DECISION-MAKING METHOD OF MECHANICAL TRANSMISSION SCHEMES BASED ON AN IMPROVED SIMILARITY MEASURE BETWEEN VAGUE SETS

摘要

Research on decision-making methods is a key technique for the optimal selection of various design schemes during the conceptual design phase. Then, theory of vague sets has provided a good method for fuzzy decision-making problems, and has applied successfully in the scheme decision. Aimed at a generalization of the concept of fuzzy sets— vague sets, 3-D meaning (affirmation, negation, and uncertainty) of a vague set, the influence of uncertainty degree (hesitancy degree) upon affirmation degree and negative degree were described. An improved similarity measure between vague sets and its application in the decision-making problem of mechanical transmission schemes were presented in the base of previous methods. The improved similarity measure between vague sets was illustrated by comparison with the previous similarity measures that it had stronger discrimination. While the decision-making of mechanical transmission schemes is being made, the similarity measure between vague sets is the measure for evaluating whether the mechanical transmission scheme is close to the expected scheme (ideal scheme) or not. The bigger the value of similarity measure is, the better the close degree between the transmission scheme and the expected scheme is. It has been expounded through an example that the application of similarity measure analysis between vague sets to the decision- making of mechanical transmission schemes is feasible. The presented method can obtain satisfactory results and give designers the theoretical warranty of scheme decisions.