eine neue runde eine neue reviewfahrt
This commit is contained in:
@@ -30,7 +30,7 @@ Care was taken to have at least two beacons in each room and a third beacon visi
|
||||
Due to the difficult architecture and the extremely thick walls of the museum, we decided on this procedure, which explains the rather large number of \SI{42}{} transmitters compared to modern buildings.
|
||||
Another reason for the high number of beacons is that we did not want to analyze the quality of the Wi-Fi signal coverage for further improvements, as this can be a very time-consuming task.
|
||||
In many areas of the building an improvement would not even be possible due to the lack of power sockets.
|
||||
To compensate that, battery powered beacons could be used but we consider this approach less practicable, so we did not take this option.
|
||||
%To compensate that, battery powered beacons could be used but we consider this approach less practicable, so we did not take this option.
|
||||
The power sockets are located at different heights ranging from \SI{0.2}{\meter} to \SI{2.5}{\meter}.
|
||||
Consequently, there were no prior requirements on how a single beacon should be placed exactly and its position is dictated by the socket's position.
|
||||
Considering all the above, the beacons were placed more or less freely and to the best of our knowledge.}
|
||||
@@ -40,7 +40,7 @@ The positions of the fingerprints are set within our 3D map editor (see fig. \re
|
||||
The reference points were placed every \SI{3}{\meter} to \SI{7}{\meter} from each other, however as can be seen in fig. \ref{fig:apfingerprint} not necessarily accurate.
|
||||
As the optimization scheme does not require equally spaced reference points, doing so would result in superfluous effort.
|
||||
Furthermore, it is not easy to adopt the exact position to take the reference measurements in the building later on.
|
||||
Of course, this could be achieved with appropriate hardware (e.g. laser-scanner), but again, this requires more time and care, which in our opinion does not justify a presumably increased accuracy of some decimeters.}
|
||||
Of course, this could be achieved with appropriate hardware (e.g. laser-scanner), but again, this requires more time and care, which in our opinion does not justify a presumably increased accuracy of some decimeters.} \addy{Therefore, we accept the resulting inaccuracy between the (reference) position stored on the map and the actual position where the measurement took place, due to the enormous time saving.}
|
||||
|
||||
\add{Summing up the above, the following initial steps are required to utilize our localization system in a building:
|
||||
\begin{enumerate}
|
||||
@@ -59,9 +59,10 @@ Creating the floor plan including walls and stairs took us approximately \SI{40}
|
||||
Adding knowledge like semantic information such as room numbers would of course take additional time.
|
||||
All remaining steps were performed on-site using our smartphone app for localization, which can be seen in fig. \ref{fig:yasmin}.
|
||||
As the museum did not provide any Wi-Fi infrastructure, we installed \SI{42}{} beacons as explained above.
|
||||
With the help of the museum's janitor, this step took only \SI{30}{\minute}, as he was well aware of all available power outlets and also helped plugging them in.
|
||||
After that, each of the \SI{133}{} reference points was scanned 30 times ($\approx \SI{25}{\second}$ scan time) using a Motorola Nexus 6 at the \SI{2.4}{GHz} Wi-Fi band.
|
||||
This took \SI{85}{\minute}, as all measurements were conducted using the same smartphone.
|
||||
With the help of the museum's janitor, this step took only \SI{30}{\minute}, as he was well aware of all available power outlets and also helped plugging them in.}
|
||||
\addy{After that, \SI{30}{} Wi-Fi scans were conducted and recorded for each of the \SI{133}{} reference points using a Motorola Nexus 6 at the \SI{2.4}{GHz} Wi-Fi band. This took approximately \SI{25}{\second} per point, as the Android OS restricts the scan rate.}
|
||||
%After that, each of the \SI{133}{} reference points was scanned 30 times ($\approx \SI{25}{\second}$ scan time) using a Motorola Nexus 6 at the \SI{2.4}{GHz} Wi-Fi band.
|
||||
\add{In total, this took \SI{85}{\minute}, as all measurements were conducted using the same smartphone.
|
||||
The optimized Wi-Fi model and the mesh can be created automatically within a negligible amount of time directly on the smartphone, which then enables the pedestrian to start the localization.
|
||||
Of course, for the experiments conducted below several additional knowledge was obtained to evaluate the quality of the proposed methods and the overall localization error.
|
||||
Thus the above provided times were measured for a pure localization installation, as for example a customer would order, while the experiments were performed in a 2-day period.
|
||||
@@ -235,7 +236,7 @@ However, as the overall error suggests, this is not always an advantage, which w
|
||||
%warum ist die optimierung tdz. ganz gut?
|
||||
As mentioned above, some areas are heavily attenuated by big walls, what simply does not fit the used signal strength prediction model.
|
||||
As discussed in section \ref{sec:relatedWork} and \ref{sec:wifi}, we only consider ceilings within the model to avoid computational expensive wall intersection-tests.
|
||||
A far higher number of reference measurements in bad areas can therefore only increase the accuracy to a limited extent.
|
||||
A far higher number of reference measurements in bad areas can therefore only increase the accuracy to a limited extent, \addy{whereas increasing the number of reference points could compensate for this, however requires additional setup time, what is then contrary to a fast deploy time.}
|
||||
Nevertheless, by optimizing all parameters (\mPosAPVec{}, \mTXP{}, \mPLE{} and \mWAF{}) the system provides far better localization results compared to using the \docAPshort{}'s real positions with empirical values or even optimized values only for \mTXP{}, \mPLE{} and \mWAF{}.
|
||||
The reason for this is obvious.
|
||||
The optimized parameters fit the (unrealistic) signal strength prediction model much better than the real ones and thus provide for a smaller error between measured RSSI and predicted RSSI.
|
||||
@@ -273,7 +274,7 @@ The 4 chosen walking paths can be seen in fig. \ref{fig:floorplan}.
|
||||
Walk 0 is \SI{152}{\meter} long and took about \SI{2.30}{\minute} to walk.
|
||||
Walk 1 has a length of \SI{223}{\meter} and Walk 2 a length of \SI{231}{\meter}, both required about \SI{6}{\minute} to walk.
|
||||
Finally, walk 3 is \SI{310}{\meter} long and takes \SI{10}{\minute} to walk.
|
||||
All walks were carried out by 4 different male testers using either a Samsung Note 2, Google Pixel One or Motorola Nexus 6 for recording the measurements.
|
||||
\addy{Each of the single walks was} carried out by 4 different male testers using either a Samsung Note 2, Google Pixel One or Motorola Nexus 6 for recording the measurements.
|
||||
All in all, we recorded \SI{28}{} distinct measurement series, \SI{7}{} for each walk.
|
||||
The picked walks intentionally contain erroneous situations, in which many of the above treated problems occur.
|
||||
\del{This allows us to discuss everything in detail.}
|
||||
|
||||
Reference in New Issue
Block a user