Research On Accuracy Compensation And Cross-coupling Control Of Servo Feed System

With the rapid development of the aerospace industry and the great material needs,higher requirements are placed on the accuracy of the servo system.Mechanical resonance and frictional interference in the servo feed system are the key factors affecting the accuracy.When the multi-axis linkage is performed,the contour accuracy is further reduced due to the mismatch of the dynamic characteristics of the axes.Therefore,studying the precision compensation and cross-coupling control technology of the servo feed system is of great significance for improving the accuracy of the servo system.This paper analyzes the causes of mechanical resonance and uses the notch filter to suppress the resonance.When the servo system resonates,the vibration energy is usually distributed asymmetrically on both sides of the resonance frequency.Therefore,in order to eliminate the negative influence of the uneven distribution of vibration energy,a center frequency asymmetric notch filter is designed.The key parameters of the notch filter,such as notch center frequency,notch bandwidth and notch depth,are described in detail.Friction is the dominant factor reducing tracking accuracy and machining surface quality in the machine tool feed-drive.This paper presents a new nonlinear friction model that includes the typical Coulomb-viscous friction,a nonlinear periodic harmonic friction term for describing the lead screw property in insufficient lubrication and a functional component of acceleration for describing the friction hysteresis caused by the acceleration and deceleration of the system.The modeling method of contour error is analyzed,and cross coupling control algorithm is designed.The algorithm can reduce the contour error of the system while improving the dynamic performance of the multi-axis linkage.The effectiveness of the proposed method is improved by the open servo algorithm of PMAC numerical control system.The effectiveness of the proposed notch filter for resonance suppression,friction feedforward compensation to improve uniaxial motion accuracy,and cross-coupling control algorithm to reduce the contour error of multi-axis operation is verified by experiments.The results show that the designed precision compensation and cross-coupling control method of the servo feed system can effectively improve the accuracy of the system and meet the requirements of the servo system.