基于IPO功能分解的嵌入式软件故障树分层构建方法

针对嵌入式软件需求阶段的安全性分析方法中故障树分析缺少构建方法的问题,结合嵌入式系统的特点,提出了一种故障树分层构建方法.为构建各功能层内部的故障树,提出了基于IPO的功能分解法,采用失效模式与影响分析方法对分解的各部分功能进行影响分析,以确定构建故障树的建树元素,并提出了功能层内部故障树构建的框架模型与各功能层故障树的层次关系,实现了部分故障树构建的自动化,提高了故障树构建的完整性、准确性与效率.在某型号发动机控制软件的安全性分析中,应用上述方法指导该嵌入式软件故障树的构建与分析,验证了该方法的可行性和有效性.

Hierarchical construction method for embedded software fault tree based on IPO function decomposition

To solve the lack of construction methods for fault tree analysis(FTA)in the safety analysis methods at the requirement stage of embedded software, a hierarchical construction method for fault tree(FT)was proposed in combination with the characteristics of embedded system. In order to construct the internal FT of each functional layer, the IPO-based(input, process, output)function decomposition method was proposed. In addition, the effect analysis of various decomposed functions were carried out through adopting the FMEA(failure modes and effect analysis)method, and the construction elements of FT were determinined. Furthermore, the hierarchical relationship between the framework model for FT construction inside function layers and FT of each functional layer was proposed. And thus, the automation of FT construction is partially realized, and the completeness, correctness and effectiveness of FT construction get improved. In the safety analysis on the control software of an engine with certain type, the above-mentioned method was used to guide the FT construction and analysis of the proposed embedded software. The feasibility and effectiveness of the method is proved.