7 Auxiliary Functions
135 SD780 Series Servo Technical Manual
7.14.2 Operating Procedure
7.15 EasyFFT (Fn401)
7.15.1 Overview
EasyFFT transfers the periodic waveform commands from the servo unit to the servo motor, and
slightly rotates the servo motor several times over a certain period, causing the machine vibration.
The servo unit detects the resonance frequency basing on the vibration generated by the machine,
and then sets the corresponding notch filter according to the resonance frequency. The notch filter
effectively eliminates high-frequency vibrations and noise. If vibration occurs with a loud sound
(abnormal sound) during operation, perform this function after the servo is turned off.
Bandwidth
setting
Auxiliary
function
Tuning mode
Any interface
MODE/SET
Gain adjustment
Long press
DATA/SHIFT
UP
Long press
DATA/SHIFT
UP/DOWN
Gain setting
Mode
selection
UP/DOWN
MODE/SET
Gain
confirmation
Flash2s
Short press
DATA/SHIFT
Cautions
!
1. It must be used in the low gain state such as the initial stage of servo adjustment. If you perform the
EasyFFT function after setting a high gain, the machine may vibrate due to mechanical characteristics and
gain balance.
2. The detected resonance frequency can be automatically set to the notch filter 1/2. If 1 has been set, it will
be automatically set to 2. If 1/2 are both set, the notch filter cannot be set by this operation.
3. When changing the amplitude setting value, gradually increase the amplitude value and change it while
observing the situation.