Research And Implementation Of EtherCAT Communication Protocol For Four-axis Servo Driver

With the development of the industry,servo system plays a more important role in the field of industrial automation,and the requirements of servo continue to rise.Meanwhile,complex industrial automation puts forward the requirements of high speed and high precision control for servo drive technology,and the traditional analog and pulse control methods are difficult to meet.With the development of communication technology,especially the emergence of industrial Ethernet,digitization and network become the major trends of servo system.Industrial Ethernet has the characteristics of fast transmission speed,high reliability,good real-time performance and precise synchronization.It is favored by servo manufacturers at home and abroad and is widely used in servo system.In this paper,EtherCAT communication of servo is studied.The hardware and software design of EtherCAT communication of four-axis servo is carried out,and the IgH master is designed.The main research contents of the thesis are as follows:Firstly,EtherCAT and CiA402 servo and motion control profile are deeply studied.Secondly,modular method is used to realize the hardware of EtherCAT communication of four-axis servo based on LAN9202 and STM32F407.The communication interface and peripheral circuits involved are analyzed in detail.Thirdly,Synchronization between slaves are studied.The initial offset compensation and clock drift compensation are theoretically analyzed,and the synchronization mode is improved to enhance the synchronization performance.Fourthly,Hierarchical method is used to realize the software of EtherCAT communication of four-axis servo,which consists of hardware driver layer,data link layer and application layer.The hardware drive layer is mainly used to implement data transmission between LAN9252 and STM32,the data link layer mainly consists of acyclic data communication and cyclic data communication.For the application layer,the CoE protocol is designed and implemented,including the process data PDO,the mailbox service SDO,the power device state machine and two standard control modes in CiA402 profile.In addition,a device description file is designed for four-axis servo slave.Fifthly,in order to realize the entire EtherCAT communication,an experimental platform is set up through different types of master.The Xenomai/Linux dual-core real-time system is built based on the x86 platform to make up the real-time performance of Master.The IgH master is designed,and the function of master is tested.Finally,a system test platform is set up to verify EtherCAT communication of four-axis servo,including state machine control,process data communication PDO,mailbox communication SDO,power device state machine and two standard servo control mode in the CiA402 profile.At the same time,the performance tests are made up of stability,real-time and synchronization.The experimental results show that four-axis servo slave can not only realize the desired function applied to servo control,but also has excellent real-time,stability and synchronization performance,meeting the requirements of servo control applications.