A Design Of Embedded Motion Controller For4-axis Industrial Robot

Motion controller technology of industrial robot has been always research focus ofrobot academic and engineering. As one of important components in industrial robotsystem and core of industrial robot control system, innovation on motion controllertechnology promotes industrial robot technology to move forward, with robotics andsystems being more widely used in modern industrial automated production. Thissubject comes from the industrial robot controller R&D project of Haier-HIT Lab inHIT (Harbin Institute of Technology) Robot Institute, aiming at designing a universal4-axis industrial robot oriented, with independent intellectual property rights and low-costembedded motion controller.This paper mainly describes the research and implementation of the4-axisindustrial robot embedded motion controller.Firstly, characteristics of the embedded motion controller based on ARM9mainprocessor+multi-FPGA coprocessors hardware architecture are introduced. Aroundthe core processor and facing the Panasonic A4digital AC servo drive, each circuitmodule is designed. These circuit modules achieve4-channel position pulse signaloutput,4-channel incremental quadrature encoder signal input,4-channel analog voltageoutput signal and the switch signal input and output, respectively. In circuit designing,opto-isolation, single ended signal to differential signal conversion and relay circuit areadopted to protect the motion controller from interference of the drive.Secondly, the distributed program architecture of the embedded motion controlleris introduced. Robot trajectory interpolation and inverse kinematics computing isimplemented in ARM9, while the underlying joint servo motor control is implementedin FPGA. The subject completes the Verilog HDL program based on FPGA. SPI buscommunication interface between ARM9and FGPA, digital to analog conversion circuitinterface, drive position pulse signal and encoder signal interface and switch signalinterface are implemented. Parallel design method is also adopted to achieve motorclosed-loop control of the position loop PID control algorithm in the FPGA, usingVerilog HDL language. By using hardware description language to implement motorclosed-loop control in the FPGA, multi-axis parallel control and greater reliability canbe realized.Finally, the motion controller motor control experiment is introduced, which leadsto the accuracy of motion controller motor position closed-loop control under the driveposition control mode and speed control mode, respectively. According to two unitexperiments--position pulse output and digital to analog conversion circuit analogvoltage output, relation between motion controller position pulse output accuracy and frequency, and the analog output accuracy are assessed. Based on two unit experiments,two motor control experiments in two motor drive control mode are accomplished aftercontrol parameter tuning of the servo drive and motion controller. At last, motorposition control accuracy is obtained.