An Efficient Motion Trajectory Planning Method in CNC System

Lines and circular arcs are commonly used in CNC systems, the numerical controller always treats them separately, in two different routines. In this paper, a circle discrete method is proposed, both linear segments and circular arcs are treated as straight lines in motion layer under permitted tolerance. One major barrier of trajectory planning on G01 segments is the transition velocity at corner. In the requirement of high speed and high accuracy, a symmetrical corner transition method is studied, with the characteristics of simplicity and computing efficiency, promotes velocity at corner. Furthermore, a look-ahead method is applied to foresee the following path and readjust corner velocity. Based on real-time period routine, trapezoidal velocity profile is used for trajectory generation. The circle discrete method is integrated in interpreter software, the symmetrical corner transition method and intelligent look-ahead algorithm are integrated in motion control module. These software modules are separately tested and integrated together. Simulation results and practical experiments verified the effectiveness of the proposed method.