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4. Servo Adjustment
4 - 13
(2) Jitter compensation (Vibration control when motor is stopped.)
The load inertia becomes much smaller than usual if the motor position enters the machine
backlash when the motor is stopped. Because this means that an extremely large VGN1 is set for
the load inertia, vibration may occur.
Jitter compensation can suppress the vibration that occurs at the motor stop by ignoring the
backlash amount of speed feedback pulses when the speed feedback polarity changes.
Increase the number of ignored pulses by one pulse at a time, and set a value at which the
vibration can be suppressed. (Because the position feedback is controlled normally, there is no
worry of positional deviation.)
When jitter compensation is set to an axis that is not vibrating is set, vibration could be induced, so
take care.
(3) Adaptive filter
The servo drive unit detects the machine resonance point and automatically sets the filter constant.
Even if the ball screw and table position relation changes causing the resonance point to change,
the filter will track these changes. If the sensitivity to detect the vibration is insufficient and the
effect of the filter is not apparent, increase the sensitivity (SV027/bitC, D). The filter coefficient is
recalculated when the power is turned ON again, so vibration may occur temporarily.
Notch filter 4 and notch filter 5 cannot be used together.
No. Abbrev. Parameter name Explanation
SV027 SSF1
Servo function
selection 1
F E D C B A 9 8 7 6 5 4 3 2 1 0
aflt zrn2 afse ovs lmc omr zrn3 vfct upc vcnt
<Jitter compensation> Removal of vibration when motor is stopped
bit Explanation
4 Set the number of compensation pulses of the jitter compensation.
5
vfct
00: Jitter compensation invalid 10: Jitter compensation 2 pulses
01: Jitter compensation 1 pulse 11: Jitter compensation 3 pulses
<Adaptive filter>
bit Meaning when "0" is set Meaning when "1" is set
C 00: Adaptive filter sensitivity standard
D
afse
11: Adaptive filter sensitivity increase (Set 2bits at a time)
E zrn2 Set to "1".
F aflt Adaptive filter stop Adaptive filter start
POINT
Jitter compensation vibration suppression is only effective when the motor is
stopped.