Siemens SINUMERIK 840D sl Function Manual page 402

Compensations (K3)
Dynamic feedforward control (following error compensation)
Please note the following in this context:
A block search stop is not effective for command or PLC axes traversing asynchronously to
the subprogram processing. To ensure that FFWON/FFWOF only has an effect on the
axis/spindle when it is next stationary during axis mode, you must set the following explicitly
for each axis/spindle during axis mode:
MD32630 $MA_FFW_ACTIVATION_MODE = 2
Setting for interpolating axes
The feedforward control parameters must be set optimally for each axis even in the case of
interpolating axes. The axes can have different feedforward control settings.
Dynamic response adaptation
For axes that interpolate with one another, but with different axial control loop response
times, dynamic response adaptation can be used to achieve identical time responses of all
axes to ensure optimum contour accuracy without loss of control quality.
With active feedforward control, the difference in the equivalent time constant of the
"slowest" speed or current control loop for the relevant axis must be entered as the time
constant of the dynamic response adaptation
(MD32910 $MA_DYN_MATCH_TIME).
The position setpoint can be optimized with a second balancing filter; please refer to:
MD32402 $MA_AX_JERK_MODE (filter type for axial jerk limitation)
References:
/FB1/ Function Manual, Basic Functions; Velocities, Setpoint-Actual Value Systems, Closed-
Loop Control (G2), Chapter "Optimization of Control"
Check contour monitoring
MD32810 $MA_EQUIV_SPEEDCTRL_TIME
(Equivalent time constant speed control loop for feedforward control)
and
MD32800 $MA_EQUIV_CURRCTRL_TIME)
(equivalent time constant current control loop for feedforward control)
Since the two equivalent time constants influence the contour monitoring, this should be
checked subsequently.
References:
/FB1/ Function Manual, Basic Functions; Axis Monitoring, Protection Zones (A3)
402
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions