Research On The Multi-axis Motion Controller Based On Ethercat

The traditional motion control systems have the following shortcomings: lackof network communication, openness, real-time and compatibility. They can notmeet the modern industrial’s needs of real-time, stability and networked. Becausethe real-time Ethernet is proposed as the fundamental solution to the deterministicand real-time of industrial control. Compared with the traditional fieldbus, real-timeEthernet fieldbus has the advantages of cost-effective, high transmission speed,large amount of data and the ability to plug into a standard Ethernet networkterminal. The motion control system based on real-time Ethernet is the developmenttrend of the modern industrial control. This paper analyzes a variety of real-timeEthernet and the research of the multi-axis motion control system based onEtherCAT is carried out.Firstly, to achieve EtherCAT-based high-speed communicating, this paper usesBeckhoff EtherCAT ASIC ET1100to design a high-speed EtherCAT-baseduniversal interface card. This paper depthly studies system components, protocoldata frame structure and servo drives agreement CoE, etc. On this basis, we test thereal-time of the high-speed interface board. Research on EtherCATSecondly, in order to be compatible with EtherCAT communication interfacecard and the DC brushless servo drive with own independent features, this paperwill establish the mathematical model of DC brushless motor and derivate the PIDtheory. Moreover, a DC brushless drive with120w drive power is developed withMicrochip’s dedicated control chip—dsPIC33FJ128MC706A. The developed DCbrushless drive will use PID control strategy to realize3loop(speed loop, positionloop and electric current loop) control.Lastly, on the basis of multi-axis motion control technology and industrialEthernet research, this paper will choose the “M3352” development board asembedded master platform and design the multi-axis motion controller compatiblewith EtherCAT interface. Considering the real-time, the application programs willbe loaded into Linux kernel space to run, which can improve the ability of real-time.What’s more, the EtherCAT protocol contained in electronic power drive protocolwill be mapped to the masters and slaves. Then the Canpopen protocol can berealized on the basis of EtherCAT communication. Furthermore, this paper doessome researches on position control and trajectory interpolation. Moreover, analysisand compare two interpolation strategies of the cubic B-spline interpolation.In the above master and slave on the basis of hardware and software systems,this paper builds a two-dimensional Cartesian coordinate manipulator. In order to test the effectiveness of interpolation algorithm and to test the real-time of thesystem, this paper conducts circumferential trajectory tracking experiments.Experimental results show that the working frequency of1KHz communicationsystem to meet the design requirements. The results also show that the interpolationalgorithm used in this paper can effectively improve the trajectory tracking accuracy,the motion smoother.