Research On Robot Control System Based On Real-time Ethernet

Industrial robots are commonly 6-axis industrial robotic arms that can respond quickly and handle them according to the current state of the environment.As the "brain" of industrial robot,the controller directly determines the efficiency and precision of robot control,while the control bus,as the "nerve" of industrial robot,pulls the movement of each joint of robot,so that the robot moves in coordination and order.As a networked motion control system,the traditional industrial robot control bus has the problems of low transmission rate,difficult maintenance and high cost.Aiming at the shortcoming of traditional control bus,a control bus based on real-time Ethernet is designed in this paper.As a small-scale control bus dedicated to industrial robot control,its advantages are as follows: real-time Ethernet communication rate is fast,up to 100 Mbps,can meet the real-time requirements;Flexible design,can increase the number of the slave station according to the control requirements,up to 32 slave stations,through the network cable for the transmission of data,easy to maintain.The main elements of work are as follows:First of all,in order to meet the control needs of industrial robots,this paper designs a modified real-time Ethernet communication protocol.In order to improve real-time performance,all master and slave stations adopt ring topology and Ethernet transmission frames in the form of "Lumped-frame",define each state and state transition in the process of real-time Ethernet communication,and study the synchronous clock protocol on the system to reduce the influence because of the clock synchronization error.Then for the modified real-time Ethernet,FPGA is used to design the IP core exclusively for MAC layer communication.Standardize the characteristics of MAC layer IP kernel and the interface used,and adopt the "Top-Down" design method,the whole internal design is divided into: TX module,RX module,TR Management module,Memory management module,Timing Management module,MII module and bus module.Through the timing simulation of the corresponding modules,the analysis results show that the module can realize the corresponding transceiver function,as well as the management function of the PHY chip.Finally,the controller is designed based on the FPGA MAC core.Different hardware types of master and slave stations are selected,and the control program of master and slave CPU is compiled.Finally,the feasibility of the scheme is verified.The results show that the control system has a communication period of 0.5 ms,the slave station has a short forwarding time,meets the requirements of high real-time control of industrial robots,and each slave station has a very low clock jitter,which can make each joint axis work almost at the same time.