Siemens SINUMERIK 840D sl Function Manual page 271

To enable the jerk filter to be optimally matched to the machine conditions, various filter modes
are available:
● 2nd-order filter (PT2)
● Sliding mean value generation
● Bandstop filter
Mode: 2nd-order filter
Owing to the fact that it is a simple low-pass filter, "2nd-order filter" mode can only meet the
requirements specified above where relatively small filter time constants (around 10 ms) are
concerned. When used in conjunction with larger time constants, impermissible contour
deviations are soon manifest. The effect of the filter is relatively limited.
This filter mode offers advantages if very large filter time constants are needed and contour
accuracy is only of secondary importance (e.g. positioning axes).
For historical reasons, this filter mode is set as the default.
Mode: Sliding mean value generation
Where minimal contour deviations are required, filter time constants within the range of 20-40
ms can be set using the "sliding mean value generation" filter mode. The smoothing effect is
largely symmetrical.
The display of the calculated servo gain factor (K
than would normally be appropriate for the filter. The contour accuracy is in fact higher than
the displayed servo gain factor (K
When changing from "2nd-order filter" to "sliding mean value generation" filter mode, the
displayed servo gain factor (K
though there is an improvement in contour accuracy.
Mode: Bandstop filter
The bandstop filter is a 2nd-order filter in terms of numerator and denominator:
where:
f :
Z
f :
N
D :
Z
D :
N
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
) may therefore drop (with identical filter time constant), even
V
Numerator natural freq.
Denominator natural freq.
Numerator damping
Denominator damping
) in the user interface, shows smaller values
V
) appears to suggest.
V
B2: Acceleration
5.2 Functions
271