Development of a high-performance haptic telemanipulation system with dissimilar kinematics

This work addresses selected practical issues regarding the development of a telerobotic system for 6-d.o.f. tasks. The system consists of a hyper-redundant 10-d.o.f. haptic input device ViSHaRD10, a redundant 7-d.o.f. manipulator and a stereo vision system. The redundancy of the haptic input device is exploited to assure large convex workspaces and singularity-free operation. The anthropomorphic construction of the telemanipulator enables intuitive manipulation and increases the user-friendliness of the overall system. As a practical benchmark, an assembly experiment in 6 d.o.f. for the case of a negligible time delay was performed. Issues regarding inverse kinematics, spatial interaction control, transparency and intuitiveness of teleoperation are discussed.     

Real-time haptic interaction with RGBD video streams

Video interaction is a common way of communication in cyberspace. It can become more immersive by incorporating haptic modality. Using commonly available depth sensing controllers like Microsoft Kinect, information about the depth of a scene can be captured in real-time together with the video. In this paper, we present a method for real-time haptic interaction with videos containing depth data. Forces are computed based on the depth information. Spatial and temporal filtering of the depth stream is used to provide stability of force feedback delivered to the haptic device. Fast collision detection ensures the proposed approach to be used in real-time. We present an analysis of various factors that affect algorithm performance. The usefulness of the approach is illustrated by highlighting possible application scenarios.     

生物软组织力反馈触觉建模测试系统研制

设计了一种结构新颖的用于生物软组织力反馈触觉建模的测试系统。阐述了系统结构与工作原理,介绍了系统的机械设计、硬件电路和系统软件。系统采用计算机测量并控制带有力和位置传感器的单自由度机械手,通过插针实验与动物软组织交互得到软组织的力反馈触觉模型。以猪肝为标本进行实验,实验结果和现有的理论模型较为符合,该系统可以用于软组织触觉建模实验研究。     

Comparing six video chat tools: A critical evaluation by language teachers

This article presents a critical comparison of the usefulness and practicality of six CMC video chat tools (CUworld, ICQ, MSN Messenger, Paltalk, Skype, and Yahoo Messenger) from the perspective of language teaching professionals. This comparison is based on the results of a semester-long project between graduate students at an American university and their counterparts at a university in Turkey. The language teachers were asked to pair up with a partner in the collaborating university to test and then evaluate each of these tools via video chat tool evaluation sheets. They also completed an overall evaluation sheet commenting on CMC tools in general and ranking the video chat tools in terms of their potential as language teaching tools and their usability for personal communication purposes. The qualitative and quantitative analyses of the evaluation sheets indicate a clear preference for MSN Messenger and Skype while placing CUworld and Paltalk at the bottom of the list. The article also provides pedagogical implications and applications for using tools for language teaching purposes.     

A haptic representation system for a virtual plain wall

The purpose of this study is to develop a virtual wall display system for a walk simulator to grope its way in an 'invisible' situation, such as in a building filled with dense smoke, etc. To reproduce the realistic haptic sense of a building wall, the implementation of the wideness and the rigidity of wall are essential. Wideness of a virtual wall was realized by a hand-tracking control combined with a small wall panel which is mounted on a three-axis Cartesian manipulator. A 6-d.o.f. magnetic tracking system was utilized for the hand position tracking in the non-contact situation of the hand and the panel. In the contact situation, high rigidity of the wall was attained as stiffness in the normal direction is provided to the wall panel to represent the haptic sense of a rigid wall. Force-based tracking provides the low stiffness in the tangential direction to make the wall panel move easily along the direction of hand movement to represent a wide plain wall. A three-axis force sensor is attached on the wall panel to detect the contact force. The realization of smooth switching between both tracking controls provides the user with the haptic feel of the presence and continuity of a virtual wall. In addition, the frictional sensation has the effect of giving the system more reality. Experimental results have shown the effectiveness of the hybrid tracking method for the virtual wall system.     

High-fidelity sliding mode control of a pneumatic haptic teleoperation system

For a pneumatic teleoperation system with on/off solenoid valves, sliding mode control laws for position and force ensuring low switching (open/close) activity of the valves are developed. Since each pneumatic actuator has two pneumatic chambers with a total of four on/off valves, 16 possible combinations (‘operating modes’) for the valves’ on/off positions exist, but only seven of which are both functional and unique. While previous work has focused on three-mode sliding-based position control of one pneumatic actuator, this paper develops the seven-mode sliding-based bilateral control of a teleoperation system comprising a pair of pneumatic actuators. The proposed bilateral sliding control schemes are experimentally validated on a pair of actuators utilizing position-position and force-position teleoperation architectures. The results demonstrate that leveraging the additional modes of operation leads to more efficient and smoother control of the pneumatic teleoperation system. It was found that viscous friction forces were crippling haptic feedback in the position-position architecture. Through the use of force sensors, the force-position architecture was able to compensate for the heavy viscous friction forces.     

Adaptive haptic rendering for time‐varying haptic and video frame rates in multi‐modal interactions

In multi‐modal interactions including haptics, problems such as input sensor noise, temporal mismatch between graphics and haptics, and non‐constant refresh rates may cause non‐smooth force/torque display. This paper proposes temporal smoothing technique for haptic interaction using a sensing glove in multi‐modal applications. The proposed technique employs two processes: (1) a noise reduction method is applied to reduce jitter noise at the sensors in the sensing glove and (2) an adaptive force extrapolation is applied for time‐varying haptic and video frame rates. To demonstrate the performance of the proposed method, we developed a test platform to assess a simple box model and relatively complex models such as gamephone, portable media player (PMP). It was subsequently demonstrated that the proposed method can support smooth haptic interactions in multi‐modal applications where a haptic device and a sensing glove are used. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of an inheritance assist system for experiencing operation skills by using a haptic function of PHANToM

At present, several commercially available surgical simulators have been used in advanced medical facilities, and most of them provide a self-learning environment for trainees who are young doctors and/or residents. Therefore, we assume that inexperienced doctors have to inherit the veteran skills of experienced doctors because the lack of doctors and nurses is one of the most serious medical issues. This article proposes a training function on a surgical simulator system which enables trainees to sense the feelings of experienced surgeons while operating. The inheritance assistance function we are constructing might be of help in compensating for the lack of experience of young doctors and be more effective than the present system. The inheritance assistance function makes it possible to record the operational data of experienced doctors, and to reproduce this data in a training scene for young trainees. Then young doctors could practice their own skills by intuitively referencing the recorded advisory data in a surgical simulator. In order to accomplish the purpose of this study, we have constructed a fundamental system. A simple virtual object based on a dynamic model reacts in terms of visualization and force against the manipulation of virtual forceps via a haptic device, PHANToM. Several laboratory students of the experimental subject were challenged to obtain training with the system developed. This article describes the system and discusses the results and future work.     

Design and validation of a complete haptic system for manipulative tasks

The present work deals with the design, implementation and assessment of a new haptic system specifically conceived for manipulative tasks in virtual environments. Such a system was designed by taking into account specific issues related to fine manipulation, such as multipoint haptics, coherence, transparency and physical representation. The haptic system described herein is integrated with a virtual environment engine for the simulation of multifinger manipulation. A preliminary evaluation of the system was conducted by comparing human performance in the manipulation of virtual objects with respect to real objects, according to the data available in the literature. The experiments confirm how the most relevant relationships among physiological and physical parameters involved in manipulation are also preserved during virtual manipulation. However, an in-depth analysis of the results shows that simulation parameters affect the level of force control during virtual manipulation and the quality of the perceived force feedback.     

On the development of a haptic system for rapid product development

This paper presents a system development that extends haptic modeling to a number of key aspects in product development. Since haptic modeling has been developed based on physical laws, it is anticipated that a natural link between the virtual world and practical applications can be established based on haptic interaction. In the proposed system, a haptic device is used as the central mechanism for reverse engineering, shape modeling, real time mechanical property analysis, machining tool path planning and coordinate measuring machine (CMM) tolerance inspection path planning. With all these features in a single haptic system, it is possible to construct a three dimensional part by either haptic shape modeling or reverse engineering, then performing real-time mechanical property analysis in which the stiffness of a part can be felt and intuitively evaluated by the user, or generating collision free cutter tool path and CMM tolerance inspection path. Due to the force feed back in all of the above activities, the product development process is more intuitive, efficient and user-friendly. A prototype system has been developed to demonstrate the proposed capabilities.     

基于多线程技术的聊天系统研究

即时聊天工具不仅实现了人们之间的即时聊天,还进一步加强了网络的资源共事的功能,Java提供的Thread线程类和一些多线程机制可用来完成客户端多点对多点的聊天.客户端之间以及客户机和服务器之间的通信可以通过Java语言提供的net包以及I/O包来实现.服务器端可使用线程池技术来处理大量的客户请求,线程池技术减少了线程创建和销毁的开销,提高了线程的可重用性,因而可以有效提高服务器端效率.     

CORBA体系在网络聊天系统中的实现

CORBA（Common Object Request Broker Architecture）是分布计算机技术的发展结果,CORBA技术在理论和技术上扩展了客户/服务器的模式.本文在分析CORBA体系架构的基础上,提出了基于CORBA体系架构的网络聊天系统的实现,并给出部分关键代码.     

Development of a real-time visual and force environment for a haptic medical training simulator

In this article, a real-time, visual and force environment for a 5-dof haptic urological training simulator is presented that deals with a low-force, high-deformation environment. A real-time graphical representation of the male urethra during the insertion of an endoscope is developed. Smooth urethra deformations are produced by a mesh of piece-wise Bézier interpolations, while its inner wall is simulated by realistic tissue textures. Efficient real-time techniques are developed that introduce endoscope camera depth-of-field effects. A novel particle-based model computes in real-time the forces fed to the haptic device. A 13 fps refresh rate is achieved on a 2-GHz computer with the depth-of-field effect activated, while the rate is doubled to 26 fps with this feature disabled. It is expected that the simulator will contribute to ethical, efficient, and modern surgical training.     

ConChat: a context-aware chat program

ConChat is a context-aware chat program that enriches electronic communication by providing contextual information and resolving potential semantic conflicts between users.ConChat uses contextual information to improve electronic communication. Using contextual cues, users can infer during a conversation what the other person is doing and what is happening in his or her immediate surroundings. For example, if a user learns that the other person is talking with somebody else or is involved in some urgent activity, he or she knows to expect a slower response. Conversely, if the user learns that the other person is sitting in a meeting directly related to the conversation, he or she then knows to respond more quickly. Also, by informing users about the other person's context and tagging potentially ambiguous chat messages, ConChat explores how context can improve electronic communication by reducing semantic conflicts.     

数字视频监控系统中预录像的实现

以数字视频监控系统中的事件触发录像为背景,说明预录像的设计原理以及在事件触发录像中如何使用所设计的预录像方法实现数字视频监控系统中的事件触发录像功能,并给出了关键的C 程序实现代码。     

Image-based haptic display via a novel pen-shaped haptic device on touch screens

Multimedia Tools and Applications - Haptic interaction is a new interactive mode in the interaction technology between human and touch screens. In this work, we present an image-based haptic...