Abstract:

Failure modes and effects analysis(FMEA) is an important means of design review and reliability evaluation, but conventional FMEA is tedious and error-prone due to its informalization. Formal methods are introduced to FMEA for electromechanical systems and an approach to FMEA for electromechanical systems based on model checking is proposed. Based on the states and events in electromechanical systems, formal modeling for the behavior process of the systems is studied and formal model for FMEA with respect to component failures is established. Computation tree logic(CTL) formulas are employed to make formal specification of the potential faults in electromechanical systems, and the negative propositions of potential fault are used to form system properties to be verified. By traversing system space, a system is checked if it satisfies the system properties and thereby the relations between component failures and the system potential faults are identified, so model checking based FMEA for electromechanical systems is realized. The above approach is applied to feed system of a CNC machine tool, and the system faults caused by limit switches are identified successfully, which demonstrates the feasibility of the proposed approach.

Key words: electromechanical systems, model checking, reliability evaluation, FMEA