基于无线冗余的时间触发架构车载总线研究
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I
摘 要
近年来，车载电子设备日益增多，车内各个控制单元之间已经从点对点通信
转变为基于总线的网络式通信。总线的引入简化了设备的连接，减少了导线的需
求量，增加了系统的集成度，降低了结构的复杂度，提高了系统的效率。但总线
结构要求信息分时传输，这就带来了延迟、仲裁、调度等问题。传统的车载总线
基于事件触发，灵活性较高，但时间确定性和可靠性得不到保证。稍晚被采用的
时间触发机制能提供确定的网络行为，并具有一定的容错能力，但灵活性差。于
是如何兼具两种机制的优点，成为车载总线面临的新难题。
现有的一些时间触发协议已经尝试了将事件触发调度加入其中。最有代表性
的是时间触发架构。这一架构初步在时间触发中实现了灵活性，但依然存在若干
问题，如状态信息会受事件调度的影响、时钟同步精度不高等，本文针对其不足
进行了一系列的改进。
在调度算法方面，提出一种基于无线冗余的通信架构，即用一条无线信道代
替用于冗余的总线信道，形成每个通信节点拥有一条总线信道和一条无线冗余信
道的通信模型。无线信道在没有随机事件信息时，与总线信道传输相同的状态信
息，实现状态信息的冗余传输。当有随机事件信息时，则立即响应，传输随机事
件信息。总线信道只传状态信息，不会被事件调度打断。状态信息按信息描述表
调度，事件信息按优先级高低存入事件队列进行调度。这种方法大大提高了总线
的稳定性和灵活性，降低了信息传输的抖动。
在时钟同步算法方面，采用了两级时钟同步模式。预同步模式用于消除节点
间的微小时钟偏差，重同步模式用于系统初始化、节点加入和节点间出现同步错
误等情况。重同步算法借鉴网络时钟同步算法，由时钟滤波、选择、合并和修正
等步骤组成。簇内采用时间服务器，实现绝对的时钟同步。
在实验测试阶段，采用无线冗余时间触发架构的通信控制器组成网络，进行
了实时性测试，可靠性测试和应用于线控转向系统的实际应用测试。实验结果表
明，无线冗余时间触发架构拥有实时性好(实时响应在 10－5s数量级)、可靠性高(达
到了 Level 4 标准，见附录 C)、容错机制全面等特点。从测试结果上看，该架构可
满足车载网络中要求最苛刻的控制网的需求。
关键词：车载总线 柔性时间触发 无线冗余 时钟同步算法 线控转向
II
ABSTRACT
In recent years, the number of electronic automobile instrument increases guraduly.
A bus-based network rather than pear-to-pear network is used to connect them. Bus
network can simplify the devices’ connection, reduce the demand of wire, increase the
density of system integration, lower the structural complexity and improve the
efficiency of the system. But the flaw of the bus, which can only allow one controller
sending messages at a time, caused delays, arbitration, scheduling and other issues. The
event-triggered bus was brought forth earlier. It has higher flexibility, but low certainty
and reliability. The time-triggered bus later provides good determination of network
behavior and fault tolerance ability, but poor flexibility. So how to combine the
advantages of the two mechanisms becomes the new problem in automobile bus
network.
Some time-triggered protocols have attempted to add in event schedular. One of
the most representative protocols is the time-triggered architecture, which achieved
primary flexibility. But still some issues are not solved, such as the state messages
transmission is affected by event scheduling; and clock synchronization accuracy is not
high enough. The paper is trying to improve the above two problems.
In respect of scheduling algorithm, the paper provides a wireless redundant channel
to replace the backup bus channel. Then each node will have a bus channel and a
backup wireless communication channel. Wireless communication channel transmits
state messages like the bus channel, as long as there are no event messages. But once
event occurrs, it responds to transmit event messages immediately. Bus channel, which
devotes to state messages transmission, will not be interrupted. State scheduling uses
message descriptor list. Event scheduling uses event queue, which is generated based on
event priority. This approach has greatly enhanced bus’ stability and flexibility, reduced
the transmission jitter.
In respect of synchronization algorithm, the paper adopts two-stage clock
synchronization. Pre-synchronization stage can eliminate little deviation of the clock
between nodes. Re-synchronization stage is used for system clock initialization, new
nodes adding in the cluster and network losting synchronization. Re-synchronization
algorithm refers to the Network Time Protocol (NTP). The algorithms go through
III
filtering, selection, combination, and amendment steps. Besides, each cluster has a
clock server to keep the real time with the outside cluster.
Testing network is made up of several wireless redundancy time-triggered
communication controllers. According to the result of real-time testing, reliability
testing and steer-by-wire system application testing, it shows that the time-triggered
structure with wireless backup channel has a good real-time feature (real-time response
is within the 10-5s magnitude), high dependability (up to the Level 4 standard, see
Appendix C), and high fault-tolerant ability. The structure can meet the demanding of
control network, which has peak trenchant demand in the automobile.
Key Word: Network in the automobile, Flexible time-triggered
scheduling, Wireless backup, Time synchronization
algorithm, Steer-by-wire
IV
目 录
中文摘要
ABSTRACT
第一章 绪 论 ...............................................................................................................1
§1.1 汽车电子的发展 ..............................................................................................1
§1.2 车载总线及时间触发架构 ..............................................................................2
§1.2.1 车载总线及其发展 ...................................................................................2
§1.2.2 时间触发架构的形成与发展 ...................................................................4
§1.3 课题来源及意义 ..............................................................................................6
§1.4 课题主要研究内容 ..........................................................................................6
§1.5 本章小结 ..........................................................................................................7
第二章 时间触发架构(TTA)理论概述 ........................................................................ 8
§2.1 稀疏时基理论 ..................................................................................................8
§2.2 时间触发方式 ..................................................................................................9
§2.3 一致性 ............................................................................................................10
§2.4 实时性 ............................................................................................................10
§2.4.1 实时实体与实时镜像 .............................................................................10
§2.4.2 实时数据库 .............................................................................................11
§2.5 状态信息与事件信息 ....................................................................................11
§2.6 节点组成及拓扑结构 ....................................................................................13
§2.6.1 节点组成与分层结构 .............................................................................13
§2.6.2 网络拓扑 .................................................................................................14
§2.6.3 通信网络接口 .........................................................................................15
§2.7 容错性能 ........................................................................................................16
§2.8 本章小结 ........................................................................................................16
第三章 无线冗余模型的柔性时间触发调度 .............................................................17
§3.1 嵌入式实时系统的调度算法 ........................................................................17
§3.2 时间触发的柔性调度算法 ............................................................................18
§3.2.1 时间触发中的事件调度 .........................................................................18
§3.2.2 动态时间触发(FTT)调度算法 ...............................................................19
§3.3 无线冗余模型及其柔性时间触发调度 ........................................................21
§3.3.1 无线冗余通信模型 .................................................................................21
V
§3.3.2 无线冗余模型的图论法分析 .................................................................22
§3.3.3 状态信息调度策略 .................................................................................24
§3.3.4 事件信息调度策略 .................................................................................28
§3.4 本章小结 .........................................................................................................30
第四章 无线冗余模型的时钟同步算法研究 .............................................................31
§4.1 时间触发架构的时钟同步 ............................................................................31
§4.1.1 时钟测量存储 .........................................................................................32
§4.1.2 容错中值算法(FTM)..............................................................................32
§4.2 其他网络的时钟同步算法 ............................................................................33
§4.2.1 无线传感网络时钟同步算法 .................................................................33
§4.2.2 网络时钟同步协议(NTP)...................................................................... 34
§4.3 无线冗余模型时钟同步算法 ........................................................................36
§4.3.1 无线冗余模型的时钟管理 .....................................................................38
§4.3.2 时钟同步流程概述 .................................................................................40
§4.3.3 时间戳及时钟测量 .................................................................................41
§4.3.4 时钟预同步算法 .....................................................................................43
§4.3.5 时钟重同步算法 .....................................................................................44
§4.3.6 软件仿真与性能比较 .............................................................................47
§4.4 本章小结 ........................................................................................................51
第五章 通信节点软硬件设计 .....................................................................................52
§5.1 通信控制器硬件设计 ....................................................................................52
§5.1.1 控制芯片及其外围电路 .........................................................................53
§5.1.2 总线收发器电路 .....................................................................................54
§5.1.3 无线收发器电路 .....................................................................................55
§5.1.4 时钟同步电路 .........................................................................................56
§5.1.5 电源及电源管理电路 .............................................................................57
§5.1.6 通信网络接口电路 .................................................................................58
§5.2 通信控制器软件设计 ....................................................................................59
§5.2.1 系统初始化 .............................................................................................59
§5.2.2 主机与通信控制器 CNI 接口程序 ........................................................60
§5.2.3 时间触发调度程序 .................................................................................64
§5.2.4 事件调度程序 .........................................................................................65
§5.2.5 时钟同步算法程序 .................................................................................66
VI
§5.2.6 校验模块及故障处理 .............................................................................68
§5.2.7 编码解码及帧组成 .................................................................................69
§5.3 本章小结 .........................................................................................................70
第六章 实验测试及性能评估 .....................................................................................71
§6.1 实时性评估 ....................................................................................................71
§6.2 可靠性评估 ....................................................................................................74
§6.2.1 可靠性统计参数 .....................................................................................74
§6.2.2 容错 .........................................................................................................76
§6.3 线控转向系统测试 .........................................................................................79
§6.3.1 方向盘及回正力矩控制节点 .................................................................80
§6.3.2 转向轮控制节点 .....................................................................................80
§6.3.3 转动控制节点 .........................................................................................81
§6.3.4 网络监控节点 .........................................................................................81
§6.3.5 线控转向通信实验 .................................................................................81
§6.4 本章小结 ........................................................................................................82
第七章 总结与展望 .....................................................................................................83
参考文献 .........................................................................................................................85
附录 .................................................................................................................................89
在读期间公开发表的论文和承担科研项目及取得成果 .............................................96
致 谢 .............................................................................................................................97
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作者：陈辉
分类：高等教育资料
价格：15积分
属性：101 页
大小：7.99MB
格式：PDF
时间：2025-01-09
