7 Utility Functions (Fn)
7-34
7.21 EasyFFT (Fn206)
EasyFFT sends a frequency waveform reference from the SERVOPACK to the servomotor and slightly rotates
the servomotor several times over a certain period, thus causing machine vibration. The SERVOPACK detects
the resonance frequency from the generated vibration and makes notch filter settings according to the reso-
nance frequency detection. The notch filter is effective for the elimination of high-frequency vibration and
noise.
Execute this function after the servo ON signal (/S-ON) is turned OFF if operation of the SERVOPACK
results in high-frequency vibration and noise.
In addition to this function, online vibration monitor (Fn207) can be used to detect machine vibration and
automatically make notch filter settings.
If a Σ-V large-capacity SERVOPACK is used to make adjustments, it is recommended to use advanced auto-
tuning. This built-in EasyFFT function is used to maintain interchangeability with previous models. There is
normally no need to use it.
(1) Preparation
The following conditions must be met to perform EasyFFT.
• The write prohibited setting parameter (Fn010) must be set to Write permitted (P.0000).
• The main circuit power supply must be ON.
• All alarms must be cleared.
• The hardwire baseblock (HWBB) must be disabled.
• The servo ON signal (/S-ON) must be OFF.
• There must be no overtravel.
• The test without a motor function must be disabled (Pn00C.0 = 0).
• An external reference must not be input.
WARNING
• The servomotor rotates slightly when EasyFFT is executed. Do not touch the servomotor or machine dur-
ing execution of EasyFFT, otherwise injury may result.
CAUTION
• Use the EasyFFT when the servo gain is low, such as in the initial stage of servo adjustment. If EasyFFT
is executed after increasing the gain, the servo system may vibrate depending on the machine character-
istics or gain balance.
Rotates the shaft slightly
Slight movement
SERVOPACK
Periodic
waveform
reference
Response
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