Siemens SINUMERIK 840D sl Function Manual page 184

Detailed description
2.3 Continuous -path mode
Activation
The smoothing of the path velocity is activated with machine data, which is active with
NewConfig:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR
With the default value 0, the function is deactivated.
Example
The following parameters are assumed:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR = 10% (smoothing factor for LookAhead)
MD32440 $MA_LOOKAH_FREQUENCY[AX1] = 20Hz (smoothing frequency for LookAhead)
MD32440 $MA_LOOKAH_FREQUENCY[AX2] = 20Hz
MD32440 $MA_LOOKAH_FREQUENCY[AX3] = 10Hz
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 t2-t1 = 2/10Hz = 200 ms, is examined.
The time t2 is the time after which, following acceleration from velocity v1, the velocity
returns to this velocity v1. The extending of the execution time is also only considered within
this range.
A time t2-t1 in excess of 200 ms or additional program processing time t3-t2 greater than
10% (= MD20460) of t2-t1, produces the following time characteristic:
Figure 2-6
However, a time t2-t1 below 200 ms and additional program processing time t3-t2 no greater
than 10% of t2-t1 produces this time characteristic:
32
Characteristic of time-optimum path velocity (without smoothing)
Basic logic functions: Continuouspath Mode, Exact Stop, LookAhead (B1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0