基于嵌入式 Ｌｉｎｕｘ平台 ＥｔｈｅｒＣＡＴ 主站设计

针对多轴同步控制中存在实时性和同步性较差的问题,提出一种基于嵌入式Linux平台的EtherCAT主站方案。在以AM3358处理器为核心的BeagleBone的嵌入式平台上,构建基于Xenomai的Linux硬实时操作系统,通过改写基于ARM的网络芯片驱动,提高主站的通讯速率和响应能力,同时采用分布时钟机制动态补偿各从站时钟,实现从站间的同步性。最后搭建一主二从伺服控制平台进行试验验证,结果表明:主站在1 ms周期任务下最大调度延时为36.397μs(3.640%),最小调度延时为1.952μs(0.195%),实时性较高,多轴同步误差精度在ns级水平,具有相当高的同步性能。

Design of the EtherCAT Master Based on Embedded Linux Platform

An EtherCAT master scheme based on embedded Linux platform was proposed here in view to the poor controlling problems of real-time and synchronous multi-axis control. An operating system with Xenomai-based hard real-time Linux was developed on the BeagleBone embedded platform with AM3358 as its core processor. The ARM’s network chip driver was rewritten to improve the master’s communication speed and response capability. The clock mechanism was proposed to compensate the slave clocks dynamically so as to achieve synchronization between the slaves. Finally, the verification of a platform with one master and two servo slaves was conducted. The maximum scheduling delay of the master is 36.397 μs(3.640%), and the minimum is 1.952 μs(0.195%) under the 1 ms periodic task, and the accuracy of multi-axis synchronization error is at the ns level, which obtains high synchronous capabilities.