Design and Assessment of a Watch Dog Timer for Safety Improvement of an Embedded Railway Signal Controller

철도신호 내장형제어기 안전성 향상을 위한 워치독타이머 설계 및 평가

  • 신덕호 (한국철도기술연구원, 전기신호연구본부) ;
  • 이강미 (한국철도기술연구원, 전기신호연구본부) ;
  • 이재호 (한국철도기술연구원, 전기신호연구본부) ;
  • 김용규 (한국철도기술연구원, 전기신호연구본부)
  • Published : 2007.12.31


In this paper, we suggest the criticality of Hidden Failure with regard to the design of watch dog timer, used to detect HALT on railway signaling embedded controller, via FMEA and FTA. Hidden Failure means reliability and safety degradation of the system due to any failure occurred on elements added for fault tolerance. In this paper, therefore, we design vital watch dog timer to prevent the system from operating in low SIL conditions and assess the safety of circuit on failure occurrence to demonstrate that safety degradation problems owing to existing design are supplemented.


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