diff --git a/papers/fmea_software_hardware/software_fmea.tex b/papers/fmea_software_hardware/software_fmea.tex index 238b64b..9771f84 100644 --- a/papers/fmea_software_hardware/software_fmea.tex +++ b/papers/fmea_software_hardware/software_fmea.tex @@ -4,37 +4,22 @@ % Software FMEA % -% -% Glaring hole in approvals FMEA is performed on hardware -% and electronics, but with software we only get guidlines ( which mostly consist of constraints!) -% -% No known method of software failure mode effects analysis--- some work has been done on -% Sofware FTA a top down approach--- -% Bottom up approach means all known failure modes must be modelled. -% SIL does not have metric or tools to analyse software for safety, -% it instead applies best practises and constraints on computer language features (i.e. -% in C limited use of pointers no recursion etc). -% -% -% Introduce concept of FMEA -% * bottom up -% * all failure modes for all componnts -% -% Concept of FMMD -% -% Look at the structure of software -% * a natural hierarchy -% -% Software written for a controlled -% Contract programming -% * describe concept -% * describe how this fits in with failure modes and failure symptoms concepts -% -% Describe how contract programming represents the failure modes of software -% -% Now describe how this fits in with the structure of FMMD - +% soandso recomends inital PHA, for the purpose of example +% let us assign an application to this 4->20mA input --- +% PHA - pretend its a boiler water level -- too low hazard of explosion CRITICAL +% to high and we get superheated water in the steam DANGEROUS +% +% System Level SFMEA +% checklist, interrupts, synch etc +% +% detailed level +% variable maps +% +% then present complete results of SFMEA +% +% alongside HFMEA +% \documentclass[twocolumn]{article} %\documentclass[twocolumn,10pt]{report}