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03/2006
6.9.10
Axis position control data
Control loops
The controller for an axis consists of the speed control loop, the current control
loop and a higher-level position control loop.
Position setpoint
from
Position
interpolator
controller
Actual position
value
(position)
Fig. 6-15
Control loops
Traversing
If the axis does not move in the desired direction, it is adapted via MD 32100:
direction
AX_MOTION_DIR (traversing direction). The value "–1" reverses the direction
of motion. Allowance is made internally for the control direction of the position
controller. If the control direction of the position measuring system is the wrong
way around, this is corrected with MD 32110: ENC_FEEDBACK_POL (actual
sign value).
Loop gain
In order to obtain high contour accuracy with an interpolation, the loop gain
factor (K
high, on the other hand, this leads to overshooting, instability and inadmissibly
high loading of the machine. The maximum permissible K
on the design and dynamic response of the drive and the mechanical quality of
the machine.
Definition of the K
V
(loop gain) factor
K
© Siemens AG 2006 All Rights Reserved
SINUMERIK 840D/810D Start-Up Guide (IADC) – 03/2006 Edition
n
i
set
set
Speed
controller
n
act
factor) of the position controller must be large. If the K
V
Velocity
=
V
Following error
6 Programming the control
6.9
Axes and spindles
Current
controller
Motor
i
act
V
[m/min]
[mm]
Encoder
factor is too
V
factor is dependent
6-103
6
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