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papers/software_fmea/abs.tex
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%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.
%
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.
Where software FMEA (SFMEA) has been applied, it is
performed a separately from the HFMEA.
%% CONCLUSIONS.
%
%
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.
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.

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papers/software_fmea/abs_pre.tex
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\documentclass[twocolumn]{article}
\documentclass{article}
%\documentclass[twocolumn,10pt]{report}
\usepackage{graphicx}
\usepackage{fancyhdr}