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To reduce the mechanical resonance
If the machine is not stiff, vibration and noise may be generated due to the resonance
by shaft torsion, and you mey not be able to set-up the higher gains. You can suppress
the resonance by 2 types of the filters.
1. Torque command filter (Pr14 and Pr1C)
Set the filter's time constant so that
the frequency components around the
resonance region can be attenuated.
You can obtain the cutoff frequency
(fc) by the following formula;
Cutoff frequency, fc (Hz) =
1/(2 \ x Parameter value x 0.00001)
2. Notch filter (Pr1D and Pr1E)
Adjust the notch frequency of the filter
to the resonance frequency.
How to measure the resonance frequency of a machine system
1) Log-on PANATERM“ and open the frequency characteristics screen.
2) Set the following parameters and measuring conditions. Note that the values shown below are
only guidance.
• Decrease the value of Pr11 (1st Velocity Loop Gain) to 25 (to make the resonance frequency more
distinguishable).
• Set the amplitude to 50 r/min (so that the torque may not saturate).
• Set the offset to 100 r/min. (to increase the amount of velocity detection information, and run the
motor in one-way rotation).
• Polarities: (+) for CCW and (-) for CW.
• Set the sampling rate to 1 (from a range between 0 and 7).
• Start the frequency characteristics analysis function.
<Notes>
• Before starting the measurement, make sure that the machine does not move beyond the limit.
Approximate speed = Offset (r/min.) x 0.017 x (Sampling rate + 1)
With a larger offset value, good results can be obtained, though the speed becomes higher.
• Set-up Pr21 (Real time auto tuning mode set-up) to 0.
<Notes>
• Set-up the offset larger than the amplitude setting, and with one-way rotation so that you can obtain
better results.
Notch
Anti-resonance
Frequency
Frequency
Resonance
Gain
Gain

Resonance characteristics

Characteristics of

notch filter

Pr1D

Pr1E

Notch frequency

Notch width
selection
Set this about 10% lower than
the resonance frequency mea-
sured by the frequency charac-
teristics analysis function of
PANATERM“.
Use the default value of 2.
Preparations and Adjustments