Danaher Motion
04/06
Using P7000Tools
4.4.8.3.
Profiling
Profiling (Multi-stepping) refers to the process of altering the acceleration in
the command sequence to reduce Jerk. Acceleration transients jar the
application and may cause unwanted vibrations. When Dynamic Smoothing
is enabled, the moment-to-moment move profile is passed through digital
filters to smooth out the acceleration/deceleration transients. If the feature is
enabled, a value is recommended for the frequency of the filters. This
recommendation is based on the moment of inertia of the motor, the load-to-
rotor inertia ratio, and torque production specified in the configuration. That
recommendation should be accepted, unless it is desired to filter more
aggressively. If the application uses course resolution such as 200 or 400
steps/rev, it may be quite helpful to invoke Multistepping (checkbox). This is
a very aggressive use of the smoothing filter, which will make full stepping
appear almost as smooth as microstepping.
Heavy filtering is accompanied by a small delay of the command sequence.
All causal low-pass filters have group delay, which is inversely proportional
to the bandwidth. In this case, the delay is 0.22/BW. Multistepping cuts the
bandwidth to 1/10 the value shown in the frequency box.
Dynamic Smoothing
is the process whereby the incoming pulse train or
move profile is filtered in such a way as to sharply reduce Jerk. This results
in a more quiet system and reduces the excitation of mechanical
resonances.
The more heavily the filtering is applied, the smoother the commanded
motion becomes. Heavy filtering is necessarily accompanied by group
delay.
The drive uses information about load-to-rotor inertia ratio to predict the
resonant frequency fr of the system. The various levels of filtering introduce
a second-order, low-pass filter into the command sequence, according to
the following table.
Dynamic Smoothing:
Frequency
:
Break frequency of a second order command input filter.
Typically set to 1/3 the natural frequency of the motor.
2
m
kg
Rotor
M
N
max
9
ToothCount
Frequency
Smoothing
⋅
⋅
•
•
=
J
T
4.4.8.4.
Stall Detection
Stall Detection is enabled and disabled using the check box. Stall detection
would be disabled if it failed to operate correctly and rendered nuisance stall
indications. This may occur with non-standard motors from other vendors. If
an application is suspected of causing nuisance stall indications, try
disabling the feature and running the move sequence. If the system makes
the move without losing synchronism, then it is likely that nuisance trips
have occurred.
M-SD-7AC-01 Rev
D
35