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7. ADJUSTMENT
7.4.2
When the machine vibrates due to machine resonance frequency
(1) Machine condition
The servo motor shaft is oscillating at high frequency (100Hz or more).
The servo motor shaft motion cannot be confirmed visually. However, if the machine generates large
noise and vibrates, make Adjustment 1.
If higher "response setting" of auto tuning increases vibration, make Adjustment 2.
(2) Adjustment procedure
(a) Adjustment 1
1) Perform auto tuning with the response setting of slow response.
Set 0101 in parameter No. 2.
2) Set 563Hz or 375Hz to the machine resonance suppression filter (Parameter No. 22).
3) Alternate a start and a stop several times, execute auto tuning, and check whether the machine
does not vibrate.
4) Decrease the machine resonance suppression filter value gradually and repeat step 3).
The optimum value is provided at the point where vibration is minimum.
5) To further shorten the settling time, gradually increase the response setting in parameter No. 2
and repeat steps 1) to 4).
(b) Adjustment 2
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) Decrease the speed loop gain 2 (parameter No. 37) to a value about 100 to 200 smaller than the
automatically set value.
The optimum value is provided at the point just before vibration increases.
5) Set 563Hz or 375Hz to the machine resonance suppression filter (Parameter No. 22).
6) Alternate a start and a stop several times, execute auto tuning, and check whether the machine
does not vibrate.
7) Decrease the machine resonance suppression filter value gradually and repeat step 6).
The optimum value is provided at the point where vibration is minimum.
8) When there is no machine resonance, check the operating status and gradually increase the speed
loop gain 2 (parameter No. 37) and repeat steps 5) to 7).
Set the value about 50 to 100 smaller than the value at which gear sound begins to be generated.
Make this gain a little if there is variation in the machine because a timing belt or the like is used.
9) To further shorten the settling time, gradually increase the response setting of parameter No. 2
and repeat steps 1) to 8).
