Self-tuned fuzzy logic control of a pH neutralization process

On-line implementation of self-tuning mechanism based adaptive fuzzy logic control of a pH neutralization process which takes care of steady state error and time taken to reach steady state under varying operating conditions has been presented in this paper. The pH neutralization system is Armfield pH Sensor Accessory (PCT42) in conjunction with Process Vessel Accessory (PCT41) and Multifunction Process Control Teaching System (PCT40). The proposed adaptive scheme updates the normalized universe of discourse of output fuzzy membership functions with varying scaling factors based on error and change of error values. The speed of response of the adaptive controller is taken care by use of coarse control technique whereas amount of deviation under steady state is accounted with the help of fine control technique. The performance of adaptive scheme is tested for pH control at equivalence point. LabVIEW software is used for online communication, control and display.