【作者】 李晶；

【导师】 何春；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2017， 硕士

【摘要】 近年来,航空电子系统向着开放式、综合化、模块化方向发展,其复杂程度越来越高,使得系统的安全性分析更为困难。为规避多故障和关联故障等风险,航空电子系统普遍采用了动态重构技术,即基于系统功能冗余,利用系统构型变化,实现实时且主动的容错控制的技术,这导致了传统的单一故障状态空间下的静态故障分析技术不再完全适用于新一代航空电子系统的安全机理分析。本文在深入研究系统安全性基础理论和技术的前提下,针对动态重构特性给航电系统带来的多故障状态空间下的安全性分析问题,围绕故障分析表格的自动化生成方法、安全性分析概率数据的获取方法,以及重构策略质量的分析与评价方法展开研究,主要工作包括:1.针对一类模块化动态重构的航电系统,给出一种系统框图抽象方法,直观且如实地描绘出系统的组成模块、容错行为方式,以及容错行为导致的模块间的关联;然后对该系统框图包含的信息进行数学抽象,定义了故障关系矩阵,实现了由系统框图到数学表达式的转换;进而以该故障关系矩阵为基础,提出一种基于故障关系矩阵的故障分析表格自动化生成方法。该方法实现了多故障状态空间分析表格的自动化生成,提高了故障分析的效率,避免了因人为因素造成的错误,并为下一步的安全性分析提供支持和数据保障。2.针对采用马尔可夫(Markov)分析获取概率数据具有的状态空间爆炸问题,给出一种基于状态流(Stateflow,即有限状态机加流程图)的数据获取方法。该方法跳过了计算系统状态概率的环节,而直接获取进行重构策略质量分析与评价时所需的概率数据,从而规避了状态空间爆炸问题的产生,同时还实现了与表格分析环节的解耦,不再需要表格数据结果的支持,避免了因表格数据错误而导致的误差传播。3.在已有的基于失效比例的分析与评价方法的基础上,给出一种基于安全概率的分析与评价方法,对航电系统的重构策略质量进行分析与评价。该方法在评价式中不仅考虑了失效比例的作用,而且将整个寿命周期内重构策略下的系统安全概率考虑进去,因此能更加全面地评价重构策略在系统安全性上的贡献。4.在以上研究基础之上,设计了一套多故障状态空间自动化安全性分析方案。测试结果表明,该方案具有高效性和实用性,能够为进一步提高航电系统的安全性提供参考。更多还原

【Abstract】 For these years,avionics system is developing to the direction of openness,synthesis and modularity.With the more and more complexity of the electronic system,the safety of avionics system faces more challenges.In order to avoid multiple failures and relevant failures,avionics system generally adopts the technology of dynamic reconfiguration,namely based on system functional redundancy and using system configuration changes to realize the real-time and active fault tolerant control,which leads to the fact that the analytical method of single failure-condition-space has not completely fit to the safety analysis of the new generation of avionics system.This thesis deeply studies the basical safety theories and technologies,and then makes research on the automated generation method of fault-analysis sheet,the getting method of probability data needed by safety-analysis,and the analysis and evaluation method of the quality of reconfiguration strategies for solving the safety problem of anvionics system under the multifailure-condition-space brought by dynamic reconfiguration characteristics.The main work is as follows:1.An abstract method of system block graph is given for a kind of modular dynamic reconfigurable anvionics system.It can authentically and directly describe the system’s component modules,fault-tolerant actions,and the relationship between modules leading by fault-tolerant actions.Then the information contained in the system block graph is abstracted as mathematic form,namely,defining a failure-connection matrix called Modularshift,which transforms the system block graph into mathematic expression.Furthermore,based on the Modularshift,an automated generation method of failure-connection-analysis sheet basing on Modularshift is proposed.It can achieve automated generation of the multifailure-condition-space analysis sheet,increase the efficiency of failure analysis,and can effectively avoid faults caused by factitious factors,and it can offer supports and data for the next safety analysis.2.For solving the problem of state-space explosion brought by using Markov analysis to get probability data,a method of getting data based on Stateflow,namely finite state machine plus flow chart,is given.It can avoid generating state-space explosion,because it can put the link of calculating system-state probabilities aside to get directly probabilities requested when doing the analysis and evaluation of the quality of reconfiguration strategies.At the same time,it achieves removing coupling,not requiring the supports from data-results in the sheet anymore,so it can avoid error propagation caused by data-errors in the sheet.3.On the basis of the method of analysis and evaluation based on failure ratio,a method of analysis and evaluation based on safety probability is given.It takes into consideration not only the effect of failure ratio,but also the safety probability relating to reconfiguration strategy in the whole lifetime.Therefore,it can more efficiently and comprehensively evaluate the contribution of reconfiguration strategies on system safety.4.Based on the above studies,a kind of automated multifailure-condition-space safety-analysis plan is designed.The testing result shows that this plan has high efficiency and practicability,and can offer references for further increase in the level of system safety.更多还原