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Evaluation of EtherCAT Clock Synchronization in Distributed Control Systems

분산 제어 시스템을 위한 EtherCAT 시계 동기화의 성능 평가

  • Kim, Woonggy (Dept. of Mechanical and Information Engineering, Univ. of Seoul) ;
  • Sung, Minyoung (Dept. of Mechanical and Information Engineering, Univ. of Seoul)
  • 김웅기 (서울시립대학교 기계정보공학과) ;
  • 성민영 (서울시립대학교 기계정보공학과)
  • Received : 2014.04.09
  • Accepted : 2014.05.20
  • Published : 2014.07.01

Abstract

Support for the precise time synchronization of EtherCAT, known as distributed clock (DC), enables the design of highly synchronized operations in distributed real-time systems. This study evaluates the performance of the EtherCAT DC through extensive experiments in a real automation system. We constructed an EtherCAT control system using Xenomai and IgH EtherCAT stack, and analyzed the clock deviation for different devices in the network. The results of the evaluation revealed that the accuracy of the synchronized clock is affected by several factors such as the number of slave devices, period of drift compensation, and type of system time base. In particular, we found that careful decision regarding the system time base is required because it has a fundamental effect on the master operation, which results in significantly different performance characteristics.

Keywords

EtherCAT;Clock Synchronization;Performance Evaluation;Real-time Ethernet;Distributed System

Acknowledgement

Supported by : 한국연구재단

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