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toni changes in franks part

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toni
2016-02-23 15:34:00 +01:00
parent 8889c4cf83
commit 822f71f633
4 changed files with 19 additions and 21 deletions
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14
tex/chapters/sensors.tex
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@@ -18,8 +18,8 @@
\include{gfx/baro/baro_setup_issue}
\caption{Sometimes the smartphone's barometer (here: Motorola Nexus 6) provides erroneous pressure readings
during the first seconds. Those need to be omitted before $\sigma_\text{baro}$ and
$\overline{\mObsPressure}$ are estimated.
\commentByFrank{fixed}}
$\overline{\mObsPressure}$ are estimated.}
\commentByFrank{fixed}
\label{fig:baroSetupError}
\end{figure}
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@@ -84,17 +84,15 @@
\subsection{Step- \& Turn-Detection}
Step- and turn-detection use the smartphone's IMU and are implemented as described in \cite{Ebner-15}.
%
However, a big disadvantage of using the state transition as proposal distribution is the high possibility of sample
A big disadvantage of using the state transition as proposal distribution is the high possibility of sample
impoverishment due to a small measurement noise. This happens since accurate observations result in high peaks
of the evaluation density and therefore the proposal density is not able to sample outside that peak \cite{Isard98:CCD}.
Additionally, erroneous or delayed measurements from absolute positioning sensors like \docWIFI{} may lead to misplaced turns.
This causes a downvoting of all states $\mStateVec_t$ with increased heading deviation.
\commentByFrank{so besser?: downvoting of states statt particles}
Therefore, we incorporate the turn-detection, as well as the related step-detection, directly into the state transition
This causes a downvoting of the posterior distribution in areas where the heading deviates.
Therefore, we incorporate the pedestrian's heading $\mObsHeading$, as well as the number of steps $\mObsSteps$, directly into the state transition
$p(\mStateVec_{t} \mid \mStateVec_{t-1}, \mObsVec_{t-1})$, which leads to a more directed sampling instead of a truly random one.
Steps and turns are detected using the smartphone's IMU and are implemented as described in \cite{Ebner-15}.