Abstract: Because the functional relationships between customer requirements and engineering characteristics and the correlations among engineering characteristics in quality func-tion deployment are uncertain, unclear and fuzzy, based on some related methods in rough set theory, the methods of de-termining them are presented, and then the initial importance ratings of engineering characteristics are determined. The effi-ciency and risk analysis are implemented on the achievement of the improvement ratio of engineering characteristic’s perform-ance, a formula of calculating the importance rating of achiev-ing the improvement ratio of engineering characteristic’s per-formance is presented. Based on a combination of the initial importance rating of engineering characteristic, the importance rating of achieving the improvement ratio of engineering char-acteristic’s performance and “technical point”, a method of determining the final importance rating of engineering charac-teristic is proposed. A case study of product development of fully automatic washing machines in a company is provided to illustrate the application of the presented method.

Key words: Engineering characteristic, Importance rating, Quality function deployment, Rough set, Rolling element bearing State space Particle filter Kurtogram