A method for real-time compensation of nonlinear error in Rotary Tool Center Point mode

In this paper, a novel method is presented for real-time compensation of nonlinear error in the Rotary Tool Center Point (RTCP) mode on five-axis Computer Numerical Control (CNC) machines. Despite the advantages of RTCP in reducing errors, they persist between interpolation points. The tool model and its temporal state description are defined in this paper, elucidates the principles and calculation methods for the generation of nonlinear error during the machining process, and proposes a method to further reduce nonlinear error in RTCP mode based on the kinematic modeling of dual rotary table machines. This method takes the direction and magnitude of error compensation as two dimensions, using the bilateral coefficient method to calculate the error compensation direction at each interpolation point based on the actual error size, and employs the root mean square roughness as an indirect indicator to measure the magnitude of nonlinear error, calculating the size of error compensation. By dividing the global optimization into optimization per single interpolation period, the method allows for the calculation and acquisition of the actual target position value of the current interpolation point after compensation within each interpolation period, providing a reference for real-time prediction and compensation.