From fed5e72c470149d0746c86161e19ff415f6691c7 Mon Sep 17 00:00:00 2001 From: "Robin P. Clark" Date: Mon, 18 Feb 2013 10:56:27 +0000 Subject: [PATCH] tidy a bit --- submission_thesis/CH3_FMEA_criticism/copy.tex | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/submission_thesis/CH3_FMEA_criticism/copy.tex b/submission_thesis/CH3_FMEA_criticism/copy.tex index c1b5ea5..3537dbd 100644 --- a/submission_thesis/CH3_FMEA_criticism/copy.tex +++ b/submission_thesis/CH3_FMEA_criticism/copy.tex @@ -111,22 +111,25 @@ Distributed real time systems are control systems where smart sensors communicate over a communications bus to a master controller. % -Most modern cars follow this pattern and use CANbus~\cite{canspec,can}. +Most modern cars follow this information technology pattern and use CANbus~\cite{canspec,can}. % -For instance, the throttle pedal will be linked to a sensor to determine how -far the pedal is pressed. This sensor will be read by a micro-controller, and passed, via CANbus, to the Engine Control Unit (ECU) +For instance, in a modern car there will be no mechanical linkage from the pedal to the engine, instead the throttle pedal will be linked to a sensor to determine how +far the pedal is pressed. +This sensor will be read by a micro-controller, and passed, via CANbus, to the Engine Control Unit (ECU) which will use that information (along with information from other sensors) to adjust the power required from the engine. +This adjustment could be direct, or could be another CANbus message passed to a micro-controller regulating engine function. In terms of FMEA, see figure~\ref{fig:distcon}, our reasoning path spans four interface layers of electronics to software. Traditional FMEA does not cater for the software hardware interface, and here we have the addition complications %with the additional complications of the communications protocol used to transmit data, and the failure mode characteristics of the communications physical layer. -(figure~\ref{fig:distcon} -The failure reasoning paths for a typical section of a distributed real time system, mean that traditional FMEA -is almost impossible to perform. +%(figure~\ref{fig:distcon} +The failure reasoning paths for a distributed real time system, mean traditional FMEA +is impossible to perform. % -The base component failure mode to system failure paradigm is utterly anachronistic in the distributed real time system environment. +The base component failure mode to system failure paradigm is +utterly anachronistic in the distributed real time system environment. \begin{figure}[h]