Omron CX-PROCESS TOOL V5.2 - REV 10-2010 Operation Manual page 330

Tuning
Checking the Fuzzy
Logic Block (016)
Membership Function
304
2. Set the degree of Response improvement, Overshooting control, and
Hunting control to any of the five levels and then click the OK Button.
Note Fine tuning will be executed with the settings in the FT Execution Dia-
log Box each time that the OK Button is clicked. The Undo Button can
be clicked to return to the previous PID constant settings. (The pre-
vious PID constant settings will be restored if the Undo Button is
pressed a second time.)
3. Fine tuning will be executed according to the settings that were input.
4. The PID constants adjusted with fine tuning will be stored automatically and
the new values will be displayed at the top of the Tuning Screen. The propor-
tional band, integral time, and derivative time settings will change.
Execute fine tuning when the control performance produced by autotuning is not
acceptable, when autotuning produces instability in the PV, or when you cannot
allow control to be interrupted.
Fine tuning improves control by automatically setting PID parameters using the
three user settings listed below along with fuzzy logic applied to previous control
conditions.
• Hunting
• Overshooting
• Responsiveness
Either one or two of the user setting can be set to any of five adjustment levels.
For example, to better control hunting and overshooting, the Overshoot and
Hunting parameters can be set to the desired levels.
Response improvement
When the fuzzy logic block (016) is being tuned, the display will show the Mem-
bership Function (MF) set with ITEMs in the Tuning Screen.
The Membership Function can be checked for each label (NL, NS, ZR, PS, and
PL) of inputs 1 to 8.
Overshooting control
In this example, hunting control
is set to level 4 and overshooting
control is set to 3.
Section 4-7
Hunting control