Fuzzy Self-Tuning; Fuzzy Self- -Tuning Function - Omron E5AK User Manual

APPENDIX

FUZZY SELF-TUNING

J Features
J Fuzzy Self- -tuning Function
F Startup
Conditions of
SRT
A--14
Fuzzy self-tuning is a function that enables the E5AK to calculate the
most suitable PID constants for the controlled object.
• 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.
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
simultaneously with the start of Temperature Controller opera-
tion. Dead time will be measured from the time the Temperature
Controller 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
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 opera-
tion and larger than the set point 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 con-
trol with fuzzy self-tuning.
At the time set point is changed
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
condition 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.