Experimental implementation of Taylor series expansion error compensation on a bi-axial CNC machine

Abstract

In this paper, a new model-based Taylor series expansion error compensation (TSEEC) strategy is proposed to improve the contouring accuracy for computer numerically controlled (CNC) machines. In TSEEC, the contour error compensation problem is formulated as a Taylor series expansion problem, in which the value of the contour error is expanded around the reference points and the compensation components are calculated as the deviations from the reference points. Simulations show that, with perfect knowledge of the axial dynamics, zero contour errors can be achieved with TSEEC for both linear and circular contours. Due to modeling errors, external disturbances, and measurement noise, some modifications and experimentation need to be made to determine suitable parameters for implementation of the TSEEC scheme on a real machine. These measurements include a low-pass filter, a choice of a compensation target, and a compensation gain. Experimental results show the effectiveness of TSEEC in reducing contour errors and demonstrate the superiority of TSEEC over inverse feedforward compensation and cross-coupled control in improving the contouring accuracy.