diff --git a/tex/chapters/experiments.tex b/tex/chapters/experiments.tex index 8bf1689..c348448 100644 --- a/tex/chapters/experiments.tex +++ b/tex/chapters/experiments.tex @@ -65,9 +65,8 @@ \input{gfx/eval/paths} \caption{The four paths that were part of the evaluation. Starting positions are marked with black circles. - For a better visualisation they were slightly shifted to avoid overlapping. + For a better visualisation they were slightly shifted to avoid overlapping.} \commentByFrank{font war korrekt, aber die groesse war zu gross im vgl. zu den anderen} - } \label{fig:paths} \end{figure} % error development over time while walking along a path @@ -76,9 +75,8 @@ \caption{Development of the error while walking along Path 4 using the Motorola Nexus 6. When leaving the suggested route (3), the error of \textbf{shortest} path \refeq{eq:transShortestPath} and \textbf{multi}path \refeq{eq:transMultiPath} increases. - The same issues arise when facing multimodalities between two staircases just before the destination (9). + The same issues arise when facing multimodalities between two staircases just before the destination (9).} \commentByFrank{hilft das bold vlt. schon um die legende zu verstehen?} - } \label{fig:errorTimedNexus} \end{figure} % detailed analysis of path 4 @@ -139,8 +137,8 @@ \begin{figure} \input{gfx/eval/error_dist_nexus} \caption{Error distribution of all walks conducted with the Motorola Nexus 6 for distinct percentile values. - Our proposed methods clearly provide an enhancement for the overall localization process. - \commentByFrank{percentile erwaehnt}} + Our proposed methods clearly provide an enhancement for the overall localization process.} + \commentByFrank{percentile erwaehnt} \label{fig:errorDistNexus} \end{figure} %\begin{figure} diff --git a/tex/chapters/grid.tex b/tex/chapters/grid.tex index 360f994..588822a 100644 --- a/tex/chapters/grid.tex +++ b/tex/chapters/grid.tex @@ -258,9 +258,11 @@ \newcommand{\pathRef}{v_\text{ref}} - Before every transition, the centre-position $\pathCentroid = (x,y,z)^T$ of the current - \commentByFrank{reicht das so schon?} - sample-set, representing the posterior distribution at time $t-1$, is calculated. + Before every transition, the centre-position $\pathCentroid = \fPos{\mStateVec_{t-1}^*}$ of the current sample-set, where +\begin{equation} +\mStateVec_{t-1}^* = \underset{\mStateVec_{t-1}}{\argmax} \enspace p(\mStateVec_{t-1} | \mObsVec_{t-1}) +\end{equation} +represents the most proper state of the posterior distribution at time $t-1$, is calculated. % % %\commentByFrank{avg-state vom sample-set. frank d. meinte ja hier muessen wir aufpassen. bin noch unschluessig wie.} @@ -345,8 +347,8 @@ \caption{Heat-Map showing the number of visits per vertex after $30.000$ walks using \refeq{eq:transMultiPath}. Both possible paths are covered and slight deviations are possible. Additionally shows the shortest-path calculation without (dashed) and with (solid) importance-factors - used for edge-weight-adjustment. - \commentByFrank{so besser?}} + used for edge-weight-adjustment.} + \commentByFrank{so besser?} \label{fig:multiHeatMap} \end{figure} diff --git a/tex/chapters/sensors.tex b/tex/chapters/sensors.tex index 3b718e4..a89f09c 100644 --- a/tex/chapters/sensors.tex +++ b/tex/chapters/sensors.tex @@ -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} % @@ -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}. diff --git a/tex/chapters/system.tex b/tex/chapters/system.tex index 9d2df8c..4bcc696 100644 --- a/tex/chapters/system.tex +++ b/tex/chapters/system.tex @@ -24,7 +24,7 @@ where $x, y, z$ represent the position in 3D space, $\mStateHeading$ the user's heading and $\mStatePressure$ the relative atmospheric pressure prediction in hectopascal (hPa). The recursive part of the density estimation contains all information up to time $t-1$. - Furthermore, the state transition models the pedestrian's movement as described in section \ref{sec:trans}. + Furthermore, the state transition $p(\mStateVec_{t} \mid \mStateVec_{t-1}, \mObsVec_{t-1})$ models the pedestrian's movement as described in section \ref{sec:trans}. %It should be noted, that we also include the current observation $\mObsVec_{t}$ in it. As \cite{Koeping14-PSA} has proven, we are able to include the observation $\mObsVec_{t-1}$ into the state transition. @@ -62,7 +62,7 @@ Therefore, numerical solutions like Gaussian filters or the broad class of Monte Carlo methods are deployed \cite{sarkka2013bayesian}. Since we assume indoor localisation to be a time-sequential, non-linear and non-Gaussian process, a particle filter is chosen as approximation of the posterior distribution. - Within this work the state transition $p(\mStateVec_{t} \mid \mStateVec_{t-1}, \mObsVec_{t})$ is used as proposal distribution, + Within this work the state transition $p(\mStateVec_{t} \mid \mStateVec_{t-1}, \mObsVec_{t-1})$ is used as proposal distribution, what is also known as CONDENSATION algorithm \cite{Isard98:CCD}.