Fuzzy PID controller to control the pH neutralization process

Research and experiments were conducted to build a Fuzzy Controlled PID Controller to control the pH neutralization process. Process modeling and control was done chiefly with the SIMULINK software in MATLAB based on the McAvoy model. The gain scheduling method was studied to aid in tuning the P control of the PID. A PID controller was designed first, and then the Fuzzy KC controller was built using the Mamdani type Fuzzy Inference System (FIS) with the controller settings based on the results obtained from the gain scheduling testing. Next, the Sugeno FIS was used to create a Fuzzy tau(1) controller to complement the Fuzzy P Controller. The compiled Fuzzy PI controller was then tested on servo and regulator problems. The servo test used a uniform random number generator to simulate set points between pH=3 to pH=11 and the simulation was run over 100s. The regulator test was run at +/-5% of acid flow, F-a. The result of the servo test was a near perfect response with no overshoot or oscillatory responses. The response time was very quick with practically no lag time. The result of the regulator test was a response that changed in tandem with the disturbances but was limited to a narrow range of <0.01 pH units.