Siemens SINUMERIK 840C - Manual (Page 889)

12 Functional Descriptions 10.94
12.14.1 Feedforward control
12.14.1 Feedforward control
The FEEDFORWARD CONTROL function
is an option.
12.14.1.1 Corresponding data
NC MD 312* P-component feedforward control for axes
NC MD 465* P-component feedforward control spindle
NC MD 1260* P-component feedforward control for rigid tapping
NC MD 1124* D-component feedforward control axes
NC MD 392* Time constant (balancing filter) for feedforward control for axes
NC MD 467* Time constant (balancing filter) for feedforward control for spindles
NC MD 1324* Time constant (balancing filter) for feedforward control for rigid tapping
NC MD 1272* Setpoint smoothing filter for axes
NC MD 486* Setpoint smoothing filter for spindles
NC MD For parameter set switchover (see functional description)
12.14.1.2 Functional description
Static feedforward control
The feedforward control can be used to compensate position errors caused by a following
error within a range of 0 to 100 %. The following error is decreased according to the P-
component when feedforward control action is applied. A differential component of the control
can also be specified for axes, although this is generally not required. As a result of the static
feedforward control, the axis also travels "harder" into the specified position.
Recommended setting: Feedforward control P-component: 1000 ˆ = 100 %
Dynamic feedforward control
A very high static feedforward control setting may however cause severe overshoots on
acceleration. In this case, the partial setpoints can be passed to the position controller, delayed
by an additional time constant for feedforward control (balancing filter). This PT1 element
compensates the rise time of the speed control loop.
Recommended setting: Feedforward control time constant: T
feedf
=0.5 . T
n
T
n
= Rise time of the speed
control loop
Setpoint
Actual value
Speed
n
12–114 © Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)