From a2c11cef25cf352fbd19c026041568bb4319062a Mon Sep 17 00:00:00 2001 From: Robin Clark Date: Thu, 2 Aug 2012 19:42:14 +0100 Subject: [PATCH] FMEA types now sub-sections---still have to think more about the conclusions... --- mybib.bib | 17 +++++++----- .../fmea_software_hardware/software_fmea.tex | 26 ++++++++++++------- 2 files changed, 26 insertions(+), 17 deletions(-) diff --git a/mybib.bib b/mybib.bib index a67ee89..6282d1b 100644 --- a/mybib.bib +++ b/mybib.bib @@ -29,17 +29,21 @@ YEAR = "2012" } -@INPROCEEDINGS{sfmeainterface, +@ARTICLE{sfmeainterface, author={Ozarin, N.W.}, -booktitle={Reliability and Maintainability Symposium, 2009. RAMS 2009. Annual}, title={Applying software failure modes and effects analysis to interfaces}, +booktitle={Reliability and Maintainability Symposium, 2009. RAMS 2009. Annual}, +journal={Reliability and Maintainability Symposium, 2009. RAMS 2009. Annual}, +title={Applying software failure modes and effects analysis to interfaces}, year={2009}, month={jan.}, +pages={533 - 538}, volume={}, number={}, -pages={533 -538}, keywords={mission-critical system;safety-critical system;software failure mode and effect analysis;software variable;system recovery;}, doi={10.1109/RAMS.2009.4914732}, -ISSN={0149-144X},} +ISSN={0149-144X}} +%%#%% + @ARTICLE{sfmea, AUTHOR = "Chris Price, Neal Snooke", @@ -191,7 +195,7 @@ Publication: } -@article {SMR:SMR580, +@article{SMR:SMR580, author = {Bachmann, Volker and Messnarz, Richard}, title = {Improving safety and availability of complex systems by using an integrated design approach in development}, journal = {Journal of Software: Evolution and Process}, @@ -199,11 +203,10 @@ publisher = {John Wiley & Sons, Ltd}, issn = {2047-7481}, url = {http://dx.doi.org/10.1002/smr.580}, doi = {10.1002/smr.580}, -pages = {n/a--n/a}, keywords = {integrated design, FMEA, safety standards}, year = {2012}, } - +%%pages = {n/a--n/a}, @ARTICLE{fafmea, AUTHOR = "Zigmund Bluvband, Pavel Grabov", diff --git a/papers/fmea_software_hardware/software_fmea.tex b/papers/fmea_software_hardware/software_fmea.tex index 488760d..db30899 100644 --- a/papers/fmea_software_hardware/software_fmea.tex +++ b/papers/fmea_software_hardware/software_fmea.tex @@ -226,7 +226,8 @@ and determining what system level failure modes could be caused. FMEA has its roots in the previous century where simple electro-mechanical systems were the norm. Modern control systems nearly always have a significant software/firmware element, and not being able to model software with current FMEA methodologies -is a cause for criticism~\cite{safeware}[Ch.12]. +is a cause for criticism~\cite{safeware}[Ch.12]. Similar difficulties in integrating mechanical and electronic/software +failure models are discussed in ~\cite{SMR:SMR580}. %Software FMEA techniques have been proposed @@ -340,7 +341,7 @@ current signal into a voltage that we can read with an ADC.% \begin{figure}[h] \centering - \includegraphics[width=200pt]{./ftcontext.png} + \includegraphics[width=250pt]{./ftcontext.png} % ftcontext.png: 767x385 pixel, 72dpi, 27.06x13.58 cm, bb=0 0 767 385 \caption{Context Diagram for {\ft} loop} \label{fig:ftcontext} @@ -386,7 +387,7 @@ value representing the voltage read (see code sample in figure~\ref{fig:code_rea %%{\vbox{ \begin{figure}[h+] -\tiny +\footnotesize \begin{verbatim} /***********************************************/ /* read_4_20_input() */ @@ -443,7 +444,7 @@ voltage value. %{\vbox{ \begin{figure}[h+] -\tiny +\footnotesize \begin{verbatim} /***********************************************/ /* read_ADC() */ @@ -510,7 +511,12 @@ the base components in this design. We now apply FMMD starting with the hardware. -\section{Hardware FMEA} +\section{Failure Mode effects Analysis} + +Four emerging and current techniques are now used to +alpply FMEA to the hardware, the software, the software medium and the software hardware insterface. + +\subsection{Hardware FMEA} The hardware FMEA requires that for each component we consider all failure modes and the putative effect those failure modes would have on the system. @@ -550,8 +556,8 @@ the multiplexer and the analogue to digital converter. The last two failures both lead to the system failure of $VAL\_ERROR$ . They could lead to low or high reading as well, but we would only be able to determine this from knowledge of the software systems criteria for these. - -\section{Software FMEA - variables in place of components} +\clearpage +\subsection{Software FMEA - variables in place of components} For software FMEA, we take the variables used by the system, and examine what could happen if they are corrupted in various ways~\cite{procsfmea, embedsfmea}. @@ -607,8 +613,8 @@ We must now determine putative system failure modes for these variables becoming \end{tabular} \end{table} } - -\section{Software FMEA - failure modes of the medium ($\mu P$) of the software} +\clearpage +\subsection{Software FMEA - failure modes of the medium ($\mu P$) of the software} Microprocessors/Microcontrollers have sets of known failure modes, these include RAM, ROM EEPROM failure\footnote{EEPROM failure is not applicable for this example.} and @@ -653,7 +659,7 @@ oscillator clock timing } \clearpage -\section{Software FMEA - The software/hardware interface} +\subsection{Software FMEA - The software/hardware interface} As FMEA is applied separately to software and hardware the interface between them is an undefined factor.