The Research On Co-simulation And Control Method Of Ball Screw Feed System

CNC machine tools with ball screw feed systems are widely used in industrial applications for high-precision and precision parts machining to meet the needs of parts machining.The feed system is a complex electromechanical coupling system,and its dynamic performance and the tracking accuracy of the feed motion to the reference trajectory play a very critical role in the machining speed,operational stability and accuracy of the processed products of the machine tool.This paper takes the ball screw feed system platform as the research object,and aims to improve the dynamic performance of the feed system and the machining accuracy of the machine tool.First,the corresponding dynamics modeling,then design a typical three-closed-loop control system,electromechanical simulation,analysis of the dynamic characteristics of the feed system,and finally,with the help of classical control theory based on transfer functions and modern control theory based on state equations,the study of the relevant control algorithms,the main research results of the paper are as follows:For the electromechanical coupling of the feed system,the state equation of the electromechanical coupling model is established to reveal the relationship between the mechanical drive system parameters and the servo control parameters;In order to study the servo control method of ball screw feed system,a single degree of freedom rigid body control model at low frequency state and a two degree of freedom flexible body control model at high frequency state of the system are established;Using 3D modeling software Solid Works,finite element analysis software ANSYS,and dynamics analysis software ADAMS to establish feed system multi-rigid body model and rigid-flexible coupling model,through dynamics simulation comparison analysis,it is proved that the rigid-flexible coupling model is more consistent with the actual motion of the feed system.To design the servo triple closed-loop control system for the influence of servo system triple closed-loop control parameters and nonlinear friction on the dynamic characteristics of the feed system,and to adjust the PID control parameters by engineering rectification method,and then to analyze the influence of different control parameters on the servo performance of the feed system by electromechanical joint simulation using the single factor method;In addition,non-linear Lu Gre friction torque is added in the joint simulation,and the displacement and velocity curves will show "clipping" and "distortion" respectively when the table is given a tracking sine wave,and the velocity planning is carried out by inputting s-type and five times spline acceleration/deceleration curves respectively to provide a basis for selecting a better motion strategy for the feed system.To optimize the uncertain quantization and scaling factors within the fuzzy PID controller offline iteratively using the aspen whisker(BAS)algorithm for the numerical optimization problem in the fuzzy PID control of the feed system.By comparing the indexes of traditional PID and fuzzy PID control methods through simulation,it shows that the optimized control method can significantly improve the control system performance and the accuracy of table trajectory tracking.To solve the jitter problem in the conventional sliding mode control of the feed system and the control problem of the system with disturbances,a control strategy based on the sliding mode control with improved convergence law combined with a nonlinear disturbance observer is proposed.The simulation results show that the adopted strategy has good robustness,the nonlinear observer can accurately observe and compensate for external disturbances,and the improved convergence law can greatly suppress the jitter in the sliding mode control and improve the trajectory tracking accuracy.