基于PMAC快速PID整定与精度补偿研究

Fast PID Tuning and Precision Compensation Research Based on PMAC

数控系统中动态性能与定位精度决定了加工质量及效率,为满足磨床数控系统控制要求及加工精度,研究快速整定PID方法及提高定位精度补偿方式,基于PMAC运动控制器搭建五轴数控工具磨床的全闭环伺服系统。针对伺服系统动态性能差、跟随误差较大等问题,阐述了基于PMAC的前馈-PID陷波滤波器伺服算法,提出了快速PID整定方法。针对定位精度差的问题,论述了定位补偿原理及方式,使用激光干涉仪进行目标点测量后制作螺距补偿和反向间隙补偿表。结果表明,PID整定方法得当,五轴磨床的动态响应性能良好,跟随误差大幅度减小;定位补偿措施合理,定位精度和重复定位精度大幅度提高,达到设计要求的3μm以内。

Dynamic performance and positioning accuracy determine the machining quality and efficiency in the CNC system.In order to meet the control requirements and machining accuracy of the CNC system of grinding machines,the rapid tuning PID method and the compensation method to improve the positioning accuracy are studied.The full closed-loop servo system of the five-axis CNC tool grinding machine is built based on the PMAC motion controller.Aiming at the problems of poor dynamic performance and large following error of the servo system,a feedforward-PID notch filter servo algorithm based on PMAC is described,and a fast PID tuning method is proposed.Aiming at the problem of poor positioning accuracy,the principle and method of positioning compensation are discussed.The pitch compensation and backlash compensation tables are made after measuring the target point with a laser interferometer.The results show that the PID setting method is appropriate,the dynamic response of the five-axis grinder is good,and the following error is greatly reduced;the positioning compensation measures are reasonable,the positioning accuracy and repeat positioning accuracy are greatly improved,and the design requirements are within 3μm.