226 Rockwell Automation Publication 2198-UM004D-EN-P - December 2022
Chapter 9 Tuning
Low Frequency Vibration Suppression in Position Mode
If the mechanism is compliant, the resonance can be present even when the
motor stops running after positioning command is executed completely. The
Low Frequency vibration suppression can reduce, or remove, the resonance.
The suppression range is between 1.0 Hz and 100.0 H
z. Both manual setting
and auto setting are available.
Automatic Setting
If you have difficulty determining the resonant frequency, you can enable the
auto low frequency vibration suppression function, which searches for the
resonant frequency. When parameter LowFreqVibrationSuppressionMode
ID139 (P1.029) is set to 1, the drive automatically searches for the resonant
frequency. This state remains active (ID139 (P1.029) =1) until a resonant
frequency is determined, or no vibration or resonance is detected. Once the
vibration suppression is applied, and the resonance is removed, this parameter
is reset to 0, and the resonant frequency that was obtained, is stored
inLowFreqVibrationSuppression1Frequency (ID135, P1.025). We recommend
that you use a LowFreqVibrationSuppressionGain ID138 (P1.028) of 1. The
second frequency suppression is used when multiple resonances are present. A
second resonance suppression operates the same way the first resonance
suppression operates.
LowFreqVibrationDetectionLevel ID140(P1.030) is used when the
LowFreqVibrationSuppressionMode =1. The detection level value is the size of
the resonance in encoder counts. Setting this value too large can result in
misrepresenting a resonance for actual motion or missing the resonance
entirely. Setting a value too small, typical motor current noise can be
misdiagnosed as a resonance. The default for this value is 8000 counts. This
value changes based on your E-Gear scaling value.
You can use any FFT tool to diagnose the resonant frequency that exists on the
mechanism.
Table 85 - Relevant Parameters
Parameter Name
ID135 (P1.025) LowFreqVibrationSuppression1Frequency
ID136 (P1.026) LowFreqVibrationSuppression1Gain
ID137 (P1.027) LowFreqVibrationSuppression2Frequency
ID138 (P1.028) LowFreqVibrationSuppression2Gain
ID139 (P1.029) LowFreqVibrationSuppressionMode
ID140 (P1.030) LowFreqVibrationDetectionLevel
IMPORTANT
When the detection level is set too small, noise might be regarded as
low-frequency vibration.
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