10-37
10-11 Feed-forward Function
OMNUC G5-Series AC Servo Drives Users Manual (Built-in MECHATROLINK-II communications type)
10
Adjustment Functions
Operating Procedure
Speed Feed-forward Operating Method
1. Set the Speed Feed-forward Command Filter (Pn111).
Set it to 50 (0.5 ms) or so.
2. Adjust the Speed Feed-forward Amount (Pn110).
Gradually increase the value of Speed Feed-forward Amount (Pn110) and finely adjust it to
avoid overshooting during acceleration/deceleration.
If the speed feed-forward amount is set to 100%, the position error is 0 in calculation. However,
a large overshooting will occur during acceleration/deceleration.
The position error during an operation at a certain speed can be smaller 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 inputs is longer than the Servo Drive control cycle,
or if the input command frequency is not uniform, the operating noise while the speed feed-forward
is enabled may increase. Apply the position command filter (first-order lag or FIR smoothing) or
raise the speed feed-forward filter setting.
Position error [command unit] = command speed [command unit/s] / position loop gain [1/s]
(100 - speed feed-forward amount [%]) / 100
Command
speed
Motor speed
Position error
Speed FF gain
50 [%]
80 [%]
0 [%]
Time
