Siemens SINUMERIK 840D sl Function Manual page 257

2.16.3 Programming
Programmability
The function is not programmable.
2.17 Jerk filter (axis-specific)
2.17.1 Detailed Description
2.17.1.1 General Information
Overview
In certain application scenarios, e.g.,when milling free-form surfaces, it may be beneficial to
smooth the position setpoint characteristics of the machine axes. This enables surface
quality to be improved by reducing the mechanical vibrations generated in the machine.
For the purpose of smoothing the position setpoint characteristic of a machine axis, a jerk
filter can be activated at position controller level, independently of the channel- and axis-
specific jerk limitations taken into account at interpolator level.
The effect of the jerk filter must be as strong as possible without having an unacceptable
impact on contour accuracy. The filter should also have as "balanced" a smoothing effect as
possible, i.e., if the same contour is traversed forwards and backwards, the contour
smoothed by the filter should be as similar as possible in both directions.
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.
Basic logic functions: Acceleration (B2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Functions
2.17 Jerk filter (axis-specific)
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