集成虚拟现实环境在工程设计分析中的应用 *

虚拟现实技术在工程设计与分析上有很大的应用潜力。可是 ,虚拟环境的创建时间长、成本高,极大地限制了虚拟现实技术在工程上的应用。为此 ,提出了虚拟现实脚本生成器的概念,将虚拟现实技术与过程的设计、分析集成化,创造性地提出了一种自上而下的设计方法———VR-IEDA,以便高效、快速地创建虚拟原型,提高计算机虚拟复杂系统工程的性价比。在 VR-IEDA中复杂系统的结构和行为被计算机捕捉并自动生成可执行的 VR仿真代码 ,从而减少了创建虚拟环境的时间,便利了基于仿真的过程分析和设计。最后 ,以武器系统的维修过程为     

虚拟环境的用户意图捕获

目的虚拟制造环境中需要复杂精确的3D人机交互。目前的虚拟环境(VE)的主要问题是人在交互过程中的认知和操作负荷太重,交互效率亟需提高。解决此问题的重要途径是提高机器的认知能力。方法本文研究了用户意图的分析和抽取,并建立多通道用户意图理解的算法,以此来提高交互效率。结果结合虚拟装配应用给出了典型意图的实验结果并给予分析。通过实验对多通道意图的可用性和可靠性,以及基于意图系统的实时性进行了评估。实验是虚拟装配空间中用户拾取对象意图的实验。当3维鼠标和对象距离为5 000 mm时,传统系统中操作平均耗时5.344 7 s,而基于意图的系统中平均耗时2.326 6 s。基于意图的系统极大地降低了操作的时间和复杂度。结论采用意图驱动的系统情景转换能在虚拟环境工作中有效地降低人的认知负荷,并能很好地帮助系统开发者进行混成系统的建模和分析,降低开发的复杂度。实践结果表明用户意图理解的多通道模型和算法能极大地提高交互式系统的交互自然性和交互效率。该方法不仅适用于本文所用的虚拟装配系统,对于所有的虚拟环境应用场景都有同样的有效性。     

虚拟场景中碰撞检测实用算法研究

碰撞检测是虚拟系统中的一项关键技术，也是提高虚拟系统现实感的一个重要因素。许多算法对碰撞检测的精度进行了研究，但对一个大型的虚拟场景，碰撞检测的范围则是影响仿真速度的主要因素。该文在包围盒检测技术研究的基础上，根据大型虚拟场景的特点，提出了碰撞发生的局部性、主动性、相邻性的观点，由此给出了虚拟游览系统中碰撞检测的DS算法，通过在本单位虚拟战场仿真系统的应用及分析表明，该算法对提高虚拟系统的运算效率是非常有效的。     

A VR Playground for Learning Abstract Mathematics Concepts

Immersive virtual reality (VR) has attracted the attention of many researchers and educators who predicted that VR would considerably affect how learning and teaching are conducted. The research presented here aims to investigate how an interactive immersive virtual learning environment affects conceptual learning, specifically learning of fractions in mathematics. A virtual environment (VE) designed to simulate a playground was created and evaluated through empirical studies with 60 primary school students between the ages of 8 and 12. Results suggest that children who fully interacted with the VE were able to problem-solve but that there was no strong evidence of the expected conceptual change. Rather, it was the passive VR environment, where a virtual robot guided activity, that seemed to support student reflection and recall, leading to indications of sustained conceptual change.     

Design evaluation and modification of mechanical systems in virtual environments

Design is one of the most important stages in the manufacturing cycle and influences all the subsequent stages of product development. In the context of today’s iterative design methodology, the modification of any design is a process involving many evaluations and improvements to the solutions chosen in earlier stages. For this purpose, in the most recent decade, 3D computer simulations have become common tools used within industry. Whilst virtual reality (VR) technology is seen as the interaction technology of the future, much of the current research in this area is carried out to explore the potential benefits and added value brought by the integration of this into standard software technologies currently used at various stages in manufacturing life cycle. A lot of attention has been given to exploring the usability and benefits of interactive VR for assembly planning, knowledge elicitation and design and simulation. However, little research has focussed on the analytical aspects of the design process, for example in the use of VR as an interface for simulation software in finite element methods and multi-body systems. This paper introduces research focussing on applications of virtual environments (VEs) for interactive design evaluation and modification adapted and used with standard simulation software. The use of such interactive visualisation offers the engineer more realistic real-time representations of the design and advanced facilities to interact with the model during the design process. While design evaluation is based mainly on visualisation; design modification requires interactive changes of the model during the simulation, and the interfaces described here highlights such applications. In this work, two software prototypes have been developed using VR technology. First, a software tool called design evaluation in virtual environments is presented together with an application in civil engineering to illustrate the mode of operation and added value of the use of an interactive visualisation environment. Linking the simulation software with the VE provides real time bi-directional communication of graphical information which can be successfully achieved even within the limits of current computer technology. The tool includes a suite of software modules and a user interface to facilitate the link between the simulation results and the VE. The second tool facilitates the design modification in virtual environments system by providing real time dynamic simulation. Two dynamic approaches are investigated in order to study the real time simulation issues in the context of design modification and system performance: the classic approach based on rigid interconnected bodies, and a new and novel approach developed by the authors based on particles dynamics. Both implementations have been tested and compared on a mechanism application under the same computing conditions. The research applications presented demonstrate the practicality, flexibility and versatility of the visualisation in virtual environment in design evaluation and modification. However, the computer efficiency whilst carrying out real time dynamic simulation is limiting the range of applications to models of moderate size; however, this is an improvement on previous similar applications.     

A research on an intelligent multipurpose fuzzy semantic enhanced 3D virtual reality simulator for complex maritime missions

In this article, the idea of multipurpose fuzzy semantic enhanced 3D virtual reality simulator for the evaluation of maritime robot algorithms, and for the analysis of maritime missions is presented. The simulator uses the digital mockup technology in blending with semantic domain knowledge of the system, to analyze the tasks remotely. The 3D virtual reality (VR) is proposed to help the operators provide the detailed information and guidance during real-time tele-operations, and the incorporation of fuzzy semantic knowledge makes the virtual environment intelligent and automatic. The integration of fuzzy scene independent ontology with the virtual environment (VE) engenders a knowledge driven inter operable virtual environment which eases the user in natural language querying, personalization, interpretations and manipulation. The distinctive semantic VR scene builder utility of the proposed system draws the VR environment automatically while getting the high level specification of the system for the client. The proposed simulator can be effectively used for real-time robots trainings and for the evaluation of AI based algorithms designed for intelligent vessels and AUV’s without knowing the complex underlying VR scene building technologies. Furthermore, it provides the benefits to optimize the pre-process physical environment operations to mimic the real world into a virtual environment. The remote operations and feasibility analysis performed on virtual simulator can efficiently save the cost, time and claims to provide the operators a preprocessor information and guide.     

Virtual and interactive environments for work of the future

Virtual reality (VR) systems and the virtual environments (VEs) experienced within them have presented challenges to human computer interaction over many years. The sheer range of different interfaces which might be experienced and of different behaviours which might be exhibited have caused difficulties in general understanding of participants’ performance within VR/VE and in providing coherent guidance for designers. We have recently completed a European Information Society Technologies (IST) project, Virtual and Interactive Environments for Workplaces of the Future (VIEW of the Future), which has made great strides in developing improved VR systems and interaction concepts and devices, based upon good understanding of participation in VEs. Particular emphasis in the VIEW of the Future project has been upon mobility and multiple active collaboration in use of VR/VE. This paper introduces a special issue devoted to this project and overviews the project as a whole. In doing so it also reviews some of the human factors issues defined for VR/VE over the years and the contribution of VIEW of the Future to addressing these.     

Integration of manufacturing services into virtual environments over the internet

Virtual reality (VR) is a rapidly developing technology that has a wide spectrum of industrial and commercial applications. Networked (distributed or shared) virtual environments (VE) are of growing interest to modern manufacturing industry; a dominating use of networked virtual manufacturing environments (VMEs) is on-line visualisation and collaborative control of 3D information. This has to be supported by real-time data transfer. To meet a broad range of common requirements for Internet-based VE communications, particularly for virtual manufacturing and collaborative design and control, this paper presents a networked virtual environment system that is designed to support networked virtual design and manufacturing. The system is implemented with manufacturing message specification (MMS) standards so as to integrate a range of manufacturing services into networked VEs over the Internet.     

Spatialized Vibrotactile Feedback Improves Goal-Directed Movements in Cluttered Virtual Environments

Spatial awareness in virtual reality (VR) is a dominant research topic. It plays an essential role in the assessment of human operators’ behavior in simulated tasks, notably for the evaluation of the feasibility of manual maintenance tasks in cluttered industrial settings. In such contexts, it is decisive to evaluate the spatial and temporal correspondence between the operator’s movement kinematics and that of his/her virtual avatar in the virtual environment (VE). Often, in a cluttered VE, direct kinesthetic (force) feedback is limited or absent. We tested whether vibrotactile (cutaneous) feedback would increase visuo-proprioceptive consistency, spatial awareness, and thus the validity of VR studies, by augmenting the perception of the operator’s contact(s) with virtual objects. We present experimental results obtained using a head-mounted display (HMD) during a goal-directed task in a cluttered VE. Results suggest the contribution of spatialized vibrotactile feedback to visuo-proprioceptive consistency.     

Human knowledge acquisition from 3D interaction in virtual environments

Recently,virtual environment (VE) based design and planning,which is a kind of interaction intensive computing,has shown great potential.Most users of such systems are specialists or technicians and their 3D interactions with the system embed a great deal of knowledge and skills.Thus,how to integrate human knowledge and skills into VE is a great challenge to researchers in the human computer interaction field.This paper proposes a method for acquiring user knowledge from VE.The main ideas and work include,abstracting the interactive process and formalizing the interactive semantics,as well as providing a semantic model of an interactive information repository,from which user interactive processes can be retrieved and all kinds of application logics can be established.A virtual assembly planning system is introduced as an example of a practical application of this method.Experiments show that the related models can well capture user knowledge and retrieve the interaction process.     

虚拟手操作技术研究及实现

人机交互是虚拟现实的关键技术之一,而虚拟手操作技术是人机交互技术的重要组成部分,是虚拟现实和运动学相结合的产物.在虚拟手操作技术中如何实现实时、准确的抓取一直是人们所关注的问题.首先研究了虚拟手在虚拟场景中的碰撞检测理论,并在此基础上制定了虚拟手对虚拟物体的稳定抓取规则,然后以Open Inventor为软件平台,采用数据手套和位置跟踪器作为主要的输入设备,实现了虚拟手对虚拟物体的抓取、移动、释放等一系列虚拟操作,实例证明了该技术具有很强的实用性.     

The physiological mirror—a system for unconscious control of a virtual environment through physiological activity

This paper introduces a system for real-time physiological measurement, analysis, and metaphorical visualization within a virtual environment (VE). Our goal is to develop a method that allows humans to unconsciously relate to parts of an environment more strongly than to others, purely induced by their own physiological responses to the virtual reality (VR) displays. In particular, we exploit heart rate, respiration, and galvanic skin response in order to control the behavior of virtual characters in the VE. Such unconscious processes may become a useful tool for storytelling or assist guiding participants through a sequence of tasks in order to make the application more interesting, e.g., in rehabilitation. We claim that anchoring of subjective bodily states to a virtual reality (VR) can enhance a person’s sense of realism of the VR and ultimately create a stronger relationship between humans and the VR.     

Perceiving affordances in virtual reality: influence of person and environmental properties in perception of standing on virtual grounds

We evaluated the perception of affordances in virtual environments (VE). In our work, we considered the affordances for standing on a virtual slanted surface. Participants were asked to judge whether a virtual slanted surface supported upright stance. The objective was to evaluate whether this perception was possible in virtual reality (VR) and comparable to previous works conducted in real environments. We found that the perception of affordances for standing on a slanted surface in virtual reality is possible and comparable (with an underestimation) to previous studies conducted in real environments. We also found that participants were able to extract and to use virtual information about friction in order to judge whether a slanted surface supported an upright stance. Finally, results revealed that the person’s position on the slanted surface is involved in the perception of affordances for standing on virtual grounds. Taken together, our results show quantitatively that the perception of affordances can be effective in virtual environments and influenced by both environmental and person properties. Such a perceptual evaluation of affordances in VR could guide VE designers to improve their designs and to better understand the effect of these designs on VE users.     

一个基于Web的网络虚拟现实系统的设计与实现

虚拟现实技术发展很快,有广泛的工业和商业应用。网络虚拟现实技术已越来越为工业制造业所关注,虚拟制造环境(VME)的一个主要用途是在线可视化和对3D信息的协作控制,这需要实时数据传输的支持。为了满足基于Internet的VE通信需求,特别是为满足虚拟制造和协作设计和控制,该文设计并实现了一个支持网络虚拟设计和制造的网络虚拟现实系统,此系统用MMS协议实现VE通信,并将工业控制服务集成于基于Internet的虚拟环境中。     

Service-oriented architecture for ontologies supporting multi-agent system negotiations in virtual enterprise

This paper offers a service-oriented architecture (SOA) for ontology-based multi-agent system (MAS) negotiations in the context of virtual enterprises (VEs). The objective of this paper is fourfold. First, it is to design a SOA which utilizes ontology and MAS to provide a distributed and interoperable environment for automated negotiations in VE. In this architecture, individual ontologies for both the VE initiator and its potential partners are constructed to describe and store resources and service knowledge. Second, a series of semantic ontology matching methods are developed to reach agents’ interoperability during the negotiation process. Third, correspondence-based extended contract net protocol is presented, which provides basic guidelines for agents’ reaching mutual understandings and service negotiation. Last, a fuzzy set theory based knowledge reuse approach is proposed to evaluate the current negotiation behaviors of the VE partners. A walkthrough example is presented to illustrate the methodologies and system architecture proposed in this paper.     

Rethinking HCI Education for Design: Problem-Based Learning and Virtual Worlds at an HCI Design Studio

The practice of teaching and learning human–computer interaction (HCI) design has to develop its own approaches that balance method and technology use with reflective and situated practice. This article presents our HCI design studio course that makes a combined use of constructivist pedagogies and virtual worlds aiming to aid students critically review and reflect on the use of related methods and technologies in design and to cultivate more general skills like self-directed learning, intrinsic motivation, and critical thinking. Our HCI design studio course can be thought of as an iterative and incremental teaching and learning process that blends HCI methods, design practice, and technology between a real and a virtual design studio. The course introduces problem-based learning to the pedagogies of project-based learning and studio-based learning currently employed in most HCI design studios. The positive student responses and our reflection and experiences focusing on a number of challenges for further implementation are also outlined.     

The effect of sub-threshold forces on human performance in multi-modal computer-aided design

In traditional CAD (computer-aided design) systems, the manipulation of points and lines is often difficult because designers manipulate virtual objects through their vision system. Nowadays, designers can explore and manipulate virtual objects in haptic-enabled CAD systems using haptic devices. Haptic devices can present force feedbacks to pull or push the users’ hands into desirable targets. Of course the intent is for the user to experience the same sensations in the virtual realm as they would in the real world. Thus, sub-threshold forces, which cannot be perceived by users, should be incorporated in the control of users’ movements. As a result, our attention is directed to study the effect of sub-threshold forces on the accuracy of movement in a haptic-enabled virtual reality (VR) system. In this study, our goal is to manipulate users’ hands using controlled forces such that users cannot notice the forces. With this in mind, we have constructed a haptic-enabled virtual environment (VE) to carry out a multi-modal Fitts’ type task. In the task, subjects could see the position of the haptic probe in the VE where forces were applied on their hands. Basically, the accuracy of subjects was measured using a performance index when the intensity and direction of forces changed. A psychophysical method was utilized to ensure that the forces were below the force threshold of the human force perception. Results indicate that the accuracy is affected by the intensity and direction of sub-threshold forces even when users are allowed to control their actions through visual feedbacks.     

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.