Dynamic transition control structure for a class of SISO nonlinear systems [chemical processes]

Most chemical processes are nonlinear in nature and large setpoint changes or load disturbances make such processes more challenging for control. Earlier a simple transition control structure was introduced so that the tradeoff between nominal performance and robust stability of the model with large uncertainties is converted into the development of several models with small uncertainties in such a way that the former problem can be solved satisfactorily. In this work, a modification to that transition control structure is proposed to address nonlinear systems. The performance of this transition control structure is demonstrated on a nonlinear pH neutralization process. The simulation results show that the proposed structure has good properties not only for setpoint changes but also for disturbance rejection