Advanced Control Foundation

Tools, Techniques and Applications

Fuzzy Logic Control

In this workshop, the control performance of fuzzy logic control will be compared to the performance of PID control when the control objective is to reach setpoint in minimum time with no overshoot. Two identical process heaters are simulated with PID and fuzzy logic control.

Step 1: Open the workshop module and initialize the IAE calculation.

Step 2: Increase the temperature setpoint to the PID and Fuzzy blocks by changing the “SP” parameter value. Note the calculated IAE once both loops achieve setpoint and use the plot to observe which control reached the setpoint faster.

Step 3: Repeat Step 2, but this time decrease the “SP” value by 10. Note that the process and control response is the same as for a temperature increase.

Step 4: Reset the IAE calculation and then introduce an unmeasured process disturbance into both heaters by changing the “DISTURBANCE” parameter from 0 to 15. Note the IAE once both loops achieve setpoint and use the plot to observe which control was the first to reach setpoint.

Step 5: Repeat Step 3, but change the “DISTURBANCE” parameter value to 0. Note that the performance equivalent to that seen in Step 3.