Real-time performance of periodic data transmission in EPA industrial Ethernet

To evaluate and improve the real-time performance of Ethernet for plant automation（EPA） industrial Ethernet,the real-time performance of EPA periodic data transmission was theoretically and experimentally studied.By analyzing information transmission regularity and EPA deterministic scheduling mechanism,periodic messages were categorized as different modes according to their entering-queue time.The scheduling characteristics and delivery time of each mode and their interacting relations were studied,during which the models of real-time performance of periodic information transmission in EPA system were established.On this basis,an experimental platform is developed to test the delivery time of periodic messages transmission in EPA system.According to the analysis and the experiment,the main factors that limit the real-time performance of EPA periodic data transmission and the improvement methods were proposed.

Real-time Performance Evaluation of Line Topology Switched Ethernet

Recently,switched Ethernet has become an active area of research because of its wide uses in industry.However,its uses have various real-time constraints on data communications.This paper analyzes the performance of the line topology switched Ethernet as a data acquisition network.Network calculus theory,which has been successfully applied to assess the real-time performance of packet-switched networks,is used to analyze the networks.To properly describe the activity of switches,a novel approach of modeling data flows into or out of switches is addressed.Based on our model,a concisely analytical expression of the maximal end-to-end delay in line topology switched Ethernet is derived.Finally,the relative simulation results are demonstrated.These results agree well with the analytical results,and thus they validate the data flow modeling techniques.

Real-Time Memory Data Optimization Mechanism of Edge IoT Agent

With the full development of disk-resident databases(DRDB)in recent years,it is widely used in business and transactional applications.In long-term use,some problems of disk databases are gradually exposed.For applications with high real-time requirements,the performance of using disk database is not satisfactory.In the context of the booming development of the Internet of things,domestic real-time databases have also gradually developed.Still,most of them only support the storage,processing,and analysis of data values with fewer data types,which can not fully meet the current industrial process control system data types,complex sources,fast update speed,and other needs.Facing the business needs of efficient data collection and storage of the Internet of things,this paper optimizes the transaction processing efficiency and data storage performance of the memory database,constructs a lightweight real-time memory database transaction processing and data storage model,realizes a lightweight real-time memory database transaction processing and data storage model,and improves the reliability and efficiency of the database.Through simulation,we proved that the cache hit rate of the cache replacement algorithm proposed in this paper is higher than the traditional LRU(Least Recently Used)algorithm.Using the cache replacement algorithm proposed in this paper can improve the performance of the system cache.

A new real-time ethernet MAC protocol for time-critical applications

The authors propose a new persistent transmission based real time Ethernet MAC protocol that provides a predictable upper bound for the delivery delay of real time frames. Moreover, it is compatible with the protocol used by the existing Ethernet controllers for conventional datagram traffic and thus standard Ethernet stations can be used in the system without any modification. The paper describes the protocol in detail and analyses the maximum delivery delay for real time traffic and the efficiency of the channel.

Real-time accurate hand path tracking and joint trajectory planning for industrial robots(Ⅰ)

Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Car-tesian space mainly through increasing the number of knots on the path and the number of the path′s segments, which results in the heavier online computational burden for the robot controller. Aiming at overcoming this drawback, the authors propose a new kind of real-time accurate hand path tracking and joint trajectory planning method. Through selecting some extra knots on the specified hand path by a certain rule and introducing a sinusoidal function to the joint displacement equation of each segment, this method can greatly raise the path tracking accuracy of robot′s hand and does not change the number of the path′s segments. It also does not increase markedly the computational burden of robot controller. The result of simulation indicates that this method is very effective, and has important value in increasing the application of industrial robots.

A Novel Medium Access Control Protocol for Real-Time Wireless Communications in Industrial Automation

In this paper, a novel Medium Access Control (MAC) protocol for industrial Wireless Local Area Networks (WLANs) is proposed and studied. The main challenge in industry automation systems is the ultra-low network latency with a target upper bound in the order of 1 ms while maintaining high network reliability and availability. The novelty of the proposed wireless MAC protocol resides in its similar latency performance as its counterpart in wired industrial LAN. First, the functional design of the MAC protocol is introduced. Then its performance results gained from hardware implementation (SystemC and VHDL) on an FPGA platform are presented. Finally, a real-time communication module which achieves the ultra-low latency required in industrial automation is described.

Real-time accurate hand path tracking and joint trajectory planning for industrial robots(Ⅱ)

Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Cartesian space mainly through increasing the number of knots on the path and the segments of the path. But, this method resulted in the heavier on line computational burden for the robot controller. In this paper, aiming at this drawback, the authors propose a new kind of real time accurate hand path tracking and joint trajectory planning method for robots. Through selecting some extra knots on the specified hand path by a certain rule, which enables the number of knots on each segment to increase from two to four, and through introducing a sinusoidal function and a cosinoidal function to the joint displacement equation of each segment, this method can raise the path tracking accuracy of robot′s hand greatly but does not increase the computational burden of robot controller markedly.

基于Ethernet-APL的新型工业控制系统设计

两线制以太网Ethernet-APL通信技术,以其供电、高带宽、远距离、防爆设计成为目前工业领域最具潜力的现场通信技术,国内产业链正在积极推动Ethernet-APL芯片、仪表、交换机、控制系统的研发。从工业控制系统角度,提出了Ethernet-APL新型工业控制系统可能的应用场景以及与之匹配的系统架构。同时,也对该控制系统的网络负荷、实时性、网络冗余、仪表IP分配等关键技术提出了设计方案。随着该技术的推广,将会助力仪表智能化及工厂智能制造的实现。

IEEE1588 Time Synchronizing System Multiplexing Industrial Ethernet of Distribution Automation

The present study explores an IEEE1588 Synchronizing System for smart distribution grid based on Industrial Ethernet. The paper first analyzes the communication system in distribution network and then proposed the project of time synchronizing system using IEEE1588 in distribution network. The study focuses on rational clock correcting time region segmentation, selecting the best clock source injection point and multiple redundant methods when correcting time method lose efficacy, etc. The precision of time synchronizing is better than that of 1 millisecond.

Standardization of Fieldbus and Industrial Ethernet

Fieldbus and industrial Ethernet standards can guide the specification andcoordinate bus optimization. The standards are the basis for the development of field-bus and industrial Ethernet. In this paper, we review complex standard systems allover the world. We discuss 18 fieldbus standards, including the International Electro-technical Commission(IEC) 61158, the IEC 61784 standard matched with IEC 61158,the controller and device interface standard IEC 62026 for low voltage distributionand control devices, and the International Organization for Standardization(ISO)11898 and ISO 11519 standards related to the controller area network(CAN) bus. Wealso introduce the standards of China, Europe, Japan and America. This paper pro-vides a reference to develop fieldbus and industrial Ethernet products for Chinese en-terprises.

PROFIBUS与Industrial Ethernet在自动化系统中的应用

介绍了PROFIBUS与Industrial Ethernet在整套自动化系统中的应用,两者的结合使用在提高自动化系统的稳定性的同时,节约成本,便于维护。

Wireless Fault-Tolerant Controllers in Cascaded Industrial Workcells Using Wi-Fi and Ethernet

A Wireless Networked Control System using 802.11b is used to model fault-tolerance at the controller level of an industrial workcell. The fault-tolerance study in this paper presents the cascading of two independent workcells where each controller must be able to handle the load of both cells in case of failure of the other one. The intercommunication is completely wireless between the cells and this feature is investigated. The model incorporates unmodified 802.11b and 802.11g for communication. Sensors send sampled data to both controllers and the controllers to exchange a watchdog. The fault-free and faulty models are both simulated using OPNET Network Modeler. External interference on the critical intercommunication link is also investigated. Results of simulations are presented based on a 95% confidence analysis, guaranteeing correct system performance.

Inter-laboratory Validation of Real-time PCR Assays for Goat-,Horse-and Donkey-derived Material in Meat Products

In this study,we performed an inter-laboratory collaborative ring trial to develop and validate specific TaqMan real-time PCR assays for goat-,horse-,and donkey-derived material in meat products.The performances of these assays in different environments and situations were comprehensively evaluated.This ring trial involved the participation of 12 laboratories in Europe and Asia.The results from the participating laboratories were analyzed to determine the specificity,accuracy,false positive rate,limit of detection(LOD),and probability of detection(POD)of the developed assays.Statistical analysis showed that the false positive and negative rates were zero,the LOD was five copies/reaction,and the laboratory standard deviation(σ_(L))was 0.30 for all three assays.Thus,the results demonstrate that the developed methods are robust and suitable for the detection and identification of goat-,horse-,and donkey-derived materials in meat products.

A Real-Time Fraud Detection Algorithm Based on Usage Amount Forecast

Real-time Fraud Detection has always been a challenging task, especially in financial, insurance, and telecom industries. There are mainly three methods, which are rule set, outlier detection and classification to solve the problem. But those methods have some drawbacks respectively. To overcome these limitations, we propose a new algorithm UAF (Usage Amount Forecast).Firstly, Manhattan distance is used to measure the similarity between fraudulent instances and normal ones. Secondly, UAF gives real-time score which detects the fraud early and reduces as much economic loss as possible. Experiments on various real-world datasets demonstrate the high potential of UAF for processing real-time data and predicting fraudulent users.

基于总线同步的多驱动系统漏电流分析与抑制

多驱动系统中漏电流的大量存在是影响数控加工装备长期稳定运行的重要因素,提出了一种邻消抑制措施,能够有效减少多驱动系统中漏电流,避免漏电保护装置频繁触发。该措施采用PWM调制策略,将空间位置相邻的两个驱动单元的共模电压矢量方向反向,以抵消它们之间的高频共模电压分量,从而有效地抑制了多驱动系统的漏电流。主要创新之处采用了一种软件控制的方式实现了对多驱动系统漏电流的抑制,该措施不但可以有效地抑制漏电流,而且实现成本低。实际测试平台的结果表明,邻消抑制措施在多驱动系统中能够有效降低70%~80%的漏电流,保证了多驱动系统的稳定运行。

Ethernet与工业控制网络

从 Ethernet的产生和特点分析 ,分析了以前 Ethernet未能应用于工业自动化的原因 ;从 Ethernet应用于工业控制领域过程监控层网络的发展趋势 ,分析了 Ethernet应用于现场总线的可行性及需要解决的关键技术难题。最后对“e网到底”应用前景进行了展望。

Ethernet/IP工业以太网的研究及应用

介绍了工业以太网的发展改进状况,对Ethernet/IP这种新型工业以太网的协议模型及其采用的"生产者/消费者"通讯模式和面向"连接"的,CIP(Common Industrial Protocol,CIP)报文通信机制做了详细分析,同时指出了Ether-net/IP网络应用在工业控制领域的优势。提出了Ethernet/IP工业以太网在高速公路隧道监控中具体的组网方案和通讯设置手段,利用Ethernet/IP网络成功地实现了对该高速公路隧道的良好监控。