Nonlinear control of particulate processes

A general methodology is proposed for the synthesis of practically-implemen table nonlinear output feedback controllers for spatially-homogeneous parti culate processes modeled by population balance equations. Initially, a nonl inear model reduction procedure based oil a combination of the method of we ighted residuals and the concept of approximate inertial manifold is presen ted for the construction of low-order ordinary differential equation (ODE) systems that accurately reproduce the dominant dynamics of the particulate process. These ODE systems are then used for the synthesis of nonlinear low -order output feedback controllers that enforce exponential stability in th e closed-loop system and achieve particle-size distributions with desired c haracteristics. Precise closed-loop stability conditions are given and cont roller implementation issues are discussed The proposed nonlinear control m ethod is successfully applied to a continuous crystallizer, and is shown to outperform a proportional-integral controller and cope effectively with mo del uncertainty and measurement delays.