From a06a911e763ae2dd59a99681f6af2c623793307f Mon Sep 17 00:00:00 2001 From: robin Date: Sun, 29 Apr 2012 14:34:49 +0100 Subject: [PATCH] ok started to say what I want... --- papers/software_fmea/abs.tex | 60 ++++++++++++++++++++++++++------ papers/software_fmea/abs_pre.tex | 2 +- 2 files changed, 50 insertions(+), 12 deletions(-) diff --git a/papers/software_fmea/abs.tex b/papers/software_fmea/abs.tex index 52a49c7..909b477 100644 --- a/papers/software_fmea/abs.tex +++ b/papers/software_fmea/abs.tex @@ -3,31 +3,69 @@ %endurance and Electro Magnetic Compatibility (EMC) testing. Theoretical, or 'static testing', %is often also required. % -Failure Mode Effects Analysis (FMEA), is a is a bottom-up technique that aims to assess the effect all + + +%% INTRO +% the problem +% the solution +% why you would want to read the paper + + +The certification process of safety critical products for European and +other international standards often demand environmental stress, +endurance and Electro Magnetic Compatibility (EMC) testing. Theoretical, or 'static testing', +is often also required. Failure Mode effects Analysis (FMEA) is a tool used +for static testing. Its use is traditionally applied to hardware (electrical and mechanical) systems. +With the increasing use of micro-controllers in smart instruments and control +systems generally, software is increasingly being seen as a missing factor in FMEA analysis. +This paper takes a simple example of a hardware/software hybrid (an industry standard {\ft} input), analyses it +using hardware and software FMEA, and then discusses the effectiveness of the +failure modelling from the perspective of the hybrid hardware/software sub-system. +This paper demonstrates the pitfalls and benefits of applying HFMEA and SFMEA +to a hybrid system. +% + + +%% MIDDLE +% some background +% how important software is today +% +Failure Mode Effects Analysis (FMEA), is a bottom-up technique that aims to assess the effect all component failure modes on a system. It is used both as a design tool (to determine weaknesses), and is a requirement of certification of safety critical products. FMEA has been successfully applied to mechanical, electrical and hybrid electro-mechanical systems. Work on software FMEA (SFMEA) is beginning, but at present no technique for SFMEA that -integrates hardware and software models known to the authors exists. +integrates hardware and software models %known to the authors +exists. FMEA performed on mechanical and electronic +systems can be termed Hardware FMEA (HFMEA). % Software generally, sits on top of most modern safety critical control systems and defines its most important system wide behaviour and communications. Currently standards that demand FMEA for hardware (e.g. EN298, EN61508), do not specify it for Software, but instead specify, good practise, review processes and language feature constraints. - -This is a weakness; where FMEA % scientifically +% +Where FMEA % scientifically traces component {\fms} to resultant system failures, software has been left in a non-analytical limbo of best practises and constraints. +Where software FMEA (SFMEA) has been applied, it is +performed a separately from the HFMEA. + +%% CONCLUSIONS. +% % -If software FMEA were possible, electro-mechanical-software hybrids could -be modelled; and could thus be `complete' failure mode models. -%Failure modes in components in say a sensor, could be traced -%up through the electronics and then through the controlling software. -Presently FMEA, stops at the glass ceiling of the computer program. -This paper presents an FMEA methodology which can be applied to software, and is compatible -and integrate-able with FMEA performed on mechanical and electronic systems. +This paper presents an analysis of a simple software/hardware hybrid sub-system (a {\ft} input circuit, MUX, ADC and two software functions +that are used to convert the electrical current signal into a value for use in software). +HFMEA is applied to the hardware and SFMEA to the software components. +The two failure models are then compared, and then compared with heuristic +knowledge about {\ft} inputs circuitry and software. + +Conclusions are then reached giving a positive and negative aspects +of analysing the hardware/software hybrid system using HFMEA and SFMEA. + + + diff --git a/papers/software_fmea/abs_pre.tex b/papers/software_fmea/abs_pre.tex index a34da06..7870043 100644 --- a/papers/software_fmea/abs_pre.tex +++ b/papers/software_fmea/abs_pre.tex @@ -1,6 +1,6 @@ -\documentclass[twocolumn]{article} +\documentclass{article} %\documentclass[twocolumn,10pt]{report} \usepackage{graphicx} \usepackage{fancyhdr}