Sharif Digital Repository

In this work performances of adaptive backstepping controller (BSC) and globally linearizing controller (GLC) are compared for pH control. First, based on the system full order model a GLC has been designed and it has been shown that this controller is identical to BSC proposed in the literature. Next in order to avoid state estimator design, BSC and GLC are designed based on pH reduced order model and their identities have been established. Through computer simulations, it has been shown that the performance of non-adaptive GLC designed based on reduced order model is better than that of adaptive BSC designed based on pH full order model which requires state measurement for implementation.... 

pH control is a challenging problem due to its highly nonlinear nature. In this paper the performances of two different adaptive global linearizing controllers (GLC) are compared. Least squares technique has been used for identifying the titration curve. The first controller is a standard GLC based on material balances of each species. For implementation of this controller a nonlinear state estimator is used. Some modifications are proposed to avoid the singularity of the observer gain. The second controller is designed based on the reduced state equation. Through computer simulations, it has been shown that the performances of the second GLC is superior and it is more robust to process...