Omron OMNUC G5 R88M-K series User Manual page 389

Torque Feed-forward Operating Method
1. Set the Inertia Ratio (Pn004).
Set the inertia ratio as correctly as possible.
 If the inertia ratio is calculated for the selected motor, input the calculated value.
 If the inertia ratio is not known, perform autotuning and set the inertia ratio.
2. Set the Torque Feed-forward Command Filter (Pn113).
Set it to 50 (0.5 ms) or so.
3. Adjust the Torque Feed-forward Amount (Pn112).
Gradually increase the value of Torque Feed-forward Amount (Pn112).
Since the position error during acceleration/deceleration at a certain speed can be brought
close to 0, it can be controlled almost to 0 throughout the entire operation range during a
trapezoidal speed pattern drive under ideal conditions where no disturbance torque is working.
In reality, disturbance torque is always applied and, therefore, the position error cannot be
completely 0.
Motor speed
Position error
Command
speed
Torque feed forward can reduce the position error in a range of acceleration/deceleration
specified.
Precautions for Correct Use
 If you raise the torque feed-forward filter time constant, the operation noise will become smaller.
However, the position error at the point of change in acceleration will become larger.
OMNUC G5-Series AC Servo Drives Users Manual (Built-in MECHATROLINK-II communications type)
Speed feed-forward amount = fixed to 100 [%]
Torque
feed-forward amount
0 [%]
50 [%]
100 [%]
10-11 Feed-forward Function
Time
10
10-38