Development of a NURBS curve interpolator with look-ahead control and feedrate filtering for CNC system

The interpolator is one of the key functions modules in CNC system, which directly effects on machining accuracy, machining efficiency, and tool motion smoothness. In this paper, an interpolator with look-ahead control and feedrate filtering is proposed for non-uniform rational B-spline curves (NURBS) interpolation while considering the contour errors and feedrate fluctuations. In the proposed interpolator, the feedrate can be adaptively adjusted according to the different curvature to meet the demand of the machining accuracy, and the looked-ahead control and feedrate filtering are applied to obtain a continuous feedrate and acceleration during the whole interpolation process. Therefore, the proposed interpolator can ensure machining accuracy, reduce mechanical shock and increase machining efficiency. Finally, the designed experiments show the effectiveness of the proposed interpolator for machining NURBS curve path.