Sensitivity compensating nonlinear control: Exact model based approach

A novel sensitivity compensating nonlinear control (SCNC) approach is proposed within generic model control (GMC) framework for processes exhibiting input sensitivity. The proposed approach consists of defining a new process, control law and set point such that the determined control action drives the original process to its desired set point. External reset feedback (ERF), used to compensate for input saturation, is extended to higher relative degree systems as extended ERF (EERF), and is incorporated in the context of SCNC approach. The proposed control algorithms are evaluated by application to an open-loop unstable CSTR control problem and a multi-product semi-batch polymerization reactor temperature control problem. The present study illustrates the versatility of the proposed SCGMC schemes compared to the basic GMC schemes in terms of output tracking and smoother input profiles. SCNC can be extended to other nonlinear model based controllers where the control law can be expressed analytically.