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7. ADJUSTMENT
7.4.3
Load inertia moment is 20 or more times
(1) Machine condition
The machine inertia moment is 20 times or more and the servo motor oscillates at low frequency (5Hz
or more). At this time, servo motor shaft vibration can be confirmed visually.
This adjustment method is valid for the following machines:
(a) Machine in which a timing belt is driven without reduction gear
Servo motor
Pulley
(b) Machine in which a disc is rotated without reduction gear
Servo motor
Disc
(c) Machine of which ballscrew lead is long
Ballscrew
Servo motor
(2) Adjustment procedure
1) Choose the response setting of slow response.
Set 0101 in parameter No. 2.
2) Set the load inertia moment ratio (machine inertia moment ratio in parameter No.34).
If an exact machine inertia moment ratio is unknown, enter an approximate value.
When the value is set in this parameter, the following parameters are set automatically. When
there is no machine resonance, the value of each parameter is set to the ideal gain for the
parameter No.34 value.
Parameter No.
Symbol
Name
No. 6
PG1
Position loop gain 1
No. 35
PG2
Position loop gain 2
No. 36
VG1
Speed loop gain 1
No. 37
VG2
Speed loop gain 2
No. 38
VIC
Speed integral compensation
3) Set parameter No. 2 to
2
(auto tuning not executed).
4) Alternate a start and a stop several times and check whether the machine does not vibrate.
5) If vibration still persists, repeat steps 1) to 4).
6) If vibration still persists, make (a) adjustment 1 and (b) adjustment 2 in paragraph (2) of Section
7.4.2.
7) If you want to further increase the response, set parameter No. 2 to "auto tuning executed" (third
digit) with operation at a stop, and increase the response setting (first digit). After that, set the
parameter to "auto tuning not executed" (third digit).
For example, after setting parameter No. 2 to "01
2", set it to "02
2".
8) Reducing the speed loop's integral time constant (parameter No. 38) may improve the perform-
ance. However, making it too small may generate vibration.
