Nonlinear State Estimation with Delayed Measurements. Application to Polymer Processes

GALDEANO, RUBEN; ASTEASUAIN, MARIANO; SANCHEZ, M.C.

Computer Aided Chemical Engineering

Elsevier

Año: 2011 vol. 29 p. 592 - 596

1570-7946

Measurement and control of polymer processes is a very challenging task due to their high nonlinearity, strong relationship between quality variables and process conditions, and the absence of reliable on-line sensors. In these processes many important variables cannot be measured on-line or can only be measured at low sampling frequencies. In this context, state estimation becomes an important step for the proper implementation of control systems. A relatively new method known as Unscented Kalman Filter (UKF) has been developed for nonlinear processes. This method overcomes disadvantages of classical techniques like the extended Kalman filter. In this work a methodology is developed for incorporating delayed measurements into the UKF framework, without resorting to re-estimation steps. In this procedure, the filter algorithm is adapted in order to include delayed measurements by modifying the gain matrix. Very good results are obtained in terms of accuracy and computational time. © 2011 Elsevier B.V.