Siemens SINUMERIK 840D sl Function Manual

Also see for SINUMERIK 840D sl: Manual Function manual Function manual Function manual Function manual

Compensations (K3)5.5 Dynamic feedforward control (following error compensation)Extended Functions388 Function Manual, 01/2008, 6FC5397-1BP10-3BA05.5.3 Speed feedforward controlIn the case of speed feedforward control, a velocity setpoint is also applied directly to theinput of the speed controller. This additional setpoint can be weighted with a factor in therange 0 to 1, where "0" means: no feedforward control. Normally, the factor has the value 1,refer to:MD32610 $MA_VELO_FFW_WEIGHTThe equivalent time constant of the speed control loop must be determined accurately andinput in a machine data to adjust the speed feed forward control correctly:MD32810 $MA_EQUIV_SPEEDCTRL_TIME0'0$B9(/2B)):B:(,*+70'0$B(48,9B63(('&75/B7,0(0'0$B)):B02'( 6,02'5,9('RU6,02'5,9($QDORJ6\VWHP1&.3RVLWLRQDFWXDOYDOXH6SHHGFRQWUROOHU3RVLWFRQWU6HWSRLQWUHIHUHQFHYDULDEOH3UHFRQWUROFigure 5-17 Speed feedforward controlParameters for speed pre-controlMD32810 $MA_EQUIV_SPEEDCTRL_TIMEEquivalent time constant of closed speed control loopThe equivalent time constant of the closed speed control loop is determined by measuringthe step response of the speed control loop. With the SIMODRIVE 611D, the settlingprocess 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 beendetermined exactly, the feedforward control factor will be approximately 1. Therefore theinitial value to be entered in the machine data is 1 (= standard default setting).