A safety system for zero velocity detection and operator alertness monitoring in rolling stock

Modern railroadapplications must fulfillproper reliability, availability,maintainabilityand safety (RAMS) specifications in compliance with the requirements of widely accepted international standards such as EN 50126-1:1999 and EN 50126-2:2007. In rolling stocktwocomplementaryhazards with potential criticalconsequences for passengers and personnel arise fromthe inability to determineifa vehicle is in motionand from the inability to detect if the operator driving the train is incapacitated. While the probabilityof occurrenceofboth events isremote, thelevel of risk of such hazards isgenerally not tolerable. To assurean adequate safety integrity level(SIL) depending on the target application,ad-hoc smart monitoring systems, typically referred to as dead-man's vigilance devices(DMVD), are generallyinstalledon board of rolling stocks. In this paper the safety analysis and the design procedure of a novel DMVD are described. The main elements of novelty of the proposed solution layinits implementation, which relies on a hardware-only, potentially redundantFPGA architecture.