Hybrid fault tree analysis using fuzzy sets

In conventional fault tree analysis (FTA), the ambiguous and imprecise events such as human errors tend not to be handled effectively. To overcome this disadvantage, a hybrid approach employing fuzzy set evaluation and probabilistic estimation for FTA is proposed to evaluate abnormal events. The safety problem of unexpected robot motion in an aircraft wing drilling system was analyzed using the proposed method. The results indicated that the proposed approach is very effective in analyzing the reliability of a man-machine system.