Servo Adjustment
6.2.6 Speed Feedback Compensation
6 -14
This function is available provided that the inertia ratio set in Pn103 is correct. Therefore, perform online auto-
tuning to obtain and save the results as the user constants. Refer to
6.3 Autotuning
for details. Alternatively,
directly set the inertia ratio.
J
J
Adjustment Procedure
When adding the value of speed feedback compensation, be sure to follow the procedure de-
scribed below and make servo gain adjustments while watching the analog monitor to observe
the position error and torque reference. Refer to
LEERER MERKER Analog Monitor
for details.
1.
Set user constant Pn110 to “0002” so that the online autotuning function will be disabled.
Refer to
6.3.4 User Constants Related to Online Autotuning
and
Appendix
LEERER MERKER List of User Constants
for details regarding Pn110.
2.
First, make normal servo gain adjustments with no feedback compensation. In this case,
gradually increase the speed loop gain in Pn100 while reducing the speed loop integral time
constant Pn101, and finally set the speed loop gain in Pn100 to the same value as that of the
position loop gain in Pn102.
The relationship between the speed loop gain and integral time constant is as follows:
Take the value obtained from the following formula as a reference value for setting the speed
loop integral time constant in Pn101.
Speed loop integral time constant
=
4
2
×
Speed loop gain [sec]
Unit of speed loop gain
:
[Hz]
Check the unit when setting the speed loop integral time constant in Pn101. Pn101 can be set in
0.01 ms increments.
The unit of speed loop gain (i.e., Hz) and that of position loop gain (i.e., 1/s) are different
to each other. Set these gains to the same value, however.
3.
Repeat step 2. to increase the speed loop gain while watching the position error of the analog
monitor to observe the setting time and the torque reference ofthe analogmonitor toobserve
any occurrence of vibration. If there is any oscillating noise or noticeable vibration, gradu-
ally increase the time constant of the torque reference filter in Pn401.
4.
Gradually increase only the position loop gain. When it has been increased about as far as
possible, then decrease the speedfeedback compensationin Pn111from 100%to 90%.Then
repeat steps 2. and 3.
5.
Decrease the speed feedback compensation to a value lower than 90%. Then repeat steps 2.
through 4. to shorten the setting time. If the speed feedback compensation is too low, how-
ever, the response waveform will vibrate.
6.
Find the condition in which the shortest setting time is obtainable within the range where
the position error or torque reference waveform observed through the analog monitor is not
vibrating or unstable.
7.
The servo gain adjustment is completed when no further shortening of the positioning time
is possible.
6
INFO
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