Generating Commands for Parametric Curve Motion Using Buffered DDA

摘要

A buffered digital differential analyzer (DDA) algorithm in a computerized numerical controller (CNC), interpolating more than one segment in a sampling interval, maintains the speed of motion, according to the programmed feed. The DDA interpolates sequential position data, where the gaps between pairs of data are variable, using a fixed increment of a parameter constrained by the required accuracy of the chord of the motion. Without considering the time function of the parameter specified by two terms of a Taylor expansion, the algorithm determines the suitable position from the interpolated position data, to ensure the accuracy of the both speed and contour of motion. A parametric curve, determined by the non-uniform rational B-spline (NURBS), is employed to verify the improvements in curve motion.