Panasonic MINAS A5-series Operating Instructions Manual page 257

5. Manual Gain Tuning (Application)
Feed forward function
With the gain set at 100%, calculatory positional deviation is 0, but significant overshoot
occurs during acceleration/deceleration.
If the updating cycle of the positional command input is longer than the driver control
cycle, or the pulse frequency varies, the operating noise may increase while the velocity
feed forward is active. If this is the case, use positional command filter (1st delay or FIR
smoothing), or increase the velocity forward filter setup value.
Usage example of torque feed forward
• To use the torque feed forward, correctly set the inertia ratio.
Use the value that was determined at the start of the real time auto tuning, or set the
inertia ratio that can be calculated from the machine specification to Pr0.04 Inertia ratio.
• The torque feed forward will become effective as the torque feed forward gain is
gradually increased with the torque feed forward filter is set at approx. 50 (0.5 ms).
• Positional deviation at a constant acceleration/deceleration can be minimized close
to 0 by increasing the torque forward gain. This means that positional deviation can
be maintained at near 0 over entire operation range while driving in trapezoidal speed
pattern under ideal condition where disturbance torque is not active .
Positional deviation
Command speed
Zero positional deviation is impossible in actual situation because of disturbance torque.
As with the velocity feed forward, large torque feed forward filter time constant decreases
the operating noise but increases positional deviation at acceleration change point.
Usage example of analog torque feed forward
• Setting bit 5 place of Pr6.10 Function expansion setup to 1 enables the analog torque
feed forward. When the analog input 3 is used by another function (e.g. analog torque
limit), the function becomes invalid.
• The voltage (V) applied to the analog input 3 is
converted to the torque via Pr6.00 Analog torque feed
forward conversion gain setup and added to the torque
command (%).
• The voltage (V) applied to the analog input 3 is
converted to the motor torque command (%) through
the process as shown in the graph below.
• The slope represents when Pr6.00 = 30. The slope
changes as the setup value changes.
Torque command (%) = 100 × input voltage (V) / (Pr6.00 setup value × 0.1)
Related page
• P.4-13... "Details of parameter"
Motor speed
Velocity feed forward gain = Fixed 100[%]
Torque feed forward
gain
0[%]
50[%]
100[%]
Positional deviation in the
region where acceleration
is constant can be reduced
Time
by torque feed forward.
Torque command [%]
333
200
−6 −10
Input voltage
−200
−333
1
2
3
4
5
6
6 10
[V]
7
5-27