面向安全关键系统的CAN总线应用研究综述*

控制器局域网适合小型安全关键系统的现场总线控制要求,能够以最大1Mbps速率发送和接收实时短消息。分析了CAN总线的结构、特点、协议仲裁机制、接口设计方法、实时特性和错误处理机制。为了支持任务关键网络,比较了事件触发协议与时间触发协议的特性,讨论了时间触发CAN协议的研究进展。     

汽车控制系统中的双速CAN总线设计

针对汽车控制系统中各控制单元对系统响应时间要求不一致的实际情况,提出建立双速CAN总线网络以连接汽车的各控制单元的方法。在系统中,对实时性要求高的计算机控制单元采用高速CAN网络传输;其他采用低速CAN网络传输。结果表明,采用高、低速两条CAN总线网络的设计思路,既方便地实现了整个系统的数据共享,又有效地缓解了整个总线的通信负担,从而提高了控制的可靠性。     

基于CAN总线的EV电控系统通信的设计与开发

以MC68376集成CAN控制器为例,阐述了纯电动车(ElectricVehicle,简称EV)电控系统采用SAEJ1939通信协议实现CAN总线通信的设计要点,给出了基于CAN通信的动力蓄电池监控系统的电池充放电特性曲线。实验证明CAN总线通信速率高、准确、可靠性高。     

基于CAN总线的电动机保护装置的设计

对三相异步电动机保护系统的硬件及软件实现进行了研究,以Freescale DSP 56F807微处理器为控制核心,配以CAN总线、液晶显示以及采样等其他功能模块.而现场总线技术把专用微处理器置于测量控制设备中,把单个分散的测量控制设备变成网络节点,将其连接成可以相互沟通信息、共同完成控制任务的网络系统.在算法上由于DSP有强大的数据处理能力,对瞬时电压、电流和负序电流的幅值进行精确的计算而不需考虑时间的问题,用软件计算的方法替代硬件逻辑,减少硬件资源的浪费.     

Xstream: a middleware for streaming XML contents over wireless environments

XML (extensible Markup Language) has been developed and deployed by domain-specific standardization bodies and commercial companies. Studies have been conducted on a wide variety of issues encompassing XML. In the use of XML for wireless computing, the focus has been on investigating ways to efficiently represent XML data for transmission over a wireless environment. We propose a middleware, Xstream (XML Streaming), for efficiently streaming XML contents over a wireless environment by leveraging the rich semantics and structural characteristics of XML documents and by flexibly managing units containing fragments of data into autonomous units, known as XDU (Xstream Data Unit) fragments. The concept of an XDU is fundamental to the operation of Xstream. It provides for the efficient transfer of documents across a wireless link and allows other issues and challenges pertaining to wireless transmission to be addressed. By fragmenting and organizing an XML document into XDU fragments, we are able to incrementally send fragments across a wireless link, while the receiver is able to perform look-ahead processing of the document without having to wait for the entire document to be downloaded. We propose a fragmenting strategy based on the value of the wireless link's Maximum Transfer Units (MTUs). In addition, we present and evaluate several packetizing strategies, i.e., strategies wherein a collection of XDUs are grouped into a packet to optimize packet delivery and processing. At the receiving end of this process, a reassembly strategy incrementally reconstructs the XML document as XDU fragments are being received, thereby facilitating client application implementation of look-ahead processing.     

CAN总线应用层协议的研究与实现

在研究CAN协议的原理及应用技术的基础上,为了满足波控系统控制策略的需要,设计了CAN总线应用层协议。该协议对网络信息进行了分类,在CAN2.0B标准基础上重新定义了标识符域,并对数据编码、网络管理机制和物理接口等作了定义。介绍了所开发的基于CAN总线的控制网络。实际运行表明,该协议具有网络负载小、通讯实时性好和可靠性高的特点。     

InCloud: a cloud-based middleware for vehicular infotainment systems

Smart vehicles form pervasive environment to enhance user experience through multimedia enabled infotainment systems. In order to realize effective infotainment system for vehicles, we need to have context-aware applications that use latest (live) information for enhanced user experience. Such latest information is abundantly available on the Internet due to explosive growth of Web 3.0, which can be accessed through wireless communication infrastructures such as VANETs and LTE. In this paper we propose a cloud-based middleware framework, InCloud, for vehicular infotainment application development. The proposed framework follows service oriented architecture in which data filtering and fusion functionalities are delegated to the cloud. Data filtering and fusion reduce the data flow over wireless link. Furthermore, because most of the processing is done on the cloud, the client becomes lightweight and loosely coupled with Internet resources and underlying platforms in vehicles. We also propose a class-based fusion method for combining information from multiple resources on the Internet. The efficacy of the proposed framework is validated by developing three infotainment applications for vehicles: context-aware music, news, and an enhanced Direction (eDirection) application.

     

Principles for designing data-/compute-intensive distributed applications and middleware systems for heterogeneous environments

The nature of distributed systems is constantly and steadily changing as the hardware and software landscape evolves. Porting applications and adapting existing middleware systems to ever changing computational platforms has become increasingly complex and expensive. Therefore, the design of applications, as well as the design of next generation middleware systems, must follow a set of guiding principles in order to insure long-term “survivability” without costly re-engineering. From our practical experience, the key determinants to success in this endeavor are adherence to the following principles: (1) Design for change; (2) Provide for storage subsystem I/O coordination; (3) Employ workload partitioning and load balancing techniques; (4) Employ caching; (5) Schedule the workload; and (6) Understand the workload. In order to support these principles, we have collected extensive experimental results comparing three middleware systems targeted at data- and compute-intensive applications implemented by our research group during the course of the last decade, on a single data- and compute-intensive application. The main contribution of this work is the analysis of a level playing field, where we discuss and quantify how adherence to these guiding principles impacts overall system throughput and response time.     

Scheduling the vehicles of bus rapid transit systems: a case study

Bus rapid transit (BRT) is a cost-efficient, traffic-free bus-based transportation system competing with subways. There are 205 municipalities around the world that implemented their own BRT systems. Istanbul, having the sixth-most congested traffic in the world, built its own BRT system (Metrobüs), which serves more than 830,000 people (6.45% of all public transportation usage) in a day with 6254 trips covered by its current fleet of 496 vehicles. In this study, we model the vehicle scheduling problem of Metrobüs as a multiple depot vehicle scheduling problem. The model aims to minimize the fleet size and total deadhead kilometers while covering all timetabled trips. We propose a new heuristic, trips merger (TM), to solve the model and show that there exists cost reduction opportunities in terms of both fleet size and deadhead kilometers. The proposed heuristic is a member of the state-space reduction heuristics family, which first reduces the problem size, then solves the reduced problem. Computational study reveals that TM performed better than the existing state-space reduction heuristics for the Metrobüs case.     

软起动器控制网络中CAN总线的应用

基于CAN总线技术的软起动器与现场总线组成的控制网络，可以提高控制精度，节约能源，增长设备寿命。本文简要介绍了软起动器的CAN控制网络，给出了CAN通信的流程图，并且描述了CAN通信模块的设计。     

基于CAN总线的呼吸机控制系统设计

文章介绍了一种基于ARM微控制器的呼吸机控制系统的设计,融合嵌入式技术和CAN现场总线技术,此系统采用LPC2368处理器,具有结构简单、性价比高、扩充灵活的特点.本文提供了系统总体设计方案,详细说明了其中的硬件与软件设计要点和程序流程图.     

双口RAM及其在CAN总线中的运用

本文介绍了双口RAM的功能和作用，论述了它在硬件开发中的特点，并将双口RAM运用在CAN总线的开发设计中，不但使一些调试问题变得简单，而且提高了硬件的可操作性。     

CAN总线技术在某型火控系统内部通信中的应用

“X型火控系统”为保证信息传输的可靠性、实时性,采用了CAN总线技术来进行系统内部的信息传输,设计了系统内部的CAN智点,给出了智能节点设计的硬件原理图和软件流程图,有助于读者学习和应用CAN总线技术。     

CAN总线在工业电源现场控制系统中的应用

本文分析了使用DSP的CAN控制器和独立CAN控制器SJA1000实现CAN通讯的硬件结构和软件设计。CAN控制系统方便的实现了系统工作状态的监测和定值设定，系统可对电压、电流、变压器温度变化迅速反应。对IGBT模块实现PWM控制。     

基于CAN总线的智能车伺服控制系统

在现代战争条件下,智能车在危险条件下代替人工进行自主作业,能够极大地减小人员伤亡风险。设计了一种基于CAN总线的智能车电机伺服控制系统,介绍了CAN总线技术的原理和功能模块,分析了DSP电机控制模块。给出了软件设计方法,实现了上位机对电机动作的实时精确控制。远程操作人员可通过GUI界面实时掌握电机运转情况,实现智能车运动状态的全方位监控。系统在某智能车上运行良好,电机在复杂环境下能够正常动作,具有较高的实用价值。     

基于CAN总线的微机联锁控制台的设计

针对铁路车站联锁系统中操作设备的特点,提出了一种基于CAN总线的微机联锁控制台的设计方案,介绍了控制台系统的结构、工作原理、控制方式、编程技术、主要功能特点以及该系统的软件设计思想,充分利用CAN总线高速通讯的特点,实现了联锁控制台的研究开发。     

基于CAN总线的分布式搬运机器人控制系统研制

本文通过深入研究现场总线和计算机控制技术,提出了一种基于现场总线的分布式机计算机控制技术,并将这种技术应用到搬运机器人实验平台的控制中,为高校开展现场总线技术、计算机控制和机器人技术的教学研究与应用提供了实验平台。     

基于主控同步的CAN总线多点实时数据采集技术

RS-485总线与CAN总线是工业现场数据采集最常用的有线组网方式,它们均有各自的局限性。针对一类多节点网络的数据实时采集问题,提出了基于主控同步的CAN总线多点实时数据采集技术,将RS-485总线主控思想应用于CAN总线的数据通信中,通过对各节点发送数据时间的同步,有效地避免了节点间数据冲突问题。实验结果证明了该方案能有效地提高数据传输的实时性和可靠性,解决了CAN总线访问冲突。     

基于CAN总线的多传感器数字式自动找平控制系统设计

为了提高建筑施工中的路面平整度,本文基于C A N总线设计了一种具有多种类型传感器,可以应用于各种通用型建筑机器的数字式自动找平控制系统。综合采用C A N总线、D S P微处理器、单片机和传感器技术,经过合理的结构设计和一系列的软硬件设计,本文成功地将反馈控制系统的基本理论应用到了数字式自动找平控制系统的设计。经实践证明,该系统能准确探测路面的状况,使建筑机器精确施工,提高路面平整度和施工质量,应用范围广泛,节省资源和时间,是一种灵活、高效的数字式自动找平控制系统。     

基于CAN总线技术的楼宇自动化安全监控系统

对楼宇自动化保安系统进行了研究,提出了一种基于CAN总线的发布式控制系统,介绍了系统的工作原理、软硬件的组成及其实现。