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[Adjustment]
Adjustment
How to Check the Resonance Frequency of the Machine
(1) Start up the Setup Support Software, "PANATERM
®
" and bring the frequency characteristics measure-
ment screen.
(2) Set up the parameters and measurement conditions. (Following values are standard.)
• Set up Pr11 (1st gain of velocity loop) to 25 or so. (to lower the gain and make it easy to identify the
resonance frequency)
• Set up the amplitude to 50 (r/min) or so. (not to saturate the torque)
• Make the offset to 100 (r/min) or so. (to increase the speed detecting data and to avoid the measure-
ment error in the vicinity of speed-zero)
• Polarity is made CCW with "+" and CW with "-".
• Setup the sampling rate to 0. (setup range to be 0-7.)
(3) Execute the frequency characteristic analysis.
<Remarks>
• Make sure that the revolution does not exceed the travel limit before the measurement.
Standard revolutions are,
Offset (r/min) x 0.017 x (sampling rate +1)
Larger the offset, better measurement result you can obtain, however, revolutions may be increased.
• Set up Pr23 (Setup of adaptive filter mode) to 0 while you make measurement.
<Notes>
• When you set a larger value of offset than the amplitude setup and make the motor run to the one direction
at all time, you can obtain a better measurement result.
• Set up a smaller sampling rate when you measure a high frequency band, and a larger sampling rate when
you measure a low frequency band in order to obtain a better measurement result.
• When you set a larger amplitude, you can obtain a better measurement result, but noise will be larger.
Start a measurement from 50 [r/min] and gradually increase it.
Relation of Gain Adjustment and Machine Stiffness
In order to enhance the machine stiffness,
(1) Install the base of the machine firmly, and assemble them without looseness.
(2) Use a coupling designed exclusively for servo application with high stiffness.
(3) Use a wider timing belt. Belt tension to be within the permissible load to the motor shaft.
(4) Use a gear reducer with small backlash.
• Inherent vibration (resonance frequency) of the machine system has a large effect to the gain adjustment
of the servo.
You cannot setup a higher response of the servo system to the machine with a low resonance frequency
(machine stiffness is low).