Nonlinear Observer for Temperatures and Emissivities in a Strip Annealing Furnace

The annealing process plays an important role for the product quality of steel strips. To achieve a high product quality, an accurate temperature control is essential, which typically requires information about the temperature evolution inside the strip annealing furnace. However, usually only a few temperatures at discrete points in the furnace can be measured. Therefore, this paper proposes an extended Kalman filter and an ad-hoc adaptive estimator for the furnace temperatures. Moreover, both observers also estimate the inexactly known strip emissivity. The observers are validated by means of measurement data from an industrial furnace. This validation demonstrates the reliability and accuracy of the ad-hoc adaptive estimator.