Speed Feedforward Control - Siemens SINUMERIK Series Function Manual

K3: Compensations
4.5 Dynamic feedforward control (following error compensation)
The feedforward control should only be activated or deactivated while the axis/spindle is
stationary in the axis mode, in order to prevent jerky motion. Hence the switchover is
delayed automatically up to the next standstill through block search stop.
Note
A preprocessing stop has no effect for command or PLC axes traversing asynchronously to
the part program processing. To ensure that
axis/spindle when it is next stationary in the axis mode, you must explicitly set MD32630 = 2
for each axis/spindle in the axis mode (see also "Forward feed control for command- and
PLC axes (Page 284)").
4.5.2

Speed feedforward control

Function
In the case of speed feedforward control, a velocity setpoint is also applied directly to the
input of the speed controller. With this value the following error can be reduced to nearly
zero (i.e. system deviation is 0) when the velocity is constant.
Commissioning
The following axis-specific parameters must be defined for the speed feedforward control
during commissioning:
Equivalent time constant of the speed control loop (MD32810)
The equivalent time constant of the speed control loop must be determined accurately (e.g.
graphically from a speed setpoint step response) and entered into the following machine
data to correctly set the speed feedforward control:
MD32810 $MA_EQUIV_SPEEDCTRL_TIME (equivalent time constant speed control loop for
feedforward control)
280
only has an effect on the
FFWON/FFWOF
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
Extended Functions