Reliability Analysis of a Computer-Based Interlocking System with a Double 2-out-of-2 Redundancy Structure using Algebraic Binary Decision Diagrams

The computer-based interlocking (CBI) system of urban rail is a safe-critical system. To keep the high reliability of the CBI system of urban rail, reliability analysis is very necessary and important work. The double 2-out-of-2 redun-dancy structure has been widely used in the CBI system which is a core part of control signal equipment in urban rail. The dynamic fault tree (DFT) is an extension of the static fault tree (SFT), which is widely used for the reliability modeling of dynamic systems. An algebraic binary decision diagram (ABDD) is an extension of a binary decision diagram (BDD) which introduces a kind of node denoting a sequence-dependency between events. The DFT can be evaluated by the ABDD. This paper firstly presents a reliability analysis of the CBI system in urban rail by using the ABDD-based method. The CBI system is modeled by the DFT, then the DFT is converted into a function based on a temporal algebraic framework. According to the temporal function, the ABDD can be built for reliability analysis. Compared to the Markov-based method, the ABDD-based method can avoid space-state explosion and have no limitation on the exponential distribution of component failure. A case study related to the CBI system is presented to show the advantage of using our method.