Multiple Linear Motor Control System Based On Nios Ⅱ

The CNC (computer numerical control) machine tool is the foundation of the modern industry, and also an important measure of industrial development. As a most important component, the linear feed system is the key factor in improving the accuracy of the CNC machine tool. The traditional linear feed system based on a rotary motor and a ball screw assembly limits the velocity and the acceleration of the CNC machine tool. The transmission mechanism based on ball screw assembly and the semi-closed loop control cause large errors, which hinder the improvement of the accuracy.In recent years, the rapid developments of linear motors make it possible to use the linear motor as the linear feed system. Linear motor without transmission mechanism can directly output linear feed motion with high-speed, high-thrust, high-precision and many other advantages. However, the CNC machine tools often require linear feed in multiple directions, while traditional linear motor control schemes using DSP or IPC as control core lack the ability to control the multiple motor in parallel. The multiple linear motor control system becomes the key factor in developing the CNC machine tools.This paper studies a multiple linear motor control system based on Nios II soft processing core. Fuzzy two degrees of freedom PID algorithm based on Kalman filter is adopted in the control system. The research is focused on the following aspects:I. The linear motor control algorithmThis paper comprehensively analyses and compares the common permanent magnet motor control algorithms and selects the fuzzy two degrees of freedom PID algorithm based on Kalman filter as the control algorithm of the system. Two degrees of freedom control algorithm can effectively solve the contradiction between the "interference suppression optimal parameters" and "tracking optimal parameters", thereby giving the system both good tracking properties and anti-jamming features. Fuzzy two degrees of freedom control algorithm ignores the detailed mathematical model of the motor, and gets stronger robustness. Kalman filter is introduced to suppress measurement noise and white noise. Fuzzy two degrees of freedom PID algorithm based on Kalman filter controls the motors with good tracking properties, anti-jamming features, robustness and precision driving.Ⅱ. The multiple linear motors coupling control algorithmFor multiple linear motor coupling control conditions, the bias coupling control structure is introduced to dynamically allocate velocity compensation signals between the motors based on the work status of each motor.III. Multiple linear motors coupling control based on Nios IIAs a control core, FPGA has good parallel computing capabilities; we study the use of an FPGA to build multiple Nios II soft-core processors to realize multi-linear motor coupling control algorithms. FPGA-based control system with abundant computing resources, can achieve more accurate real-time control. Since each motor control channels are integrated in a single chip, coupling control channels communicate in high speed.Ⅳ. Experiment platform and comparison testsA multiple linear motor control system based on FPGA is set up to test the control quality. Tests between the control system based on DSPs and system based on FPGA is did to prove the advantages of the system based on FPGA. The result proves that the control system based on FPGA has quickly response, anti-jamming performance and coupling properties.Simulation analysis and experimental tests prove that the control system based on FPGA has quickly response, anti-jamming performance and coupling properties. The research which promotes the quality of the linear feed drive system has a high scientific and practical value.