Failure Mode Modular De-Composition Using Spider Diagrams
Electronical Notes in Theoretical Computer Science
This paper concentrates on a possible application for spider diagrams; using them to simplify the task of identifying the effect of individual component failures, leading to system failures in safety critical software or hardware designs. http://www.energytechnologycontrol.com/ Open access under CC BY-NC-ND license. • This process should dramatically reduce the number of checks to perform in safety critical analysis. • Spider diagrams can include a default spider, being that which is is not
... which is is not specifed explicitly (a kind of catch all undefined cases spider). Note this paper does not concern itself with the reliability of the system (i.e. mean time between failure etc) but with possible resultant states of the system due to component failures. The safety of potentially dangerous or explosive industrial plant is far more important than its reliability. The overriding philosophy here is that a system should be able to detect that it has become faulty, and revert to a safe operational mode. Human intervention can then assess and repair faults. It has been long known that components of systems and operational modes can be modelled with Z  : thus Spider diagrams can be used to model components and their operational and/or failure modes.