Technical data

Rexroth IndraDyn T Operating Torque Motors 12-13

DOK-MOTOR*-MBT********-PR03-EN-P

Note: Use the functional description of the drive controller for more

additional information.

Digital drives from Rexroth are able to provide narrow-band suppression

of vibrations that are produced due to the power train between the motor

and the mechanical axis system. This results in increased drive dynamics

with good stability.

The position or velocity feedback in the closed control circuit excites the

mechanical system to perform mechanical oscillations. This behavior,

known as “two-mass vibration”, 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 vibration” has a clear resonance frequency

that can selectively be suppressed by a cutoff filter in the drive.

Suppressing the mechanical resonance frequency may improve the

dynamic properties of the velocity control loop and of the position control

loop compared with closed-loop operation without the cutoff filter.

This leads to an increased profile accuracy and to smaller cycle times for

positioning processes at a sufficient distance from the stability limit.

The cutoff frequency and bandwidth of the filter can be selected. The

highest attenuation takes effect on the cutoff frequency. The bandwidth

defines the frequency range at which the attenuation is less than -3dB. A

higher bandwidth leads to less attenuation of the cutoff frequency!

rejection frequency f

sperr

-3

damping in dB

frequency fbandwidth

SPERRFILTER-MBT-EN.EPS

Fig. 12-7: Amplitude response of cutoff filter depending on bandwidth,

qualitative

Filtering mechanical resonance

vibrations