MINIMIZATION OF THE EFFECT OF UNCERTAINTY ON MODEL ESTIMATION

The objective of this paper is to minimise the effect of an uncertain oil him bearing model on the estimation of a foundation model from run -down measurements on a turbo-generator. To do this a method is presen ted to identify a dynamic transfer matrix relating the response vector of the foundation at the bearings to an estimated force which is inse nsitive with respect to the oil film model. Analytically this transfer matrix is related to that of the foundation simply by the multiplicat ion by a transformation matrix which only depends on the model of the rotor and on the model of the oil film, and which of course retains th e sensitivity of the original problem with respect to the oil film mod el. But since the estimation error of the robust transfer matrix estim ate is minimum the retained error is mainly due to the erroneous oil f ilm model used in the transformation matrix. The use of the robust est imate to calculate the contribution of the support on the dynamics of the mounted machine for variations of the oil film model increases the reliability of the predictions. (C) 1998 Academic Press Limited.