Omron ACCURAX G5 User Manual page 355

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 (Pn112).
Set it to 50 (0.5 ms) or so.
3. Adjust the Torque Feed-forward Amount (Pn113).
Gradually increase the value of Torque Feed-forward Amount (Pn113).
Since the position error during acceleration/deceleration at a certain speed can be brought
close to 0, it can be brought 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 present 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.
When operating in position control, this function normally is used together with the velocity
feedforward.
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.
Accurax G5 AC SERVOMOTOR AND SERVO DRIVE USER'S MANUAL
Speed feed-forward amount = fixed to 100 [%]
Torque
feed-forward amount
0 [%]
50 [%]
100 [%]
6-16 Feed-forward Function
Time
6
6-55