Data-driven direct control method for coagulation dosing large time-delay process in water works

To deal with the large time-delay in the coagulation dosing process in water works,we,in combining with Smith predictor,propose a novel data-driven direct control method based on the iterative feedback tuning(IFT) method.In considering the characteristics of the large time-delay,we add to the performance index a penalty factor of predictive errors in the controller design.A novel step size setting scheme is proposed in which the rate of descent of the step size is adjustable.Three closed-loop experiments are carried out to perform the gradient descent optimization of the cost function which is computed totally from the I/O data in the close-loop system.The parameters of controller and predictor are automatically tuned for an unknown plant.Simulation studies with a practical coagulation dosing process model are conducted.Results show that the convergence and stability of this algorithm outperform classical IFT in large time-delay applications and with less dependence on the initial parameters.This scheme can be applied to the initial tuning of the controller or for the automatic tuning during the dosing process.