diff --git a/fmmd_concept/template-_abstract_submitted.odt b/fmmd_concept/System_safety_2011/abstract_as_accepted.odt similarity index 100% rename from fmmd_concept/template-_abstract_submitted.odt rename to fmmd_concept/System_safety_2011/abstract_as_accepted.odt diff --git a/fmmd_concept/System_safety_2011/full-paper-template-system-safety-1.pdf b/fmmd_concept/System_safety_2011/full-paper-template-system-safety-1.pdf new file mode 100644 index 0000000..0e72873 Binary files /dev/null and b/fmmd_concept/System_safety_2011/full-paper-template-system-safety-1.pdf differ diff --git a/fmmd_concept/System_safety_2011/submission.tex b/fmmd_concept/System_safety_2011/submission.tex new file mode 100644 index 0000000..f83bb47 --- /dev/null +++ b/fmmd_concept/System_safety_2011/submission.tex @@ -0,0 +1,167 @@ + \documentclass[twocolumn]{article} +%\documentclass[a4paper,10pt]{report} + +\usepackage{graphicx} +\usepackage{fancyhdr} +\usepackage{tikz} +\usetikzlibrary{shapes,snakes} +\usepackage{amsfonts,amsmath,amsthm} +%\input{../style} +\usepackage{ifthen} +\usepackage{lastpage} + +\newboolean{paper} +\setboolean{paper}{true} % boolvar=true or false + + +%\newtheorem{definition}{Definition:} + +\begin{document} +\pagestyle{fancy} +\fancyhf{} +%\renewcommand{\chaptermark}[1]{\markboth{ \emph{#1}}{}} +\fancyhead[LO]{} +\fancyhead[RE]{\leftmark} +%\fancyfoot[LE,RO]{\thepage} +\cfoot{Page \thepage\ of \pageref{LastPage}} +\rfoot{\today} +\lhead{Developing a rigorous bottom-up modular static failure mode modelling methodology} + +%\outerhead{{\small\bf Developing a rigorous bottom-up modular static failure mode modelling methodology}} +%\innerfoot{{\small\bf R.P. Clark } } + % numbers at outer edges +\pagenumbering{arabic} % Arabic page numbers hereafter +\author{R.P.Clark} +\title{Developing a rigorous bottom-up modular static failure mode modelling methodology} +\maketitle + + +\abstract{ +This paper proposes a methodology for +creating failure mode models of safety critical systems, which +has a common notation +for mechanical, electronic and software domains and applies an +incremental and rigorous approach. + +The four main static failure mode analysis methodologies were examined and +in the context of newer European safety standards, assessed. +Some of the deficiencies identified in these methodologies led to +a wish list for a more rigorous methodology. +%% +%% What I have found +%% +From the wish list +%and considering some constraints determined from +%the evaluation of the four established methodologies, +a new +methodology is developed and proposed. +This has been named Failure Mode Modular De-Composition (FMMD). + +%% Sell it +%% +In addition to addressing the traditional weaknesses of +Fault Tree Analysis (FTA), Fault Mode Effects Analysis (FMEA), Failure Mode Effects Criticality Analysis (FMECA) +and Failure Mode Effects and Diagnostic Analysis (FMEDA), FMMD provides the means to model multiple failure mode scenarios +as specified in newer European Safety Standards \cite{en298}. +The proposed methodology is bottom-up and can guarantee to leave no component failure mode un-handled. +It is also modular, meaning that the results of analysed components may be re-used in other projects. +} + +\section{Introduction} + The certification process of safety critical products for European and +other international standards often involve environmental stress, +endurance and EMC testing. Theoretical, or 'static testing', + is often also required to highlight modifications that must be made to + improve the product safety, or identify theoretical weaknesses in the design. + This paper proposes a new theoretical methodology for creating failure mode models of safety critical systems. + It has a common notation for mechanical, electronic and software domains and is modular and hierarchical. + These properties provide advantages in rigour and efficiency when compared to current methodologies. +Current methodologies We briefly analyse the four current methodologies: +Fault Tree Analysis (FTA) is a top down methodology in which a diagram is drawn for + each undesirable top level event, presenting the conditions that must arise to cause + the event. It is suitable for large complicated systems with few undesirable top + level events and focuses on those events considered most important or most catastrophic. + Effects of duplication/redundancy of safety systems can be readily assessed. +It uses notations that are readily understood by engineers. +However, it cannot guarantee to model all base component failure modes +or be used to determine system level errors other than those modelled. +Each diagram is a separate model, creating duplication of modelled elements, +and there is no facility to cross check between diagrams. It has limited +support for environmental and operational states. +Fault Mode Effects Analysis (FMEA) is used principally in manufacturing. +Each defect is assessed by its cost to repair and its frequency, using a +failure mode ratio. A list of failures and their cost is generated. +It is easy to identify single component failure to system failure scenarios +and an estimate of product reliability can be calculated. It cannot focus on +component interactions that cause system failure modes or determine potential +problems from simultaneous failure modes. It does not consider environmental +or operational states in sub-systems or components. It cannot model +self-checking safety elements or other in-built safety features or +analyse how particular components may fail. +Failure Mode Criticality Analysis (FMECA) is a refinement of FMEA, using +two extra variables: the probability of a component failure mode occurring +and the probability that this will cause a top level failure, and the perceived +criticality. It gives better estimations of product reliability/safety and the +occurrence of particular system failure modes than FMEA but has similar deficiencies. +Failure Modes, Effects and Diagnostic Analysis (FMEDA) is a refinement of +FMEA and FMECA and models self-checking safety elements. It assigns two +attributes to component failure modes: detectable/undetectable and safe/dangerous. + Statistical measures about the system can be made and used to classify a +safety integrity level. It allows designs with in-built safety features to be assessed. +Otherwise, it has similar deficiencies to FMEA but has limited support +for environmental and operational states in sub-systems or components, +via self checking statistical mitigation. +Requirements for an improved methodology The deficiencies identified in the +current methodologies are used to establish criteria for an improved methodology. +It must include all component failure modes and therefore should be bottom-up, +starting with individual component failure modes. Components should be broken +down into small functional groups to enable the examination of the effect of a + component failure mode on the other components in the group. +Development of the new methodology An ontology is developed of +failure modes and their relationship to environmental factors, +operational states and the hierarchical nature inherent in product design, +defining the relationships between the system as a whole, components, +failure modes, operational and environmental states. The ontology is used +to determine the nature of a hierarchy modelling the system, and to which +entities, various conditions/procedures are germane. From the ontology, +we determine that environmental effects relate to components, and +operational states to functional groups. A functional group can be +analysed with respect to its component failure modes, operational +states and environmental conditions and from this a set of failures +modes, or symptoms for the functional group can be determined. A functional group +can be treated as a derived component. Derived components can be +used to build functional groups at a higher level. In this manner we +can build a hierarchical model with each layer consisting of +components derived from the functional groups of derived components. +From the ontology, a set of rules for simplifying the failure +modes (collecting them into common symptoms) as we traverse up the +hierarchy is developed. The hierarchical model can have layers added +until it converges to a top level single functional group. On collecting +symptoms from this, we are left with the top level, or system level, failure modes. +The model is presented in a diagrammatic notation that has been +designed to be intuitive and understandable. It uses well tested +visual techniques to represent the elements of the model and their +relationships. Software support for the development of models in this +notation has been designed and proof-of-concept tools have been implemented. +This new approach is called +Failure Mode Modular De-Composition (FMMD) and is designed +to be a superset of the current four approaches, that is to say, +from an FMMD model, we should be able to +derive models that the other four methodologies would have been +able to create. As this approach is modular, many of the results of +analysed components may be re-used in other projects, so +test efficiency is improved. +FMMD is based on generic failure modes, so it is not constrained to a +particular field. It can be applied to mechanical, electrical or software domains. +It can therefore be used to analyse systems comprised of electrical, +mechanical and software elements in one integrated model. + + +% + +\bibliographystyle{plain} +\bibliography{../vmgbibliography,../mybib} + +\today +\end{document} + diff --git a/invopamp/invopamp.tex b/invopamp/invopamp.tex index ca2d0b3..4e898bb 100644 --- a/invopamp/invopamp.tex +++ b/invopamp/invopamp.tex @@ -66,7 +66,7 @@ A standard non inverting op amp (from ``The Art of Electronics'' ~\cite{aoe}[pp \begin{figure}[h] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/noninv.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/noninv.png} % noninv.jpg: 341x186 pixel, 72dpi, 12.03x6.56 cm, bb=0 0 341 186 \caption{Standard non inverting amplifier configuration} \label{fig:noninvamp} @@ -127,7 +127,7 @@ to represent each failure mode, taken from the components R1 and R2, in the current balance/virtual ground, shown in figure \ref{fig:fg1}. \begin{figure}[h] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/fg1.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/fg1.png} % fg1.jpg: 430x271 pixel, 72dpi, 15.17x9.56 cm, bb=0 0 430 271 \caption{current balance/virtual ground `functional group' failure modes} \label{fig:fg1} @@ -200,7 +200,7 @@ in table~\ref{pdfmea}. \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/fg1a.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/fg1a.png} % fg1a.jpg: 430x271 pixel, 72dpi, 15.17x9.56 cm, bb=0 0 430 271 \caption{current balance/virtual ground with test cases} \label{fig:fg1a} @@ -303,7 +303,7 @@ We can represent the collection of these symptoms by drawing connecting lines be the test cases and naming them (see figure \ref{fig:fg1b}). \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/fg1b.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/fg1b.png} % fg1b.jpg: 430x271 pixel, 72dpi, 15.17x9.56 cm, bb=0 0 430 271 \caption{Collection of current balance/virtual ground failure mode symptoms} \label{fig:fg1b} @@ -319,7 +319,7 @@ We can use the symbol $\bowtie$ to represent taking the analysed %We could represent it algebraically thus: $ \bowtie(PotDiv) = \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/dc1.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/dc1.png} % dc1.jpg: 430x619 pixel, 72dpi, 15.17x21.84 cm, bb=0 0 430 619 \caption{From functional group to derived component} \label{fig:dc1} @@ -378,7 +378,7 @@ latchup(12.5\%), latchdown(6\%), nooperation(31.3\%), lowslewrate(50\%). We can represent these failure modes on a diagram (see figure~\ref{fig:op1}). \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/op1.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/op1.png} % op1.jpg: 406x221 pixel, 72dpi, 14.32x7.80 cm, bb=0 0 406 221 \caption{Op Amp failure modes} \label{fig:op1} @@ -438,7 +438,7 @@ from the current balance/virtual ground {\dc}, represented by figure~\ref{fig:fg \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/fgamp.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/fgamp.png} % fgamp.jpg: 430x330 pixel, 72dpi, 15.17x11.64 cm, bb=0 0 430 330 \caption{Amplifier Functional Group} \label{fig:fgamp} @@ -450,7 +450,7 @@ regions) see figure~\ref{fig:fgampa}. \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/fgampa.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/fgampa.png} % fgampa.jpg: 430x330 pixel, 72dpi, 15.17x11.64 cm, bb=0 0 430 330 hno \caption{Amplifier Functional Group with Test Cases} \label{fig:fgampa} @@ -506,7 +506,7 @@ For this amplifier configuration we have three failure modes, $AMPHigh, AMPLow, We can now derive a `component' to represent this amplifier configuration (see figure ~\ref{fig:noninvampa}). \begin{figure}[h+] \centering - \includegraphics[width=200pt,keepaspectratio=true]{./noninvopamp/noninvampa.png} + \includegraphics[width=200pt,keepaspectratio=true]{./invopamp/noninvampa.png} % noninvampa.jpg: 436x720 pixel, 72dpi, 15.38x25.40 cm, bb=0 0 436 720 \caption{Non Inverting Amplifier Derived Component} \label{fig:noninvampa} @@ -1023,4 +1023,4 @@ Software used to edit these diagrams, keeps the model in a directed acyclic grap for this purpose. \clearpage -%\end{document} \ No newline at end of file +%\end{document} diff --git a/thesis.tex b/thesis.tex index 37cdb7c..0d852b6 100644 --- a/thesis.tex +++ b/thesis.tex @@ -147,6 +147,12 @@ \typeout{ ---------------- non inv op amp} \input{noninvopamp/noninvopamp} +\chapter{FMMD functional~groups to \\derived component example : Inverting Op-AMP} +\setboolean{dag}{false} % boolvar=true or false +\setboolean{pld}{true} % boolvar=true or false +\typeout{ ---------------- non inv op amp} +\input{invopamp/invopamp} + \chapter{FMMD functional~group to \\derived component example: `ON/OFF' Switch} \typeout{ ---------------- switch1} %\input{switch1/switch1}