A Mamdani-type fuzzy gain adapter for PID controller on a thermal system using PLC

摘要

This paper presents the development and real-time implementation of on-line, automatic gain-tuning proportional-integral-derivative (PID) controller using the programmable logic controller (PLC) on a heater-furnace system. The mamdani-type fuzzy logic controller (FLC) tunes only the PID gains and the structure of the PID is not altered. Thereby the robustness of the PID to linear parameter variations is maintained. With the help of the fuzzy controller PID is made to overcome the nonlinear disturbances that can occur in a real-time environment. The developed controller is implemented on a heater-furnace system and the algorithms are developed using the ladder functions of the PLC. The real-time implementation of the conventional velocity-form PID and the Fuzzy-PID gain tuner are carried out and the results are presented. This approach provides more flexibility to use the control program with those PLCs which do not support ready PID and fuzzy-PID blocks. It is shown that the developed fuzzy tuned PID is able to track the parameter variations quickly than the conventional one with minimum overshoot and faster settling time.