Model Based Dependability Verifying Method For High-Speed Train Control System

With the rapid development of the Train Control System, people are increasingly concerned about its ability to safe and reliable completion of the transport tasks, while its dependability reaches corresponding demand is the most important fact. Making use of scientific and systematic dependability verifying approaches to verify High-speed train control system both from structure and function is an indispensable component in the designing and development process of this type of system. With the fast development of computer technology, the complexity and embedded of the system brings a great challenge to the dependability verifying of high-speed train control system.Based on the characteristics of high-speed train control system and the in-depth analysis of the focus and limitation of the existing dependability verifying approaches, this paper has determined that the content of dependability verification includes four attributes and two parts. Four attributes are reliability, availability, maintainability and safety; while two parts are structure dependability analysis and functional dependability test; while for the embedded high-speed train control system, structure dependability satisfied the demand is the basis of functional dependability test. Focus on the limitation of existing structure dependability analysis, this paper proposes a multi-formalism fusing approach, which fusing the following four formal methods:Extended Parametric Fault Tree (EPFT), Repairable Fault Tree (RFT), Hybrid Morkov Chain (HMC) and Extended Colored Petri Net (ECPN), and finally get the HMC-PRFT structure analysis approach which provide a more accurate and efficient analysis methods for the dependability analysis of system structure. Further focus on the important component of functional dependability--unctional safety, this article proposes the CPN and Bayesian assumption based functional SILs level quantitative evaluation testing approach, which makes use of probability to determine whether the functional safety requirements have been satisfied and effectively improve the efficiency of the test, reduce the test load, and provides a theoretical basis for the quantitative assessment of system safety.The main innovations of this article are as follows:(1) Focus on the limitation of traditional methods'modeling capabilities, including ccomplex redundancy strategy modeling capacity and complex repairing strategy modeling capacity, the study extends the modeling capability of parametric fault tree, and proposes hybrid Markov Chain for the complex repairing policy modeling;(2) Against traditional methods cannot get the numerical results, the study extended the stochastic distribute description capability and numerical calculating capability of CPN. On this basis, the study proposes a multiformalism fusion method to get HMC-PRFT, which improves the modeling capabilities and implements the numerical calculating of system structure dependability.(3) Focus on the uncertain contents of functional safety testing, this thesis proposes a safety quantitative evaluation testing method, which makes use of CPN to modeling and generating, including:test case generating algorithms, functional test sequences and input field generating algorithm and induction functional execution sequences generating method.(4) Focus on the uncertain criteria of functional safety testing; this article proposes Bayesian assumption based SILs level quantitative evaluation testing method, which helps to calculating the required unfail passed test cases number under two different situations:with history testing data and without history testing data.Finally in this thesis, the important subsystem of Chinese Train Control System Level3-Radio Block Center (RBC) is taken as a case study. HMC-PRFT method is implemented to analysis RBC structure dependability. Through the comparation of different repairing strategies, the components'sensitivity analysis and redundancy policy sensitivity analysis, give some recommendations to RBC system structure design; CPN and Bayesian assumption based functional safety quantitative evaluation testing method is used for test design of RBC functional safety assessment testing, provides proof for the safety inspection of the RBC system.