tring to finish the sigma delta analysis, keeps becoming 10pm too quickly

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Robin Clark 2012-05-08 21:43:41 +01:00
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commit b46bcd00d9
5 changed files with 163 additions and 49 deletions

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@ -51,9 +51,9 @@ paper
{ {
chapter chapter
} }
starts with a worked example of the new methodology Failure Mode Modular De-composition (FMMD), and then starts with a worked example using the new methodology, Failure Mode Modular De-composition (FMMD), and then
describes the data types and concepts for the method, using these a UML class model is built develops an ontological structure for the methodology using UML class models.
and then notation is developed. A notation is then described to index and classify objects created in FMMD models.

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@ -4,7 +4,8 @@ PNG_DIA = blockdiagramcircuit2.png bubba_oscillator_block_diagram.png circuit1
dubsim1.png invamp.png mvampcircuit.png pd.png plddouble.png plddoublesymptom.png \ dubsim1.png invamp.png mvampcircuit.png pd.png plddouble.png plddoublesymptom.png \
poss1finalbubba.png poss2finalbubba.png pt100.png pt100_doublef.png pt100_singlef.png \ poss1finalbubba.png poss2finalbubba.png pt100.png pt100_doublef.png pt100_singlef.png \
pt100_tc.png pt100_tc_sp.png shared_component.png stat_single.png three_tree.png \ pt100_tc.png pt100_tc_sp.png shared_component.png stat_single.png three_tree.png \
tree_abstraction_levels.png vrange.png sigma_delta_block.png ftcontext.png ct1.png hd.png tree_abstraction_levels.png vrange.png sigma_delta_block.png ftcontext.png ct1.png hd.png \
sigdel1.png

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@ -1706,7 +1706,7 @@ and fed into the summing integrator completing the negative feedback loop.
The partslist for the $\Sigma \Delta $ADC The partslist for the $\Sigma \Delta $ADC
$$\{ IC1, IC2, IC3 IC4 \} $$. $$\{ IC1, IC2, IC3, IC4, R1, R2, R3, R4, C1 \} $$.
IC1,2 and 3 are all Op-amps and we have failure modes from section~\ref{sec:opampfm}. IC1,2 and 3 are all Op-amps and we have failure modes from section~\ref{sec:opampfm}.
@ -1722,8 +1722,12 @@ The resistors and capacitor failure modes we take from EN298~\cite{en298}[An.A]
$$ fm ( R ) = \{OPEN, SHORT\} $$ $$ fm ( R ) = \{OPEN, SHORT\} $$
$$ fm ( C) = \{OPEN, SHORT\} $$ $$ fm ( C ) = \{OPEN, SHORT\} $$
\subsection{Identifying initial {\fgs}}
\subsubsection{Summing Junction}
We now need to choose {\fgs}. The signal path is circular, but we can start We now need to choose {\fgs}. The signal path is circular, but we can start
with the input voltage, which is applied to $R2$, we can term this voltage $V_{in}$. with the input voltage, which is applied to $R2$, we can term this voltage $V_{in}$.
$R2$ and $R1$ form a summing junction to IC1. $R2$ and $R1$ form a summing junction to IC1.
@ -1732,7 +1736,7 @@ This can be our first {\fg}. For the symptoms, we have to think in terms of the
on its performance as a summing junction and not be on its performance as a summing junction and not be
distracted by the integrator formed by $C_1$ and $IC1$. distracted by the integrator formed by $C_1$ and $IC1$.
$$G^0_1 = \{R1, R2\}$$ $$G^0_1 = \{R1, R2 \}$$
\begin{table}[h+] \begin{table}[h+]
\caption{R1,R2 Summing Junction: Failure Mode Effects Analysis} % title of Table \caption{R1,R2 Summing Junction: Failure Mode Effects Analysis} % title of Table
@ -1757,15 +1761,21 @@ From the analysis in table~\ref{tbl:sumj}, we can now create a derived component
$SUMJ$ which has the failure modes from collecting its symptoms. $SUMJ$ which has the failure modes from collecting its symptoms.
We can state We can state
$$ fm(SUMJ) = \{ V_{in} DOM, V_{in} DOM \} $$ $$ fm(SUMJ) = \{ V_{in} DOM, V_{fb} DOM \} $$
\subsubsection{Buffered Integrator}
Following along the signal path, the next functional group is the integrator. Following the signal path, the next functional group is the integrator.
This integrator is simply by $IC2$. This performs the function of This integrator is formed by $C$ by $IC2$\cite{aoe}[ch.4].
isolating the integrator from any load on its output. We can therefore include this as well. The output of the integrator is fed into IC2, which acts as a buffer.
%performing the function of
isolating the integrator from any load on its output.
These three components work together to form a buffered integrator,
and nicely form a {\fg}.
$$G^0_2 = \{IC1, C1, IC2\}$$ $$G^0_2 = \{IC1, C1, IC2\}.$$
The buffered integrator is analysed in table~\ref{tbl:intg}.
\begin{table}[h+] \begin{table}[h+]
@ -1796,10 +1806,111 @@ $$G^0_2 = \{IC1, C1, IC2\}$$
From the analysis in table~\ref{tbl:intg}, we can now create a derived component From the analysis in table~\ref{tbl:intg}, we can now create a derived component
$SUMJ$ which has the failure modes from collecting its symptoms. $BFINT$ which has the failure modes from collecting symptoms from the analysis in table~\ref{tbl:intg}.
We can state We can state
$$ fm (SUMJ) = \{ HIGH, LOW, NO\_INTEGRATION , LOW\_SLEW \} $$ $$ fm (BFINT) = \{ HIGH, LOW, NO\_INTEGRATION , LOW\_SLEW \} $$
\subsubsection{Digital level to analogue level conversion ($DL2AL$).}
Digital level to analogue level conversion is performed by IC3 in conjunction with a potential divider formed by R3,R4.
The potential divider provides a mid rail reference voltage
to the inverting input of IC3.
\paragraph{Potential divider Formed by R3,R4.}
We re-use the analysis from section~\ref{sec:pd}, and used the derived component $PD$
to represent the potential divider formed by R3 and R4. Because PD is a derived component, we can denote this
by super-scripting it with its abstraction level of 1, thus $PD^1$.
$$
fm(PD^1) = \{ HIGH, LOW \}.
$$
IC3 is an op-amp and has the failure modes
$$fm(IC3) = \{\{ HIGH, LOW, NOOP, LOW\_SLEW \} . $$
The digital signal is supplied to the non-inverting input.
The output is a voltage level in the analogue domain $-V$ or $+V$.
We now form a {\fg} from $PD^1$ and $IC3$.
$$ G^1 = \{ PD^1, IC3 \} $$
We now analyse the {\fg} $G^1$ in table~\ref{tbl:DS2AS}.
\begin{table}[h+]
\caption{$PD^1, IC3$ Digital level to analogue level converter: Failure Mode Effects Analysis} % title of Table
\label{tbl:DS2AS}
\begin{tabular}{|| l | l | c | c | l ||} \hline
\textbf{Failure Scenario} & & \textbf{failure result } & & \textbf{Symptom} \\
& & & & \\
\hline \hline
FS1: $PD^1$ $HIGH$ & & output perm. low & & LOW \\
FS2: $PD^1$ $LOW$ & & output perm. low & & HIGH \\ \hline
\hline
FS3: $IC3$ $HIGH$ & & output perm. high & & HIGH \\
FS4: $IC3$ $LOW$ & & output perm. low & & LOW \\ \hline
FS5: $IC3$ $NOOP$ & & no current drive & & LOW \\
FS6: $IC3$ $LOW\_SLEW$ & & delayed signal & & LOW\_SLEW \\ \hline
\hline
\end{tabular}
\end{table}
We collect the symptoms of failure $\{ LOW, HIGH, LOW\_SLEW \}$.
We can now derive a new component to represent the level conversion and call it $DL2AL$.
$$ DL2AL = D(G^1) $$
$$ fm (DL2AL) = \{ LOW, HIGH, LOW\_SLEW \} $$
\subsubsection{digital clocked memory (flip-flop).}
This is a single component as a {\fg}, and we can state
$$ fm (DCM) = \{ HIGH, LOW, NOOP \} $$
\subsection{First {\fgs} analysed}
We have analysed the initial {\fgs} and can now take stock of the situation
and see what is now required. Figure~\ref{fig:sigdel1} shows how far the
hierarchy has been built.
\begin{figure}[h+]
\centering
\includegraphics[width=400pt]{./CH5_Examples/sigdel1.png}
% sigdel1.png: 766x618 pixel, 72dpi, 27.02x21.80 cm, bb=0 0 766 618
\caption{First stage of FMMD analysis: Sigma delta Converter}
\label{fig:sigdel1}
\end{figure}
IC4 is as yet unused, the signal path connects IC4 and DL2AL. These seem natural candidates
for the next {\fg}.
BFINT and SUMJ are adjacent in the signal path and these are chosen as a {\fg} as well.
\subsubsection{{\fg} BFINT and SUMJ}
\subsubsection{{\fg} IC4 and DL2AL}
\subsection{Final, top level {\fg} for sigma delta Converter}
% ] % ]
% into % into
% %
@ -1819,40 +1930,41 @@ $$ fm (SUMJ) = \{ HIGH, LOW, NO\_INTEGRATION , LOW\_SLEW \} $$
% and IC3. % and IC3.
% The output from this is sent to the summing integrator as the signal summed with the input. % The output from this is sent to the summing integrator as the signal summed with the input.
\subsection{Identifying initial {\fgs}}
\subsubsection{Summing Junction formed by R1 and R2}
The resistors R1, R2 form a summing junction
to the negative input of IC1.
Using the earlier definition for resistor failure modes,
$fm(R)= \{OPEN, SHORT\}$, we analyse the summing junction
in table~\ref{tbl:sumjunct} below.
\begin{table}[h+]
\caption{Summing Junction: Failure Mode Effects Analysis: Single Faults} % title of Table
\label{tbl:sumjunct}
\begin{tabular}{|| l | l | c | c | l ||} \hline
\textbf{Failure Scenario} & & \textbf{Summing} & & \textbf{Symptom} \\
& & \textbf{Junction} & & \\
\hline
FS1: R1 SHORT & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
FS2: R1 OPEN & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
FS3: R2 SHORT & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
FS4: R2 OPEN & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
\hline
\end{tabular}
\end{table}
% PHS45
This summing junction fails with two symptoms. We create a {\dc} called $SUMJUNCT$ and we can state,
$$fm(SUMJUNCT) = \{ R1\_IN\_DOM, R2\_IN\_DOM \} $$.
% The resistors R1, R2 form a summing junction
% to the negative input of IC1.
% Using the earlier definition for resistor failure modes,
% $fm(R)= \{OPEN, SHORT\}$, we analyse the summing junction
% in table~\ref{tbl:sumjunct} below.
%
% \begin{table}[h+]
% \caption{Summing Junction: Failure Mode Effects Analysis: Single Faults} % title of Table
% \label{tbl:sumjunct}
%
% \begin{tabular}{|| l | l | c | c | l ||} \hline
% \textbf{Failure Scenario} & & \textbf{Summing} & & \textbf{Symptom} \\
% & & \textbf{Junction} & & \\
% \hline
% FS1: R1 SHORT & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
% FS2: R1 OPEN & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
% FS3: R2 SHORT & & R2 input dominates & & $R2\_IN\_DOM$ \\ \hline
% FS4: R2 OPEN & & R1 input dominates & & $R1\_IN\_DOM$ \\ \hline
%
% \hline
%
% \end{tabular}
% \end{table}
% % PHS45
%
% This summing junction fails with two symptoms. We create a {\dc} called $SUMJUNCT$ and we can state,
% $$fm(SUMJUNCT) = \{ R1\_IN\_DOM, R2\_IN\_DOM \} $$.
The D type flip flop
%\subsection{FMMD Process applied to $\Sigma \Delta $ADC}. %\subsection{FMMD Process applied to $\Sigma \Delta $ADC}.
T%he block diagram in figure~\ref{fig T%he block diagram in figure~\ref{fig

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@ -11,8 +11,9 @@ and apply FMEA analysis locally on this {\fg}.
% %
In this way, we determine how that {\fg} can fail. In this way, we determine how that {\fg} can fail.
We can then go further and consider these to We can then go further and consider these to
be symptoms of failures in the components of the {\fg}. be symptoms of failure of the {\fg}.
We can collect common symptoms of failure for the {\fg}. Because component failures will often manifest themselves as the same symptoms of failure,
we are able to collect common symptoms of failure for the {\fg}.
% %
% %
With the collected common symptoms, we can treat the {\fg} With the collected common symptoms, we can treat the {\fg}
@ -37,7 +38,7 @@ Once a hierarchy is in place, it can be converted into a fault data model.
\fmmdgloss \fmmdgloss
% %
From the fault data model, automatic generation From the fault data model, automatic generation
of FTA \cite{nasafta} (Fault Tree Analysis) and mimimal cuts sets \cite{nucfta} are possible. of FTA \cite{nasafta} (Fault Tree Analysis) and minimal cuts sets \cite{nucfta} are possible.
Also statistical reliability/probability of failure~on~demand \cite{en61508} and MTTF (Mean Time to Failure) calculations can be produced Also statistical reliability/probability of failure~on~demand \cite{en61508} and MTTF (Mean Time to Failure) calculations can be produced
automatically\footnote{Where component failure mode statistics are available \cite{mil1991}}. automatically\footnote{Where component failure mode statistics are available \cite{mil1991}}.
% %
@ -315,7 +316,7 @@ aircraft.}) of the failure modes to
form `test cases'. form `test cases'.
\item If required, create test cases from all valid double failure mode combinations within the {\fg}. \item If required, create test cases from all valid double failure mode combinations within the {\fg}.
% \item Draw these as contours on a diagram % \item Draw these as contours on a diagram
% \item Where si,ultaneous failures are examined use overlapping contours % \item Where simultaneous failures are examined use overlapping contours
% \item For each region on the diagram, make a test case % \item For each region on the diagram, make a test case
\item Using the `test cases' as scenarios to examine the effects of component failures, \item Using the `test cases' as scenarios to examine the effects of component failures,
we determine the failure~mode behaviour of the functional group. we determine the failure~mode behaviour of the functional group.