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- merged with matts changes

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commit d4269a30c3c70250a39f840f4733f13023a82c94 1 parent f165484
Michael Schultz authored
Showing with 73 additions and 55 deletions.
  1. BIN  doc/paper/report.pdf
  2. +73 −55 doc/paper/report.tex
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@@ -303,13 +303,13 @@ \subsection{Hardware}
\subsubsection{Parking Space Monitors}
-The Parking Space Monitors need to be able to do more than just determine
+The Parking Space Monitors (PSMs) need to be able to do more than just determine
if a vehicle is present in a parking space.
They must be able to run on a set of batteries for an extended period of
time, support multiple sensor types and interfaces, and wirelessly transmit
the required data to a base station for further processing.
For all these reasons we chose the Telos Revision B (TelosB) wireless
-sensor module as the base for our Parking Space Monitors.
+sensor module as the base for our PSMs.
\begin{figure}
\begin{center}
@@ -319,7 +319,6 @@ \subsubsection{Parking Space Monitors}
\label{fig:telosb}
\end{figure}
-
Shown in Figure~\ref{fig:telosb}, the TelosB provides many
features and sensors while still managing to use little power and support
fast wireless communications. We chose the TelosB because it includes a
@@ -327,17 +326,20 @@ \subsubsection{Parking Space Monitors}
sensors; low power consumption; an on-board antenna; simple
programming/collection interface; and a 10+6-pin expansion slot allowing
analog, digital, or serial connections~\cite{moteiv:telosb}.
-% TODO was a itemized list, now it is integrated paragraph.
-The TelosB includes many different interfaces we could use
-TODO **Finish describing the TelosB interface we could connect sensors to. Such as analog, UART, I2C, Digital**
+The TelosB includes many different interfaces we could use to attach
+sensors too.
+These include analog to digital, UART, I2C, and digital connections, this
+selection gives us a very flexible platform.
+It's this flexibility that will make our system a viable option for parking
+structures.
\begin{figure}
\begin{center}
\includegraphics[width=\columnwidth]{figures/range_finder}
\end{center}
\caption{LV-MaxSonar\textsuperscript{\textregistered}-EZ1\textsuperscript{\texttrademark}
- by MaxBotix\textsuperscript{\textregistered} (our ``sonar sensor'').}
+ by MaxBotix\textsuperscript{\textregistered} (``EZ1'').}
\label{fig:range_finder}
\end{figure}
@@ -346,16 +348,17 @@ \subsubsection{Parking Space Monitors}
range finders, pressure sensors, and inductive sensors.
We chose to use the
LV-MaxSonar\textsuperscript{\textregistered}-EZ1\textsuperscript{\texttrademark}
-by MaxBotix\textsuperscript{\textregistered} (hereafter ``sonar sensor'')
-because of its price and feature set~\cite{maxbotix:maxsonar-datasheet}.
-These include:
-\begin{itemize}
- \item TODO **Clean up this List**
- \item Supports supply voltage from 2.5V to 5.5V
- \item Detects objects from 6 inches out to 254 inches with 1 inch
- resolution (0-6 inches range as 6 inches)
- \item Output formats include pulse width, analog voltage, and serial digital
-\end{itemize}
+by MaxBotix\textsuperscript{\textregistered} (hereafter ``EZ1'')
+because of its price and feature set.
+The EZ1 supports a wide range of standard supply voltage inputs.
+This allows us a great deal of flexibility in choosing how to power the
+EZ1.
+It can detect objects from 6 inches to 254 inches.
+This is enough range to cover the complete parking space.
+The EZ1 supports many output formats including pulse width, analog voltage,
+and serial digital.
+This gives us multiple ways to connect the same sensor depending on the
+environment~\cite{maxbotix:maxsonar-datasheet}.
\subsubsection{Base Station}
A MacBook Pro was used as the base-station in this project.
@@ -369,19 +372,25 @@ \subsubsection{Base Station}
computer~\footnote{\url{http://www.wikipedia.org/wiki/Plug_computer}}.
The base station must be able to have IEEE 802.15.4 communications with the
-Parking Space Monitors, this can be achieved by connecting a TeloB via USB
-and using a simple serial connection to allow the two devices to
-communicate.
+PSMs, this can be achieved by connecting a TeloB via USB and using a simple
+serial connection to allow the two devices to communicate.
\subsection{Collection Software}
\subsubsection{Parking Space Monitors}
-The Parking Space Monitors operate using TinyOS.
-TinyOS fully supports the TelosB platform and provides many features that
-rapidly speed-up development and TODO ** Finish describing the Parking
-Space Monitor software functionality**
-
+The PSMs are powered by TinyOS.
+We chose TinyOS because it fully supports the TelosB and provides many
+features that rapidly speed-up development.
+These include mesh networking and communication protocols as well as native
+support built in for all the connection interfaces described earlier.
+
+The PSMs receive configuration data from the base-station and then begin
+monitoring sensor values.
+Every sample period the PSMs sample the sensors ten times and average the
+values.
+Those values are then wirelessly transmitted to the base-station every
+fifteen seconds.
One of our key design goals was wireless reliability.
Packets containing sensor details must always make it back to the base station for processing.
This can be very difficult in dynamic environment such as a parking
@@ -408,20 +417,26 @@ \subsubsection{Base Station}
The base station software has multiple functions. It was written in C so
as to be compatible with most current versions of Unix/Linux.
-It is responsible for configuring the Parking Space Monitors, monitoring their status, collecting data from them, and sending the collected data to the aggregation software over the Internet.
+It is responsible for configuring the PSMs, monitoring their status, collecting data from them, and sending the collected data to the aggregation software over the Internet.
Since the base station needs to communicate with the motes over IEEE
-802.15.4 a TelosB is connected via USB as part of the base station.
+802.15.4, a TelosB is connected via USB as part of the base station.
The TelosB is running the default BaseStation app (included with the TinyOS
install) with only minor tweaks to support CTP.
-The base-station has the ability to send configuration packets to the
-Parking Space Monitors. TODO **Finish describing the config process**
+The base-station has the ability to send configuration packets to the PSMs.
+It is through this configuration process that the PSMs are assigned their
+parking space IDs.
+The configuration packet structure was designed to be easily extended to
+support future needs.
+For example, the base station could adjust sensor read rates or data
+transmission rates based on the time of day to increase PSM battery life.
-The base station collects sensor readings from the parking space monitors
-and then determines what data is required by the aggregation software and
-then encodes the data a JSON packet similar to the one in
-Figure~\ref{fig:clientserverjson}.
+The base station's primary purpose is to collect sensor readings from the
+PSMs and relay it to the aggregation software.
+The data is encoded as a JSON packet (as seen in
+Figure~\ref{fig:clientserverjson}) and transfered via HTTP \texttt{PUT} to
+the backend for processing.
\subsection{Aggregation Software}
@@ -508,26 +523,28 @@ \subsection{Sensing and Sending}
\end{figure}
A large amount of testing was performed on the sensing and sending portion
-of this project. Figure~\ref{fig:parking_sensor} shows a Parking Space
-Monitor mounted on a tripod. This set-up was used to test the system with
-an actual vehicle. This testing found issues with the sensing range of our
-Parking Space Monitors.
-Our sonar sensor should support a distance up to 254-inches, however we
+of this project.
+Figure~\ref{fig:parking_sensor} shows a PSM mounted on a
+tripod.
+This set-up was used to test the system with an actual vehicle.
+This testing found issues with the sensing range of our PSMs.
+The EZ1 should support a distance up to 254-inches, however we
were only able to detect a vehicle up to approximately 120-inches (10
-feet). Though this did not cause an issue detecting a vehicle, it could be
-an issue with detecting smaller objects such as motorcycles. More testing
-and analysis would need to be performed to determine if the ten foot range
-of the sonar sensor would really be an issue.
-
-Testing also found an issue with the supply voltage to the sonar sensor.
-The sonar sensor will support a supply voltage of 2.5V - 5.5V.
-We chose to power the sonar sensor using the TelosB analog supply which
+feet).
+Though this did not cause an issue detecting a vehicle, it could be an
+issue with detecting smaller objects such as motorcycles.
+More testing and analysis would need to be performed to determine if the
+ten foot range of the EZ1 would really be an issue.
+It was determined while testing this issue that it was caused by the supply
+voltage to the EZ1.
+The EZ1 will support a supply voltage of 2.5V - 5.5V.
+We chose to power the EZ1 using the TelosB analog supply which
supplies about 3.1V.
-When we used an external supply to test just the sonar sensor at around 5V
-it had a much greater range compared to 3.1V.
+When we used an external supply to test just the EZ1 at 5V it had a much
+greater range compared to 3.1V.
If after more testing it is determined to be an issue, there are solutions
-such as using an external power supply for the sonar sensor or possibly
-mounting the sensor above the space to cover a greater area of the space.
+such as using an external power supply for the EZ1 or possibly mounting the
+sensor above the space to cover a greater area of the space.
\subsection{Backend and Frontend}
@@ -601,11 +618,12 @@ \section{Lessons Learned}\label{sec:lessons}
If we were to pursue this project into the future we would probably modify
the design to allow a single TelosB to monitor multiple sensors. The
ultrasonic range finder we used has multiple output types, one of them
-being a two wire digital serial connection. This connection allows for up
-to twelve sensor connections (which can include our sonar sensors).
-This would allow us to either use two sensors per space to improve accuracy
-and monitor six spaces per TelosB or continue with a single range finder
-per space and monitor twelve parking spaces per TelosB.
+being a two wire digital serial connection.
+This allows for up to twelve EZ1s to be used with a single serial
+connection.
+This allows either two sensors per space to improve accuracy and monitor
+six spaces per TelosB or continue with a single range finder per space and
+monitor twelve parking spaces per TelosB.
This could greatly decrease the cost and power consumption of the overall
system.
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