Technical data

12-12 Startup, Operation and Maintenance Rexroth IndraDyn H
DOK-MOTOR*-MBS-H******-PR02-EN-P
Rexroth digital drives are able to provide narrow-band suppression of
oscillations that are produced due to the power train between the motor
and mechanical axis system. This results in increased drive dynamic
with good stability.
The position or velocity feedback in the closed control circuit excites the
mechanical system of the slide that is moved by the motor to perform
mechanical oscillations. This behavior, known as “two-mass oscillation”,
is mainly in the frequency range between 400 and 800 Hz. It depends on
the rigidity of the mechanical system and the spatial expansion of the
system.
In most cases, this “two-mass oscillation” has a clear resonant frequency
that can selectively be suppressed by a rejection filter in the drive.
When the mechanical resonant frequency is suppressed, improving the
dynamic properties of the velocity control circuit and of the position
control circuit compared with control without the stop filter may be
possible.
This leads to an increased profile accuracy and to smaller cycle times for
positioning processes at a sufficient distance to the stability limit.
The stop frequency and bandwidth of the filter can be selected. The
highest attenuation takes effect on the stop frequency. The bandwidth
defines the frequency range at which the attenuation is less than -3 dB.
A higher bandwidth leads to less attenuation of the stop frequency!
rejection frequency f
sperr
0
-3
damping in dB
frequency fbandwidth
SPERRFILTER-IndraDynH-EN.EPS
Fig. 12-7: Amplitude frequency curve stop filter vs. bandwidth, qualitative
Filtering mechanical resonance
oscillations