A petri net based modelling approach for operating methods in train control systems

摘要

Higher Standards in performance and safety of future train control systems require the use of formal methods for the safe and efficient system development in this domain. At the beginning of each life-cycle an operation method which views the train control system in its interaction with the driver and the physical process has to be developed. To describe the system dynamcis, especially considering the concurrency between vehicle and track components of the train control system, Petri Nets are used as formal language. The present contribution considers the question what the functional requirements specifications have to contain and how they can be described formally by Petri Nets. "A concept of structuring for the formal specification of operation methods will be introduced which allows a systematic modelling of the permissible system behaviour on the requirement level. The permissibe system behaviour contains the regular functions and the management of permissible faults. The concept of structuring intends to model the physical process and the train control system in different models which can then be coupled suitably. Furthermore, the the train control system is decomposed into models which correspond to physical components which possess precise communication interfaces and which are usually distributed. The engiener's view is supported by this approach and a model structure is created which leads to an unambiguous description of permissible process behaviour related to the tasks of the control system.