A multiuser virtual-reality environment for a tele-operated laboratory

In engineering studies, concepts taught through lectures are often complemented by laboratory experimentation. This contribution presents a collaborative virtual environment for a tele-operated laboratory. Students have access to the tele-operated laboratory via the Internet from anywhere at any time. They control the experiments exclusively with their standard Web browser; no additional software is needed. The collaborative environment allows the experimentation in a team. Group members are able to interact and discuss the results of their work. A real collaboration, such as in local experimentation, is possible. The tele-operated laboratory is based on a client/server architecture, which is implemented in the Java programming language.     

A low-cost PC-oriented virtual environment for operator training

Virtual environment (VE) technologies have been shown to provide invaluable training in the performance of complex procedural tasks. Of paramount importance to the success of any VE is realism; entities must move and behave believably and approximate the complexity of the real world. Such real-world fidelity is accompanied by the challenge of making immersive training in virtual reality (VR) more widely available, at costs significantly less prohibitive. A solution is presented to recreate the VE on low-cost PCs, reducing the cost of the VR software itself, yet preserving real-time performance. This paper presents a low-cost, PC-based VR development system within the framework of ESOPE-VR, a VR operator training simulator (OTS) prototype for power-utility personnel. PC-ESOPE-VR aims to provide the same or improved functionality and performance as the original, with a 3-D visual interface, voice recognition and feedback, navigation and manipulation facilities, and expert system, multimedia and multi-user (distributed) support, yet address the practical demands raised above. The PC-based system is also compatible with the original; it can draw on existing ESOPE-VR power component libraries and support the automatic synthesis of a virtual power station environment from its single-line diagram representation. The approach used towards fulfilling all these issues is described, followed by key implementation results     

A virtual reality environment for designing and fitting neural prosthetic limbs.

Building and testing novel prosthetic limbs and control algorithms for functional electrical stimulation (FES) is expensive and risky. Here, we describe a virtual reality environment (VRE) to facilitate and accelerate the development of novel systems. In the VRE, subjects/patients can operate a simulated limb to interact with virtual objects. Realistic models of all relevant musculoskeletal and mechatronic components allow the development of entire prosthetic systems in VR before introducing them to the patient. The system is used both by engineers as a development tool and by clinicians to fit prosthetic devices to patients.     

A virtual environment for protective relaying evaluation and testing

Protective relaying is a fundamental discipline of power system engineering. At Georgia Tech, we offer three courses that cover protective relaying: an undergraduate course that devotes one-third of the semester on relaying, a graduate course entitled "Power System Protection," and a three-and-a-half-day short course for practicing engineers. To maximize student understanding and training on the concepts, theory, and technology associated with protective relaying, we have developed a number of educational tools, all wrapped in a virtual environment. The virtual environment includes a) a power system simulator, b) a simulator of instrumentation for protective relaying with visualization and animation modules, c) specific protective relay models with visualization and animation modules, and d) interfaces to hardware so that testing of actual relaying equipment can be performed. We refer to this set of software as the "virtual power system." The virtual power system permits the in-depth coverage of the protective relaying concepts in minimum time and maximizes student understanding. The tool is not used in a passive way. Indeed, the students actively participate with well-designed projects such as a) design and implementation of multifunctional relays, b) relay testing for specific disturbances, etc. The paper describes the virtual power system organization and "engines," such as solver, visualization, and animation of protective relays, etc. It also discusses the utilization of this tool in the courses via specific application examples and student assignments.     

Telerehabilitation using a virtual environment improves upper extremity function in patients with stroke.

In this paper, we describe our experience in designing a virtual environment-based (VE) telerehabilitation system, and the results of a clinical study of the first 11 subjects with stroke to use the system. Our telerehabilitation system allows a therapist to conduct interactive VE treatment sessions remotely with a patient who is located at home. The system, software architecture, and development experience are described. Results of the clinical study on subjects with stroke showed significant improvements in upper extremity function following 30 1-h VE treatment sessions as measured by three standard clinical tests: Fugl-Meyer test of motor recovery (FM) (p < 0.0001), Wolf motor test (WMT) (p = 0.0097, and shoulder strength (ShS) (p = 0.0027). Grip strength (GS) showed a trend toward improvement (p = 0.025). These changes were maintained, for the most part, at four-months follow-up (FM +7.6, WMT -18.4 s, ShS, +169%, GS, +53%).     

A Web-based virtual environment for operator training [for powersystems]

The wide accessibility and low cost of virtual reality (VR) on the World Wide Web with the advent of the Virtual Reality Modelling Language (VRML) and VRML interpreters makes it ideal for use in providing cost-effective training for operators in selected complex technical environments. This paper presents SEDA-VRML, a VR-based learn-by-doing system developed for the training of maintenance workers in the troubleshooting and inspection of power transformers at Hydro-Quebec that is accessible from a Web browser. SEDA-VRML is a prototype application of a reuse-driven design incorporating VRML, Java and an expert system within a user interface system (UIS) architecture. The paper describes the functionality and design principles of SEDA-VRML, with key implementation results, to show how SEDA-VRML's design can indeed answer to the limitations of VRML to act as a cost-effective alternative to traditional operator training systems for operator training in VR, as well as a basis for the rapid development of future operator training systems     

电力系统虚拟环境的研究及应用

简述了虚拟现实技术的功能特征及相关技术概念,探讨该技术在电力系统仿真培训中的应用。以变电站虚拟屏台为例,说明电力系统虚拟环境开发过程,并介绍了用三维驱动控件技术构建变电站虚拟屏台的方法。利用虚拟现实技术,极大地方便了电力系统的仿真培训,具有显著的经济效益和社会效益。     

基于虚拟仪器的电磁环境监测系统

介绍基于虚拟仪器的电磁环境检测系统的硬件构成、软件设计及数据采集、数据后续处理和系统的整体架构。该系统已实际应用,并取得了很好的效果。     

REAL: a virtual laboratory for mobile robot experiments

This paper presents REAL (Remotely Accessible Laboratory), a virtual laboratory accessible through the Internet. The objective of REAL is to provide remote access to a mobile robots infrastructure. REAL has been implemented as a new generation telecommunication service, not as a commonplace World Wide Web (WWW) application. As such, it employs a sophisticated access framework, a communication infrastructure able to support multimedia flows, and a component-based software construction. The architecture of REAL relies on open standards, such as WWW and its related technologies (HTTP, HTML, XML, Java, etc.) and a common object request broker architecture (CORBA).     

人工生命体在虚拟环境中的数据采集方法

文中介绍基于多智能体技术的人工生命体在虚拟环境中的数据采集及处理方法,给出系统的软、硬件设计过程和调试结果。该方法可以帮助测试人工生命体在虚拟环境中的生存能力和交互功能,具有实现简单、性能稳定、界面友好等优点。     

An oral tactile interface for blind navigation.

An oral tactile interface was designed and evaluated to provide directional cues through the tactile channel, which may be utilized by a blind traveler to obtain directional guidance in outdoor navigation. The device was implemented as a mouthpiece with a microfabricated electrotactile display on top for tactile presentation onto the roof of the mouth and a tongue touch keypad at the bottom for simultaneous operation by the tongue. An experimental system allowed a user to communicate with a computer tactilely by using the oral interface. Directional cues were presented to the user as line or arrow patterns with four moving directions (leftward, rightward, forward, and backward). Electrotactile presentation on the roof of the mouth was evaluated in experiments of threshold measurement and identification of directional cues. Experimental results from six human subjects showed that the roof of the mouth required stimulation intensities around 15 V for threshold sensation, and around 25-30 V for comfortable and well-perceived stimulation. Furthermore, identification of leftward or rightward movements was highly accurate while performance on forward or backward moving patterns was mixed and varied considerably among subjects.     

Graphical tactile displays for visually-impaired people.

This paper presents an up-to-date survey of graphical tactile displays. These devices provide information through the sense of touch. At best, they should display both text and graphics (text may be considered a type of graphic). Graphs made with shapeable sheets result in bulky items awkward to store and transport; their production is expensive and time-consuming and they deteriorate quickly. Research is ongoing for a refreshable tactile display that acts as an output device for a computer or other information source and can present the information in text and graphics. The work in this field has branched into diverse areas, from physiological studies to technological aspects and challenges. Moreover, interest in these devices is now being shown by other fields such as virtual reality, minimally invasive surgery and teleoperation. It is attracting more and more people, research and money. Many proposals have been put forward, several of them succeeding in the task of presenting tactile information. However, most are research prototypes and very expensive to produce commercially. Thus the goal of an efficient low-cost tactile display for visually-impaired people has not yet been reached.     

Study and simulation of video communications under wireless environment based on blind source separation

A new scheme is proposed to separate several compressed video signals transferred in multiple wireless channels using the blind source separation method. The scheme selects IEEE 802.11b and XVID compression as the wireless communications channel and MPEG-4 video compression, respectively. A simulation model is then made for the video communications under a wireless environment. The model can separate several video signals using blind source separation. Simulations show that the normalized whiten plus cyclic whiten based on cyclostationary (NWCW-CS) algorithm based upon the cyclostationary characteristics of signals has the best separation performance and fast convergence. Besides, the algorithm can solve the mixing of video signals. The image of the transferred video signals decompressed by XVID is nearly consistent with the source ones. The new method meets the requirement of real-time video communications. __________ Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(1): 13–17 [译自: 东南大学学报(自然科学版)]     

Technical and patient performance using a virtual reality-integrated telerehabilitation system: preliminary finding.

Telerehabilitation is the provision of rehabilitation services at a distance by a therapist at a remote location. Integration with virtual reality (VR) is a relatively new addition to this field. This paper describes the technical and patient performance of a telerehabilitation application the remote console (ReCon) that is integrated with a VR system. The VR system consists of the Rutgers Ankle prototype robot, a local PC which is connected with a remote PC connected over the Internet. Six individuals in the chronic phase poststroke participated in a four week training program. They used the robot to interact with two VR simulations, while the therapist was in the same room during the first three weeks or in another room during the fourth week. Technical and patient performance was assessed in the transition from the third to the fourth week of training. Technical performance of the system was assessed based on bandwidth and lag of message transmission, which were found to be suitable for clinic-to-clinic communication. Patient performance (in terms of accuracy of ankle movement, exercise duration and training efficiency, mechanical power of the ankle, and number of repetitions) did not decrease during telerehabilitation in the fourth week. These preliminary findings over a short telerehabilitation intervention support the feasibility of remote monitoring of VR-based telerehabilitation without adverse effects on patient performance.     

A virtual reality testbed for brain-computer interface research.

Virtual reality promises to extend the realm of possible brain-computer interface (BCI) prototypes. Most of the work using electroencephalograph (EEG) signals in VR has focussed on brain-body actuated control, where biological signals from the body as well as the brain are used. We show that when subjects are allowed to move and act normally in an immersive virtual environment, cognitive evoked potential signals can still be obtained and used reliably. A single trial accuracy average of 85% for recognizing the differences between evoked potentials at red and yellow stop lights will be presented and future directions discussed.     

Design of a haptic data visualization system for people with visual impairments.

Data visualization is a technique used to explore real or simulated data by representing it in a form more suitable for comprehension. This form is usually visual since vision provides a means to perceive large quantities of spatial information quickly. However, people who are blind or visually impaired must rely on other senses to accomplish this perception. Haptic interface technology makes digital information tangible, which can provide an additional medium for data exploration and analysis. Unfortunately, the amount of information that can be perceived through a haptic interface is considerably less than that which can be perceived through vision, so a haptic environment must be enhanced to aid the comprehension of the display. This enhancement includes speech output and the addition of object properties such as friction and texture. Textures are generated which can be modified according to a characteristic or property of the object to which it is applied. For example, textures can be used as an analog to color in graphical displays to highlight variations in data. Taking all of these factors into account, methods for representing various forms of data are presented here with the goal of providing a haptic visualization system without the need for a visual component. The data forms considered include one-, two-, and three-dimensional (1-D, 2-D, and 3-D) data which can be rendered using points, lines, surfaces, or vector fields similar to traditional graphical displays. The end result is a system for the haptic display of these common data sets which is accessible for people with visual impairments.     

Perceptual limits for a robotic rehabilitation environment using visual feedback distortion.

Imperceptible visual distortion, in the form of a disguised progression of performance goals, may be a helpful addition to rehabilitation after stroke and other brain injuries. This paper describes work that has been done to lay the groundwork for testing this hypothesis. We have constructed and validated an experimental environment that provides controllable visual distortion and allows precise force and position measurements. To estimate the amount of visual distortion that should be imperceptible, we measured the limits for force and distance/position perception in our rehabilitation environment for young and elderly unimpaired subjects and for a single traumatic brain injury (TBI) patient. We found the Just Noticeable Difference (JND) for produced force to be 19.7% (0.296 N) and the JND for movement distance/finger position to be 13.0% (3.99 mm) for young subjects (ages 18-35). For elderly subjects (ages 61-80), the JND for force was measured to be 31.0% (0.619 N) and the JND for distance/po'sition was 16.1% (5.01 mm). JNDs of 46.0% (0.920 N) and 45.0% (14.8 mm) were found for the motor-impaired individual. In addition, a subject's rating of effort was found to be profoundly influenced by visual feedback concerning the force magnitude. Even when this feedback was distorted, it accounted for 99% of the variance of the effort rating. These results indicate that substantial visual distortions should be imperceptible to the subject, and that visual feedback can be used to influence the subject's perceived experience in our robotic environment. This means that we should be able to use imperceptible visual distortion to alter a patient's perception of therapeutic exercise in a robotic environment.     

Brain-computer communication: motivation, aim, and impact of exploring a virtual apartment.

The step away from a synchronized or cue-based brain-computer interface (BCI) and from laboratory conditions towards real world applications is very important and crucial in BCI research. This work shows that ten naive subjects can be trained in a synchronous paradigm within three sessions to navigate freely through a virtual apartment, whereby at every junction the subjects could decide by their own, how they wanted to explore the virtual environment (VE). This virtual apartment was designed similar to a real world application, with a goal-oriented task, a high mental workload, and a variable decision period for the subject. All subjects were able to perform long and stable motor imagery over a minimum time of 2 s. Using only three electroencephalogram (EEG) channels to analyze these imaginations, we were able to convert them into navigation commands. Additionally, it could be demonstrated that motivation is a very crucial factor in BCI research; motivated subjects perform much better than unmotivated ones.     

A haptic force feedback device for virtual reality-fMRI experiments.

Simulation of real-world tasks using virtual reality (VR) and measurement of associated neural activity by functional magnetic resonance imaging (fMRI) have potential utility in research and clinical stroke applications. However, development of fMRI-compatible sensory feedback technology is required. Presented here is the development of a prototype force feedback device for VR-fMRI. Experiments validated device performance in terms of force output, interaction bandwidth, transmission delay, and fMRI-compatibility. A subsequent VR-fMRI experiment involved six participants touching a virtual object and verified modulation of brain activity with force feedback versus no force feedback. This device may facilitate further experiments to clarify the effect of haptics in VR, and may be adapted for characterizing brain function and behaviour associated with stroke-related hand paresis.     

基于VPB和osgGIS的流域三维虚拟环境建模方法

三维虚拟环境建模是实现流域虚拟仿真模拟的基础工作,快速智能地生成三维地形地物则是流域建模的关键技术。结合松花江流域地形建模和哈尔滨市建筑物建模,基于VirtualPlanetBuilder（VPB）和osgGIS进行了地形地物建模方法研究。阐述了基于地形DEM和遥感影像的流域多层次地形建模技术,探讨了多源数据的组织与利用方法。分别研究了线状地物和面状地物的参数设置方法,包括线状地物随地形起伏的设置、建筑物高度及顶面与侧面纹理的设置等。基于VPB和osgGIS的建模方法可以支持不同格式、不同精度和坐标系的原始数据,建模自动化程度高,生成的模型支持多层细节和基于外存的调度模式,可以为海量模型的实时调度渲染提供模型支持,是流域仿真模拟中三维地形地物的快速生成方案。