Conference Paper

Reliability and Sensitivity Analysis of Embedded Systems with Modular Dynamic Fault Trees

Dept. of Comput. Sci., Nat. Tsing Hua Univ., Hsinchu
DOI: 10.1109/TENCON.2005.300968 Conference: TENCON 2005 2005 IEEE Region 10
Source: IEEE Xplore

ABSTRACT Fault trees theories have been used in years because they can easily provide a concise representation of failure behavior of general non-repairable fault-tolerant systems. But the defect of traditional fault trees is lack of accuracy when modeling dynamic failure behavior of certain systems with fault-recovery process. A solution to this problem is called behavioral decomposition. A system will be divided into several dynamic or static modules, and each module can be further analyzed using BDD or Markov chains separately. In this paper, we will show a decomposition scheme that independent subtrees of a dynamic module are detected and solved hierarchically for saving computation time of solving Markov chains without losing unacceptable accuracy when assessing components sensitivities. In the end, we present our analyzing software toolkit that implements our enhanced methodology.

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    ABSTRACT: In the traditional method for the reliability analysis of fault-tolerant system, the system structure is described by means of binary decision diagram (BDD) and Markov process, and then the reliability indexes are calculated. However, as the size of system augments, the size of state space will increase exponentially. Additionally, Markov approach requires that the failure and repair time of the components obey an exponential distribution. In this study, by combining dynamic fault tree (DFT) and numerical simulation based on the minimal sequence cut set (MSCS), a new method to evaluate reliability of fault-tolerant system with repairable components is proposed. The method presented does not depend on Markov model, so that it can effectively solve the problem of the state-space combination explosion. Moreover, it is suitable for systems whose failure and repair time obey an arbitrary distribution. Therefore, our method is more flexible than the traditional method. At last, an example is given to verify the method. Key wordsreliability analysis-fault-tolerant repairable system-dynamic fault tree (DFT)-minimal sequence cut set (MSCS) CLC numberTB 114.3
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    ABSTRACT: A fault tree illustrates the ways through which a system fails. It states different ways in which combination of faulty components result in an undesired event in the system. Being used in phases such as designing and exploiting industrial systems, and the designers able to evaluate the dependability attributes such as reliability, MTTF and sensitivity. In addition, in the mentioned ability, the fault tree is a systematic method for finding systems bottlenecks and weakness point. In spite of its extensive use in evaluating the reliability of systems, fault tree is rarely used in calculating sensitivity. In the last decade, few researches has been conducted in this field, however these methods are not applicable to large scale systems and are not systematic. This paper provides a systematic method for evaluating system sensitivity through fault tree. Then, it introduces sensitivity of NMR architecture as one of the common structures of fault tolerance which is used for enhancing systems’ reliability, safety and availability in industry. This article presents a comprehensive and parameterized formula for NMR structure's sensitivity. The presented method can be a great help for designing and exploiting reliable systems engineers in systematic and instant calculation of sensitivity by means of fault tree.
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