Basis weight and filler content: decoupled Smith predictor approach

Abstract A control strategy for basis weight and filler content of paper is presented. The largest cross effect between basis weight and filler content is avoided by using fiber and filler weights for control. The effect of broke filler in thick stock is compensated for by feed-forward control. A circulation model with retention as a parameter is used as a Smith predictor model. The controllers for both fiber and filler are ordinary PI controllers.