Extended UML Model Design And Fault Tree Algorithm Based On Train Control System

The software and hardware components of safety-critical system require a high level of safety standard because their failure could result in significant life and property loss. In order to avoid loss of life and economy, the design and development process of safety-critical systems must be careful. Redundancy is often used to increase system reliability of safety-critical systems. But the redundant structure also makes the safety-critical system more complex, which brings an enormous challenge for the safety analysis of safety-critical systems.The purpose of this paper is to achieve automatic conversion from UML extended model to dynamic fault tree. After the conversion is completed, the dynamic fault tree is the basis of safety analysis. In this paper, the following results are achieved.1. A method of UML model extension related to fault tree generation is proposed.Firstly, UML method is chosen to model and design the safety-critical system as developers and designers prefer to use it in engineering practice. A UML modeling and extension method is designed because the standard UML cannot describe the safety features of system. Stereotype extension mechanism is used to describe the semantics of failure and a description of the semantic table is provided as a reference to show the semantic of elements, associations and stereotypes and the corresponding fault tree implementation. The proposed method successfully embeds the safety information to the system model. It provides designers a great deal of freedom and flexibility to carry model-based development and safety analysis.2. A dynamic fault tree generation algorithm based on UML extended model is proposed.The UML models in this method are built by IBM’s Rational Software Architect. The EMX file generated by RSA is parsed to realize the communication between RSA and fault tree generation software. After further analyzing the semantic feature of the EMX file on behalf of the UML model, a fault tree automatic generation algorithm is developed. This algorithm imitates traditional manual analysis process to generate a dynamic fault tree. The aforementioned findings are implemented at the software level to develop an analysis tool. Finally the fault tree automatic generation software from UML model is finished and the research findings are implemented at the software level.3. Application and verification are performed on on-board ATP of CTCS-3train control system. The fault tree automatic generation algorithm is performed to on-board ATP of CTCS-3train control system. And the fault tree automatically generated by the algorithm is compared to the dynamic fault tree artificially constructed. The result proves that the proposed method in this paper is superior to the artificial method. Our method is more efficient and correct.In this paper, depth studies about modeling and safety analysis of safety-critical systems are implemented. All these studies lay a good foundation for safety analysis and design platform of high-speed rail operation control system.