Design Of EtherCAT Master Station For Industrial Robot Communication System

In this new era of intelligent manufacturing,the real-time response and clock synchronization error accuracy requirements for industrial robot communication systems in the manufacturing field continue to increase.In order to comply with the network and intelligence of the future industrial robot manufacturing field,the EtherCAT technology that has emerged in recent years not only has higher bandwidth capacity and transmission efficiency than traditional industrial field buses,but also the clock synchronization mechanism greatly improves the synchronization of communications.Suitable for industrial robots.It is mainly used in industrial robots for high-speed processing such as packaging and welding.This paper aims at the communication requirements of high real-time and high synchronization of the communication system of industrial robots,on the embedded industrial control platform of Advantech,the software and hardware environment of the master station is completed,and the design of the open source master station based on IGH EtherCAT is implemented.The main design The content is as follows.First,briefly describe the research status of industrial Ethernet.After comparing and analyzing the three types of industrial Ethernet,choose EtherCAT with better real-time performance and synchronization performance for development.Starting with the software structure and hardware structure of the EtherCAT system,the hardware architecture of the master and slave stations is analyzed,the principles of the EtherCAT protocol operation phase are analyzed,and the principles of data frame structure and distributed clock are discussed in depth.According to the needs of EtherCAT communication,determine the X86 hardware platform;in terms of software structure,choose the Linux + Xenomai master station operating system with better real-time performance,and the master station software module uses the open source IGH EtherCAT Master.Secondly,analyze the open source IGH master station software module,introduce the three key structures of the EtherCAT software module: user module,master station software module and network card driver with EtherCAT function,briefly describe the interrelationship between each module.In-depth analysis of the standard network card driver,starting with the standard Intel IGB network card driver,real-time transformation of it,designing the IGB local dedicated network card driver with EtherCAT function.In the designed driver,the polling data sending and receiving function is used after the interrupt is closed,and the bottom layer transfers data by calling the IGH EtherCAT network stack.Based on the Xenomai + IGH EtherCAT Master,an open source framework,the design of the IGH master station application is completed from the master and slave station configuration and periodic tasks.In order to improve the real-time performance of the application program,the Xenomai program interface is used to transform the real-time task module of the application program in real time to improve the control accuracy of the task cycle.Aiming at the clock synchronization needs of slave stations in industrial robots,a distributed clock synchronization technique is used to propose a synchronization method to compensate for clock deviations.Realize accurate clock synchronization between slave stations.Finally,the test environment of the master station system was set up.The hardware platform of the master station was Advantech industrial computer ARK-2121.It tested the operating system task scheduling delay,master station communication stability,real-time data transmission and synchronization between the two slave stations.The test obtained the maximum task delay of Xenomai is 28.019?s;real-time test when the length of the network cable is 1 meter and the number of slave stations is 2,the average cycle time of the master station after sending a frame of data is measured to be 7.80?s;the synchronization test measured The synchronization time error between the two slave stations is maintained at 70 ns.The test results show that the EtherCAT master station designed in this paper has good stability,and at the same time,the better system real-time and synchronization between the slave stations meet the application requirements of industrial robots.