11-30
11-11 Feed-forward Function
OMNUC G5-series AC Servomotors and Servo Drives User’s Manual (with Built-in EtherCAT Communications)
11
Adjustment Functions
Operating Procedure
Speed Feed-forward Operating Method
1. Set the Speed Feed-forward Command Filter (3111 hex).
Set it to approx. 50 (0.5 ms).
2. Adjust the Speed Feed-forward Gain (3110 hex).
Gradually increase the value of the Speed Feed-forward Gain (3110 hex) and finely adjust it
to avoid overshooting during acceleration/deceleration.
If the speed feed-forward gain is set to 100%, the position error is calculated at 0. However,
large overshooting will occur during acceleration/deceleration.
The position error during an operation at a certain speed will decrease based on the following
formula according to the speed feed-forward gain value.
The position error in the range of constant speed becomes smaller as the speed feed-forward
gain increases.
Precautions for Correct Use
 If the updating cycle of the position command input is longer than the Servo Drive control cycle,
or if the input command frequency is not uniform, the 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 setting.
Position error [command units] = Command speed [command units/s]/Position loop gain [1/s]
× (100 - Speed feed-forward gain [%])/100
Command
speed
Motor speed
Position error
Speed FF gain
50 [%]
80 [%]
0 [%]
Time
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