Interpolation of continuous micro line segment trajectories based on look-ahead algorithm in high-speed machining

Abstract

To machine complicated contours of special parts, such as dies and space components, continuous micro line segments are introduced to approach the theoretical contours under the limitation of an appointed profile error. For precise machining the contour trajectory consisting of many micro segments, the coordinates for both axes X and Y of each interpolation step should be decided according to the characteristics of the trajectory. Thus, in this paper, an interpolation method based on look-ahead algorithm is presented. In the research, the length of each micro line segments range from 0 to 40 um, and the command feedrate and acceleration capacity of the machine tool are set as 20 mm/s and 600 mm/s2, respectively. The look-ahead based feedrate planning is elaborated in this paper from the aspects of trajectory feedrate description, feedrate preplanning, and feedrate planning. With the function of feedrate planning, CNC systems can predict the variation of the curvature of the coming trajectory so that adaptively determining whether accelerates interpolation feedrate to enhance machining efficiency or decelerates the feedrate to guarantee the machining precision. In addition, the trajectory planning is analyzed, realizing the generalization of the coordinates for each interpolation step. Finally, both simulation results using MATLAB and experimental results are introduced to verify the efficiency of the proposed interpolation algorithm.