Siemens SINUMERIK 840Di Function Manual page 442

Detailed Description
2.5 Optimization of the control
In this case, the torque feedforward control with X1 is enabled continuously, also in JOG
mode. MD20150 $MC_GCODE_RESET_VALUES[ ], FFWON and FFWOF have no effect on
X1. This can be practical if the machine is only permitted to run with feedforward control, e.g.
for reasons of accuracy, or if you also want to test the feedforward control without a program
during startup.
For more information about the effect of the feedforward control relating to the speed and
torque position controller setpoints, please refer to:
References:
/FB2/Description of Functions, Extended Functions; Compensations (K3),
Chapter: "Description of machine data"
Note
The setting of the feedforward control must be the same for all axes of an interpolation
group.
2.5.3 Position controller position setpoint filter: new jerk filter
Application
In some applications, such as when milling sculptured surfaces, it can be advantageous to
smooth the position setpoint curves to obtain better surfaces, due to reduced excitations of
machine vibrations.
Functionality
The filter effect of the position setpoints must be as strong as possible without impermissibly
affecting contour accuracy.
The smoothing behavior of the filter must also be as "symmetrical" as possible, i.e. if the
same contour was to be traveled in both forward and reverse, the characteristic rounded by
the filter should be as similar as possible in both directions.
The effect of the filter can be monitored by means of the effective servo gain factor (K
which is displayed on the Axis service screen form. The filtering effect rounds the position
setpoints slightly, thus reducing the path accuracy so that with increasing filter time a smaller
effective servo gain factor (K
Advantages
The filter available since software version 1, which is set via:
MD32400 $MA_AX_JERK_ENABLE = 1
and
MD32410 $MA_AX_JERK_TIME = filter time,
meets the requirements for a strong filter effect with smoothing behavior that is as
symmetrical as possible for small time constants of up to approximately 10 ms.
2-68
) is displayed.
V
Velocities, Setpoint/Actual-Value Systems, Closed-Loop Control (G2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
),
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