的力反馈设备的基本结构, 从能量耗散的角度分析了线绳张力对设备显示高刚度虚拟物体时稳定性的影响,并分析线绳预紧力与力觉交互透明性之间的关系． 为同时满足稳定性和透明性的要求,根据设备操作末端与虚拟物体的接触状态,对线绳的预紧力进行动态调整．实验结果表明, 该方法能够在保持设备透明性的同时,有效提高其稳定性,从而提高设备显示的阻抗范围．     

基于力反馈技术的毛笔笔道仿真

本文将力反馈技术引入虚拟绘制过程,提出一种基于力反馈技术的笔道仿真方法.首先通过分析力对毛笔变形的影响机理,采用弹簧-振子模型构建了一种新的毛笔力反馈仿真模型;然后通过计算毛笔模型变形时每个采样点处的笔触形状,得到笔触变化的时间序列,获得完整的笔道,实现力对笔道的动态控制.文中利用Phantom Desktop力反馈设备,成功地实现了具有力觉反馈的笔道仿真.仿真结果表明,该方法再现了传统笔道绘制中通过力触觉控制绘制的过程,有效地增强了虚拟绘制过程的真实感.     

一种基于非线性弹簧模型的虚拟手交互新方法

基于虚拟手的交互技术在人机交互和人机工程学测试等应用中发挥着重要的作用。为了实现直观自然、实时准确、接近真实世界中的虚拟手与虚拟物体的交互,并计算出反馈作用力,首先提出了用非线性弹簧模型计算抓取作用力,使虚拟手和虚拟环境之间实现了基于物理的交互;然后将计算结果以视觉渲染的形式反馈给用户,并对仿真的速率做了定量分析,以便使仿真速率可以达到屏幕刷新频率和力反馈刷新频率的要求。实验结果表明,虚拟手不仅可以直观自然地抓取3维虚拟物体,而且和3维物体之间能够进行实时交互,同时可计算出反馈作用力。     

Interaction model between elastic objects for haptic feedback considering collisions of soft tissue

The simulation of organ–organ interaction is indispensable for practical and advanced medical VR simulator such as open surgery and indirect palpation. This paper describes a method to represent real-time interaction between elastic objects for accurate force feedback in medical VR simulation. The proposed model defines boundary deformation of colliding elements based on temporary surface forces calculated by temporary deformation. The model produces accurate deformation and force feedback considering collisions of objects as well as prevents unrealistic overlap of objects. A prototype simulator of rectal palpation is constructed on general desktop PC with a haptic device, PHANToM. The system allows users to feel different stiffness of a rear elastic object located behind another elastic object. The results of experiments confirmed the method expresses organ–organ interaction in real-time and produces realistic and perceivable force feedback.     

Whole-hand kinesthetic feedback and haptic perception in dextrous virtual manipulation

One of the key requirements for a Virtual Reality system is the multimodal, real-time interaction between the human operator and a computer simulated and animated environment. This paper investigates problems related particularly to the haptic interaction between the human operator and a virtual environment. The work presented here focuses on two issues: 1) the synthesis of whole-hand kinesthetic feedback, based on the application of forces (torques) on individual phalanges (joints) of the human hand, and 2) the experimental evaluation of this haptic feedback system, in terms of human haptic perception of virtual physical properties (such as the weight of a virtual manipulated object), using psychophysical methods. The proposed kinesthetic feedback methodology is based on the solution of a generalized force distribution problem for the human hand during virtual manipulation tasks. The solution is computationally efficient and has been experimentally implemented using an exoskeleton force-feedback glove. A series of experiments is reported concerning the perception of weight of manipulated virtual objects and the obtained results demonstrate the feasibility of the concept. Issues related to the use of sensory substitution techniques for the application of haptic feedback on the human hand are also discussed.     

A rod-mass method of soft tissue modeling and three dimensional force vector estimation for tele-surgery training

In a tele-surgery training system, the transparency is extremely important so as to ensure the success of the operation and the safety of soft objects. Due to current technique limits, it is difficult to mount force sensors at the end of the slave manipulator. In this paper, we propose a novel rod-mass algorithm and construct the model of soft objects. Through the modeling process, the accurate three dimensional contact force vector between the end of the manipulator and the soft object can be estimated in real time. A virtual spring using Hooke s law is introduced to the novel mass–spring method. Applying an impedance model, the three dimensional contact force estimates can be calculated from the deformation of masses’ positions and velocities. In order to verify our methods, a virtual reality interaction platform is constructed including the Omni master manipulator, a four joints manipulators, a virtual reality display, and the soft object’s model. Numerical simulations and experiments are performed to verify the accuracy and the feasibility of soft objects grasping. Results show the high effectiveness and efficiencies of our methods.     

虚拟手抓持力觉生成算法真实性的评价

目的 虽然许多学者研发了多种虚拟手交互触力觉生成算法,但是如何评价虚拟手交互触力觉生成算法的真实性是一个富有挑战性的新问题,值得深入研究.方法 构建手指抓持力测量平台,设计3种抓持姿态下指尖静力抓持球体实验内容,测得各指尖作用力的实测值;通过虚拟手静力抓持力觉生成算法,求得这3种抓持姿态下各手指作用力的理论值;对实测值进行统计和分析,并与理论值进行对比和讨论;结果 日常抓持经验和实测值是完全相符的,实测值和理论值很接近且偏差均在可接受范围之内.单个手指作用力或多个手指合力的实测值与理论值的偏差均在1%6%.结论 本文实现了一种基于物理的实验方法,评价和分析了虚拟手静力抓持力觉生成算法的真实性,证实此算法可以逼真地生成虚拟手抓持力,可应用于具有力反馈的自然的虚拟手交互.     

面向人机工程学测试的虚拟手仿真模型

以人机工程学测试为目标提出虚拟手仿真模型,建立虚拟手运动学模型。提出一种曲线拟合的校准方法,以获取精确的数据,更好地控制虚拟手的运动。建立弹簧模型计算手与被抓取物体之间的受力,以视觉渲染的形式将其反馈给用户。实验结果表明,虚拟手可自然地抓取三维虚拟物体,视觉反馈的使用可免于购买昂贵的力反馈设备。     

SPH haptic interaction with multiple-fluid simulation

Physics-based fluid interaction plays an important role in computer animation, with wide applications in virtual reality, computer games, digital entertainment, etc. For example, in virtual reality education and games, we often need fluid interactions like acting as an alchemist to create a potion by stirring fluid in a crucible. The traditional input devices such as a mouse and keyboard can basically input 2D information without feedback. In recent years, the continuous development of haptic device not only can achieve six degrees-of-freedom input, but also can calculate the force in virtual scenes and feedback to the user to make a better virtual experience. How to use haptic device in different kinds of virtual fluid scenarios to provide better experience is an important issue in the field of virtual reality. On the other hand, the researches on multiple-fluid interaction especially based on smoothed particle hydrodynamics (SPH) method are very lacking. Therefore, we study the key techniques of haptic interaction with SPH multiple-fluid to compensate this defect in computer graphics community. Different from the single-phase flow, interaction with multiple-fluid flow has difficulties in the realization of properties of different phases. After adding the multiple-fluid simulation, it is also important to keep haptic interaction real time. Our research is based on the mixture model. We guarantee the authenticity of multiple-fluid mixing effect while changing the drift velocity solver to improve efficiency. We employ a unified particle model to achieve rigid body–liquid coupling, and use FIR filter to smooth feedback force to the haptic device. Our novel multiple-fluid haptic simulation can provide an interactive experience for mixing liquid in virtual reality.     

虚拟现实中手与虚拟物体碰撞检测的一种算法

在虚拟现实技术中，人与虚拟空间物体的碰撞检测是非常重要的研究课题之一。由于空间物体结构的复杂性和碰撞响应的多样性，故找出一种通用检测算法是极为困难的。该文针对飞机机舱内的可操纵物体：开关，按钮，油门杆，停车杆等，实现了一种实时精确的碰撞检测算法。     

具有力感觉的声带肿物切除仿真方法研究

在虚拟手术系统中，实时的图形显示和使操作者感觉到真实的操作力是非常重要的。该文介绍了在建立虚拟手术系统中，具有力感觉的声带肿物切除的仿真方法。首先介绍了软组织声带以及声带肿物的几何建模办法，考虑到虚拟手术中对实时性的要求，采用了分块建模的方法；然后通过对软组织生物力学特性的分析，利用弹簧-质量-阻尼模型对其建模。采用的算法减小了计算量，真实地仿真了声带肿物取出时声带的变形以及操作者感觉到的力。