CHAPTER 5 SERVO ADJUSTMENT
Special Adjustment (Vibration Suppression) 5-29
5
Principles of vibration suppression
A machine model is contained inside, and the control works inside the model to eliminate vibration of
the position of the assumed workpiece held in the model. The control amount is added as an offset to
the position and speed control of the motor, thereby suppressing vibration of the actual workpiece
position.
Mechanical characteristics and conditions that make vibration suppression effective
Applicable machine characteristics and conditions
Vibration is caused at the end of the arm due to the shock of traveling/stopping of the robot arm
or similar.
The machine itself vibrates due to the shock of traveling / stopping of a part of the machine.
The vibration frequency is about 1 to 300 Hz.
Inapplicable mechanical characteristics and conditions
Vibration is observed continuously without relations to traveling / stopping.
Eccentric vibration is caused in synchronization to the rotation of the motor or machine.
The vibration frequency is less than 1 Hz or more than 300 Hz.
The traveling time is less than the vibration period.
There is backlash in the mechanical joint to the vibrating mechanism.
(Numerator 0 of electronic gear ratio / Denominator of electronic gear ratio) > 250 (18-bit
encoder)
(Numerator 0 of electronic gear ratio / Denominator of electronic gear ratio) > 1000 (20-bit
encoder)
If the command pulse frequency is equal to or less than 20 kHz
Motor position/Speed control
Machine model
Position of assumed
workpiece
Vibration suppressing
control
M
Position
command
Amplifier
Workpiece
Position/speed offset
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