Method and system for producing linear contouring movement

Abstract

A method and system for producing relative movement of an element along two perpendicular axes to closely approximate a desired path with the movement being sub-divided into a plurality of successive lengths with a determination being made of the number of steps for each axis that is needed to constitute each length. The number of steps in adjacent lengths on each axis is made to vary only within a constant amount so that the minimum and maximum lengths of each next length is determinable from its preceding length. The determination for each length involves calculating in one operation the deviation from the desired path for a minimum length and then calculating the addition of individual steps thereto within limits of deviation and velocity to arrive at the most acceptable length. This reduces the number of calculations as compared to prior known systems which calculate each individual step. The determination for each length produces a number for each axis and each number is translated into essentially constant rate pulses occurring over a time interval. The time interval is preferably made constant for all lengths and is dictated by a motor means ability to translate a pulse into a step so that at the end of each time interval, the motor means velocity essentially equals the pulse rate on each axis in the length.