关于SpaceWire总线接口可靠性的研究

为满足航天器有效载荷间高速数据传输的发展需求,提出了两种SpaceWire总线可靠性的改进方案;在SpaceWire总线描述的基础上,分析了字符的正确性校验和传输过程中的错误及检测恢复机制等提高可靠性的方法;针对通信链路发生物理性故障的问题,提出了两种基于硬件冗余机制的SpaceWire可靠性改进方案,一种是在系统间建立两个相独立的协议装置,另一种是使用多路输出选择器进行切换将数据传输给目的节点;通过实验验证,两种方案能够处理通信链路出现物理故障的问题。     

基于Actor模型的软总线设计

为提高网络化嵌入式系统的安全性与可靠性,提出一种基于Actor模型的软总线设计方法,以解决分布式全数字仿真测试中系统及组件间的通信问题。采用以Actor模型为中心的发布/订阅机制,实现分布式节点之间的同步、异步通信。在此基础上,提出一种基于线程池技术的任务调度方法,实现Actor模型的协同工作,并通过规则链表进行Actor消息的处理及转发。实验结果表明,与HLA、OpenDDS总线相比,在大数据量并发处理的情况下,该软总线程序执行效率提升30%以上,能够满足网络化嵌入式系统测试对实时性与并发性的需求。     

车载CAN网络中直接NM逻辑环的实现

为实时监控车载网络中的节点,在使用控制器区域网络(CAN)总线的车载网络中,设计并实现一种基于OSEK/VDX规范直接网络管理(NM)的车载NM系统。由车载网关通过CAN总线收集各网络节点的故障信息,通过IPv6无线网络上传至远程故障诊断服务器,并将得到的故障处理信息下发至有关节点,实现车载CAN网络与远程故障诊断服务器的信息交互。测试结果表明,各网络节点上线后能快速建立稳定的逻辑环通信,并为远程故障诊断提供操作平台。     

基于CAN总线的电子节气门控制系统设计

介绍一种以Microchip PIC16F877A微控制器、MCP2510独立CAN总线控制器和PCA82C250收发器为核心组成的CAN总线电子节气门位置传感器智能节点的设计方法,在此基础上构建了车辆线控电子节气门系统CAN总线通信控制网络并给出其软硬件原理及控制方法,实现了控制系统中不同节点间高效数据传输、全部节点之间的数据共享以及相互之间的协同工作。试验结果表明智能传感器采集数据准确,数据传递效率和利用率高,系统响应速度较快,控制系统达到了预期的目标。     

单个CAN控制器的双总线冗余网络实现

提出了一种新的双CAN总线冗余网络拓扑,其每个CAN节点只需一个CAN控制器和模拟多路开关,当一条总线上出现短路或断路等故障致使通讯不能正常进行时,系统可自动切换到另一条无故障的总线上继续工作,使总线通讯的可靠性得到大大提高。另外,系统还可对总线上的节点进行周期性的查询,及时发现节点故障。对实验系统的测试结果表明,该系统动作可靠,方案可行,成本低廉,便于实现。     

CAN节点总线关闭状态下通信中断的解决方法

CAN总线通信中,当某一节点进入总线关闭状态后,不会与总线其他节点通信.针对这个问题,分析了节点从总线关闭状态转化为主动错误状态的条件,提出了采用模拟开关和电压基准主动实现这种转化条件的解决方法,解决了CAN节点恢复时间不确定的问题.     

基于CAN总线的无人机网络系统研究

通过对无人机系统的航空总线类型的应用背景分析,给出了无人机系统CAN总线网络结构图;针对无人机工作可靠性的苛刻要求和CAN总线的底层协议,详细讨论了航空航天领域专用的较高层协议CANaerospace协议,并应用于某型无人机系统上,对总线的通信时间和处理故障性能加以分析,估算后通信时间和故障性能处理时间完全满足无人机系统设计要求,实现了机载电子设备间的网络化通信,提高了系统可靠性。     

基于LabVIEW的虚拟车身CAN总线节点设计

为研究汽车车载CAN总线节点网络控制功能,通过对大众PASSAT1.8车身CAN总线系统的数据测试得该系统网络控制是以控制数据帧和状态数据帧的传输实现;选用通用CAN总线接口卡,上位机采用LabVIEW编程,设计虚拟左前门控单元节点模型样机;经实验表明,基于PC平台的虚拟车身CAN总线节点可替代实体车身CAN总线节点来实现原车网络控制功能,具有较强的开放性与灵活性,并可为车载CAN总线系统网络设计、测试与教学提供支撑.     

基于CAN总线的车用智能传感器系统设计

介绍一种以Microchip PIC16F877A微控制器、MCP2510独立CAN总线控制器和PCA82C250收发器为核心组成的CAN总线智能传感器的设计方法,在此基础上构建了车辆线控电子节气门系统CAN总线通信控制网络,并给出其软硬件原理和控制方法,实现了控制系统中不同节点间高效数据传输、全部节点之间的数据共享以及相互之间的协同工作。实验结果表明:智能传感器采集数据准确,数据传递效率和利用率高,系统响应速度较快,控制系统达到了预期的目标。     

基于冗余CAN总线的实时通信系统设计

针对航天现场工业环境对通信系统的可靠性有较高的要求,该文提出了基于冗余CAN总线的实时通信系统设计方法,该方法为系统的CAN网络主节点进行节点冗余设计,同时对CAN网络中的每个节点进行总线冗余设计.当主节点出现故障时系统切换到备份主节点工作,当总线出现故障时系统切换到备份总线上工作.该系统制定了统一的通信协议,系统主控模块FPGA对整个CAN网络中的节点进行实时监控,有效提高了系统数据传输的可靠性.     

矿用新能源电机车CAN通信网络软件优化方法

针对矿用新能源电机车CAN节点发送错误造成关键信息丢失的隐患,在TTCAN协议的基础上提出了CAN总线发送容错方法,即对CAN节点发送失败的报文重新发送,当发送成功或者达到预设的最大重发次数后退出该报文的发送;给出了一种CAN总线高效接收、处理报文方法,在中断接收报文期间对报文进行缓存操作,同时修改接收到的报文数量,主程序以此为依据逐条对存放在缓冲区的报文进行后续处理,实现了报文接收与处理的分时操作。测试结果表明,该优化方法可有效提高CAN总线通信的实时性和可靠性,同时减小了各CAN节点CPU开销,提高了工作效率。     

AUV内部通讯总线设计

设计了基于CAN协议的AUV内部通讯总线系统．系统通过协议转换器的模块化、可配置性设计满足AUV系统对其内部通讯总线的开放性要求．协议转换器内部的容错处理能力以及紧急事件处理节点的设计为增强AUV系统的可靠性和容错能力、为避免AUV在深海工作环境下丢失增加有力的保障措施．     

带式输送机故障定位系统网关的设计

以带式输送机故障定位系统为应用背景,提出了一种基于STM32F103VE微处理器的CAN总线与Profibus-DP总线网关的设计方案。该网关在CAN网络中作为一个CAN通信节点,在Profibus-DP网络中作为一个从站;带式输送机沿线分布若干个CAN检测节点,每个节点负责检测其段内的4种传感器设备采集的实时数据,如果检测到故障信息,CAN检测节点就会向网关发送故障信息报文,网关接收CAN检测节点发送的报文并进行存储;当网关与Profibus-DP主站连通后,作为Profibus-DP从站的网关可以通过查询方式把故障信息报文传送到Profibus-DP主站中,从而实现故障定位功能。实际应用表明,该网关运行稳定、可靠,实现了带式输送机故障定位系统中CAN总线及Profibus-DP总线的互联。     

Latency based group discovery algorithm for network aware cloud scheduling

Cloud computing is a big paradigm shift of computing mechanism. It provides high scalability and elasticity with a range of on-demand services. We can execute a variety of distributed applications on cloud’s virtual machines (computing nodes). In a distributed application, virtual machine nodes need to communicate and coordinate with each other. This type of coordination requires that the inter-node latency should be minimal to improve the performance. But in the case of nodes belonging to different clusters of the same cloud or in a multi-cloud environment, there can be a problem of higher network latency. So it becomes more difficult to decide, which node(s) to choose for the distributed application execution, to keep inter-node latency at minimum. In this paper, we propose a solution for this problem. We propose a model for the grouping of nodes with respect to network latency. The application scheduling is done on the basis of network latency. This model is a part of our proposed Cloud Scheduler module, which helps the scheduler in scheduling decisions on the basis of different criteria. Network latency and resultant node grouping on the basis of this latency is one of those criteria. The main essence of the paper is that our proposed latency grouping algorithm not only has no additional network traffic overheads for algorithm computation but also works well with incomplete latency information and performs intelligent grouping on the basis of latency. This paper addresses an important problem in cloud computing, which is locating communicating virtual machines for minimum latency between them and group them with respect to inter-node latency.     

基于CAN总线的容错冗余技术研究

CAN总线网络的可靠性历来是CAN总线网络设计时需要考虑的一项重要指标;CAN协议本身具有容错控制的功能,但是当网络信息负载较大时,网络容易出错,且CAN总线网络排除永久性故障的能力较差,不能满足对实时性和可靠性要求较高的网络需求;为了提高总线网络工作的可靠性,实现对CAN总线网络的实时控制,在传统冗余技术的基础上提出一种新型的CAN总线容错冗余技术;实验结果表明这种新型的CAN总线冗余技术在总线信息负荷较少的情况下能达到预期的效果。     

Recovery Strategies for Streaming Media Service in a Cluster-Based VOD Server with a Fault Node

Due to the economic cost and good scalability, cluster-based server architecture is used for VOD services. This server consists of a front-end node and multiple backend nodes. In this server architecture, backend nodes are added simply to support large-scale on-demand clients. However, as the number of backend nodes increases, the possibility of backend node failure also increases. A backend node fault not only degrades the quality of serviced streaming media but also decreases the number of streams supported in the VOD server. For successful VOD service, even if a backend node enters a fault state, the streaming service in progress should be re-continued after a short recovery time. As the recovery strategy, when legacy RAID methods are applied to cluster-based VOD servers, the excessive internal network traffic between the backend nodes causes performance degradation. In addition, the backend nodes demonstrate inefficient CPU utilization for the recovery process. In this paper, to address these problems, a new fault recovery strategy is proposed based on the pipeline computing concept. The proposed method not only distributes the network traffic generated from the recovery operations but also makes efficient use of the CPU time available in the backend nodes. Based on these advantages, even if the cluster-based server has a backend node that fails, the proposed method provides more QoS streams compared to the existing recovery method. In addition, since the proposed method needs a very short recovery time, the streaming services in progress are sustained without degradation of media quality.     

基于节点可靠度的虚拟SDN网络映射算法

为应对网络故障,提升网络的可靠性,该文针对SDN网络环境设计了节点的可靠度指标,提出了基于节点可靠度的虚拟SDN映射算法。在初始可靠映射阶段,该算法根据节点可靠度指标进行vSDN映射,部署控制器时兼顾了控制器与交换机的时延,同时考虑控制网络的重要性,为控制网络构建相应的备份资源;在故障恢复阶段,针对物理SDN网络单节点或单链路故障,算法使用迁移方法应对控制节点失效的情况,使用重映射方法应对其他故障。仿真结果表明,算法在请求接受率、故障恢复率、有效承载率和平均控制时延等指标上取得了较好的结果。     

Reliable multistage interconnection network design

High-performance supercomputers generally comprise millions of CPUs in which interconnection networks play an important role to achieve high performance. New design paradigms of dynamic on-chip interconnection network involve a) topology b) synthesis, modeling and evaluation c) quality of service, fault tolerance and reliability d) routing procedures. To construct a dynamic highly fault tolerant interconnection networks requires more disjoint paths from each source-destination node pair at each stage and dynamic rerouting capability to use the various available paths effectively. Fast routing and rerouting strategy is needed to provide reliable performance on switch/link failures. This paper proposes two new architecture designs of fault tolerant interconnection networks named as reliable interconnection networks (RIN-1 and RIN-2). The proposed layouts are multipath multi-stage interconnection networks providing four disjoint paths for all the source-destination node pairs with dynamic rerouting capability. The designs can withstand switch failures in all the stages (including input and output stages) and provide more reliability. Reliability analysis of various MIN architectures is evaluated. On comparing the results with some existing MINs it is evident that the proposed designs provides higher reliability values and fault tolerance.     

Intelligent detection of unstable power swing for correct distance relay operation using S-transform and neural networks

The conventional power swing schemes used in distance relay operation are not fast enough to detect and distinguish a fault, stable swing and unstable swing and this may lead to unintended tripping of protection devices. Therefore, there is a need for fast detection of unstable swings so as to improve the reliability of distance relay operation. This paper presents an intelligent approach for detecting unstable swings during distance relay operation using the S-transform signal processing technique and artificial neural networks. To illustrate the effectiveness of the proposed approach, simulations were carried out on the IEEE 39 bus test system using the PSS/E software. Test results showed that the proposed approach using S-transform, multi layer perceptron network and probabilistic neural network can accurately detect and classify fault, stable swing, unstable swing, fault clearance and post fault events for correct distance relay operation.     

SpaceWire冗余网络故障检测恢复技术实现

为提高SapceWire网络可靠性,基于SpaceWire-D提出了一种应用于SpaceWire冗余网络的故障检测恢复技术。网络节点通过比较主、备份端口收到的时间码来判断链路故障状态,在确认主链路发生故障后,节点自动启用备份端口工作。通过引入时间码抖动容限参数,提高了节点对故障判断的准确性,避免了故障误判。测试结果表明,即使故障链路未与节点直接连接,节点也能够在一个时间槽长度内检测到链路故障并自动切换至备份链路。此技术保证了网络故障情况下的数据正确传输,提高了SpaceWire网络的可靠性,是一种稳定可靠的故障检测恢复技术。