Setting up Compax3 C3I22T11
208 192-120114 N5 C3I22T11 June 2008
Feedforward channels
In this chapter you can read about:
Influence of the feedforward measures ........................................................................... 208
Motion cycle without feedfor
ward control......................................................................... 209
Motion cycle with feedfor
ward measures......................................................................... 209
The feedforward channels are used for the specific influence of the guiding behavi-
or of a control. The calculated and evaluated status variables are coupled into the
corresponding places within the controller cascade. In practice, the feedforward
control offers the following advantages:
Minimal following error
Improves the transient response
Gives greater dynamic range with lower maximum current
The Compax3 servo controller disposes of four feedforward measures (see in the
standard cascade structure):
Velocity feed-forward
Acceleration feed-forward
Current feed-forward
Jerk feed-forward
The above order represents at the same time the effectiveness of the individual
feedforward measures. The influence of the jerk feedforward may be, depending
on the profile and the motor, negligeably small.
But the principle of feedforward control fails in limiting the motor current or the mo-
tor speed during the acceleration phase!
Influence of the feedforward measures
Following error minimization by feedforward control / course of the setpoint genera-
tor signals
xws: Position setpoint value of the setpoint generator
nws: Velocity setpoint - setpoint generator
aws: Acceleration setpoint value setpoint generator
rws: Jerk setpoint value setpoint generator
Please note!
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