A nonlinear model-based control scheme for pH-neutralisation process

Control of pH has always been a critical task because of the highly complex nonlinear characteristic of the titration curve. This paper is concerned about the design of an adaptive nonlinear model-based tracking control scheme and its application in a benchmark pH-neutralisation process. The scheme exploits a deterministic process model to generate the model state which reflects the actual process dynamics, and utilises three different adaptive tuning methods to update the controller gain on real-time basis. Simulation results show that the proposed scheme ensures closed-loop stability and facilitates satisfactory set-point tracking (both time-varying and constant) performance despite parameter variation, exogenous disturbance and measurement noise.