HEIDENHAIN ND 1300 CNC Setup - Manual (Page 32)

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Drift offset
Motor amplifier offset is the positive or negative voltage that can appear at a servo amplifier output when
the amplifier input is zero. Since this offset appears inside the PID control loop, it is amplified and can
prevent the axis from reaching its final target. The drift offset parameter compensates for amplifier offset
by inserting another offset of the opposite polarity into the loop.
Drift offsets are displayed at the bottom of the CNC Setup screen during CNC loop tuning and testing in
the Current voltage field. Enter this value into the Drift offset field. When
the offset is very high, the separate Drift test and amplifier adjustment de-
scribed later in this chapter might be necessary.
Jerk factor
The jerk factor smooths abrupt axis
velocity transitions by preventing
excess acceleration. Adding jerk can
extend the life of motors and mechan-
ical axis components. The amount of
smoothing is inversely proportional to
the jerk factor value; large values of
jerk provide small amounts of transi-
tion smoothing. A value of 0 disables
jerk. Small amounts of smoothing
have little or no impact on PID loop performance and should be included before tuning the PID loop as a
means of reducing system wear. An initial value of 7500 is recommended. Systems with large axis masses
might benefit from more smoothing (lower Jerk factor values). Enter the jerk
factor value into the Jerk field.
CNC Setup and PID Loop Tuning Guide