U Page 29
Digital controller RK 4004
Window width
.1.4. dual rate width
Error of uneven
edge
Set position
The values may also be calculated arithmetically:
Amplification (G) = parameter .4.5. / parameter .1.3.
Correction positioning path (SK) = control deviation * amplication (G)
Example 1:
Example 2:
G = 25/2 = 12.5
G = 25/3.5 = 7.14
SK = 1.5 mm * 12.5
SK = 1.5 mm * 7.14
VK = 18.75 mm
VK = 10.71 mm
Integral actuator optimisation:
Reduce the proportional range by small steps only. Following each
change of the parameter value the a web deviation should be produ-
ced manually in automatic mode so that oscillation may be detected
immediately.
Reduce the proportional range until the guider starts to oscillate. The
increase the proportional range again until no more oscillation may
be observed.
.1.4. dual rate width
.1.5. dual rate level
These two parameters have no function with an integral guider.
If the web edge is subject to certain fluctuations (uneven edges) the-
se two parameters may be used to determine a range in which, given
a deviation from the set position, the correction velocity of the actua-
tor is reduced in the case of proportional guiders.
Given a web edge progression as illustrated opposite, the actuator
would normally try to correct the deviation according to the broken
line. The actuator would only oscillate and the control result would not
be satisfactory. The broken line represents the controller amplification
(parameter .1.3. / .1.6.).
Within the set window width ".1.4. dual rate width" the positioning
velocity is reduced in the case of a control deviation. The positioning
velocity reduction is set in parameter ".1.5. dual rate level". Potential
oscillation due to edge errors may thus be reduced. If the edge error
exceeds the set window width range the positioning velocity is
increased (see fig. on left).
Both parameter values are % entries and are related to the set valu-
es of parameter ".1.3. prop range ±" and ".1.6. velocity auto"
Example:
The following values are set in the parameters.
.1.3. prop range ±
:
10.0 mm
.1.6. velocity auto
:
20 mm/s
Positioning velocity
reduction
.1.5. dual rate level
