Apply Degree of Match & Fuzzy Rule Based Mode for FMECA in Flight Control System

Failure Mode, Effecte and Criticality Analysis (FMECA) is used widely in engineering practices such as aerospace, medical facilities, naval vessels and shipping, which improves the reliability and safety of the products significantly. It can eliminate potential failures, errors and problems from design, system and process. To overcome the drawback in the traditional Risk Priority Number (RPN) [1], Gargama, H. proposes a model based on the combination DM (Degree of Match) and fuzzy rule-base employing fuzzy logic method [2]. Consider the situation that the different expert may has different opinions and knowledge backgrounds, they will give different criteria. Due to the incomplete information, less data and various uncertainties, three traditional risk factors O (Occurrence), S (Severity) and D (Detectability) can be treated as fuzzy numbers, therefore, the fuzzy linguistic terms provides a very appropriate way for modeling this case. The degree of matching is used to estimate the matching between the experimental team members' assessed information and the fuzzy number by transformation the assessed information into convex normalized fuzzy sets. An engineering example, flight control system (FCS) in unmanned vehicle, is presented to demonstrate the proposed fuzzy FMECA method. The illustrated example has shown that the proposed method advances the reliability and safety for it can model various uncertainties effectively.