一种状态事件故障树的时间特性分析方法

状态事件故障树是一种适合于描述构件化嵌入式系统失效因果链的建模技术,其顶层事件描述失效发生的结果.对顶层事件发生的平均时间进行分析,是获得系统平均失效时间参数的一种有效方法,可为系统的安全性评估提供支持.由于状态事件故障树缺乏严格语义,使得必须先对其进行形式化描述才能进行定量分析.为此,提出了一种基于交互马尔可夫链的状态事件故障树时间特性分析方法.首先,精化交互马尔可夫链的交互动作,建立接口交互马尔可夫链模型,并基于该模型对状态事件故障树的构件和逻辑门进行形式语义描述;其次,通过并行组合构件与逻辑门的形式语义模型,得到整个状态事件故障树的形式语义模型,并在该过程中使用弱互模拟对状态空间进行约简;然后,基于状态事件故障树的形式语义给出顶层事件发生的平均时间计算方法;最后,给出飞机着陆雷达控制系统和喷淋防火系统的状态事件故障树时间特性分析的实例研究.为构件化系统失效时间特性的分析提供了一种新方法.

Time Property Analysis Method for State/Event Fault Tree

State/Event fault tree (SEFT) is a modeling technique for describing the causal chains which lead to failure in component-based embedded systems, and the top event of SEFT describes the result of the failure. One important way for capturing the mean time parameter of system failure is to quantitatively analyze the mean time of the top event occurrence, which provides support for system safety evaluation. However, it is necessary to formally describe SEFT semantics in order to quantitatively analyze the time property. In this paper, a time property analysis method for SEFT based on interactive Markov chain (IMC) is presented. Firstly, interface interactive Markov chain (Interface-IMC) is proposed based on refining the interactive action of IMC. Secondly, semantics of components and logic gates in SEFT are formally described by Interface-IMC. Thirdly, the semantics of SEFT is obtained by composing all the Interface-IMCs generated in the above steps. During this process, weak bisimilarity technique is applied to reduce state space. Then, a quantitative time analysis method is presented based on the formal semantic model of SEFT. Finally, the time analysis processes for the SEFT of aircraft radar landing control system and sprinkler system are illustrated by the proposed method. The method provides a new solution for analyzing time properties of component-based system failure.