A virtual environment-based system for the navigation of underwater robots

Efficient teleoperation of underwater robot requires clear 3D visual information of the robot's spatial location and its surrounding environment. However, the performance of existing telepresence systems is far from satisfactory. In this paper, we present our virtual telepresence system for assisting tele-operation of an underwater robot. This virtual environment-based telepresence system transforms robot sensor data into 3D synthetic visual information of the workplace based on its geometrical model. It provides the operators with a full perception of the robot's spatial location. In addition, we propose a robot safety domain to overcome the robot's location offset in the virtual environment caused by its sensor errors. The software design of the system and how a safety domain can be used to overcome robot location offset in virtual environment will be examined. Experimental tests and its result analysis will also be presented in this paper.     

通用装备虚拟维修训练系统的设计与实现

着眼装备使用维护人员的训练需求,探讨了通用装备虚拟维修训练系统所应具备的功能。采用将训练科目解析为由多道操作工序构成的层次模型,并以有限状态机的方法处理操作工序状态,以基于三维虚拟场景的关键帧动画表现各工序动作的设计思路,基于自主研发的视景仿真软件平台开发了支持三维交互式训练的通用装备虚拟维修训练系统。最后介绍了系统的应用模式和案例。     

Design and development of a maintenance and virtual training system for ancient Chinese architecture

Ancient Chinese architecture is an important aspect of traditional Chinese culture and has been studied by many scholars around the world via historical documents, photographs, and three-dimensional models. In this paper, a building information model (BIM) and virtual reality (VR) and video analysing technology are used to develop a maintenance and virtual training system for ancient architecture. A digital ancient architecture model that includes a three-dimensional model and attributes is established, and the model can be visualized using a VR video processing system. Based on this system, we propose a method of fire detection in the maintenance system to ensure the safety of ancient buildings. After performing lightweight processing of the three-dimensional model, the Forge platform, which can achieve high-speed browsing via Web browsers, is used to perform the virtual construction, dismantling and other functions. By providing an immersive experience, users will develop a deeper understanding of ancient architectural structures and construction processes, which will accelerate research on ancient architecture.     

Towards a customizable immersive virtual reality serious game for earthquake emergency training

Earthquake emergencies require a variety of behavioral responses in order to ensure the safety of occupants, which is different from simply exiting a building in fire emergencies. This makes it more complex to train building occupants in order to acquire skills that align to best practices for immediate earthquake response and post-earthquake evacuation. In recent years, Immersive Virtual Reality (IVR) and Serious Games (SGs) have become popular as training tools for earthquake emergencies. IVR SGs have been introduced to train individuals for specific building layouts or settings with fixed training objectives. However, the lack of flexibility in existing IVR SGs makes it challenging to have widespread uptake as trainees require different training objectives, pedagogical strategies, context, and content. As a result, the effectiveness of IVR SGs training is jeopardized if the customization ability is limited. To overcome this limitation, this paper presents a customization framework for IVR SGs suited to earthquake emergency training, using the concept of adaptive game-based learning. Trainees can receive training in context by customizing virtual environments, storylines, and teaching methods. A case study was undertaken to validate the proposed framework. Results showed the potential to carry out the customization process with ease, to generate a customized training experience, and to deliver the customized training for optimum learning.     

Circuit diagnosis support system for electronics assembly operations

Diagnosis and repair operations are often major bottlenecks in electronics circuit assembly operations. Increasing board density and circuit complexity have made fault diagnosis difficult. But, with shrinking product life cycles and increasing competition, quick diagnosis and feedback is critical for cost control, process improvement, and timely product introduction. This paper describes a case-based diagnosis support system to improve the effectiveness and efficiency of circuit diagnosis in electronics assembly facilities. The system stores individual diagnostic instances rather than general rules and algorithmic procedures, and prioritizes the tests during the sequential testing process. Its knowledge base grows as new faults are detected and diagnosed by the analyzers. The system provides distributed access to multiple users, and incorporates on-line updating features that make it quick to adapt to changing circumstances. Because it is easy to install and update, this method is well-suited for real manufacturing applications. We have implemented a prototype version, and tested the approach in an actual electronics assembly environment. We describe the system's underlying principles, discuss methods to improve diagnostic effectiveness through principled test selection and sequencing, and discuss managerial implications for successful implementation.     

Real-time simulation for a virtual reality-based MIG welding training system

This paper describes a real-time welding simulation method for use in a desktop virtual reality simulated Metal Inert Gas welding training system. The simulation defines the shape of the weld bead, the depth of penetration, and the temperature distribution in the workpiece, based on inputs from the motion-tracking system that tracks the position of the welding gun as a function of time. A finite difference method is used to calculate the temperature distribution, including the width of the weld bead and the depth of penetration. The shape of the weld bead is then calculated at each time step by assuming a semi-spherical volume, based on the width of the weld bead, the welding speed, and the wire feed rate. The real-time performance of the system is examined, and results from the real-time simulation are compared to physical tests and are found to have very good correlation for welding speeds up to 1,000 mm/min.     

Analysis of assembly operations difficulty: a fuzzy expert system approach

Typical mechanical products can be assembled in various sequences of assembly operations. These sequences have high impact on the assembly time, machine utilization and even on the product quality. In order to select the best sequence of assembly operations, proper evaluation of the various sequences of assembly operations is required. This, in turn, requires the consistent evaluation of each assembly operation in the sequence. The assembly operations can be evaluated for various criteria, of which the operation difficulty is the most meaningful. This paper describes a methodology to analyse the assembly operations and calculates an operation's degree of difficulty using an expert system. This analysis consists of two steps: the first one identifies the main parameters that affect the assembly difficulty and assigns fuzzy triangular values to these parameters. The second step assigns weights to the parameters in order to maximize the agreement with a domain expert. The expert system analyses the difficulty of the assembly operation performed in two orientations: horizontal and vertical. The expert system then assigns a triangular fuzzy number as the aggregate measure of the operation's difficulty.     

基于3D虚拟现实技术的弹药检测虚拟训练系统设计

目前提出的弹药检测虚拟训练系统接收检测信号接收率较低,检测虚拟训练成功率较低。基于3D虚拟现实技术设计一种新的弹药检测虚拟训练系统,硬件由主控操作机、检测总线接口以及资源测试器组成,软件部分在3D虚拟现实技术下构建虚拟空间,在开放式软件结构构建的基础上进行检测指标划分,对用户界面的文件进行整改,按照弹药检测的指标数据提升整改的方向正确性,选用自检公式对检测的信息进行系统自检,依据检测到的问题的发生形式判断下一次问题发生的触发机制,由此避免下一次问题的产生,从而实现软件流程。实验结果表明,基于3D虚拟现实技术的弹药检测虚拟训练系统能有效提高信号接收率,增强虚拟训练接收成功率,具有较强的应用性。     

一种燃气灶安全操作虚拟演示系统的设计

提出了一种基于单片机和PC的燃气灶安全操作演示系统的实现方案。用单片机仿真燃气灶的点火和开关控制,配合PC可实现模拟真实场景的燃气灶安全使用操作训练。实际测试表明,该方案操作简易方便且仿真效果好,硬件成本极低,可在公众消防安全教育中推广使用。     

精馏系统的虚拟装配技术研究

将虚拟装配技术引入化工流程中,对可视化设计化工流程、培训工人操作技能以及化工厂的数字化建设具有很大的应用价值。通过分析精馏系统,搭建了可视化装配平台。根据装配约束条件建立了可装配设备模型。提出了"1+1"和"1+n"普遍化的装配方法,实现了装配复杂精馏系统。通过输出装配信息,获取精馏系统装配过程中的装配方式和装配序列,验证装配操作的正确性。装配测试表明装配方法正确可行,其真实性、准确性和有效性满足了精馏系统虚拟装配的要求,实现了自由选择设备装配所需的精馏系统。系统可扩展性强,通过添加其它单元设备,可以实现所有化工流程的虚拟装配。     

Structured development of a virtual shared memory system

In this paper we formalise three different views of a virtual shared memory system and show that they are equivalent. The formalisation starts with five basic component processes specified in the language of CSP [Hoa85], which can be adapted as necessary by two operations called labelling and clamping, and are combined in two basic ways: either they are chained, so that the output of one component becomes the input of the next, or they are put in parallel, so that their communications are arbitrarily interleaved. Using the laws of CSP we show that these basic processes and operators satisfy a number of algebraic equivalences, which enable us to prove equivalence of the different models of the memory system by reasoning entirely at the level of processes, instead of at the lower and more complicated level of events. As a result the proofs of equivalence of the different models are purely algebraic and very simple.The specification is intended to provide a general framework for any architecture using an interconnection network, such as the on-chip interconnect between macrocells or the networks of processor nodes connected by bit-serial interconnect which are described in [Jon93]. It addresses architecture independent design issues such as access transparency, connectivity, addressing models and serialisability. By structuring it as a hierarchy of models it is hoped that the treatment of these many issues is made as clear and tractable as possible, whilst the proofs of equivalence ensure consistency.Funded by Esprit Project 7267/ OMI-Standards.     

Towards an immortal operating system in virtual environments

Many OS crashes are caused by bugs in kernel extensions or device drivers while the OS itself may have been tested rigorously. To make an OS immortal we must resurrect the OS from these crashes. We present a novel OS-hypervisor infrastructure that allows automated and transparent OS crash diagnosis and recovery in a virtual environment. This infrastructure eliminates the need for reboots or checkpoint-restart mechanisms, which require preserving the states of critical applications before the crash happens and also require extensive modifications to those applications. At the core of our approach is a small hidden OS-repair-image that is dynamically created from the healthy running OS instance. When an OS crashes, the hypervisor dynamically loads this repair-image to perform diagnosis and repair. One way of repair we have experimented with, is to quarantine the offending process and resume the running of the fixed OS automatically without a reboot. Experimental evaluations demonstrated that it takes less than 3 s to recover from an OS crash. This approach can significantly reduce the downtime and maintenance costs in data centers, and is the first design and implementation of an OS-hypervisor combo capable of automatically resurrecting a crashed commercial server-OS. In addition to online diagnosis and recovery, this infrastructure can also be used for offline diagnosis and can be incorporated into the technical support tools of the OS vendor. Additionally, we have used parts of this infrastructure to speed-up the diagnosis of AIX OS-crashes for the IBM technical support teams.     

Construction of virtual patient model for maxillofacial palpation training system

Palpation has been considered as one of the important diagnostic skills for doctors, which is conducted on a patient to identify the size, the consistency, and the location of a subcutaneous tumor. Accurate palpation skill often detects the cause of disease early. Even in the field of dentistry, palpation has been considered as the important diagnostic skill for dentists. By the way, any practical training of palpation against a patient did not implemented in the dental education because the patient safety has a priority more than its educational effect. Then we propose a training system for maxillofacial palpation by using virtual reality and haptic interface. The details of modeling a virtual patient model for the training system are shown in this paper, and the experimental results are also described.     

A cooperative virtual prototyping system for mechatronic solution elements based assembly

In order to catch up with the steps of rapidly changing markets, the product development period of modern mechatronic products has to be as short as possible. However, mechatronic engineering is based on the interaction of mechanical engineering, electronic engineering, and computer science. Therefore, inefficient communication between the engineers who come from different domains becomes a manifest obstruction for accelerating the design of mechatronic products. Nevertheless, innovations in the field of virtual prototyping offer some potential solutions to this problem. In this paper, we present a cooperative virtual prototyping system, which utilizes the concept of solution elements and virtual reality techniques to facilitate assembling and analyzing virtual mechatronic prototypes in a multi-disciplinary workgroup.     

A virtual prototyping system for rapid product development

This paper describes a virtual prototyping (VP) system that integrates virtual reality with rapid prototyping (RP) to create virtual or digital prototypes to facilitate product development. The proposed VP system incorporates two new simulation methodologies, namely the dexel-based and the layer-based fabrication approaches, to simulate the powder-based and the laminated sheet-based RP processes, respectively. The dexel-based approach deposits arrays of solid strips to form a layer, while the layer-based approach directly forms a complete layer by extruding the slice contours. The layer is subsequently stacked up to fabricate a virtual prototype. The simulation approaches resemble the physical fabrication processes of most RP systems, and are therefore capable of accurately representing the geometrical characteristics of prototypes. In addition to numerical quantification of the simulation results, the system also provides stereoscopic visualisation of the product design and its prototype for detailed analyses. Indeed, the original product design may be superimposed on its virtual prototype, so that areas with dimensional errors beyond design limits may be clearly highlighted to facilitate point-to-point analysis of the surface texture and the dimensional accuracy of the prototype. Hence, the key control parameters of an RP process, such as part orientation, layer thickness and hatch space, may be effectively tuned up for optimal fabrication of physical prototypes in subsequent product development. Furthermore, the virtual prototypes can be transmitted via the Internet to customers to facilitate global manufacturing. As a result, both the lead-time and the product development costs can be significantly reduced.     

Evaluation of a low-cost 3D sound system for immersive virtual reality training systems

Since head mounted displays (HMD), datagloves, tracking systems, and powerful computer graphics resources are nowadays in an affordable price range, the usage of PC-based "virtual training systems" becomes very attractive. However, due to the limited field of view of HMD devices, additional modalities have to be provided to benefit from 3D environments. A 3D sound simulation can improve the capabilities of VR systems dramatically. Unfortunately, realistic 3D sound simulations are expensive and demand a tremendous amount of computational power to calculate reverberation, occlusion, and obstruction effects. To use 3D sound in a PC-based training system as a way to direct and guide trainees to observe specific events in 3D space, a cheaper alternative has to be provided, so that a broader range of applications can take advantage of this modality. To address this issue, we focus in this paper on the evaluation of a low-cost 3D sound simulation that is capable of providing traceable 3D sound events. We describe our experimental system setup using conventional stereo headsets in combination with a tracked HMD device and present our results with regard to precision, speed, and used signal types for localizing simulated sound events in a virtual training environment     

Knowledge kanban system for virtual research and development

Virtual research and development (R&D) is inevitable to reduce the product life cycle. Enterprises tend to rely on their foreign partners for supporting technology and knowledge acquisition to conduct and improve firms’ product development with low R&D risk. R&D is a highly creative and knowledge-intensive activity, Therefore, efficient knowledge flow, which transmits the right knowledge to the right people at the right time, is key to improving efficiency of the R&D process.     

Fatigue evaluation in maintenance and assembly operations by digital human simulation in virtual environment

Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible, and it has been integrated into VR applications to complete ergonomic evaluation tasks. In order to generalize the evaluation task in VE, especially for physical fatigue evaluation, we integrated a new fatigue model into a virtual environment platform. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the difficulty level. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time models. A framework based on digital human modeling technique is established to realize the comparison of physical status. An assembly case in airplane assembly is simulated and analyzed under the framework in VRHIT experiment platform. The endurance time and the decrease of the joint moment strengths are simulated. The experimental result in simulated operations under laboratory conditions confirms the feasibility of the theoretical approach: integration of virtual human simulation into virtual reality for physical fatigue evaluation.     

Towards a narrative theory of virtual reality

Virtual Reality (VR), by its nature and characteristics, is of specific interest to the AI community, particularly in the domains of Storytelling and Intelligent Characters. We argue that VR must be considered a particular narrative medium alongside Theatre, Literature or Cinema. This paper reviews relevant work in narrative theory from Plato onwards, including the work and theories of literary critics [1], cinema critics [2–4] and theatrical dramaturges [5], and analyses the specific characteristics of VR relevant to this theory. Less studied media such as Live Role Playing Games, improvisational drama and participatory drama are also considered. Finally, this document argues for a participatoryprocess-oriented narrative, with particular attention to the specificities and particularities of stories and their possible representation, adapted to the narrative medium Virtual Reality.