8.13 Manual Tuning
8.13.1 Tuning the Servo Gains
8-78
Speed Loop Gain
This parameter determines the response characteristic of the speed loop. If the response char-
acteristic of the speed loop is low, it becomes a delay factor for the position loop located out-
side of the speed loop. This will result in overshooting and vibration in the speed reference.
Therefore, setting the speed loop gain as high as possible within the range that will not cause
the machine system to vibrate will produce a stable Servo System with a good response char-
acteristic.
The default setting of Pn103 (Moment of Inertia Ratio) is 100. Before you tune the servo, calcu-
late the moment of inertia ratio with the above formula and set Pn103 to the calculation result.
Speed Loop Integral Time Constant
To enable response to even small inputs, the speed loop has an integral element. The integral
element becomes a delay factor in the Servo System. If the time constant is set too high, over-
shooting will occur, positioning settling time will increase, and the response characteristic will
suffer.
Pn102
(2102
hex)
Position Loop Gain
Setting Range
Setting Unit
Default Setting
When Enabled
Classification
10 to 20,000
0.1/s
400
Immediately
Tuning
For machines for which a high position loop gain (Pn102) cannot be set, overflow alarms can
occur during high-speed operation. If that is the case, you can increase the setting of the fol-
lowing parameter to increase the level for alarm detection.
Use the following condition as a guideline for determining the setting.
If you use a position reference filter, transient deviation will increase due to the filter time con-
stant. When you make the setting, consider deviation accumulation that may result from the
filter.
Pn100
(2100
hex)
Speed Loop Gain
Setting Range
Setting Unit
Default Setting
When Enabled
Classifica-
tion
10 to 20,000
0.1 Hz
400
Immediately
Tuning
Pn103
(2103
hex)
Moment of Inertia Ratio
Setting Range
Setting Unit
Default Setting
When Enabled
Classifica-
tion
0 to 20,000
1%
100
Immediately
Tuning
Pn101
(2101
hex)
Speed Loop Integral Time Constant
Setting Range
Setting Unit
Default Setting
When Enabled
Classifica-
tion
15 to 51,200
0.01 ms
2,000
Immediately
Tuning
Position
Information
Pn520
Pn102 ÷ 10 (1/s)
2.0
Maximum feed speed [reference units/s]
Pn520
(2520
hex)
Position Deviation Overflow Alarm Level
Setting Range
Setting Unit
Default Setting When Enabled
Classification
1 to
1,073,741,823
1 reference
unit
5,242,880
Immediately
Setup
Position
Speed
Position
Torque
Setting of Pn103 =
×
100(%)
Load moment of inertia at motor shaft (
J
L
)
Servomotor moment of inertia (
L
M
)
Speed
Position
Torque
Speed
Position
