-\chapter{Experiment 1: Original Movement Behaviour}
+\chapter{Experiment 1: Original Movement Behavior}
\label{sec:exp1}
-In the first experiment, the Roomba's original movement behaviour is
+
+The concepts described in the previous chapter are now used to set up a test
+series with the purpose to measure the error in the Roomba's movement and
+to improve its accuracy.
+
+In the first experiment, the Roomba's original movement behavior was
measured to get an overview of the errors that occur while moving, and to
establish a pool of data for correction approaches to work on later.
There was no error correction involved (apart from any possible error
\caption{Measuring turn angles with laser pointer\label{fig:laserpointer}}
\end{figure}
-The test equipment consisted of a small x86 \index{netbook} netbook which was
+The test equipment consisted of a small x86 netbook\index{netbook} which was
mounted on an iRobot Roomba~530\index{Roomba} robot, as seen in
Figure~\ref{fig:roombasetup}. The netbook controlled the Roomba over a
\acs{USB}-to-serial converter plugged into the \ac{ROI}\index{Roomba
Open Interface} port on the Roomba, and hosted as the environment for
executing the Wiselib \index{Wiselib} code.
-In this experiment, the Roomba started right off with the full velocity the
-movement was executed with; so there was no control to adhere a constant
-acceleration when starting or stopping the movement. As mentioned before, due to
-limitations in the \ac{ROI}\index{Roomba Open Interface} it is only possible to
-explicitly start and stop the Roomba's movements at different times, so the
-Wiselib's implementation of the Roomba control code first starts the Roomba's
-movement, keeps track of the turned angle and dcovered distance, and then stops
-the Roomba if these values exceed the target values.
+In this experiment, the Roomba started and stopped with the full velocity the
+movement was executed with; so there was (ideally speaking) an infinite
+acceleration and deceleration at the start and the end of the movement. As
+mentioned before, due to limitations in the \ac{ROI}\index{Roomba Open
+Interface} it is only possible to explicitly start and stop the Roomba's
+movements at different times, so the Wiselib's implementation of the Roomba
+control code first starts the Roomba's movement, keeps track of the turned angle
+and covered distance, and then stops the Roomba if these values exceed the
+target values.
The tests were done in two atomic drive modes: letting the Roomba walk a
specific straight distance with a specific velocity in its viewing direction and
letting it turn on the spot with a specific velocity about a specific angle.
Each of the two modes was carried out on two different floor types\index{floor
-type}, a laminated floor and a carpet floor, to see if the movement behaviour
+type}, a laminated floor and a carpet floor, to see if the movement behavior
significantly depended on the floor type. The side brush was removed, since the
Roomba tends to turn slightly towards the left when driving straight on a
carpet floor. Without the side brush, this was not the case.
-The actual travelled distance of the straight drive tests were determined using
+The actual traveled distance of the straight drive tests were determined using
a measuring tape with an accuracy of 1~mm. Only the distance in the Roomba's
original viewing direction was considered, as it turned out that the offset
perpendicular to the viewing direction and a possible shift in orientation were
For the straight drive tests, the arrays with predefined values were:\\
\begin{tabular}{@{}ll@{}}
-Distances: & 20, 50, 100, 200, 500, 1000, 2000, and 4000~mm \\
-Velocities: & 20, 50, 70, 100, 150, 200, 300, and 400~mm/s
+Distances: & 20, 50, 100, 200, 500, 1000, 2000 and 4000~mm \\
+Velocities: & 20, 50, 70, 100, 150, 200, 300 and 400~mm/s
\end{tabular}
For the turn tests, the arrays with predefined values were: \\
\begin{tabular}{@{}ll@{}}
-Turn angles: & 5, 15, 30, 45, 90, 120, 180, 360, 530, and 720~degree \\
-Velocities: & 20, 50, 70, 100, 150, 200, 300, and 400~mm/s
+Turn angles: & \phantom{0}5, 15, 30, 45, 90, 120, 180, 360, 530 and 720~degree\\
+Velocities: & 20, 50, 70, 100, 150, 200, 300 and 400~mm/s
\end{tabular}
According to the implementation of the Wiselib Roomba control, the velocities
-were given in mm/sec and referred to the distance the wheels travelled when the
+were given in mm/s and referred to the distance the wheels traveled when the
Roomba turned on the spot, which was a circle of 230~mm in diameter.
\section{Results}
\label{exp1:results}
The following graphs show the difference from the measured value to the input
value for driving or turning with different velocities. Positive values mean
-that the Roomba had turned too much or travelled more than the target value,
-negative values mean that the Roomba had turned or travelled too less. The
+that the Roomba had turned too much or traveled more than the target value,
+negative values mean that the Roomba had turned or traveled less. The
plots show multiple test runs; given are the minimum, the maximum and the
arithmetic mean\index{arithmetic mean} of all results for a data point.
\begin{figure}[p!]
\centering
\includegraphics[width=\textwidth]{images/iz250flur_drive_data.pdf}
- \caption{Original behaviour on laminated floor, straight drive movements
+ \caption{Original behavior on laminated floor, straight drive movements
\label{fig:orig:lam:drive}}
\end{figure}
\begin{figure}[p!]
\centering
\includegraphics[width=\textwidth]{images/iz250flur_turn_data.pdf}
- \caption{Original behaviour on laminated floor, turn movements
+ \caption{Original behavior on laminated floor, turn movements
\label{fig:orig:lam:turn}}
\end{figure}
\begin{figure}[p!]
\centering
\includegraphics[width=\textwidth]{images/seminarraum_drive_data.pdf}
- \caption{Original behaviour on carpet floor, straight drive movements
+ \caption{Original behavior on carpet floor, straight drive movements
\label{fig:orig:carpet:drive}}
\end{figure}
\begin{figure}[p!]
\centering
\includegraphics[width=\textwidth]{images/seminarraum_turn_data.pdf}
- \caption{Original behaviour on carpet floor, turn movements
+ \caption{Original behavior on carpet floor, turn movements
\label{fig:orig:carpet:turn}}
\end{figure}
carpet floor when the distance grows.
On the other hand, rising the velocity always seems to cause the
-error to increase.
+error to increase. This illustrates the effect of accumulating errors which
+represents the crucial drawback of dead reckoning\index{dead reckoning}.
The same effects also apply for turn tests. Additionally, there could be errors
-resulting from false assumptions about the Roomba's wheel base\index{wheel base}
-diameter, resulting in false calculations of the circle the Roomba's wheels
+resulting from false assumptions about the Roomba's wheel base\index{wheel
+base}, resulting in bogus calculations of the circle the Roomba's wheels
describe while turning, and therefore leading to false results.
+
+In the following, two approaches to correct errors and improve the accuracy of
+the movement are presented.
projects / bachelor-thesis / written-stuff.git / blobdiff