Feedback Control With Following Error - HEIDENHAIN iTNC 530 Technical Manual

Feedback control
with following error
February 2002
Following error (also known as servo lag) is a gap that remains between the
nominal position commanded by the NC and the actual position.
Simplified representation:
S
Noml
S
Actl
The nominal position value s
position value s and the resulting difference is the following error s
actl
s = s – s
a Noml Actl
s = following error
a
s = nominal position value
Noml
s = actual position value
Actl
The following error is multiplied by the k
velocity value:
v = k · s
v a
v = nominal velocity value
noml
Analog axes:
For stationary axes, the integral factor has an additional effect (MP1080.x). It
produces an offset adjustment.
Digital axes:
There is no offset. MP1080.x has no function.
The Control Loop
for a given axis is compared with the actual
noml
factor and passed on as nominal
v
v
Noml
:
a
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