Siemens SINUMERIK 840DE SL - Page 244

Detailed Description
2.17 Jerk filter (axis-specific)
Acceleration (B2)
2-32 Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Since a vibration-capable filter setting is not expected to yield useful results in any case, as
with the jerk filter's "2nd-order filter" (PT2) low-pass filter (PT2) mode there is no setting op-
tion for the denominator damping D
N
. The denominator damping D
N
is permanently set to 1.
The bandstop filter can be parameterized in 2 different ways:
• Real bandstop filter
• Bandstop filter with additional amplitude response increase/decrease at high frequencies
Real bandstop filter
The real bandstop filter is applied when identical numerator and denominator natural
frequencies are selected:
• f
Z
= f
N
= f
block
(blocking frequency)
If numerator damping setting = 0 is selected, the blocking frequency is equivalent to
complete attenuation. In this case the 3 dB bandwidth is calculated as follows:
• f
3 dB bandwidth
= 2 * f
block
If instead of complete attenuation, a reduction by a factor of k is all that is required, then
numerator damping should be selected in accordance with k. In this case the above formula
for calculating the 3 dB bandwidth no longer applies.
Bandstop filter with additional amplitude response increase/decrease at high frequencies
In this case, the numerator and denominator natural frequencies are set to different values.
The numerator natural frequency determines the blocking frequency.
By selecting a lower/higher denominator natural frequency than the numerator natural
frequency, you can increase/decrease the amplitude response at high frequencies. An
amplitude response increase at high frequencies can be justified in most cases, as the
controlled system generally possesses a lowpass characteristic itself, i.e., the amplitude
response drops at high frequencies anyway.
Supplementary conditions
If too high a numerator natural frequency is selected, the filter is disabled. In this case the
limiting frequency f
Zmax
depends on the position-control cycle:
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The limit is enabled for a specific axis using the machine data:
MD32400 AX_JERK_ENABLE (axial jerk limitation)
and set (with time specification) for the smoothing filter via the machine data:
MD32410 AX_JERK_TIME (time constant for axial jerk filter).