In practice this means that some kind of directionality has to be introduced into the system excitation, through feedback or a priori information of the system directionality. Modern robust control design methods require, in addition to a nominal model of a plant, bounds on possible deviations from this model. The estimation of this uncertainty has not been extensively studied, and the existing methods rely on a priori assumptions of information not available in a practical situation. A pilot-scale distillation column is available for experiments. It is shown that black-box methods can easily give models completely useless for control design.
Experiments designed to excite different directions give better results.
Multimodel identification of an ill-conditioned distillation column. A multimodel identification method is developed and tested on real data. The multimodel description can be used for robust control design. Uncertainty estimation for robust control design. An ill-conditioned system is very sensitive to model uncertainty.