U Page 27
Digital controller RK 4004
By reducing the proportional range the characteristic curve (see fig.)
will become steeper. The steeper the characteristic curve the greater
the positioning velocity will be in the case of a control deviation and
the system thus more sensitive. The positioning velocity of the actua-
tor may be determined on the basis of the characteristic curve re-
gardless of the control deviation.
In this example a proportional range of 2 mm or 3.5 mm has been
assumed at a maximum motion speed of 20 mm/s.
Given a control deviation of 1.5 mm the positioning velocity is
15 mm/s for a proportional range of 2 mm and 8.0 mm/s for a pro-
portional range of 3.5 mm.
The values may also be calculated arithmetically:
Amplification (G) = parameter .1.6. / Parameter .1.3.
Correction velocity (VK) = control deviation * amplification (G)
Example 1: Example 2:
G = 20/2 = 10
1
/
s
G = 20/3.5 = 5.71
1
/
s
VK = 1.5 mm * 10
1
/
s
VK = 1.5 mm * 5.71
1
/
s
VK = 15 mm/s VK = 8.6 mm/s
Proportional actuator optimisation:
Reduce the proportional range by small steps only. Following each
change of the parameter value a web deviation should be produced
manually in automatic mode so that oscillation may be detected im-
mediately.
Reduce the proportional range until the guider starts to oscillate. The
increase the proportional range again until no more oscillation may
be observed.
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