Siemens SINUMERIK 840Di Function Manual page 171

MD32440
Machine data:
MD32440 LOOKAH_FREQUENCY
contains a smoothing frequency for LookAhead.
Acceleration and braking operations, which take place at a higher frequency than that set in
this MD, are smoothed in machine data
MD20460 LOOKAH_SMOOTH_FACTOR
and
MD20465 ADAPT_PATH_DYNAMIC
on the basis of the parameter settings or the dynamic response is reduced.
The minimum value for all axes involved in the path is always calculated.
If vibration is excited in the mechanical system of this axis and if the corresponding
frequency is known, this MD should be set to a value smaller than this frequency.
The required resonance frequencies, for example, can be calculated using the built-in
measuring functions.
The minimum value for this MD32440 is calculated as
involved in the path.
Only accelerations, during which the initial or final velocity of this motion is returned to within
time:
t = t2-t1 = 2/
are taken into account for smoothing.
Note
The smoothing of the path velocity does not lead to contour errors. Variations in axis velocity
due to curvatures in the contour at constant path velocity may continue to occur and are not
reduced at this point.
Variations in path velocity due to the input of a new feedrate are not changed either. This
remains the responsibility of the programmer of the subprogram.
Activation
The smoothing of the path velocity is activated with machine data:
MD20460 LOOKAH_SMOOTH_FACTOR,
which is active with NewConfig.
With the default value 0, the function is deactivated.
Continuous-Path Mode, Exact Stop, LookAhead (B1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
fPath
Detailed Description
2.3 Continuous-path mode
fPath
on the basis of the axes
2-23