Multivariable disturbance modelling for web processes

This paper considers suitable disturbance models for use in the design of c ontrol systems for web forming processes. It suggests a practical disturban ce representation and, using spectral factorization, presents a multivariab le aggregated model of the disturbance. The paper compares generalized mini mum variance (GMV) controllers designed using uncorrelated and cor related disturbance models and demonstrates the improvement in performance of a mul tivariable GMV controller which is designed to accommodate the cross direct ion correlation in the disturbance compared to the GMV controller that is c ommonly used in practice, which is based on a model that ignores the effect s of correlated disturbances.