SURVEILLANCE EN LIGNE DE LA SÉCURITÉ BASÉE SUR LES MODES DE SÉCURITÉ ONLINE SAFETY MONITORING USING SAFETY MODES

Summary Computer systems have to carry out more and more complex task s, including ones where humans can be endangered. Residual d esign faultsin such systems, as well as the inevitability of physical fau lts and interaction faults during operation, motivate the u se of safety monitors toprevent catastrophic failures. We present an approach and a formalization of the process for determining safety rules. It consists in identifyingsafety modes , according to the different tasks carried out by the monitor ed system. In practice, each safety mode is related to one or s everalfunctional modes and is specie d by a permissiveness vector that den es the authorized domains of variation of key physi cal variables. Theset of safety modes can be partially ordered according to the ir authorization vectors and can thus be represented as a dir ected acyclic graph.This graph is used to automatically build a model representi ng safety modes and their transitions, which can be implemen ted in an independentsafety monitor. A case study has been carried out on a mobile m anipulator robot, working in a factory alongside humans.Keywords : Dependability, Safety mode, Online Monitoring, Robotics