Fault detection observer design for networked control system with long time-delays and data packet dropout

Focusing on the networked control system with long time-delays and data packet dropout,the problem of observerbased fault detection of the system is studied.According to conditions of data arrival of the controller,the state observers of the system are designed to detect faults when they occur in the system.When the system is normal,the observers system is modeled as an uncertain switched system.Based on the model,stability condition of the whole system is given.When conditions are satisfied,the system is asymptotically stable.When a fault occurs,the observers residual can change rapidly to detect the fault.A numerical example shows the effectiveness of the proposed method.

Controller design for networked control system with data packet dropout and transmission delays

In this paper, the stabilization problem for a class of networked control systems （NCSs） with data packet dropouts and transmission time delays is considered, where the delays are time-varying and uncertain, the data packet dropout is modeled as a two-state Markov chain. To compensate the lost packet, a data packet dropout compensator is established. Thus a more realistic model for such NCSs is presented. Sufficient conditions for the stabilization of the new resulting system are derived in the form of linear matrix inequalities （LMIs）. Numerical example illustrates the solvability and effectiveness of the results.

Stabilization for nonlinear systems via a limited capacity communication channel with data packet dropout

This paper addresses the stabilization problem for a class of nonlinear systems. It is assumed that the controller can only receive the transmitted sequence of finite coded signals via a limited digital communication channel. Both state and output feedback coder-decoder-controller procedures are proposed. Stabilization conditions involving the size of coding alphabet, the sampling period, system state growth rate and data packet dropout rate are obtained. Finally, an example is given to illustrate the design procedures and effectiveness of the proposed results.

H_(∞) control for a networked Markovian jump system subject to data packet loss based on the observer

This study researches the H_(∞) control issue for a networked Markovian jump system with data packet loss occurring not only in the channel from sensor to controller but also in the channel from controller to actuator via an observer.The mathematical model for the closed‐loop networked Markovian jump system with data packet loss is established.The necessary and sufficient conditions for the closed‐loop system to be stochastically stable are derived.The design approach of the controller and the minimal performance index of the external disturbance suppression are also given in the case that the transition possi-bilities of the system modes and the data packet loss are both partially unavailable.Finally,two numerical examples are used to illustrate the effectiveness of the proposed method.

Efficient Packet Scheduling Technique for Data Merging in Wireless Sensor Networks

Wireless Sensor Networks(WSNs) has become a popular research topic due to its resource constraints. Energy consumption and transmission delay is crucial requirement to be handled to enhance the popularity of WSNs. In order to overcome these issues, we have proposed an Efficient Packet Scheduling Technique for Data Merging in WSNs. Packet scheduling is done by using three levels of priority queue and to reduce the transmission delay. Real-time data packets are placed in high priority queue and Non real-time data packets based on local or remote data are placed on other queues. In this paper, we have used Time Division Multiple Access(TDMA) scheme to efficiently determine the priority of the packet at each level and transmit the data packets from lower level to higher level through intermediate nodes. To reduce the number of transmission, efficient data merge technique is used to merge the data packet in intermediate nodes which has same destination node. Data merge utilize the maximum packet size by appending the merged packets with received packets till the maximum packet size or maximum waiting time is reached. Real-time data packets are directly forwarded to the next node without applying data merge. The performance is evaluated under various metrics like packet delivery ratio, packet drop, energy consumption and delay based on changing the number of nodes and transmission rate. Our results show significant reduction in various performance metrics.

基于Packet Tracer数据链路层帧结构仿真实现

数据链路层位于OSI/RM参考模式的第2层,该层传输的协议数据单元称为帧。在计算机网络原理学习过程中,对于各种类型数据链路层帧结构的理解非常重要。通过在Packet Tracer仿真软件上设计数据链路层帧网络结构、配置网络连通性以及抓取相应帧的协议数据单元,分析数据链路层帧的结构。通过比较理论上的数据链路层帧结构和实际抓取的数据链路层帧结构,进一步加深对数据链路层帧结构的理解。

基于Packet Tracer的OSI模型的数据传输仿真与分析

利用Packet Tracer模拟软件对网络上数据包传输进行了仿真实验,结合OSI七层模型所描述的信息或数据的传输,针对ARP、ICMP等协议中PDU的变化情况,分析了不同节点之间,或同一节点层与层之间的数据通信情况,为仿真软件用于网络协议分析进行了有益的探索。

基于DataSocket设备数据的发布和远程监测

利用网络化在信息交换、资源共享方面的优势 ,设计和开发了网络化监测诊断系统中的远程监测模块。介绍了数据信息包的组织 ,对基于DataSocket进行实时数据发布及远程监测等方面的若干技术问题进行了探讨 ,给出了相关软件的设计流程 ,并结合远程监测、分析设计进行实例演示 ,实现了设备数据发布和远程监测功能。

基于Cisco Packet Tracer的智能机场网络开发设计研究

Packet Tracer是Cisco Systems设计的跨平台可视化仿真工具,允许用户创建网络拓扑并模拟计算机网络。它帮助网络开发人员设计网络原型模型,并提供一个虚拟网络仿真平台,帮助模拟项目并观察其在真实世界中的运行效率。本文使用Cisco Packet Tracer开发了一个智慧机场网络模型,解释了该网络系统在现实生活中的工作过程,并提供了数据传输的过程,搭建一个为机场技术人员进行网络培训的虚拟平台。

Optimal Packet Size of Underwater Sensor Networks

Parameter optimization of nodes communication is the foundation of underwater sensor networks.The packet size is an important indicator of the impact of communication performance.As a result,the optimal packet size selection is a critical issue in improving the communication performance.This paper aims to make a model reflecting the communication characteristics as the optimization target,because underwater sensor networks have the characteristics of high time delay,high energy consumption and high bit error rate.Finally,simulation experiments and theory have demonstrated the effectiveness and timeliness of simultaneous perturbation stochastic approximation(SPSA) algorithm.

Proposed Caching Scheme for Optimizing Trade-off between Freshness and Energy Consumption in Name Data Networking Based IoT

Over the last few years, the Internet of Things (IoT) has become an omnipresent term. The IoT expands the existing common concepts, anytime and anyplace to the connectivity for anything. The proliferation in IoT offers opportunities but may also bear risks. A hitherto neglected aspect is the possible increase in power consumption as smart devices in IoT applications are expected to be reachable by other devices at all times. This implies that the device is consuming electrical energy even when it is not in use for its primary function. Many researchers’ communities have started addressing storage ability like cache memory of smart devices using the concept called—Named Data Networking (NDN) to achieve better energy efficient communication model. In NDN, memory or buffer overflow is the common challenge especially when internal memory of node exceeds its limit and data with highest degree of freshness may not be accommodated and entire scenarios behaves like a traditional network. In such case, Data Caching is not performed by intermediate nodes to guarantee highest degree of freshness. On the periodical updates sent from data producers, it is exceedingly demanded that data consumers must get up to date information at cost of lease energy. Consequently, there is challenge in maintaining tradeoff between freshness energy consumption during Publisher-Subscriber interaction. In our work, we proposed the architecture to overcome cache strategy issue by Smart Caching Algorithm for improvement in memory management and data freshness. The smart caching strategy updates the data at precise interval by keeping garbage data into consideration. It is also observed from experiment that data redundancy can be easily obtained by ignoring/dropping data packets for the information which is not of interest by other participating nodes in network, ultimately leading to optimizing tradeoff between freshness and energy required.

Modeling of Data Reduction in Wireless Sensor Networks

In this paper, we present a stochastic model for data in a Wireless Sensor Network (WSN) using random field theory. The model captures the space-time behavior of the underlying phenomenon being observed by the network. We present results regarding the size and spatial distribution of the regions of the network that sense statistically extreme values of the underlying phenomenon using the theory of extreme excursion regions. These results compliment many existing works in the literature that describe algorithms to reduce the data load, but lack an analytical approach to evaluate the size and spatial distribution of this load. We show that if only the statistically extreme data is transmitted in the network, then the data load can be significantly reduced. Finally, a simple performance model of a WSN is developed based on a collection of asynchronous M/M/1 servers that work in parallel. We derive several performance measures from this performance model. The presented results will be useful in the design of large scale sensor networks.

Analysis and Impact of Surface Acoustic Wave Filter in-Band Ripple on Testing and Measurement of High Data Rate Communications

In this paper, we present a background and theory of the effect of Surface Acoustic Wave (SAW) Filter Module (SFM) in-band ripple on high data rate communications parameters such as the Error Vector Magnitude (EVM). In addition, we present analyses and statements for the choice of unbalanced S-parameters set of the SFM over balanced S-parameters set of the SFM in measurements and Agilent’s Advance Design System (ADS) Ptolemy simulations. A test and measurement setup using Agilent’s equipment will be presented.

打造数据业务链,迎接Mobile Data 2.0时代

在介绍移动数据业务链发展趋势的基础上,从无线接入、分组核心、计费系统、增值应用和服务保障等5个方面着重阐述了移动数据业务链中的5个重要环节。

基于相关波形不变性的数据丢包检测方法

针对数据采集处理系统中数据丢包检测问题,依据连续余弦信号自相关波形不变特性,提出一种基于相关波形不变性的数据丢包检测方法。该方法利用窄带数据自相关波形稳定性,通过对数据传输单元输出数据进行自相关处理求取数据相关波形,通过自相关波形差异化处理对该数据是否丢包实现检测。当数据传输单元输出数据存在丢包时,该数据由单码元调相变为多码元调相,致使数据带宽发生变化,进而引起相关波形发生变化,基于此,可对数据传输单元是否存在数据丢包实现检测和判决。理论分析和实验验证结果均证明了所述方法可行性和有效性。

基于EEMD-WPT的温室环境数据优化处理研究

【目的】解决温室系统中的数据采集传感器容易受到多种环境因素的干扰,从而导致数据中存在噪声的问题。【方法】提出一种集合经验模态分解(Ensemble empirical mode decomposition,EEMD)与小波包自适应阈值(Wavelet packet adaptive threshold,WPT)算法联合的数据降噪处理方法,并采用卡尔曼滤波与自适应加权平均算法对降噪后的数据进行融合。【结果】将EEMD-WPT算法应用于含噪温、湿度数据的降噪处理,相较于降噪前的数据,信噪比提升了73.08%。该算法相较于传统WPT算法具有更好的降噪效果,处理后的数据信噪比提升了40.31%,均方根误差降低了84.75%。【结论】该算法能解决数据跳动、冗余和丢失等问题,并为温室控制系统提供了有效的参数,具有较大的实际应用价值。

Modeling and Simulation Study of Space Data Link Protocol

This research paper describes the design and implementation of the Consultative Committee for Space Data Systems (CCSDS) standards REF _Ref401069962 \r \h \* MERGEFORMAT [1] for Space Data Link Layer Protocol (SDLP). The primer focus is the telecommand (TC) part of the standard. The implementation of the standard was in the form of DLL functions using C++ programming language. The second objective of this paper was to use the DLL functions with OMNeT++ simulating environment to create a simulator in order to analyze the mean end-to-end Packet Delay, maximum achievable application layer throughput for a given fixed link capacity and normalized protocol overhead, defined as the total number of bytes transmitted on the link in a given period of time (e.g. per second) divided by the number of bytes of application data received at the application layer model data sink. In addition, the DLL was also integrated with Ground Support Equipment Operating System (GSEOS), a software system for space instruments and small spacecrafts especially suited for low budget missions. The SDLP is designed for rapid test system design and high flexibility for changing telemetry and command requirements. GSEOS can be seamlessly moved from EM/FM development (bench testing) to flight operations. It features the Python programming language as a configuration/scripting tool and can easily be extended to accommodate custom hardware interfaces. This paper also shows the results of the simulations and its analysis.

基于压缩感知追踪算法的低计算量分组稀疏均衡方案

在广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统中,为了应对复杂的信道带来的符号间干扰,基于信道的稀疏特性,使用广义记忆多项式(Generalized Memory Polynomial,GMP)模型对均衡器输入信号进行非线性建模,进而提出了一种基于压缩感知追踪算法和分组数据模式的低计算量分组稀疏均衡方案。该方案中,为了适应复杂变化的信道,均衡过程中采用了分组数据模式,此外,利用分块矩阵求逆的原理,摒弃了复杂的矩阵求逆运算,在每步的循环中使用矩阵乘法进行迭代计算的方式对正交匹配追踪(Orthogonal Matching Pursuit,OMP)算法及双正交匹配追踪(Double OMP,DOMP)算法进行了改进。仿真结果表明,此分组数据模式有效地改善了均衡效果,同时提出的改进算法在保证误符号率性能的前提下明显地降低了计算量,提升了运算速度。

计及信息不确定性的多端交直流混合配电网分布式二级协同控制

分布式一致性控制(distributed consensus control,DCC)因其灵活协同能力成为交直流混合配电网二次控制的新途径.然而,传统DCC并未考虑实际通信环境中存在的随机时变时延和数据丢包问题,这致使其在非理想通信环境下难以稳定跟踪一致性期望目标.为此,本文提出一种计及信息不确定性的分布式二级协同控制策略.利用变量累加补偿机制,对时变时延和数据丢包进行统一等效.进而基于附加一致性算法(surplus consensus algorithm,SCA)构建具有零稳态误差特性的估计器,并对其收敛性进行推导证明.在此基础上,设计稳态收敛性能不受通信约束干扰的SCA-DCC控制器,实现非理想通信环境下的精准平均电压偏差调节和有功功率成比例分配.随后,以时延容忍度为指标优化SCA-DCC控制器参数,满足系统在不同通信条件下的稳定需求,进一步增强控制器的通信鲁棒性.仿真结果表明,在不同功率扰动和故障工况下,与现有控制策略相比,所提控制策略能够克服时变时延和数据丢包产生的负面影响,在维持较优动态响应性能的同时使稳态电压偏差降低73.08%~85.25%,具有控制精度高和抗扰动能力强的特点.

XFDU标准在遥测数据定义上的应用研究与设计

固定的星载数据格式设计会造成数据冗余,占用遥测数据下行带宽,导致不关注、不需要的数据被传输等问题.参照OAIS模型中XFDU的设计思路,提出了采用CCSDS XFDU标准进行数据格式的包装方法,采用PUS标准的参数定义方法给出了星载数据定义的方法模型,设计了相应的元数据schema,元数据编码表以及进一步的XFDU格式文件.相应设计了XFDU转换器,支持对描述数据格式的星载二进制数据串到XML文件的转换,基于元数据schema生成元数据文本,并进行了相应的测试验证.通用的XFDU转换器可以提供给不同的系统,供其识别和解析收到的数据格式,从而支持异构系统之间异构信息的解读.采用XFDU可以将卫星遥测场景下的数据定义模型与OAIS模型进行衔接,有利于星地的标准化数据流转、处理和保存,从而进行星载数据的灵活定义,成为定义卫星的一个手段.