Siemens SINUMERIK 840D sl Function Manual page 212

B1: Continuous-path mode, Exact stop, Look Ahead
4.4 Dynamic adaptations
Acceleration and deceleration processes, which run with a high frequency, are smoothed
depending upon the parameterization of the following machine data or else are reduced in
dynamics:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR (smoothing factor for LookAhead)
MD20465 $MC_ADAPT_PATH_DYNAMIC (adaptation of the dynamic path response)
For further information on MD20465, see Section "Adaptation of the dynamic path response
(Page 213)".
Note
If vibrations are generated in the mechanical system of an axis and if the corresponding
frequency is known, MD32440 should be set to a value smaller than this frequency.
The needed resonance frequencies can be calculated using the built-in measuring functions.
Mode of operation
The minimum value for MD32440 is calculated as f
path. For the smoothing only those acceleration processes are taken into consideration, in
which the start and the end velocity of this motion are reached within the time given below:
t = t
These acceleration processes are dispensed with if the resulting extension in the processing
time does not exceed the limit specified in excess of the smoothing factor (MD20460).
Example
The following parameters are assumed:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR = 10%
MD32440 $MA_LOOKAH_FREQUENCY[AX1] = 20 Hz
MD32440 $MA_LOOKAH_FREQUENCY[AX2] = 20 Hz
MD32440 $MA_LOOKAH_FREQUENCY[AX3] = 10 Hz
The path involves the three axes X = AX1, Y = AX2, Z = AX3.
The minimum value of MD32440 for these three axes is thus 10 Hz. This means that any
acceleration, which is completed within a period of t
time t
from velocity v
If the time t
than 10% (= MD20460) of t
212
- t = 2 / f
2 1 path
is the time it takes to reach velocity v
2
. The extending of the execution time is also only considered within this range.
1
- t is greater than 200 ms or if the additional program execution time t
2 1
again following an acceleration process starting
1
- t , the following time characteristic applies:
2 1
on the basis of the axes involved in the
path
- t = 2/10 Hz = 200 ms, is examined. The
2 1
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
- t is more
3 2
Basic Functions