Cooperative teleoperation of a multirobot system with force reflection via Internet

With the rapid development of information technology, the Internet has evolved from a simple data-sharing media to an amazing information world where people can enjoy various services. Recently, the use of the Internet has been expanded to the field of automation, i.e., using the Internet as a tool to control equipment located at remote sites. This work presents a system that enables multiple operators at different sites to cooperatively control multiple robots with real-time force reflecting via the Internet. To overcome instability and reliability problems caused by random time delay of the Internet communication, we adopt an event as the reference for the controller design. To improve real-time efficiency and reduce the complexity of the controller, a distributed approach is proposed for the control of remote robots, so that the time delay in one control loop does not affect performance of the others. A vision-based method is developed to monitor and render interactions between the robots. The usefulness and effectiveness of the developed method and system have been verified by teleoperation experiments on a two-robots cooperative system among Hong Kong, mainland China, and the U.S.     

Haptic information in Internet-based teleoperation

Many tasks can be done easily by humans turn out to be very difficult to accomplish with a teleoperated robot. The main reason for this is the lack of tactile sensing, which cannot be replaced by visual feedback alone. Once haptic devices are developed, their potential in many fields is obvious. Especially, in teleoperation systems, where haptic feedback can increase the efficiency and even render some tasks feasible. This paper studies Internet-based teleoperation systems that include haptic feedback, concentrating on the control of such systems and their performance. The potential of this technology and its advantages are explored. In addition, key issues, such as stability, synchronization, and transparency are analyzed and studied. Specifically, an event-based planning and control of Internet-based teleoperation systems is presented with experimental results of several implemented system scenarios in micro- and macro-scales     

模型预测控制在网络闭环控制中的应用研究

在基于Internet的远程控制系统中,通过Internet进行信息传输的时间延时的不确定性对实时闭环控制系统的设计带来较大的困难.研究了网络传输延时对网络闭环控制系统的影响,提出了通过基于神经网络的预测控制方法解决存在网络随机延时的控制系统闭环控制的可行性.仿真结果表明该方法能够反映并预测该测量数据所代表的网络路径之间的时延特性,并能在基于Internet的闭环控制系统的设计中有效地替代实际网络进行研究;而所用的方法具有快速、准确的特点,能用于在线学习网络模型并对网络的时延值进行预测,为基于Internet的远程闭环控制提供了新的思路.     

移动蜂窝物联网无线网络规划的探讨

时代在进步,物联网已深入应用到社会产业体系,强化了我国各个社会产业体系的联系,且向服务行业渗透。我国的经济建设目标聚焦在物联网上,移动通信网络在物联网建设发挥了关键的作用。基于此,本文介绍了移动蜂窝物联网技术,详细研究了蜂窝物联网规划,希望为有关企业提供合理建议。     

Multirate Control in Internet-Based Control Systems

One of the major challenges in Internet-based control systems is how to overcome the Internet transmission delay. In this paper, we investigate the potential of using the multirate control scheme and the time-delay compensation to overcome the Internet transmission delay. A two-level hierarchy is used for the Internet-based control systems. At the lower level, a local controller is implemented to control the plant at a higher frequency. At the higher level, a remote controller is employed to remotely regulate the desirable set-point at a lower frequency for the local controller. A compensator located at the feedback channel is designed to overcome the time delay occurring in the transmission from the local site to a remote site. Another compensator in the feedforward channel is designed to compensate the time-delay occurring in the control action transmission. The simulation and experimental application results illustrate that the multirate control scheme with the time delay compensation offers a promising way to efficiently reduce the effect of Internet time delay on control performance     

基于主流移动操作系统的移动终端视频监控指挥通信技术研究

本文介绍的一种基于主流移动操作系统的移动终端视频监控指挥通信技术,提出使用移动中间件模式来解决视频监控软件在各种移动平台上的复杂性、差异性问题,将远程视频监控、会议、控制等重要功能有效地扩展到移动系统上,兼容各种无线网络和主流移动操作系统,能够很好地解决由于无线网络带宽的局限性以及视频编解码技术瓶颈所造成的分辨率低、延时等问题,可满足应急指挥过程实时监控、视频通信、可视化调度的应用需求;能让决策者及相关专家同步"巡视现场",制定科学的指挥调度方案,做到快速判断、科学决策、精准指挥,有效提高相关部门处置突发公共安全事件的能力。     

Maximum runlength-limited codes with error control capabilities

New methods are presented to protect maximum runlength-limited sequences against random and burst errors and to avoid error propagation. The methods employ parallel conversion techniques and enumerative coding algorithms that transform binary user information into constrained codewords. The new schemes have a low complexity and are very efficient. The approach can be used for modulation coding in recording systems and for synchronization and line coding in communication systems. The schemes enable the usage of high-rate constrained codes, as error control can be provided with similar capabilities as for unconstrained sequences     

Intermediate Representations for Design Automation of Multiprocessor DSP Systems

Self-timed scheduling is an attractive implementation style for multiprocessor DSP systems due to its ability to exploit predictability in application behavior, its avoidanceof over-constrained synchronization, and its simplified clocking requirements.However, analysis and optimization of self-timed systems under real-time constraintsis challenging due to the complex, irregular dynamics of self-timed operation.In this paper, we review a number of high-level intermediate representationsfor compiling dataflow programs onto self-timed DSP platforms, including representationsfor modeling the placement of interprocessor communication (IPC) operations;separating synchronization from data transfer during IPC; modeling and optimizinglinear orderings of communication operations; performing accurate design spaceexploration under communication resource contention; and exploring alternativeprocessor assignments during the synthesis process. We review the structureof these representations, and discuss efficient techniques that operate onthem to streamline scheduling, communication synthesis, and power managementof multiprocessor DSP implementations.     

Quasi-tree mobility management for internet connectivity of mobile ad hoc networks

The location of mobile nodes must be managed to enable Internet connectivity of mobile ad hoc networks. Node mobility can be managed efficiently using a tree topology in which a mobile node registers with an Internet gateway along a tree path without using flooding. However, a node that loses connectivity to its parent has to find and connect to a new parent through a join-handshaking process. This tends to increase control overhead and impose some delay on on-going communication. Furthermore, the node may join its descendant because of the synchronization delay in updating topology change, creating a loop that significantly increases control overhead. We improve these problems by maintaining a quasi-tree topology in which a node maintains multiple parents. We also present a technique for detection and resolution of loops. The simulation results show that the quasi-tree mobility management approach far outperforms the traditional approaches and is highly robust against the significant increases in tree size and node mobility.     

Force-reflecting teleoperation over the Internet: the JBIT project

An ever-growing number of Internet-connected devices are now accessible to a multitude of users. Being an ubiquitous communication means, the Internet could enable any user to reach and command any device connected to the network. This paper reports the successful application of real-time closed-loop control over the Internet in the Java-Based Interface for Telerobotics (JBIT) system, in which the Internet users can access and command a two-degrees-of-freedom robot in real time, receiving both visual and force feedback. When closed-loop control of a remote system comes into play, careful evaluation of the performance and limits of the communication system in use is mandatory. The reported analysis shows that the main Internet limits are unknown available throughput, variable delay, and loss of some data packets, in particular when the network is congested. Once the limits of the communication system are known, it is shown that it is possible to use the Internet for the remote closed-loop control of a slave robot, provided that suitable strategies to guarantee operability and safety of the controlled system are implemented. Such strategies are concerned with on-line identification of the connection characteristics, adaptation of the data rate to the available throughput, recovery of the missing packet, and handling of the variable delay. Moreover, visual feedback dataflow shares the same Internet connection with the real-time control data. To prevent congestion, new tools for adaptive dataflow management have been developed. Finally, an improved coordinating force control scheme, aimed at enhancing the transparency of the teleoperator, is presented.     

移动终端GPRS嵌入式协议栈的实现

在智能交通调度系统中,在车载移动终端安装GPRS模块,通过GSM扩展的包交换业务使终端接入IP网络,实现调度中心与移动终端的交互,是一种经济、实用、高效的数据传输手段。介绍了该系统的组网方式,以及移动终端的软硬件构成,说明了移动终端通过GPRS模块接入Internet网络,与调度中心通信的方法,并对具体协议栈的实现过程进行了详细的分析。     

Mobile WiMAX: a technology update

The success and growth of Internet-based services has profoundly impacted the global economies, as well as the ways people communicate and their lifestyles. With ever increasing demands for accessing the Internet via mobile devices, the focus of next-generation mobile wireless technology development is to enable and efficiently deliver broadband mobile multimedia and Internet services to users. The communication industry is making big strides in the design of next-generation broadband mobile networks which are poised to enormously increase the value of the Internet and its usage by bringing the Internet to users as opposed to having users go to the Internet.     

宽带短波信道建模综述

宽带短波通信系统作为中远程主要通信手段受到了人们的广泛关注,研究宽带短波系统的重点和难点是宽带短波的信道建模。Watterson信道模型作为比较经典的窄带模型,从它的基础上衍生出2种宽带短波信道模型,Watterson后接高斯随机延迟模型和Watterson后接群延迟特性滤波器模型。另外还介绍了电离层物理模型、Volger决定性模型、ITS信道模型及其改进、基于并行子路径结构的宽带信道模型、伪决定性信道模型和子带并行-宽带窄带化模型。对这几种模型的建模思想以及基本原理进行了叙述,对其复杂度进行了比较并且对可行性进行了分析。     

A Novel Artificial Intelligence Based Timing Synchronization Scheme for Smart Grid Applications

The smart grid control applications necessitate real-time communication systems with time efficiency for real-time monitoring, measurement, and control. Time-efficient communication systems should have the ability to function in severe propagation conditions in smart grid applications. The data/packet communications need to be maintained by synchronized timing and reliability through equally considering the signal deterioration occurrences, which are propagation delay, phase errors and channel conditions. Phase synchronization plays a vital part in the digital smart grid to get precise and real-time control measurement information. IEEE C37.118 and IEC 61850 had implemented for the synchronization communication to measure as well as control the smart grid applications. Both IEEE C37.118 and IEC 61850 experienced a huge propagation and packet delays due to synchronization precision issues. Because of these delays and errors, measurement and monitoring of the smart grid application in real-time is not accurate. Therefore, it has been investigated that the time synchronization in real-time is a critical challenge in smart grid applications, and for this issue, other errors raised consequently. The existing communication systems are designed with the phasor measurement unit (PMU) along with communication protocol IEEE C37.118 and uses the GPS timestamps as the reference clock stamps. The absence of GPS increases the clock offsets, which surely can hamper the synchronization process and the full control measurement system that can be imprecise. Therefore, to reduce this clock offsets, a new algorithm is needed which may consider any alternative reference timestamps rather than GPS. The revolutionary Artificial Intelligence (AI) enables the industrial revolution to provide a significant performance to engineering solutions. Therefore, this article proposed the AI-based Synchronization scheme to mitigate smart grid timing issues. The backpropagation neural network is applied as the AI method that employs the timing estimations and error corrections for the precise performances. The novel AIFS scheme is considered the radio communication functionalities in order to connect the external timing server. The performance of the proposed AIFS scheme is evaluated using a MATLAB-based simulation approach. Simulation results show that the proposed scheme performs better than the existing system.

     

MiniGUI-Threads与MiniGUI-Lite下多串口通信的设计与实现

MiniGUI是目前较成熟的嵌入式Linux系统的图形用户界面，具有小巧、可配置和可移植等特点。MiniGUI可以编译成两个截然不同的运行模式：MiniGUI—Threads模式适用于实时性高，功能相对简单的系统，比如工控仪器等；而MiniGUI-Lite模式多用于功能丰富，结构复杂的系统，如PDA等信息产品。文章介绍了如何在这两个运行模式下设计并实现多个串口的实时双工通信，最后还指出了两种模式下实现串口监听程序和同步问题方面的差别。     

同步卫星移动通信系统的网络内部通信

本文论述了采用 Ｆ Ｄ Ｍ Ａ ／ Ｔ Ｄ Ｍ Ａ 体制的区域卫星移动通信系统的基本特点、组成以及网络内部通信。文中对网络内部通信划定了界线,明确了它的主要任务,并对内部通信链路和同步过程作了详细的描述。     

A Bandwidth Control Method Providing Entrance QoS for Multimedia Communication

1 Motivation Nowadays , the QoS provided by the wideband IPnetwork starts at an edge-router and ends at anotheredge-router .Therefore ,the trunk QoSisfinished,suchas RSVP[1]and DiffServ[2].In order to complete theend-to-end QoS,the mechanism of entrance QoS (thebandwidth controller) is introduced. As Fig.1 shows ,if the bandwidth controller circledby the dashed frame is not used,the Ethernet is con-nected with the router directly through 100 Mbit/sbandwidth. Then this router is connect…     

基于无线局域网的移动IPv6链路层切换

随着实时业务(如VOIP)的快速发展,移动IPv6技术的切换过程时延已经不能满足现代通信的需求,因此改进切换时延,提高切换质量很有必要.本文介绍了当一个移动节点(MN)尝试进行基于无线局域网的MIPv6链路层的切换时,利用邻居图算法或邻居缓存机制来减少扫描延迟,从而减少总切换延迟.     

Web-interfaced, force-reflecting teleoperation systems

An ever-growing number of Internet-connected devices is now accessible to a multitude of users. Being a ubiquitous communication means, the Internet could allow any user to reach and command any device connected to the network. This paper reports the successful application of real-time closed-loop control over the Internet in the Java Based Interface for Telerobotics (JBIT) system, in which Internet users can access and command a two-degrees-of-freedom robot in real time, receiving both visual and force feedback. When the closed-loop control of a remote system comes into play, careful evaluation of the performance and limits of the communication system in use is mandatory. The analysis reported shows that the main limits of the Internet are the unknown available throughput, the variable delay, and the loss of some data packets, in particular, when the network is congested. Once the limits of the communication system are known, it is shown that it is possible to use the Internet for the remote closed-loop control of a slave robot, provided that suitable strategies to guarantee operability and safety of the controlled system have been implemented. The strategies implemented in order to overcome the limits posed by the present Internet characteristics are described, along with an improved coordinating force control scheme, which enhances the transparency of the teleoperator     

Video transmission over mobile satellite systems

Mobile satellite communication channels are characterized by long transmission delays, variation of these delays, high bit‐error‐rates, shadowing and the multipath effect which severely reduce the quality of video services. Error control techniques including feedback mechanisms, error concealment methods, forward error correction techniques and error resilience schemes are examined in this paper for achieving a high‐integrity video transmission over a mobile satellite channel. The application of three different error resilience algorithms, namely Turbo codes, error‐resilient entropy codes and two‐way decoding using reversible codes is presented. Their joint performance is also examined. Furthermore, a low‐delay and low‐complexity video transcoding algorithm which fully interconnects two very low bit rate video communication standards: MPEG‐4 and H.263 is also elaborated. This transcoder works as a gateway tool which links two heterogeneous multimedia networks, such as a mobile satellite network and a land‐based network, with negligible processing delay and complexity. Copyright © 2000 John Wiley & Sons, Ltd.