Speed Feedforward Control - Siemens SINUMERIK 840D sl Function Manual

Compensations (K3)
5.5 Dynamic feedforward control (following error compensation)
5.5.3

Speed feedforward control

In the case of speed feedforward control, a velocity setpoint is also applied directly to the
input of the speed controller. This additional setpoint can be weighted with a factor in the
range 0 to 1, where "0" means: no feedforward control. Normally, the factor has the value 1,
refer to:
MD32610 $MA_VELO_FFW_WEIGHT
The equivalent time constant of the speed control loop must be determined accurately and
input in a machine data to adjust the speed feed forward control correctly:
MD32810 $MA_EQUIV_SPEEDCTRL_TIME
Figure 5-17
Parameters for speed pre-control
MD32810 $MA_EQUIV_SPEEDCTRL_TIME
Equivalent time constant of closed speed control loop
The equivalent time constant of the closed speed control loop is determined by measuring
the step response of the speed control loop. With the SIMODRIVE 611D, the settling
process can be displayed using the commissioning tool.
References:
/FB1/ Function Manual, Basic Functions; Velocities, Setpoint-Actual Value Systems, Closed-
Loop Control (G2), Chapter "Optimization of Control"
MD32610 $MA_VELO_FFW_WEIGHT
(feedforward control factor for speed feedforward control)
If the control loop for axis/spindle is optimally set and the equivalent time constant has been
determined exactly, the feedforward control factor will be approximately 1. Therefore the
initial value to be entered in the machine data is 1 (= standard default setting).
388
Speed feedforward control
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions