An Approach to Concept Evaluation of Mechanical System Using Vague Sets

To deal with the fuzzy information existing in the process of concept evaluation, vague sets theory is introduced in concept evaluation of mechanical design and a vague sets based evaluation model is structured in this paper. Under this model, decision matrix is converted into objective-grade-membership matrix firstly. Then by computing the sets of objectives being in favor, against and neutral, the vague evaluation is acquired for each alternate, in which objective value is integrated with the corresponding weight to generate the vague value using the objective-grade-membership matrix. Finally an improved score function is adopted to rank all the concepts and the best one is selected. An example shows the effectiveness of this proposed approach. Compared with the fuzzy set based evaluation method, this proposed model considers both the weight and the decision value of each objective, and has fairly strong and flexible intuition expression ability for handling indefinite data. It is concluded that the model developed is more suitable to be used for concept evaluation in the imprecise and uncertain design environment.