HEIDENHAIN ND 1300 CNC Setup User Manual

Page 30

Continuation zone

Stage motion is halted and the probe is fired a short time (continuation zone debounce time) after the

probe moves into the continuation zone. The continuation zone is a diameter specified around the target.

The minimum should be 5 scale counts. For example, a 0.001 um resolution axis should have a minimum

continuation zone of 0.005 um. The zone can be larger. Enter the desired

continuation zone radius into the continuation zone field.

Derivative factor

The derivative gain term is used in servo systems and reduces PID loop gain for rapidly changing following

errors caused by under-damped motion or axis oscillation. This gain reduction for rapidly changing sig-

nals increases system damping and eliminates oscillations without decreasing loop gain for the smoother

trapezoidal portions of the CNC move.

High levels of derivative can cause loop instability, so the derivative term should be incrementally in-

creased. Adding derivative sometimes requires a process of alternately adjusting proportional and de-

rivative gains until the best balance of accurate positioning and smooth motion is achieved. When this

balance is achieved, but the final position has still not reached the target, the integral term is also required

to complete the CNC move. Enter the derivative value into the derivative

factor field.

CNC Setup and PID Loop Tuning Guide