
APPENDIX
E5AK
A--14
FUZZY SELF-TUNING
Fuzzy self-tuning is a function that enables the E5AK to calculate the most
suitable PID constants for the controlled object.
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Features
·
The E5AK determines by itself when to perform fuzzy self-tuning.
·
At the time of fuzzy self-tuning, the E5AK does not output any signal
that disturbs the temperature or output value.
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Fuzzy Self--tuning Function
The fuzzy self-tuning function has three modes.
In SRT(step response tuning) mode, the PID constants are tuned
using a step response method at the time the set point is changed.
In DT(disturbance tuning) mode, the PID constants are amended
so that the controlled temperature will be within the target range
set in advance when there is external disturbance.
In HT(hunting tuning) mode, when hunting occurs, the PID
constants are amended to suppress the hunting.
Note:
Be sure to turn on the power supply to the load either before or si-
multaneously with the start of Temperature Controller operation.
Dead time will be measured from the time the Temperature Con-
troller starts operating. If a load such as a heater is turned on after
the Temperature Controller is turned on, dead time longer than the
actual value will be measured and inappropriate PID constants will
be obtained. If an extremely large amount of dead time is measured,
the control amount will be set to 0% for a short period of time before
being returned to 100%, and the constants will then be returned.
Retuning is performed only for large amounts of dead time, so be
sure to follow the precaution given above when starting operation.
SRT will start if the following conditions are satisfied simultaneously
when the E5AK is turned on or the set point is changed.
At the time the E5AK starts operation
At the time set point is changed
1) The set point at the time the E5AK
starts operating is different from the
set point used at the time SRT was
last executed (see note).
2) The process value at the time the
E5AK starts operating is smaller than
the set point in reverse operation and
larger than the set point in normal
operation.
1) The new set point is different from the
set point used at the time SRT was
executed last (see note).
2) The process value is in stable condi-
tion before the set point is changed.
3) A larger set point value is set in
reverse operation and a smaller set
point is set in normal operation.
Note:
The last SRT-executed set point is set to 0 before shipping and when
changing from advanced PID control to advanced PID control with
fuzzy self-tuning.
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Startup
Conditions of
SRT