NONLINEAR CONTROL OF A FLUIDIZED-BED REACTOR USING APPROXIMATE FEEDBACK LINEARIZATION

Two approaches to approximate feedback linearization are applied to th e nonlinear control of a fluidized bed reactor. The first approach, th ird order approximate input-state linearization, results in improved p erformance for setpoint tracking over a narrow region around the opera ting point. On the basis of an analysis of the assumptions of approxim ate input-state linearization, an approximate input-output linearizati on scheme is proposed. Implementation of a control scheme for the flui dized bed reactor based upon this approach resulted in excellent setpo int tracking over a 30 degrees C temperature range in the reactor. The issues of nonlinear model selection and computational issues are disc ussed. Finally, a novel internal model control based nonlinear anti-wi ndup scheme is implemented to ensure that improved performance is obta ined without violating hard actuator constraints.