Research on safety analysis for airborne system based on extended functional model

With the widespread use of embedded system in safety critical areas, system safety assurance has become one of the research hotspots of engineering technologies. System safety analysis mainly concentrates on the requirement specification and the recent design, and in the process of the actual development of the software, safety requirement analysis and design are two independent processes. This article expands the safety requirements described by fault tree into state diagram and proposes the new concept “fault state diagram,” which can unify safety requirement model and functional model. Based on the fault state diagram, this article proposes the method of airborne system safety analysis, including the following: gives out one method for abstracting and describing safety requirements from system fault tree based on Backus Normal Form; defines the transformation rules from fault tree logic gates and continuous time into state diagram elements; designs safety requirement information mapping table which translates safety requirements into state diagram elements; and designs the automatic construction algorithm of fault state diagram, which is based on the transformation rules and mapping table. Finally, a small gas stove control system case using the method proves the feasibility and effectiveness of the proposed method.