arrrghhhhh..... so muh work....

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Robin Clark 2012-11-21 21:54:49 +00:00
parent 06bd918d54
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@ -269,6 +269,19 @@ Database
} }
@article{sanjeev,
author = {Sanjeev Kumar Appicharla},
title = {Analysis and modelling of space shuttle challenger accident using management oversight and risk tree(MORT)},
journal = {7th IET System Safety Conference 2012},
publisher = {IEEE},
issn = {},
url = {},
doi = {},
keywords = {System approach to safety, groupthink bias, technology standards, safety critical decision making},
year = {2012},
}
@article{SMR:SMR580, @article{SMR:SMR580,
author = {Bachmann, Volker and Messnarz, Richard}, author = {Bachmann, Volker and Messnarz, Richard},
title = {Improving safety and availability of complex systems by using an integrated design approach in development}, title = {Improving safety and availability of complex systems by using an integrated design approach in development},

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@ -1,4 +1,6 @@
%%% CHAPTER 2
\label{sec:chap2}
The generic and statistical European Safety Standard, EN61508:6\cite{en61508}[B.6.6] The generic and statistical European Safety Standard, EN61508:6\cite{en61508}[B.6.6]
describes Failure Mode Effect Analysis (FMEA) as: describes Failure Mode Effect Analysis (FMEA) as:
@ -141,16 +143,28 @@ approach in looking for system failures.
\section{Theoretical Concepts in FMEA} \section{Theoretical Concepts in FMEA}
\paragraph{The unacceptability of a single component failure causing a catastrophe} \paragraph{The unacceptability of a single component failure causing a catastrophe}
% NEED SOME NICE HISTORICAL REFS HERE
FMEA, due to its inductive bottom-up approach, is very good FMEA, due to its inductive bottom-up approach, is good
at finding potential single component failures that could have catastrophic implications. at mapping potential single component failures to system level faults/events.
Used in the design phase of a project FMEA is an invaluable tool Used in the design phase of a project FMEA is an invaluable tool
for unearthing these failure scenarios. for unearthing potential failure scenarios.
It is less useful for determining catastrophic events for multiple FMEA is always performed in the context of the use of the equipment.
This, put in terms of philosophy, is the subjective and the objective.
We can using objective reasoning trace a component level failure to a system level event,
but only in
the subjective sense can we determine its severity.
Failure mode analysis on the leaks possible from the O ring on the space shuttle
did not link this failure to the catastrophic failure of the spacecraft~\cite{challenger,sanjeev}.
It is less useful for determining events for multiple
simultaneous\footnote{Multiple simultaneous failures are taken to mean failure that occur within the same detection period.} failures. simultaneous\footnote{Multiple simultaneous failures are taken to mean failure that occur within the same detection period.} failures.
\paragraph{Failure modes, dectectable and undetectable}
Often the effects of a failure mode may be easy to detect, and our equipment can react by raising an alarm or compensating for the resulting fault.
Some failure modes may cause undetectable failure, for instance a component that causes
a measured reading to change could have dire consequences yet not be obvious.
In fault diagnosis failures are said to be observable and unobservable.
\paragraph{Impracticality of Field Data for modern systems} \paragraph{Impracticality of Field Data for modern systems}
Modern electronic components, are generally very reliable, and the systems built from them Modern electronic components, are generally very reliable, and the systems built from them

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@ -33,29 +33,30 @@ a variety of typical embedded system components including analogue/digital and e
% %
%This is followed by several example FMMD analyses, %This is followed by several example FMMD analyses,
\begin{itemize} \begin{itemize}
\item The first example applies FMMD to an operational amplifier inverting amplifier (see section~\ref{sec:invamp}) \item The first example applies FMMD to an operational amplifier inverting amplifier (see section~\ref{sec:invamp}),
%using an op-amp and two resistors; %using an op-amp and two resistors;
this demonstrates how the re-use of a potential divider {\dc} from section~\ref{subsec:potdiv}. this demonstrates re-use of a potential divider {\dc} from section~\ref{subsec:potdiv}.
This inverting amplifier is analysed again, but this time with a different This inverting amplifier is analysed again, but this time with a different
composition of {\fgs}. The two approaches, i.e. choice of membership for {\fgs}, are then discussed. composition of {\fgs}. The two approaches, i.e. choice of membership for {\fgs}, are then discussed.
\item Section~\ref{sec:diffamp} analyses a circuit where two op-amps are used \item Section~\ref{sec:diffamp} analyses a circuit where two op-amps are used
to create a differencing amplifier. to create a differencing amplifier.
Building on the two approaches from section~\ref{sec:invamp}, re-use of the non-inverting amplifier {\dc} from section~\ref{sec:invamp} Building on the two approaches from section~\ref{sec:invamp}, re-use of the non-inverting amplifier {\dc} from section~\ref{sec:invamp}
is discussed in the context of this circuit, is examined,
where its re-use is appropriate in the first stage and where re-use is appropriate in the first stage and
not in the second. not in the second.
\item Section~\ref{sec:fivepolelp} analyses a Sallen-Key based five pole low pass filter. \item Section~\ref{sec:fivepolelp} analyses a Sallen-Key based five pole low pass filter.
This demonstrates re-use the first Sallen-Key analysis, %encountered as a {\dc} It demonstrates re-use the first Sallen-Key analysis, %encountered as a {\dc}
increasing test efficiency. This example also serves to show a deep hierarchy of {\dcs}. increasing test efficiency. This example also serves to show a deep hierarchy of {\dcs}.
\item Section~\ref{sec:bubba} shows FMMD applied to a \item Section~\ref{sec:bubba} shows FMMD applied to a
loop topology---using a `Bubba' oscillator---demonstrating how FMMD id different to fault diagnosis techniques. loop topology---using a `Bubba' oscillator---demonstrating how FMMD differs from fault diagnosis techniques.
%which uses %which uses
%four op-amp stages with supporting components. %four op-amp stages with supporting components.
Two analysis strategies are employed, one using Two analysis strategies are employed, one using
initially identified {\fgs} and the second using a more complex hierarchy of {\fgs} and {\dcs}, showing initially identified {\fgs} and the second using a more complex hierarchy of %{\fgs} and
{\dcs} showing
that a finer grained/more de-composed approach offers more re-use possibilities in future analysis tasks. that a finer grained/more de-composed approach offers more re-use possibilities in future analysis tasks.
\item Section~\ref{sec:sigmadelta} demonstrates FMMD can be applied to mixed analogue and digital circuitry \item Section~\ref{sec:sigmadelta} demonstrates FMMD can be applied to mixed analogue and digital circuitry
using a sigma delta ADC. by analysing a sigma delta ADC.
%shows FMMD analysing the sigma delta %shows FMMD analysing the sigma delta
%analogue to digital converter---again with a circular signal path---which operates on both %analogue to digital converter---again with a circular signal path---which operates on both
%analogue and digital signals. %analogue and digital signals.

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@ -1,5 +1,7 @@
%%% CHAPTER 6
\label{sec:chap6}
\section{Software and Hardware Failure Mode Concepts} \section{Software and Hardware Failure Mode Concepts}
\label{sec:elecsw} \label{sec:elecsw}
@ -798,7 +800,9 @@ $$fm (micro-controller) =\{ PROM\_FAULT, RAM\_FAULT, CPU\_FAULT, ALU\_FAULT, CLO
We must start from the bottom-up with the software, and consider the hardware elements We must start from the bottom-up with the software, and consider the hardware elements
used (if any) by each software function. used (if any) by each software function.
Starting at the bottom Starting at the bottom we form a {\fg} with
the function read\_ADC.