Dynamic output feedback control of minimum-phase multivariable nonlinear processes

This paper concerns the synthesis of dynamic output feedback controllers for minimum-phase multivariable nonlinear processes with a nonsingular characteristic matrix. State-space controller realizations are derived that induce a linear input/output behavior of general form in the closed-loop system. A combination of input/output linearizing state feedback laws and state observers is employed for the derivation of the controllers. For open-loop stable processes, the process model is used as an open-loop state observer. In the more general case of possible open-loop instability, a reduced-order observer is used based on the forced zero dynamics of the process model. The performance and robustness characteristics of the proposed control methodology are illustrated through simulations in a chemical reactor example.