基于实时以太网的分布式IO系统

发布时间：2018-04-27 16:10

本文选题：实时以太网 + 时间同步　；参考：《中国科学院研究生院（上海应用物理研究所）》2014年硕士论文

【摘要】：在上海光源装置、质子治疗装置等大型加速器系统的控制中，存在由多个控制器组成的分布式系统实现高速实时控制的需求，如上海光源的机器快联锁保护系统，其时间响应需求为1ms，其IO信号围绕432米周长的储存环分布于20个单元中。课题采用基于实时以太网的解决方案。为了实现课题目标，课题研究在1ms的时间内完成100个IO站点之间的实时通信的方法，设计按照时间分片原理进行实时数据的传输，并指出实现时间同步是实现实时以太网的关键，同时分析比较了现有的时间同步协议，最终本课题采用IEEE1588精准时间同步协议实现所有站点的时间同步。论文首先介绍了IEEE1588精准时间同步协议的相关理论知识，包括IEEE15-88时间同步的基本原理和IEEE1588协议的时钟类型，并分析了IEEE1588硬件时间戳的标记、影响时间同步的各种因素和实现IEEE1588的各种方案。其次，课题采用FPGA和千兆以太网实现IEEE1588时间同步和实时以太网，并根据需求定制了IO板，完成了分布式IO系统的基础硬件框架。最后，课题在FPGA平台上编写VHDL硬件语言程序完成IEEE1588时间同步和实时以太网的相关模块设计，并且针对普通晶振的频率偏差造成IEEE1588同步精度低的问题，，本文提出了一种频率动态补偿的算法，使主时钟和从时钟实现更高的时间同步精度。课题采用两种测试方案进行IEEE1588时间同步的测试。采用IEEE1588时间同步测试方案一验证了频率动态补偿算法的可行性，极大地提高了时间同步的精度；采用IEEE1588测试方案二分别测试了在不同同步周期以及在特定同步周期条件下采用不同的连接方式时的时间同步精度，并分析了交换机的延迟抖动和同步周期对时间同步精度的影响。由于上海光源的网络系统的延迟抖动比较大，在上海光源的网络拓扑结构中测试的IEEE1588的时间同步结果无法满足需求，也就无法在现有的上海光源的网络拓扑结构中实现本文设计的实时以太网。但在实验室条件下，本文设计的实时以太网的测试得到了相对比较满意的结果。论文的最后，对整个论文进行了总结，并针对上海光源的网络系统的延迟抖动大造成无法实现高精度的时间同步的问题，本文提出了新的网络拓扑结构进行实时以太网的设计。
[Abstract]:In the control of large accelerator systems such as the Shanghai light source device and the proton therapy device, there is a need for high speed real-time control in a distributed system composed of multiple controllers, such as the machine fast interlocking protection system of the Shanghai light source, whose time response demand is 1ms, and its IO signal is distributed around the 20 units around the 432 meter circumference.
The project uses real-time Ethernet based solutions. In order to achieve the goal of the project, the task is to complete the real-time communication between 100 IO sites in the time of 1ms, design the real-time data transmission according to the time fragmentation principle, and point out that time synchronization is the key to realize real-time Ethernet. At the same time, the analysis and comparison are made. Some time synchronization protocols. Finally, this topic uses IEEE1588 precise time synchronization protocol to achieve the time synchronization of all sites.
The thesis first introduces the relevant theoretical knowledge of IEEE1588 precise time synchronization protocol, including the basic principle of IEEE15-88 time synchronization and the clock type of the IEEE1588 protocol, and analyzes the tags of the IEEE1588 hardware timestamp, the various factors that affect the time synchronization and the various schemes to realize the IEEE1588. Secondly, the topic uses FPGA and Gigabit Ethernet. The network implements IEEE1588 time synchronization and real-time Ethernet, and customize the IO board according to the requirement, complete the basic hardware framework of the distributed IO system. Finally, the task is to write the VHDL hardware language program on the FPGA platform to complete the related module design of the IEEE1588 time synchronization and the real-time Ethernet, and to cause the IEEE1 in the frequency deviation of the ordinary crystal oscillator. 588 the problem of low synchronization accuracy is presented in this paper. A frequency dynamic compensation algorithm is proposed to achieve higher time synchronization accuracy between the master clock and the clock.
Two kinds of test schemes are used to test the time synchronization of IEEE1588. The feasibility of the frequency dynamic compensation algorithm is verified by the IEEE1588 time synchronization test scheme, and the time synchronization accuracy is greatly improved. The IEEE1588 test scheme two is used to test the different same step period and the specific synchronization period. The time synchronization precision of different connection modes is used, and the effect of delay jitter and synchronization period on the time synchronization precision is analyzed. Because the delay jitter of the network system of the Shanghai light source is larger, the time synchronization results of the IEEE1588 which are tested in the network topology of the Shanghai light source can not meet the demand, and it is impossible. The real time Ethernet designed in this paper is implemented in the existing network topology of the Shanghai light source. But under the laboratory conditions, the test of real-time Ethernet designed in this paper has been relatively satisfactory.
At the end of this paper, the whole paper is summarized, and the problem that the delay jitter of the network system of Shanghai light source can not be realized with high precision time synchronization. This paper proposes a new network topology for real-time Ethernet design.

【学位授予单位】：中国科学院研究生院（上海应用物理研究所）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.11

【参考文献】