Why is Indexer LPTs contouring considered so advanced?
Indexer LPT will accelerate and decelerate as necessary to maintain a consistent vector (cutting) speed. Transition points, however, present transient stresses to the control system due to changes of speed on each axis inherent in tracking the geometry of direction changes. Indexer LPT will look ahead, and smoothly adjust the velocity in order to negotiate the transition points without over-stressing the system. Indexer LPT will look ahead AS MANY TRANSITION POINTS AS NECESSARY to avoid over-stress, while at the same time following the geometry of the contour exactly. (Even some of the most expensive controllers have only a two object look-ahead). When used with stepper drives, this advanced feature guards against missed steps due to pull out. When used with servo drives, inaccuracy due to following error is tightly controlled and thereby minimized.
