| Computer-based Interlocking(CBI)system of urban rail transit is one of the most important systems to ensure train safety.The health status of different CBI systems is not the same.Considering saving the operating cost and maintenance cost,it is extremely necessary to make a scientific and reasonable lifetime prediction of the CBI system.This paper analyzes the reliability and safety of the CBI system of urban rail transit based on the Fault Tree Analysis(FTA)and Markov model.Based on the analysis results,the lifetime of system can be predicted and the maintenance strategy can be optimized.Firstly,according to the composition and structure of the CBI system to establish the dynamic fault tree model with dynamic logic gate.The application of dynamic logic gates is added based on the traditional fault tree analysis to establish the dynamic fault tree of the CBI system and analyze the factors that affect the system service life.Secondly,divide the whole CBI system into three parts.Each part can be regard as a small whole and its reliability and security can be calculated by using Markov state transition model.This reasonable method of division not only avoids the Markov space state explosion problem that is easily caused by the large system,but also connects the three parts through an "OR" gate.Because of the "OR" gate,the three parts can be converted into a tandem system.Finally,using Python software and Mathcad software to simulate and analyze the reliability and security of CBI system.Based on the simulation results to predict the lifetime of the CBI system and optimize the existing repair and maintenance strategy.This can not only ensure the safe and reliable operation of the urban rail CBI system,but also save the maintenance costs and technical costs. |
