High Speed Contouring Control Algorithm for CNC Machine Tools

Abstract

Abstract A method of estimating contouring error and its minimization using a control law are presented. The contouring error is estimated in real time by projecting the actual tool position on the desired tool path. Sudden deviations in the tool path are considered in evaluating the contouring error, which is decoupled in the axis directions. The tracking error in each axis is first minimized by cascaded zero phase error tracking and pole placement control laws. In addition to axis tracking error, the components of contouring error in each axis are also regulated with PID controllers. Smoothing the axis position commands further enhances the overall system performance, and avoids discontinuities in the velocity and acceleration values in discrete time domain. The proposed method is compared to other methods suggested in literature (ZPETC, CCC) and its effectiveness is verified in simulations and with experiments, performed on a linear d.c. motor driven high speed x-y table.