A fuzzy logic and variable structure based controller for pH control

The pH control is a difficult problem to solve. This is due strong nonlinearities and extreme sensitivity to disturbances in the process. The possible combination of the variable structure system with fuzzy logic theory for the pH problem is treated. This paper shows how this theory can improve the variable structure controller applied to this process. A Smith predictor is utilized to account for the pH process time delay. This paper proposes the controller gains adjustment by means of fuzzy logic. The simulation results obtained are presented.