Recovery from virtual environment exposure: expected time course of symptoms and potential readaptation strategies

OBJECTIVE: This study investigated potential means of facilitating a return to normal functioning following virtual environment (VE) exposure using a peg-in-hole exercise in recalibrating hand-eye coordination, a targeted gait movement (rail walking) in recalibrating vestibular (i.e., postural) aftereffects, and natural decay. BACKGROUND: Despite technology advances and considerable efforts focused on the identification and quantification of VE aftereffects, few have addressed means for recuperation, the focus of the current study. METHOD: After 15 min-60 min of VE exposure and recalibratory exercises, hand-eye coordination and postural stability were assessed electronically, the former via a 3-D measure capturing pointing errors, and the latter by head and body oscillations while standing in the tandem Romberg position. Both measurements were collected immediately after VE exposure and every 15 min up to 1 hr thereafter. Results: Participants (more than 900 college students) who experienced the peg-in-hole readaptation strategy had a significant decrease (p < 0.000 in pointing errors following the exercise; the other two methods (i.e., rail walking, natural decay) showed no significant change. For posture, all groups showed significant improvement during the 15 minutes after VE exposure, yet none returned to baseline by 1 hr postexposure. CONCLUSION: Although hand-eye coordination readaptation strategies showed noticeable effects immediately after they were performed, aftereffects were not completely eliminated after 1 hr; hence further research on readaptation strategies is essential to achieve more substantial recalibratory gains in hand-eye coordination and posture. Additionally, hand-eye coordination and vestibular aftereffects may require a period exceeding the VE immersion time in order to recover. APPLICATION: These findings may serve as a guide in the development of monitoring policies following VE exposure.     

Adaptive walking control of quadruped robots based on central pattern generator （CPG） and reflex

This paper presents a central pattern generator (CPG) and vestibular reflex combined control strategy for a quadruped robot. An oscillator network and a knee-to-hip mapping function are presented to realize the rhythmic motion for the quadruped robot. A two-phase parameter tuning method is designed to adjust the parameters of oscillator network. First, based on the numerical simulation, the influences of the parameters on the output signals are analyzed, then the genetic algorithm (GA) is used to evolve the phase relationships of the oscillators to realize the basic animal-like walking pattern. Moreover, the animal’s vestibular reflex mechanism is mimicked to realize the adaptive walking of the quadruped robot on a slope terrain. Coupled with the sensory feedback information, the robot can walk up and down the slope smoothly. The presented bio-inspired control method is validated through simulations and experiments with AIBO. Under the control of the presented CPG and vestibular reflex combined control method, AIBO can cope with slipping, falling down and walk on a slope successfully, which demonstrates the effectiveness of the proposed walking control method.     

面向联盟企业的智能化专业搜索体系设计与实现

1.引言联盟企业是指在日益激烈的市场竞争中具有不同、互补的技术和生产能力的企业间为响应市场需求而进行动态联合的方式,是一种随着市场需求变化的可重构、可重用、可扩展的动态组织形态。其成员或网络用户是否通过协同网络在分布式组织结构中高效、快捷地获得用户需求、用户定单、产品市场前景和企业生产资源、加工能力、产品资源信息以及虚拟企业内各单元的生产状况、数据、文档等信息,将直接影响     

Measurement of postural stability before and after immersion in a virtual environment

Research into the effects of simulators has led to suggestions that postural instability occurring after immersion in a virtual reality virtual environment (VR/VE) may have direct implications for the safety of post-immersion activities such as driving or operating machinery. However, experimental studies have highlighted a lack of standardisation in the postural stability measurement techniques applied and subsequent inconsistencies in the results obtained. An experiment was conducted to evaluate the use of static, dynamic and posturographic postural stability measures in determining the effect of participation in an interactive virtual environment (VE) for 20 min. The results demonstrate differences in the sensitivity of postural stability measurement techniques and variations in inter- and intra-individual responses to measures. The VE immersion was found to produce postural instability only when measured using a posturographic technique under normal stance static posture, and then only mildly and not long-lasting. No associations were found between reported symptoms of simulator sickness and postural stability with postural stability measures. This paper discusses issues relating to postural stability measurement and the implications for evaluation of virtual environment effects.     

虚拟制造技术在VE型分配泵研发中的实现

该文基于虚拟制造技术,从面向产品伞生命周期的角度,以汽车发动机VE型分配泵为研究对象,研究了以设计为中心的虚拟制造技术在汽车零部件设计中的实现。研究内容主要包括虚拟设计、虚拟样机、虚拟装配、有限无分析、虚拟加工仿真等,并对研究结果进行了实验验证。该文利用该研究力’法重点分析了VE型分配泵传动部件易断裂问题,并结合企业实际给出了解决方案。企业的成功实践表明．将虚拟制造技术应用于产品的开发与改进,是一种切实可行的设计理念和方法。     

UML在虚拟企业集成模型中的应用

建立虚拟企业集成模型是虚拟企业创建和运作的关键。在分析虚拟企业建模和其面临问题的基础上,提出使用面向对象的、可视化的统一建模语言UML,来为虚拟企业集成模型进行建模,并详细介绍了UML如何对虚拟企业集成模型各视图进行描述。最后,还提出了UML对虚拟企业建模的集成支持环境。     

Selecting manufacturing partners in push and pull-type smart collaborative networks

The idea of Collaborative Manufacturing, also known as the Production Networks or Social Manufacturing, has been around for more than 25 years. It is a production concept based on non-hierarchical collaboration among enterprises often referred as Virtual Enterprise (VE). Despite many scientific research and projects with this topic, it is difficult to find an example of fully operational non-hierarchical production network anywhere in the world. However, that fact could be changed very soon. Namely, the new industrial revolution, called Industry 4.0, encourages industrial enterprises to adopt information-communication technology (ICT) and Internet of Things (IoT) into their production systems, thus creating Cyber-Physical Production System (CPPS). From the aspect of production networks, CPPS represents crucial infrastructure, or a missing link between enterprises. Now, with CPPS in place, non-hierarchical networking and collaboration becomes possible through Smart Collaborative Production Networks. In this research, the concept of information system for Smart Collaborative Production Networks was developed and called ‘VENTIS’. Although the idea of the concept is to manage the collaboration inside Virtual Enterprise, in this research, a special focus has been put on manufacturing planning phase in which optimization problem known as the Partner Selection Problem (PSP) occurs. Since the PSP in manufacturing phase is far more complex than partner selection during the collaborative product development phase, new research premises regarding the Virtual Enterprise type have been set. Two types of Virtual Enterprise business models – Push-type and Pull-type – have been defined in this research. If VE is Push-type, HUMANT algorithm is used to solve PSP that occurs in that case. If VE is Pull-type, a special procedure, inspired by phenomenological reduction, has been established in which set of a priori created VEs is compared with theoretically ‘the best’ VE and theoretically ‘the worst’ VE. Enterprises’ data of production network from Dalmatia (Split-Dalmatia County, Croatia) is used as a Case Study to present ‘VENTIS’ concept and to present the procedure for creation of sustainable Virtual Enterprise.     

面向虚拟企业的PDM系统研究

分析了虚拟企业对虚拟产品数据管理（VPDM）的功能要求，并从整个产品生命周期涉 及的多个领域出发，提出面向虚拟企业的VPDM体系结构。在此基础上，给出了VPDM在全局模 型、冲突与协商、系统集成等方面的实现技术。     

Active video game head movement inputs

Virtual reality has been extensively studied for applications in rehabilitation. With the development of active video games, these commercial products can also be considered for inclusion in a patient’s rehabilitation program. In this study, the Sony EyeToy ^® and PlayStation 2 ^® were used with the AntiGrav? game to evaluate the user’s head movement actions. The game required lateral head, body, and arm movements. Over the course of 9 sessions of game play, average and maximum head excursions remained constant. However, the frequency of head movement increased over the sessions. The results suggest that the video game could be used for postural balance rehabilitation through head movements, and their effect on the vestibular system. Future work will evaluate how such vestibular exercise, and an increase in head movement frequency over training sessions can support postural balance improvements.     

基于贝叶斯正则化神经网络虚拟企业敏捷性评价

高敏捷性是虚拟企业适应不断变化的市场必备的素质,如何对它进行准确评价是虚拟企业运行中的重要问题,针对此问题先对虚拟企业及其盟员敏捷性之间的关系分析,然后提出在已知虚拟企业盟员敏捷性的基础上用贝叶斯正则化神经网络来计算虚拟企业的敏捷性,最后通过仿真试验测试了该方法的可行性。实验结果证明与非正则化神经网络相比,贝叶斯正则化神经网络的泛化能力强,评价数据结果稳定。该方法可用于各种规模的虚拟企业评价。     

Sensory reweighting: a common mechanism for subjective visual vertical and cybersickness susceptibility

Virtual Reality - The malaise symptoms of cybersickness are thought to be related to the sensory conflict present in the exposure to virtual reality (VR) content. When there is a sensory mismatch...     

Motion Sickness Simulation Based on Sensorimotor Control

Sensorimotor control is an essential mechanism for human motions, from involuntary reflex actions to intentional motor skill learning, such as walking, jumping, and swimming. Humans perform various motions according to different task goals and physiological sensory perception; however, most existing computational approaches for motion simulation and generation rarely consider the effects of human perception. The assumption of perfect perception (i.e., no sensory errors) of existing approaches restricts the generated motion types and makes dynamical reactions less realistic. We propose a general framework for sensorimotor control, integrating a balance controller and a vestibular model, to generate perception‐aware motions. By exploiting simulated perception, more natural responses that are closer to human reactions can be generated. For example, motion sickness caused by the impairments in the function of the vestibular system induces postural instability and body sway. Our approach generates physically correct motions and reasonable reactions to external stimuli since the spatial orientation estimation by the vestibular system is essential to preserve balance. We evaluate our framework by demonstrating standing balance on a rotational platform with different angular speeds and duration. The generated motions show that either faster angular speeds or longer rotational duration cause more severe motion sickness. Our results demonstrate that sensorimotor control, integrating human perception and physically‐based control, offers considerable potential for providing more human‐like behaviors, especially for perceptual illusions of human beings, including visual, proprioceptive, and tactile sensations.     

虚拟环境产生器中几何对象的描述及视觉处理

虚拟环境(VE,Virtual Environments),又称虚拟现实(vR,Virtual Reality),是二十世纪末展起来的一种高新技术。对于虚拟环境这个概念有两种理解方式:一种把VE作为一个图形应用系,在这种系统中能以自然技能与合成环境进行交互,且有     

基于Jack的虚拟环境中一种防止穿越的实现

在虚拟环境下虚拟人手和虚拟物体的交互中,会发生穿越现象。为了解决穿越问题,在人体模型系统Jack的虚拟环境中,根据约束Constraint对象的特点,利用Constraint对象来模拟物体对人手阻挡作用,并利用约束队列实现了对场景中Constraint对象的管理,达到防穿越的效果。     

基于Web Services面向服务架构的虚拟企业解决方案

虚拟企业是一种跨企业间协作的企业模式,因而企业间的应用集成是建立虚拟企业的关键问题之一。针对传统虚拟企业集成方案的复杂、强耦合以及难以维护等不足,利用WebServices技术及UDDI体系实现虚拟企业的优势,提出一个相应的虚拟企业解决方案模型,以达到与环境无关、主动集成和易于维护等目的。     

基于WebService和元数据的虚拟企业信息集成框架

针对虚拟企业对异构分布性信息资源集成的要求,提出了一个基于元数据和Webservice的虚拟企业信息集成框架。详细分析了信息集成协议栈的层次结构,给出虚拟企业服务共享方案和数据共享系统结构。本信息集成框架克服了传统跨平台技术及数据共享技术在实现虚拟企业信息集成中的局限。     

Virtual enterprise and its intelligence management

Virtual enterprise (VE) will be the efficient organization form in the future owing to the rapid development of computer techniques and information technology. This paper exposes systematically the concept of VE and its structure. Methodology for intelligentized management is described. An integrated system based on client/server is proposed, which is useful for intelligent decision making in VE management.     

基于VESA的虚拟企业构建方案的研究

虚拟企业是二十一世纪制造企业的主要模式,它面向全球范围的企业资源,通过构建虚拟企业的联盟之间重组,实现了联盟企业间的柔性化。如何迅速构建虚拟企业是敏捷制造企业要解决的首要问题。Internet的飞速发展,为企业利用互联网实现虚拟企业的构建提供了基础。文章提出了采用ISP形式的虚拟企业构建方案——虚拟企业服务代理商（Virtual Enterprise Service Agent,VESA）,并探讨了VESA的应用构建框架和处理业务。     

基于任务的虚拟企业组织设计研究

虚拟企业构建具有明显的任务导向特征.当某企业面临资源缺乏或能力限制而导致无法独立完成某项生产任务时,就可以以盟主企业身份通过构建虚拟企业来完成该任务.组织设计关系到虚拟企业运作的成败,因此组织设计问题成为虚拟企业研究一个关键问题.本文以注塑模开发任务为例,探讨了虚拟企业组织设计问题,提出虚拟企业组织设计框架,并对组织设...