Reference-Pulse Circular Interpolators for CNC Systems

Abstract

Interpolation techniques for CNC manufacturing systems are either of the Reference-Pulse or Reference-Word type. Reference-Pulse interpolations emit a sequence of pulses as reference signals to the control loops, whereas Reference-Word interpolators provide binary words as references to Sampled-Data control loops. In the present paper, a number of Reference-Pulse interpolation methods are described, all of which function in an online iterative mode controlled by an external interrupt source. These methods are compared in terms of accuracy, maximum radius, uniformity of feedrate along the circular path, and maximum feedrate attainable. Selection of the appropriate interpolation method is found to depend on the specific application. Reference-Word interpolators will be covered in a subsequent paper.