arrrghhhhh..... so muh work....
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mybib.bib
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mybib.bib
@ -269,6 +269,19 @@ Database
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}
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@article{sanjeev,
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author = {Sanjeev Kumar Appicharla},
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title = {Analysis and modelling of space shuttle challenger accident using management oversight and risk tree(MORT)},
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journal = {7th IET System Safety Conference 2012},
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publisher = {IEEE},
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issn = {},
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url = {},
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doi = {},
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keywords = {System approach to safety, groupthink bias, technology standards, safety critical decision making},
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year = {2012},
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}
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@article{SMR:SMR580,
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@article{SMR:SMR580,
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author = {Bachmann, Volker and Messnarz, Richard},
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author = {Bachmann, Volker and Messnarz, Richard},
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title = {Improving safety and availability of complex systems by using an integrated design approach in development},
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title = {Improving safety and availability of complex systems by using an integrated design approach in development},
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@ -1,4 +1,6 @@
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%%% CHAPTER 2
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\label{sec:chap2}
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The generic and statistical European Safety Standard, EN61508:6\cite{en61508}[B.6.6]
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The generic and statistical European Safety Standard, EN61508:6\cite{en61508}[B.6.6]
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describes Failure Mode Effect Analysis (FMEA) as:
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describes Failure Mode Effect Analysis (FMEA) as:
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@ -141,16 +143,28 @@ approach in looking for system failures.
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\section{Theoretical Concepts in FMEA}
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\section{Theoretical Concepts in FMEA}
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\paragraph{The unacceptability of a single component failure causing a catastrophe}
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\paragraph{The unacceptability of a single component failure causing a catastrophe}
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% NEED SOME NICE HISTORICAL REFS HERE
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FMEA, due to its inductive bottom-up approach, is very good
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FMEA, due to its inductive bottom-up approach, is good
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at finding potential single component failures that could have catastrophic implications.
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at mapping potential single component failures to system level faults/events.
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Used in the design phase of a project FMEA is an invaluable tool
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Used in the design phase of a project FMEA is an invaluable tool
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for unearthing these failure scenarios.
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for unearthing potential failure scenarios.
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It is less useful for determining catastrophic events for multiple
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FMEA is always performed in the context of the use of the equipment.
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This, put in terms of philosophy, is the subjective and the objective.
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We can using objective reasoning trace a component level failure to a system level event,
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but only in
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the subjective sense can we determine its severity.
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Failure mode analysis on the leaks possible from the O ring on the space shuttle
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did not link this failure to the catastrophic failure of the spacecraft~\cite{challenger,sanjeev}.
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It is less useful for determining events for multiple
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simultaneous\footnote{Multiple simultaneous failures are taken to mean failure that occur within the same detection period.} failures.
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simultaneous\footnote{Multiple simultaneous failures are taken to mean failure that occur within the same detection period.} failures.
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\paragraph{Failure modes, dectectable and undetectable}
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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.
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Some failure modes may cause undetectable failure, for instance a component that causes
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a measured reading to change could have dire consequences yet not be obvious.
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In fault diagnosis failures are said to be observable and unobservable.
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\paragraph{Impracticality of Field Data for modern systems}
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\paragraph{Impracticality of Field Data for modern systems}
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Modern electronic components, are generally very reliable, and the systems built from them
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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
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%
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%
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%This is followed by several example FMMD analyses,
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%This is followed by several example FMMD analyses,
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\begin{itemize}
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\begin{itemize}
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\item The first example applies FMMD to an operational amplifier inverting amplifier (see section~\ref{sec:invamp})
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\item The first example applies FMMD to an operational amplifier inverting amplifier (see section~\ref{sec:invamp}),
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%using an op-amp and two resistors;
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%using an op-amp and two resistors;
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this demonstrates how the re-use of a potential divider {\dc} from section~\ref{subsec:potdiv}.
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this demonstrates re-use of a potential divider {\dc} from section~\ref{subsec:potdiv}.
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This inverting amplifier is analysed again, but this time with a different
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This inverting amplifier is analysed again, but this time with a different
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composition of {\fgs}. The two approaches, i.e. choice of membership for {\fgs}, are then discussed.
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composition of {\fgs}. The two approaches, i.e. choice of membership for {\fgs}, are then discussed.
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\item Section~\ref{sec:diffamp} analyses a circuit where two op-amps are used
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\item Section~\ref{sec:diffamp} analyses a circuit where two op-amps are used
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to create a differencing amplifier.
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to create a differencing amplifier.
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Building on the two approaches from section~\ref{sec:invamp}, re-use of the non-inverting amplifier {\dc} from section~\ref{sec:invamp}
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Building on the two approaches from section~\ref{sec:invamp}, re-use of the non-inverting amplifier {\dc} from section~\ref{sec:invamp}
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is discussed in the context of this circuit,
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is examined,
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where its re-use is appropriate in the first stage and
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where re-use is appropriate in the first stage and
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not in the second.
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not in the second.
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\item Section~\ref{sec:fivepolelp} analyses a Sallen-Key based five pole low pass filter.
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\item Section~\ref{sec:fivepolelp} analyses a Sallen-Key based five pole low pass filter.
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This demonstrates re-use the first Sallen-Key analysis, %encountered as a {\dc}
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It demonstrates re-use the first Sallen-Key analysis, %encountered as a {\dc}
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increasing test efficiency. This example also serves to show a deep hierarchy of {\dcs}.
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increasing test efficiency. This example also serves to show a deep hierarchy of {\dcs}.
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\item Section~\ref{sec:bubba} shows FMMD applied to a
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\item Section~\ref{sec:bubba} shows FMMD applied to a
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loop topology---using a `Bubba' oscillator---demonstrating how FMMD id different to fault diagnosis techniques.
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loop topology---using a `Bubba' oscillator---demonstrating how FMMD differs from fault diagnosis techniques.
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%which uses
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%which uses
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%four op-amp stages with supporting components.
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%four op-amp stages with supporting components.
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Two analysis strategies are employed, one using
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Two analysis strategies are employed, one using
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initially identified {\fgs} and the second using a more complex hierarchy of {\fgs} and {\dcs}, showing
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initially identified {\fgs} and the second using a more complex hierarchy of %{\fgs} and
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{\dcs} showing
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that a finer grained/more de-composed approach offers more re-use possibilities in future analysis tasks.
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that a finer grained/more de-composed approach offers more re-use possibilities in future analysis tasks.
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\item Section~\ref{sec:sigmadelta} demonstrates FMMD can be applied to mixed analogue and digital circuitry
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\item Section~\ref{sec:sigmadelta} demonstrates FMMD can be applied to mixed analogue and digital circuitry
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using a sigma delta ADC.
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by analysing a sigma delta ADC.
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%shows FMMD analysing the sigma delta
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%shows FMMD analysing the sigma delta
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%analogue to digital converter---again with a circular signal path---which operates on both
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%analogue to digital converter---again with a circular signal path---which operates on both
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%analogue and digital signals.
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%analogue and digital signals.
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@ -1,5 +1,7 @@
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%%% CHAPTER 6
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\label{sec:chap6}
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\section{Software and Hardware Failure Mode Concepts}
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\section{Software and Hardware Failure Mode Concepts}
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\label{sec:elecsw}
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\label{sec:elecsw}
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@ -798,7 +800,9 @@ $$fm (micro-controller) =\{ PROM\_FAULT, RAM\_FAULT, CPU\_FAULT, ALU\_FAULT, CLO
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We must start from the bottom-up with the software, and consider the hardware elements
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We must start from the bottom-up with the software, and consider the hardware elements
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used (if any) by each software function.
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used (if any) by each software function.
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Starting at the bottom
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Starting at the bottom we form a {\fg} with
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the function read\_ADC.
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