45
Auto-tuning (AT)
In order to decide each value of P, I, D and ARW automatically, the auto-tuning
process should be made to fluctuate to obtain an optimal value.
(1) In the case of a large difference between the setting value and processing
temperature as the temperature is rising.
When AT bias is set to 20 , the AT process will fluctuate at the temperature 20
lower than the setting value.
(1)
Calculating
PID
constant
(2) PID constant
calculated
(3) Controlled by the
PID constant set
by auto-tuning.
(4) AT bias value
(Fig.
10.5-1)
(2) In the case of a stable control
The AT process will fluctuate around the setting value.
(1) Calculating PID
constant
(2) PID constant
calculated
(3) Controlled by the
PID constant set
by auto-tuning.
(Fig.
10.5-2)
(3) In the case of a large difference between the setting value and processing
temperature as the temperature is falling
When AT bias is set to 20 , the AT process will fluctuate at the temperature
20 higher than the setting value.
(1) Calculating PID
constant
(2) PID constant
calculated
(3) Controlled by the
PID constant set
by auto-tuning.
(4) AT bias value
(Fig.
10.5-3)
For DC input, AT process will fluctuate around the setting value under conditions described in
(1), (2) and (3).
Temperature 20 lower than the setting value
Temperature 20 higher than the setting value
(1)
(2)
(3)
(4)
AT starting point
Setting value
Temperature
Time
AT starting point
(1)
(2)
(3)
Temperature
Setting value
Time
AT starting point
(1)
(2)
(3)
(4)
Temperature
Setting value
Time