Research On The Robot Control Bus Based On EtherCAT

As the robot is widely applied, it has a profound impact on many fields, such as production,daily life, military, scientific research, etc. Since the1960s, robotics has become one of thehotspots. Although robot technology research is very broad and complex, there is no specificservo communication bus available for robot system in the international at present. In practice,one of the common bus (CAN, USB, RS485) is used in robot considering the systemrequirements, which belongs to serial bus with low communication rate. Therefore, it is of greatsignificance to introduce industrial real-time Ethernet of high-speed into the robot control bus.According to the characteristics of the robot control system, a solution based on industrialEthernet is proposed for the servo communication system. Through a comparative analysis ofexisting six kinds of industrial real-time Ethernet, EtherCAT is chosen as the basic protocol, andthe EtherCAT-based robot control protocol has been designed. What’s more, the SOEM protocolstack has been extended for robot control protocol. EtherCAT has some obvious features, such ashigh communication efficiency, high speed and great data packets capacity, so the application ofEtherCAT in complex robot control will be of great prospects.This work is part of the863project (2009AA043901). An experimental platform adopting thelinear topology is built to research the robot servo bus based on industrial Ethernet and combinedwith embedded technology. In the master section, hardware is based on X86/ARM platform andstandard network interface card, software is based on Linux RTOS and SOEM which is a opensource protocol stack, while a motor control function library and a GUI application using QT aredesigned. In the slave section, robot joint controller consist of COMX module, STM32anddigital servo is designed, and slave firmware program based on the STM32controller isdeveloped, accomplishing the COMX driver and realizing the EtherCAT communication. Aftercompleting the experimental platform, the packet capture tool and Real-Time-Ethernet-KitToolbox are used to analyze the performance parameters of the bus, proving the feasibility andsuperiority through experiments.