• Document: EtherCAT Tutorial, an introduction for real-time hardware communication on Windows
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1 EtherCAT Tutorial, an introduction for real-time hardware communication on Windows Kevin Langloisa , Tom van der Hoevena , David Rodriguez Ciancaa , Tom Verstratena , Tomislav Baceka , Bryan Convensa , Carlos Rodriguez−Guerreroa , Victor Grosua , Dirk Lefebera and Bram Vanderborghta a Robotics and Multibody Mechanics Research Group (R&MM), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene. The R&MM Research Group is a partner of Flanders Make. Abstract—Setting up a real-time hardware communication ideal case, the reader should be able to have a simple test-setup for applications such as precise motion control can be time- running in a matter of hours and with limited hardware costs. consuming and confusing. Therefore, a tutorial on the deployment The fully detailed step-by-step tutorial can be obtained from of an EtherCAT protocol is introduced. In this article, the authors situate EtherCAT, briefly discuss the origins and working prin- the online appendix of this paper. Additionally, the tutorial ciples, and mention advantages over other widely used protocols. contains successful implementations on several systems, such Additionally, the main objectives of the tutorial and the required as the Cyberlegs Beta-prosthesis (figure 1). software to complete it are presented. Online supplements are included with this article, explaining all steps to run a Simulink model in real-time on a Windows machine within a few hours. II. E THER CAT IN LAYMAN ’ S TERMS Index Terms—EtherCAT, TwinCAT, Robotics, Realtime, Hard- In this section the functionality of the EtherCAT protocol is ware communication. presented. To begin with, the general concepts and origins of industrial communication are briefly recalled, after which, the general working principles that apply specifically to EtherCAT I. I NTRODUCTION will be mentioned. All of this will be discussed with a certain Particular application domains in the field of robotics and level of abstraction, as the goal of this tutorial is only to industrial automation, require precise motion control capabil- give the reader a basic understanding of the system in order ities. To achieve this, real-time control systems are key to to successfully deploy the protocol. Specific resources are develop highly dynamic and intelligent robotic systems such conveyed to the reader interested to delve deeper into the field. as prosthetic devices [1], [2], exoskeletons [3], legged robots [4], humanoids [5], etc. A. EtherCAT origins In these high-end motion control applications, there is a need for very fast low-level control loops with data rates in the Technologies such as programmable microcontrollers and region of 250 microseconds to 1 millisecond [6]. digital signal processors allowed for the replacement of purely Furthermore, these systems require accurate time synchroniza- analog control loops with digital controllers such as PLCs. tion and high data throughput to which Real-Time Ethernet This led to the core of industrial networking, termed fieldbus (RTE) protocols have recently emerged as the leading solution protocols. in industry. Many fieldbusses were developed in parallel, and essentially, EtherCAT (Ethernet for Control Automation Technology) is a every company designed their own protocols, which naturally widely used RTE protocol, which has shown excellent perfor- led to confusion for consumers and developers [11]. mances at a relatively low cost [7], [8], [9]. To conclude, the As a reaction to this, the Fieldbus War; a web of company simplicity with which it can be deployed and run a Simulink politics and marketing interests which in 2000, led to the model in real-time, makes EtherCAT a practical solution for establishment of an international fieldbus standardization, the robotic prototyping. IEC 61158 [12], [13], [14], [15]. This article serves as an introduction to a detailed tutorial on In the mean time, Ethernet protocols were already well es- how to deploy an EtherCAT master running a Simulink model tab

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