Rockwell Automation RSLogix 5000 Fuzzy Designer - Manual (Page 17)

Publication LOGIX-UM004A-EN-P - March 2007
Get Started with FuzzyDesigner 17
Nonlinear, Fuzzy Rule Based Supervisor of a PID Controller
The great advantage of fuzzy supervision is that it can be applied to
existing control and there is little danger of making errors in design.
Most frequently used is a supervised PID controller where PID gains,
feedforward action, or setpoints are being modified dynamically by
rules depending on the process status and external conditions defined
through setpoints.
Smart Switching Between Conventional Controllers, Takagi-Sugeno Controller
Another popular control structure with fuzzy logic is smart switching
between local controllers. A local controller is an analytical controller
designed to work around specific process operation conditions. Once
the conditions change, the rule based supervisor decreases the
influence of one controller and gives more weight to another
controller that has been designed to work in the new conditions.
SP
PV
FUZZY
SUPERVISOR
FUZZY
SUPERVISOR
PLANT PLANT
PID
gains
CV
PID
CONTROLLER
PID
CONTROLLER
feedforward
Plant States
SP
PV
FUZZY
SUPERVISOR
FUZZY
SUPERVISOR
PLANT PLANT
PID
gains
CV
PID
CONTROLLER
PID
CONTROLLER
feedforward
Plant States
CONTROLLER
1
CONTROLLER
1
CONTROLLER
2
CONTROLLER
2
CONTROLLER
3
CONTROLLER
3
FUZZY SUPERVISOR FUZZY SUPERVISOR
+
+
+
Setpoints
PLANT PLANT
Ч
Ч
Process Variables
Plant State
Schedule weights ∈ [0,1]
CV
×
CONTROLLER
1
CONTROLLER
1
CONTROLLER
2
CONTROLLER
2
CONTROLLER
3
CONTROLLER
3
FUZZY SUPERVISOR FUZZY SUPERVISOR
+
+
+
Setpoints
PLANT PLANT
Ч
Ч
Process Variables
Plant State
Schedule weights ∈ [0,1]
CV
Ч