A coupled pH and level control in pH process by data-driven based, input-output linearization

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Sirawich Lohprasert
Chanin Panjapornpon


A pH process is one of the essential units used in many industries for preparing substance to be under proper conditions before sending to consequent units. A highly nonlinear of pH characteristics, process disturbances, process condition, and interaction between control pairs create difficulty in developing a high-quality physical model for a controller development. In this work, a data-driven based control is presented to handle a coupled control of the pH and liquid level in the pH reactor. A real-time, estimation of the process data is implemented to provide robustness in empirical modeling. This developed model is used in a formulation of a discrete-time, input/output (I/O) linearizing controller. The proposed control method has a simple model structure and controller equations that are suitable for a control application. The proposed control method is embedded in myRIO, and its performance is evaluated and compared with the PI controller through the servo test with a bench-scale pH reactor in real-time. The experimental results showed that the proposed control method provides faster response and less overshoot in the outputs than the PI controller.

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