The development of a novel servo motor controller based on EtherCAT and FPGA

This paper focuses on the design of a novel SMC (servo motor controller) based on EtherCAT in order to realize flexible networked multi-axis motion control with low cost and high performance. FPGA is chosen as only kernel component of the SMC to improve the integration level of the system. Combined with some necessary peripheral chips, those functions such as EtherCAT communication, encoder signal acquisition and processing, D/A conversion and logic I/O control can be executed independently and parallelly at high speed. Simple control algorithm is implemented to achieve the closed-loop control of a single motor by embedding Nios II soft core in FPGA. For the application of multi-axis control, multiple SMCs as the EtherCAT slaves can be connected to an IPC (Industrial PC) as the EtherCAT master to establish a flexible networked multi-axis motion control system. Based on SOEM (Simple Open EtherCAT Master), the EtherCAT master program is developed in the form of dynamic link library, which can realize more advanced control algorithm to meet the needs of complex applications with the help of powerful computing ability of an IPC. In general, the novel SMC is with the advantages of low cost, compact size, simple connection, high flexibility and good real-time performance, and expects a promising application prospect in the field of motion control.