HEIDENHAIN TNC 430 PA - Feedback Control with Following Error

6 – 122 HEIDENHAIN Technical Manual TNC 426, TNC 430
MP1391 Velocity feedforward control in the MANUAL and
HANDWHEEL operating modes
Format: %xxxxxxxxx
Input: Bits 0 to 8 correspond to axes 1 to 9
0: Operation with following error (lag)
1: Operation with velocity feedforward control
Feedback control
with following error
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:
The nominal position value s
noml
for a given axis is compared with the actual
position value s
actl
and the resulting difference is the following error s
a
:
s
a
= s
Noml
– s
Actl
s
a
= following error
s
Noml
= nominal position value
s
Actl
= actual position value
The following error is multiplied by the k
v
factor and passed on as nominal
velocity value:
v = k
v
· s
a
v
noml
= nominal velocity value
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.
Note
M90 (lag mode: Constant contouring speed at corners) is effective only if
operation with following error is selected for all axes (MP1392 =
%000000000).
v
Noml
S
Noml
S
Actl