From 609d37d013425f7ea815f4c19412bcf0e52e598f Mon Sep 17 00:00:00 2001 From: Robin Clark Date: Mon, 3 Oct 2011 20:03:31 +0100 Subject: [PATCH] Example milli-volt amplifier given a diagram --- presentations/fmea/fmea_pres.tex | 62 ++++++++++++++++++++++--------- presentations/fmea/mvamp.dia | Bin 0 -> 2460 bytes 2 files changed, 44 insertions(+), 18 deletions(-) create mode 100644 presentations/fmea/mvamp.dia diff --git a/presentations/fmea/fmea_pres.tex b/presentations/fmea/fmea_pres.tex index b883409..941f73e 100644 --- a/presentations/fmea/fmea_pres.tex +++ b/presentations/fmea/fmea_pres.tex @@ -45,20 +45,42 @@ \begin{frame} - + \frametitle{ FMEA Example: Milli-volt reader} Example: Let us consider a system, in this case a milli-volt reader, consisting of instrumentation amplifiers connected to a micro-processor that reports its readings via RS-232. +\begin{figure} + \centering + \includegraphics[width=175pt]{./mvamp.png} + % mvamp.png: 561x403 pixel, 72dpi, 19.79x14.22 cm, bb=0 0 561 403 +\end{figure} + + +\end{frame} + + +\begin{frame} + \frametitle{FMEA Example: Milli-volt reader} Let us perform an FMEA and consider how one of its resistors failing could affect it. -For the sake of example let us choose a resistor in an OP-AMP -reading the milli-volt source and that if it were to go open, we would have a gain -of 1 from the amplifier. +For the sake of example let us choose resistor R1 in the OP-AMP gain circuitry. +\begin{figure} + \centering + \includegraphics[width=175pt]{./mvamp.png} + % mvamp.png: 561x403 pixel, 72dpi, 19.79x14.22 cm, bb=0 0 561 403 +\end{figure} +\end{frame} + + + + +\begin{frame} + \frametitle{FMEA Example: Milli-volt reader} \begin{itemize} \pause \item \textbf{F - Failures of given component} The resistor could fail by going OPEN or SHORT (EN298 definition). \pause \item \textbf{M - Failure Mode} Consider the component failure mode OPEN - \pause \item \textbf{E - Effects} This will disconnect the feedback loop in the amplifier causing a LOW READING + \pause \item \textbf{E - Effects} This will disconnect the feedback loop in the amplifier, driving the minus input HIGH causing a LOW READING \pause \item \textbf{A - Analysis} The reading will be out of normal range, and we will have an erroneous milli-volt reading \end{itemize} \end{frame} @@ -83,26 +105,28 @@ approach in looking for system failures. Consider the analysis where we look at all the failure modes in a system, and then see how they can affect all other components within it. - - -We need to look at a large number of failure scenarios -to do this completely (all failure modes against all components). -This is represented in equation~\ref{eqn:fmea_state_exp}, -where $N$ is the total number of components in the system, and -$cfm$ is the number of failure modes per component. \end{frame} -\begin{frame} + \begin{frame} \frametitle{Rigorous Single Failure FMEA} - +We need to look at a large number of failure scenarios +to do this completely (all failure modes against all components). +This is represented in the equation below. %~\ref{eqn:fmea_state_exp}, +where $N$ is the total number of components in the system, and +$cfm$ is the number of failure modes per component. + \begin{equation} \label{eqn:fmea_single} N.(N-1).cfm % \\ %(N^2 - N).cfm \end{equation} +\end{frame} + +\begin{frame} +\frametitle{Rigorous Single Failure FMEA} This would mean an order of $N^2$ number of checks to perform to perform `rigorous~FMEA'. Even small systems have typically 100 components, and they typically have 3 or more failure modes each. @@ -330,7 +354,7 @@ safety Integrity. For Hardware FMEDA does force the user to consider all components in a system -by requiring that a MTTF value is assigned. +by requiring that a MTTF value is assigned for each failure~mode. This MTTF may be statistically mitigated (improved) if it can be shown that selfchecking will detect failure modes. \end{frame} @@ -421,8 +445,8 @@ FMEDA is a modern extension of FMEA, in that it will allow for self checking features, and provides detailed recommendations for computer/software architecture. It also has a simple final result, a Safety Integrity Level (SIL) from 1 to 4 (where 4 is safest). -FMEA can be used as a term simple to mean Failure Mode Effects Analysis, and is -part of product approval for many regulated products in the EU and the USA... +%FMEA can be used as a term simple to mean Failure Mode Effects Analysis, and is +%part of product approval for many regulated products in the EU and the USA... \end{frame} @@ -672,7 +696,9 @@ not all the components in the system. \textbf{traceability} Because each reasoning stage contains associations ($FailureMode \mapsto Sypmtom$) we can trace the `reasoning' from base level component failure mode to top level/system -failure. +failure, by traversing the tree. + + \end{frame} \begin{frame} diff --git a/presentations/fmea/mvamp.dia b/presentations/fmea/mvamp.dia new file mode 100644 index 0000000000000000000000000000000000000000..ccf9f9acbb3397465992203128504fa36b3ea084 GIT binary patch literal 2460 zcmV;N31jvjiwFP!000021MOW~bK5o+e)q4?D35g@+%Hw_PP)6D-I?udCrzI{l*Gu~ z(xir>?f7MX`yPODY>A{K3xs2~)J&p_A$$aQ@O=k32ha~cez{3UcX6>!^6X+v5FU@> zY@RQYY z<>q;s7o)o>lIErkcrCJ$ve2May_r#L*w^RbzMWKFg-g~~tGpO1$6>xtA94zt-gR3MAs)t7x&<7Q>z9U?fhfxs1QmdTEy!cFMH%gmVeE%I$cMExzL(!fjLU zJS&@k?B}D;(M^&*!1YAgdOTW}50)8VP*-35XPn-}WipSR6WGhIpk`i;_eA6E2loTr zrkkcgst^|E22te)v@Jq=W-1u_0fCFR%x>c5yBTM_uMgor7j$WSX5>{P_#L%lPVCFf<}^Tb>5N7zCsDf}s(m zAQ(apdeMbm{05}Eh>8Ws#V0!mo(01;dcnN)0%@RcjA+Oyh66E(X)2~1QAr&nSF{JL z@vm%kTmHqUgMd0oqqV_WC~CB!!I`7M4F3$wfdeo{+nTz&q}^fhbSdn>SnGz6xGy2e zYL!Z=kc8wwGzg>;Qw^^zqBg1rboAkuUk5S@Oh!#6IFL~f$w+v6N8B!m8bnA?_sF4G z-x-60L@8pJYpaGrn77YJza;Y_UlsX0Ua#|Fa^~L8fkKKrP2*xP2F_4Ato{riaH_M>n)Vc3Cp$`T}BHOXlLkl(4Blgb*dIk54#15qX|x*;Sk^ zTvJ}wz=pjJw#12fNN~sJt6lu2eMT>G`Lo4UR22DryMa;aS@l&KXUl!_my45@iF^rhr zkC+xem(UKT+y=}<1|BgLiZw<-r&J@xC@76a#PGN8>wf(0J!SOFZh9Pi-tZIfx;+j~ z?^||yf6dc}Wu7$&I`hv-vesaNCM0Qad!;owN;RDtWQZ~ZKoJ=IiDJHjF1b3W!jhUdUuV7++_ z+fLoJd<*ZdlYkiUP9oCP01F!t({_jghF!rU=M*CnG9u>Nq~juDcsocX14hI!+S-nz zlu>=;u@)2dPAqXLMsUAPNE7DB(inhD1(M>N5~M=fuy31=v0*T)tzF2{K{W`eSZlz@xE1KMzfA(60=U4;y@TU|6#+Vmir^4-}mu?&6&N6iL@X=M*X zyF~l55qC>ZA}AYiYiv|IGEz)AGGe{hclUnaqTpOqv%rCi`WV+W9UMkyEdh(5r_o_< zu(W(+Bo|Yg^+uR+7KpJ4yin25!p3DTin-%ROoZscl0}O}&<>6#1jm))u%{C;qowO? z$vMpV7<4+bOBYz2s){eLhn@B{nv8igP;zPp)|;>f(!n-3Ub(Fz?5Q$JVd_?qHRV%4 z6&O2Q`y4v;qp6LJC(&q%l`F_tkBx$MwX7+_l7umgSr`s4rUro*A>AsG6gYG?P(uq_ zm;?&-S}#}!$4+U5*=FqOpvM&|ZnztO)R@hgg;;L}WaxlLYdbp+h;@?qV%r7X2RD0N zo3=gvWpoYZVP`!sw=MH3UOIaE^Tn9gk7?eiwIeI^j^+|$fAraV&QEcnKI3zbU&4B|hP9PC zeek^rC6wLFoLE>RaDI^@Hby4kg`GSB1sRLWF=nqad14350ZK`GfwF%BD7P6%z7_*@ z5aOcT`p5R>FdR1PggbMiY-$}b!ngy~!Bb9Jo7j|{A|8uUja83Xse@>PWG*cTX1Pj} zpfLxGm2#=!)TJXSs%*>)Ci9HZ;KtF?%%-Aty-B;%&dsSkGGwQR%uYXr!|{g0soCc6 z`c!R?0O0NKlFkL-A8DGb){R5mdodp)Xa9l(J<=1qWe*r;((W3Sh@Mk$LbM8c477LC zjyeb0?hkmLN5ev<>|ms+@CTda#Ud^a4>_`dA>3d>Bzc7lp`Bk!3wanW_W!{RWy1nt z^V}Xmuno)GGxm*jlSwb4@*l|%mJb}3Z?eH5F5kl(Ax8Xn4{%EjLF4ic1B9VEn_D_S z+7B+G0~ZD6q6PyTsHl%rDX@!&-ekfpIq;@+TDCwJ0 aQuW^b{_f@3)(`Yvp8X#*`RQxKe*ge5$futG literal 0 HcmV?d00001