further small changes

This commit is contained in:
toni
2018-10-18 12:59:46 +02:00
parent e0c800bdbc
commit 96d7b92683
3 changed files with 24 additions and 12 deletions

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@@ -69,7 +69,7 @@ It implements the standard Android sensor functionalities and provides a very si
As smartphones we used either a Samsung Note 2, Google Pixel One or Motorola Nexus 6.
The computation of the state estimation as well as the \docWIFI{} optimization are done offline using an Intel Core i7-4702HQ CPU with a frequency of \SI{2.2}{GHz} running \add{\SI{8}{threads} on \SI{4}{cores}} and \SI{16}{GB} main memory.
\add{An offline computation has practical advantages, such as easier evaluation of the results or shorter waiting times due to higher computing power.
Nevertheless, Android App and offline application are both based on the same C++ backend for localization.}
Nevertheless, Android app and offline application are both based on the same C++ backend for localization.}
%However, similar to our \add{previously presented system}, the setup is able to run completely on commercial smartphones as it \add{is} written in high performant C++ code \cite{torres2017smartphone}.
@@ -118,7 +118,9 @@ Finally, the respective estimation methods are discussed in section \ref{sec:eva
\end{figure}
To compare our old graph-based model with our novel transition model presented within section \ref {sec:transition}, we chose a simple scenario, in which a tester walks up and down a staircase several times.
We used 1000 particles and did not perform an evaluation and resampling step to maintain the pure performance of the transition (step and heading).
We used \SI{5000}{} particles and did not perform an evaluation and resampling step to maintain the pure performance of the transition (step and heading).
\add{The number of particles was heuristically chosen and is based on our previous experience from other scenarios and competitions.
In addition, it sill allows a stable performance of our Android app for localization.}
The filter starts at a fixed position and is updated after every newly recognized step.
We set $\sigma_\text{step} = 0.1$ and $\sigma_\text{turn} = 0.1$ likewise.
The cells of the gridded graph were \SI{20}{} x \SI{20}{\centi\meter} in size and the transition implemented as described in \cite{Ebner-16}.
@@ -268,7 +270,7 @@ Here, we differ between the respective anti-impoverishment techniques presented
The simple anti-impoverishment method is added to the resampling step and thus uses the transition method presented in chapter \ref{sec:transition}.
In contrast, the $D_\text{KL}$-based method extends the transition and thus uses a standard cumulative resampling step.
We set $l_\text{max} =$ \SI{-75}{dBm} and $l_\text{min} =$ \SI{-90}{dBm}.
For a better overview, we only used the KDE-based estimation, as the errors compared to the weighted-average estimation differ by only a few centimeter.
For a better overview, we only used the KDE-based estimation, as the errors compared to the weighted-average estimation differ by only a few centimeter.
\begin{table}[t]
\centering
@@ -310,7 +312,7 @@ Walking down the stairs at \SI{80}{\second} does also recover the localization s
\begin{figure}
\centering
\input{gfx/errorOverTimeWalk0/errorOverTime.tex}
\caption{Error development over time of a single Monte Carlo run of walk 0. Between \SI{10}{\second} and \SI{24}{\second} the Wi-Fi signal was highly attenuated, causing the system to get stuck and producing high errors. Both, the simple and the $D_\text{KL}$ anti-impoverishment method are able to recover early. However, between \SI{65}{\second} and \SI{74}{\second} the simple method produces high errors due to the high random factor involved.}
\caption{Error development over time of a single particle filter run of walk 0. Between \SI{10}{\second} and \SI{24}{\second} the Wi-Fi signal was highly attenuated, causing the system to get stuck and producing high errors. Both, the simple and the $D_\text{KL}$ anti-impoverishment method are able to recover early. However, between \SI{65}{\second} and \SI{74}{\second} the simple method produces high errors due to the high random factor involved.}
\label{fig:errorOverTimeWalk0}
\end{figure}
@@ -379,7 +381,8 @@ Ironically, this is again some type of sample impoverishment, caused by the afor
\subsection{Activity Recognition}
\label{sec:eval:act}
Wie gut ist die Activity...
\commentByToni{Wie gut ist die Activity...}
%%estimation
@@ -421,7 +424,7 @@ Due to a right turn the lower red particles are walking against a wall and thus
Although, situations as displayed in fig. \ref{fig:walk1:kde} frequently occur, the KDE-estimation is not able to improve the overall estimation results.
This can be seen in the corresponding error development over time plot given by fig. \ref{fig:walk1:kdeovertime}.
Here, the KDE-estimation performs slightly better then the weighted-average, however after deploying \SI{100}{} Monte Carlo runs, the difference becomes insignificant.
Here, the KDE-estimation performs slightly better then the weighted-average, however after deploying \SI{100}{} runs of the particle filter, the difference becomes insignificant.
It is obvious, that the above mentioned "correct" mode, not always provides the lowest error.
In some situations the weighted-average estimation is often closer to the ground truth.
Within our experiments this happened especially when entering or leaving thick-walled rooms, causing slow and attenuated Wi-Fi signals.
@@ -472,7 +475,8 @@ We hope to further improve such situations in future work by enabling the transi
To summarize, the KDE-based approach for estimation is able to resolve multimodalities.
It does not provide a smooth estimated path, since it depends more on an accurate sensor model than a weighted-average approach, but is suitable as a good indicator about the real performance of a sensor fusion system.
At the end, in the here shown examples we only searched for a global maxima, even though the KDE approach opens a wide range of other possibilities for finding a best estimate.
At the end, in the here shown examples we only searched for a global maxima, even though the KDE approach opens a wide range of other possibilities for finding a best estimate.
\add{A detailed examination of the runtime performance of the used estimation methods in comparison to the state-of-the-art can be found in \cite{Bullmann-18}.}
\commentByToni{Diskussion, wie die Contributions uns jetzt geholfen haben. Nochmal zusammengefasst.}