Research on Error Compensation of CNC Machine Tool Based on Multibody System Kinematics

Abstract

This paper focuses on the error compensation of CNC machine tools based on the theory of multibody system kinematics. By abstracting the structure CNC machine tools into a multibody system composed of motion pairs and components, a complete spatial error model from driving input to tool execution is constructed using homogeneous coordinate transformation matrix which deeply reveals the generation, transmission, accumulation and coupling mechanism of various geometric errors. The article describes in detail the establishment of coordinate system in multibody system, the homogeneous coordinate method of points and vectors, and the process of constructing the zero-order kinematic equation, and on this basis, the general geometric error model with dual branches of "workpiece- tool" and "tool-machine tool" is established, and the mathematical expressions of position error and attitude error are derived, and the error compensation condition equation for realizing precision machining proposed. In the experimental verification, Renishaw ML10 dual-frequency laser interferometer is used to measure and compensate the error of Z-axis of VMC-500 CNC machine, the results show that the variance of error after compensation is significantly reduced from 6.4534 and 5.8352 before compensation to 3.61, the error fluctuation range is significantly narrowed, and the effectiveness and engineering applicability of the proposed model and compensation method are verified. The research provides systematic theoretical support and path for the precision improvement of CNC machine tools.