Interpolation algorithms for numerical control

In numerically controlled systems (machine tools, plotters, flamecutters, etc.), interpolation is defined as the process of synthesizing a prescribed curve from a large number of small orthogonal steps. This paper investigates the evolution of interpolation algorithms from the early days of numerical control to the present.The algorithms presented are the most attractive computationally, since they rely on addition and subtraction alone for generating the next step. The DDA method, which dominated the premicroprocessor era, is still fully competitive when properly implemented on a general purpose computer. Now, however, its use is mostly confined to generating straight lines, where the degradation problem is absent. For higher degree curves, the pattern recognition approach provides superior accuracy.