Siemens SINUMERIK 828D Function Manual page 182

B1: Continuous­path Mode, Exact Stop, LookAhead
3.4 Dynamic adaptations
(Refer to "Adaptation of the dynamic path response [Page 183]" for further information about MD20465)
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.
Principle
The minimum value for MD32440 is calculated as f
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 - t = 2 / f
2 1 path
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 3 axes X = AX1, Y = AX2, Z = AX3.
The minimum value of MD32440 for these 3 axes is thus 10 Hz. This means that any acceleration, which is
completed within a period of t
velocity v again following an acceleration process starting from velocity v
1
is also only considered within this range.
If the time t - t is greater than 200 ms or if the additional program execution time t
2 1
(= MD20460) of t - t , the following time characteristic applies:
2 1
Figure 3-7 Characteristic of time-optimum path velocity (without smoothing)
182
path
- t = 2/10 Hz = 200 ms, is examined. The time t
2 1
on the basis of the axes involved in the path. For the
. The extending of the execution time
1
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
is the time it takes to reach
2
- t is more than 10%
3 2
Basic Functions