Siemens SINUMERIK 840D Function Manual page 375

Various filter types are available to enable the jerk filter to be optimally matched to the specific
machine characteristics:
● 2nd order filter (PT2)
● Moving average calculation
● Band-stop
● Double moving average calculation
Filter type: 2nd order filter
Because it is a simple low-pass filter, a "2nd order filter" mode can only meet the requirements
specified above where relatively small filter time constants (around 10 ms) are involved. When
used in conjunction with larger time constants, inadmissible contour deviations soon become
apparent. The filter effect is relatively low.
For historical reasons, this filter mode is set as the default.
Filter type: Moving average calculation
Where low contour deviations are required, filter time constants within the range of 20 - 40 ms
can be set using the "moving average calculation" filter mode. The smoothing effect is largely
symmetrical.
The display of the calculated servo gain factor (K
values than would normally be appropriate for the filter. The contour accuracy is higher than the
displayed servo gain factor (K
When changing from "2nd-order filter" to "moving average calculation" filter mode, the
displayed servo gain factor (K
even though there is an improvement in contour accuracy.
Filter type: Band-stop
The use is not recommended and is (still) only available for compatibility reasons.
The band-stop filter is a 2nd order filter in terms of numerator and denominator:
With:
f :
N
f :
D
D :
N
D :
D
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
) appears to suggest.
V
) may therefore decrease (with identical filter time constant),
V
Numerator natural frequency
Denominator natural frequency
Numerator damping
Denominator damping
B2: Acceleration and jerk
) in the user interface, indicates smaller
V
12.2 Functions
375