Manual Gain Adjustment - Mitsubishi melservo-j2 series Installation Manual

2. OPERATION
2 - 6 Adjustments
2 - 6 - 1 Auto tuning
In general machines, gains are automatically adjusted by auto tuning. As the corresponding parameter is
factory-set to make auto tuning valid, merely running the servo motor will automatically set the optimum
gains for the machine without special operation or setting.
However, if you are not satisfied with machine motions during operation, change and adjust the response
level setting (parameter No. 9) of auto tuning in the following procedure.
Actual Machine Motion
Settling time is long (Note)
Overshoot occurs at a stop.
Gear noise is generated from the
machine.
Note: Settling time indicates a period of time from when the command pulse value is zeroed to when the servo motor comes to a
stop.

2 - 6 - 2 Manual gain adjustment

In most machines, gains can be adjusted automatically by auto tuning.
In the following cases, however, the gains should be adjusted manually.
Manual Gain Adjustment Is Required When
The machine vibrates at a low-range
resonance frequency.
1)
The servo motor vibrates on a machine
whose ratio of load inertia moment to
servo motor inertia moment is 20 or
2)
more times.
The settling time provided by auto
3)
tuning should be further decreased.
The position control gain of each axis
should be set to the same for
4)
interpolation operation with two or
more axes.
Ideal Machine Motion
Shorter settling time Increase the set value of the response level.
Decrease the set value of the response level. Select "large
Less overshoot
friction" in machine selection.
Decrease the set value of the response level.
Smaller gear noise
Phenomenon
The servo motor shaft vibrates at a high frequency (10Hz
or more)
a. When the machine generates large noise and vibrates,
the motion of the servo motor shaft is invisible.
b. When the response level setting is increased by auto
tuning, vibration increases.
The servo motor shaft vibrates at a low frequency (5Hz or
less).
a. When vibration occurs, the lateral vibration of the
servo motor shaft is visible.
b. The ratio of load inertia moment to servo motor inertia
moment is extremely large.
2 - 19
Parameter No. 9 Setting Method
Adjustment Procedure
Adjustment 1
Adjustment 2
Adjustment 3
Adjustment 4
Adjustment 5