6 Applied Functions
6 - 48
OMNUC G5-series (Pulse-train Input Type) AC Servomotors and Servo Drives User’s Manual
1
Set Speed Feed-forward Command Filter (Pn111).
Set this to approximately 50 (0.5 ms).
2
Adjust Speed Feed-forward Amount (Pn110).
Gradually increase the value set in Speed Feed-forward Amount (Pn110) and finely adjust it to
avoid overshooting during acceleration/deceleration.
If Speed Feed-forward Amount is set to 100%, the position error is calculated as 0. However,
large overshooting will occur during acceleration/deceleration.
The position error when the Servomotor is operating at a constant speed will decrease based on
the following formula according to the speed feed-forward gain value.
The position error in the constant speed range becomes smaller as the speed feed-forward gain
increases.
Precautions for Correct UsePrecautions for Correct Use
If the update cycle of the position command input is longer than the Servo Drive control cycle, or
if the pulse frequency is not uniform, operating noise may increase while the speed feed-forward
is enabled. Apply the position command filter (first-order lag or FIR smoothing) or increase the
speed feed-forward filter value.
6-15-3 Operating Procedure
Speed Feed-forward Operating Method
Position error [command units] = Command speed [command units/s]/Position Loop Gain [1/s] x
(100 – Speed Feed-forward Amount [%])/100
Command
speed
Motor speed
Position error
Speed FF gain
50 [%]
80 [%]
0 [%]
Time
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