基于磁流变液的力/触觉再现系统研究进展

力/触觉再现技术是当前新兴的研究领域.介绍了最近10年来基于磁流变液的力/触觉再现系统的国内外研究进展情况.总结了基于磁流变液的力/触觉再现技术的研究内容,包括执行装置的结构设计、模型研究以及再现系统控制研究,讨论了基于磁流变液的力/触觉再现系统开发过程中的关键技术.如提高便携式触觉接口中执行装置的力矩/重量比.减小静态力、克服被动系统力/触觉表达局限性,指出了今后发展的趋势.阐述了基于磁流变液的力/触觉再现系统的优势,并展望了其应用前景.     

基于RTX的力/触觉再现系统实时性实现方法研究

针对虚拟环境力/触觉再现系统中作用力计算的实时性要求,研究了Windows操作系统下循环控制的实现方法:时间查询法、多媒体定时器法和基于实时扩展RTX(real-time extension)的方法.利用Delta 6-DOF力/触觉手控器建立了一个基于PC的力/触觉再现原型系统,分别在系统空载、并存网络通信、并存音频播放和并存视频播放4种系统负载状态下对3种实现方法进行了实验.实验结果表明,基于RTX的方法能够获得较理想的实时循环控制性能,适用于力/触觉再现等需要较高实时性计算循环的应用系统.     

虚拟现实的力触觉交互技术发展现状与趋势

虚拟现实通过模拟人的视觉、听觉、力触觉等,使人处于一种与真实世界非常逼真的虚拟世界中,来感受、体验和评价虚拟世界中的场景和设备。力触觉在虚拟现实环境中有其突出优越性,力触觉使得虚拟现实环境变得真实,是唯一的既可接受周围环境输入又可以对周围环境输出的感知通道,可极大增强可视化表达的效果。虚拟现实的力触觉交互技术包括力触觉再现技术和虚拟环境的力触觉建模。介绍了这两方面的发展现状、存在的问题和今后的发展趋势。     

图像的力/触觉表达技术研究综述

总结了图像的力/触觉表达技术研究的现状及特点,分析了图像的力/触觉表达研究中存在的问题,并展望了该技术的发展前景.     

彩色图像的纹理力/触觉渲染方法

针对图像纹理力/触觉再现技术中用灰度变化表征纹理所导致的彩色图像在灰度变换后丢失纹理信息的缺点,用颜色变化表征纹理,提出彩色图像的纹理力/触觉渲染方法.该方法中,切向力的计算基于像素力场算法,法向力的计算基于惩罚算法,根据颜色和空间感的心理学效应提出由亮度和色调决定约束空间,合力通过手控器反馈给操作者.实验结果表明,文中方法能够有效地对彩色图像纹理进行力/触觉渲染.     

基于位移控制的线圈自动绕线系统研究

在电磁式力触觉再现系统中,电磁铁线圈绕制质量的好坏直接决定了力触觉再现的真实感和沉浸感。该系统基于手摇绕线机、步进电机、电缸平移台、张力控制器、STM32单片机等模块,设计开发了大尺寸电磁铁线圈自动绕制系统。研究了以STM32为核心的精准排线控制算法,实现了大尺寸空盘片骨架自动绕线排线工作。以实际绕制的线圈为研究对象,通过与人工绕制线圈的效果对比,验证了排线算法的可靠性和稳定性;通过测量线圈的电阻值与理想值的对比,证明了线圈绕制质量的可行性。该系统为大尺寸线圈绕制提供了有效的解决方案,对促进力触觉的发展具有重要的研究意义。     

机器人射流触觉显示器及系统研制

介绍了一种基于水射流刺激的机器人触觉显示器及触觉再现系统.该触觉显示器采用6根内径为2 mm的紫铜管折弯焊接构成2×3射流阵列并经环氧树脂包封而成,射流水压由微型水泵提供并经柔性塑料软管与喷嘴连接.讨论了射流水柱高度及射流时延问题.由该触觉显示器组建的触觉再现系统上的实验表明该触觉显示器可以较好地满足主从机器人触觉信息反馈的需求,并具有温和舒服安全有效的特点.     

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。     

基于射流方法的几何图形触觉再现技术研究

针对触觉临场感技术中几何形状再现的问题,提出了基于射流触觉方法的几何图形触觉再现技术,论述了射流几何图形触觉临场感再现的原理,探讨了几何图形的触觉表达,并进行了相关实验验证.在实验的基础上,提出并讨论了关于几何图形再现的触觉满意度评估指标.     

柔顺性触觉再现技术的研究

柔顺性触觉再现的研究难点主要集中在对触觉机理了解不深入、动态的感知过程、装置性能有限等方面.介绍了当前几种有代表性的柔顺性触觉再现装置:基于电流变液的触觉再现装置、气囊触觉再现装置、气动阵列触觉再现装置和基于弹性梁触觉再现装置.在此基础上讨论了这些装置的优缺点,并进行了比较.最后总结了柔顺性触觉再现技术的发展思路.     

高度复杂拟凸体的实时触觉绘制

触觉绘制目前已成为虚拟现实的研究热点之一,其核心是触觉代理与目标物体的实时碰撞检测与距离计算,对高度复杂模型的触觉绘制仍然是虚拟现实领域的难题,原因是对模型复杂度敏感的算法均不能满足触觉绘制苛刻的时间要求.提出触觉包围盒概念,并针对拟凸体提出一种基于触觉包围盒的实时触觉绘制算法.触觉包围盒记录了离散的采样光线与目标物体的相交信息,进行触觉计算时,只需要执行1次线段与包围盒求交运算和5次双线性插值运算即可高速求出碰撞信息,且所得到的碰撞信息可直接用于反馈力计算.实验结果表明,该算法不仅快速有效,而且具有与触觉绘制模型复杂度不相关的优点.     

A Survey of Haptic Rendering Techniques

Computer Graphics technologies have developed considerably over the past decades. Realistic virtual environments can be produced incorporating complex geometry for graphical objects and utilising hardware acceleration for per pixel effects. To enhance these environments, in terms of the immersive experience perceived by users, the human's sense of touch, or haptic system, can be exploited. To this end haptic feedback devices capable of exerting forces on the user are incorporated. The process of determining a reaction force for a given position of the haptic device is known as haptic rendering. For over a decade users have been able to interact with a virtual environment with a haptic device. This paper focuses on the haptic rendering algorithms which have been developed to compute forces as users manipulate the haptic device in the virtual environment.     

视触觉融合的增强现实三维注册方法

增强现实技术是近年来人机交互领域的研究热点。在增强现实环境下加入触觉感知,可使用户在真实场景中看到并感知到虚拟对象。为了实现增强现实环境下与虚拟对象之间更加自然的交互,提出一种视触觉融合的三维注册方法。基于图像视觉技术获得三维注册矩阵;借助空间转换关系求解出触觉空间与图像空间的转换关系;结合两者与摄像头空间的关系实现视触觉融合的增强现实交互场景。为验证该方法的有效性,设计了一个基于视触觉增强现实的组装机器人项目。用户可触摸并移动真实环境中的机器人零件,还能在触摸时感受到反馈力,使交互更具真实感。     

纹理力触觉建模与表达技术研究综述

力触觉再现作为一种新兴的信息传递方式,对提高人机交互的真实感和准确性具有重要意义.纹理的力触觉表达是借助触觉反馈通道反映人与环境交互过程中物体表面凹凸特性.介绍了纹理力触觉表达的研究背景,阐述了纹理力触觉表达系统的基本原理,归纳了纹理力触觉表达的触觉特征提取和建模方法,并对不同类别的建模方法的特点和问题进行了分析,最后给出了纹理力触觉表达技术的未来研究方向和建议.     

虚拟装配中基于导纳控制的力觉渲染技术

传统的力触觉渲染多采用阻抗控制,不能很好地满足虚拟装配的应用要求,相比之下导纳控制模式更适用这一领域.为此提出一种基于导纳控制的双线程力觉渲染构架,并给出相应的力觉渲染算法.首先建立用于导纳控制的动力学模型,并讨论了碰撞和约束这2个状态下的力觉渲染;为了使用力觉交互接口进行虚拟装配中的小间隙装配,提出物理约束与几何约束结合的力觉渲染方法;最后针对物理计算和力反馈循环2个线程刷新频率不匹配的问题,利用二次拉格朗日多项式进行数值插值,实现了力觉交互接口的平稳输出.通过力反馈设备与自主开发的虚拟装配原型系统VAPP的连接与应用,验证了所提出的算法满足虚拟装配系统中力觉交互的应用要求.     

用于实时柔性触觉再现的平行菱形链连接模型

精度高且实时性好的柔性触觉变形模型是实现触觉再现系统的关键。提出了一种新的基于物理意义的平行菱形链连接触觉变形模型,系统中各个链结构单元相对位移的叠加对外等效为物体表面的变形,与之相连的弹簧弹性力的合力等效为物体表面的接触力。使用Delta 6-DOF手控器,建立了触觉再现实验系统,对柔性体的接触变形和实时虚拟触觉反馈进行仿真, 实验结果表明所提出的模型不仅计算简单,而且能够保证触觉接触力和形变计算具有较高精度,满足虚拟现实系统对精细作业和实时性的要求。     

Haptic rendering for dental training system

Immersion and interaction are two key features of virtual reality systems, which are especially important for medical applications. Based on the requirement of motor skill training in dental surgery, haptic rendering method based on triangle model is investigated in this paper. Multi-rate haptic rendering architecture is proposed to solve the contradiction between fidelity and efficiency requirements. Realtime collision detection algorithm based on spatial partition and time coherence is utilized to enable fast contact determination. Proxy-based collision response algorithm is proposed to compute surface contact point. Cutting force model based on piecewise contact transition model is proposed for dental drilling simulation during tooth preparation. Velocity-driven levels of detail haptic rendering algorithm is proposed to maintain high update rate for complex scenes with a large number of triangles. Hapticvisual collocated dental training prototype is established using half-mirror solution. Typical dental operations have been realized including dental caries exploration, detection of boundary within dental cross-section plane, and dental drilling during tooth preparation. The haptic rendering method is a fundamental technology to improve immersion and interaction of virtual reality training systems, which is useful not only in dental training, but also in other surgical training systems. Supported by National Natural Science Foundation of China (Grant Nos. 60605027, 50575011), National High-Tech Research & Development Program of China (Grant No. 2007AA01Z310)     

Improved passivity criterion in haptic rendering: influence of Coulomb and viscous friction

In this paper, a new criterion for passivity of haptic devices is obtained. This criterion creates a relationship between Coulomb friction coefficient, viscous friction coefficient, sampling rate, and the maximum simulated stiffness. The process of derivation of the passivity criterion is described in detail. This criterion is improved compared with other existing criteria and predicts passivity in haptic rendering more accurately. In particular, for speeds of less than 5?cm/s, the new passivity criterion should replace the previous criteria to avoid unwanted vibrations of stiff virtual walls. Analytical and numerical investigations are presented to validate the new criterion. A specific trajectory is designed and the movement of the haptic robot is investigated on this trajectory to validate and compare this passivity criterion with the previous criteria.     

Neuro-cognitively inspired haptic user interfaces

Haptic systems and devices are a recent addition to multimodal systems. These devices have widespread applications such as surgical simulations, medical and procedural training, scientific visualizations, assistive and rehabilitative devices for individuals who have physical or neurological impediments and assistive devices for individuals who are blind. While the potential of haptics in natural human machine interaction is undisputable, the realization of such means is still a long way ahead. There are considerable research challenges to development of natural haptic interfaces. The study of human tactile abilities is a recent endeavor and many of the available systems still do not incorporate the domain knowledge of psychophysics, biomechanics and neurological elements of haptic perception. Development of smart and effective haptic interfaces and devices requires extensive studies that link perceptual phenomena with measurable parameters and incorporation of such domain knowledge in the engineering of haptic interfaces. This paper presents design, development and usability testing of a neuro-cognitively inspired haptic user interface for individuals who are blind. The proposed system design is inspired by neuro-cognitive basis of haptic perception and incorporates the computational aspects and requirements of multimodal information processing system. Usability testing of the system suggests that a biologically inspired haptic user interfaces may form a powerful paradigm for haptic user interface design.