Research On The Control System Of Industrial Robot Based On EtherCAT

ITER(International Thermonuclear Experimental Reactor) is one ofthe world’s most largest and far-reaching international scientific researchcooperation projects, its device is the superconducting tokmak which canproduce large-scale fusion reaction,commonly known as "man-made sun".In order to ensure the MCF (magnetic confinement fusion)equipment ingood and normal condition, it’s necessary to carry out online monitoringand intelligent maintenance for the performance status of its component.The nuclear reactor has radiation, high temperature, so its dailymaintenance should be realized with the aid of industrial robot. Theproject designs a industrial robot with12-degree freedom to simulate themaintenance task in real tokmak, providing theoretical basis andreference for the practical application. This paper studies the modelingand trajectory planning about the robot, establishes the control systembased on EtherCAT bus.The main work is as follows.1. Kinematics modeling and simulation of the arm and forearm jointis carried out in DH method. In considering of the real-time and obstacle-avoidance requirement of the forearm, we use cubic-splineinterpolation in joint space for the trajectory planning.2. According to characteristics of EtherCAT bus, the master andslave station of the control system is established. Industrial PC withTwinCAT3is the core part of master station. Control algorithm of thejoint movement is written in C++program.Data communication betweenC++and PLC module of the software is realized by R3IO interface.Theslave station includes servo driver,motor, encoder and I/O modulessupporting EtherCAT. The network topology of control system andtransformation between different protocols is implemented with couplingmodules. Circuit connection during the driver, motor and encoder isdesigned, acquisition and feedback of the encoder information is gotthrough the driver port.3. The control system is tested based on the robot control platform.Wireshark is used to analyze the communication quality of the network.Test result shows that trajectory-planning algorithm is applicable to therobot joints in this paper, the robot control system based on EtherCATcommunication has good real-time performance and stability.Inhigh-speed data exchange, the network delay is in microsecond level,satisfies the requirement of control system.