8-9
8-2 Gain Parameters
OMNUC G5-SERIES AC SERVOMOTOR AND SERVO DRIVE USER'S MANUAL
8
Parameters Details
8-2 Gain Parameters
Adjust the position loop response to suit the machine rigidity.
The responsiveness of the servo system is determined by the position loop gain. Servo systems
with a high position loop gain have a high responsiveness and fast positioning. To increase the
position loop gain, you must improve machine rigidity and increase the specific vibration
frequency. This should be 500 to 700 (0.1/s) for ordinary machine tools, 300 to 500 (0.1/s) for
general-use and assembly machines, and 100 to 300 (0.1/s) for industrial robots. The default
position loop gain is 400 (0.1/s), so be sure to lower the set value for machines with low machine
rigidity.
Increasing the position loop gain in systems with low machine rigidity or systems with low specific
vibration frequencies may cause machine resonance, resulting in an overload alarm.
If the position loop gain is low, you can shorten the positioning time using feed forward.
This parameter is automatically changed by executing realtime autotuning function. To set it
manually, set the REALTIME AUTOTUNING mode Selection (Pn002) to 0.
Position loop gain is generally expressed as follows:
Response when the position loop gain is operated
If the speed loop gain and position loop gain are optimally set, the motor operation for the
command will be delayed 2/Kp at acceleration and delayed 3/Kp at deceleration.
Pn100
Position Loop Gain
Setting
range
0 to 30,000
Unit
0.1/s
Default
setting
40
Power OFF
and ON
−
Position Full closing
Position loop gain (Kp)
=
Command pulse frequency (pulse/s)
Error counter accumulated pulse (pulse)
(0.1/s)
Motor speed
Time
Position loop gain is high.
Position loop gain is low.
Kp
3
Kp
2
Motor speed
Time
Position
command
Motor operation