Slave Control System Research Of Visual Robot Based On Ethercat Real-time Industrial Ethernet

Photoelectric vision robot is an important branch of robots, and widely used in industrial production and manufacturing. Its research level can be regard as the important standard for national industrial automation. So far, the robot core technology is still controlled by foreign advanced groups, such as ABB, KUKA, AnChuan etc. Domestic robot market is monopolized by foreign countries, they mostly choose to import a complete set of machine abroad, because foreign robot has higher control accuracy and stability, but the cost is very high. The core technology of photoelectric vision robot is at identifying the object quickly and accurately, planning the optimal motion path, and real-time & high precision controlling. At present, the domestic robots are mostly based on MCU(Micro Controller Unit) without visual identification system, which restrict the using of robot in a large extent. And the mature communication interface module such as CAN(Controller Area Network) bus, serial port, and USB(Universal Serial Bus) can not meet the real-time requirements of robot.PC is used as the master of the control system, and it is responsible for sending motion instructions, displaying human-computer interaction interface, etc. The slave is constructed by FPGA(Field-Programmable GateArray), which has highly parallel execution ability. It is responsible for executing master’s commands. The communication interface of master and slave is EtherCAT real-time Ethernet, which has less than 100 us refresh cycle. EtherCAT can largely improve the control accuracy depends on the real-time data transmission. The higher position refresh efficiency is, the more accurate the master can plan the position.In this thesis, several hardware circuits are designed and produced, such as FPGA core board, EtherCAT real-time communication module, interface of servo drive and photoelectric sensor, and others. At the same time, the slave software codes are mainly divided into two parts, which are both completed in FPGA. The verilog hardware control codes are edited in the Quartus II, another part is built on NIOSII soft core for EtherCAT real-time Ethernet transport protocol. Transplanting EtherCAT real-time Ethernet in the robotic system has very important significance for robot control, because it greatly shortens the transmission and feedback cycle.Our photoelectric vision robot is successfully uesd in materials handling up and down, grinding and palletizing in the industrial noise environment. The repeat accuracy of robot is 0.02 mm. Its horizontal linkage fastest speed is 5.6 m/s. And it can move back to the zero position within two pulses error.