\end{table}
\subsection{Evaluation}
-\subsubsection{Realisation}
+\subsubsection{Requirements realisation}
%implemented features and mission range
The final implementation satisfies all the \emph{must have} requirements.
Besides all the most important requirements it also supports all \emph{should
we had some time left which we used to implement \emph{ER2} since it was
relatively simple.
+\paragraph{Mission range}
The range of missions the robot can support is a lot bigger then reflected by
the met functional requirements. All actions specifiable in a behaviour consist
of atomic operations that take very little time leading to the action being
can make missions very complex. Possible combinations of behaviour can perform
actions such as: counting, following moving objects and grouping objects.
-In the beginning of the running program, the user need to press any button to start
-the program in the robot. This is because both bricks need to start the bluetooth
-communication pairing at the same time. If we were given more time we would make
-the bluetooth pairing automatically run from the beginning of the program without
-waiting button press in order to limit the user involvement in the robot.
+One could argue that due to the lack of control structures it is very difficult
+to program complex missions. This is the case, for example if we would add a
+\emph{while} construction it would increase the range of missions very much.
+However, it also makes programming the robot much more difficult and will
+reduce the usability. With the current structure, the subsumption
+architecture and the rudimentary memory, we actually can create such control
+structures but it takes a little more effort.
-The DSL can accomodate the improvement in the case of adding new sensors or actuators.
-For instance, if we want to add a new sensor, then it is easy to add new \emph{StoppingExpression}
-in the DSL. In addition, if we want to add a new actuator to the robot, we can just add
-a new action defined in the DSL and implement the use of the action in the program.
+\paragraph{Flexibility}
+The DSL can very easily be improved in the case of adding new sensors or
+actuators. For sensors we can just add clauses in the grammar within the
+\emph{StoppingExpression} that will process the values. For actuators the same
+thing can be done in the \emph{Action} rule. A change in the robot's
+configuration can also be handled very quickly albeit not in the DSL itself. We
+specifically chose not to incorporate the hardware configuration in the DSL to
+keep is a simple as possible and thus less error prone. This means that if the
+hardware configuration changes the underlying library must be changed as well.
+However, due to the modularity of the library this is very easy.
-\subsubsection{Discussion}
-%development process, use of dsl/technologies, general lessons
-From our experience, the most important think in the development process was to
-start working from a small functionality and to test it. As soon as we knew
-something wrong with the program we can fix and test it again in order to ensure
-the functionality worked. This would be good for the development of the next
-functionality. The difficulty in the development was in the testing phase. The
-reason was sometimes we got an error when running the program in the robot (for
-example: sensor exception) and it took so much time for loading all sensors to be
-ready for testing. Moreover, there was a time when the robot was crashed and needed
-to be restarted which took some time from the development time.
\ No newline at end of file
+\paragraph{Safety}
+The DSL by design does not generate \emph{safe} code implicitly. A programmer
+can make a program that can destroy the robot very easily. While safety is very
+important it would limit the range of missions a lot if some basic behaviours
+used in the demonstration for safety would be inherently present.
+
+\subsubsection{Development process}
+\paragraph{Feedback loop}
+Booting the bricks takes around a minute to complete. When the robot is
+programmed launching the application takes another 30 seconds followed by
+another 30 seconds waiting on the initialization of the sensors. About once
+every 10 times on high battery and about every other time on low battery the
+ultrasonic sensor fails to initialize. We did not have the time to investigate
+this properly but the fault was hidden somewhere deep in the \emph{LeJOS} code.
+When all sensors were initialized the Bluetooth connection could be commenced
+by pressing a button on both bricks. Connecting via Bluetooth has about the
+same error rate as the ultrasonic sensor has and takes about 30 seconds.
+
+This very long start up led to a rough development process with long feedback
+loops. After a long time we and other groups found out that applying power to
+the bricks during the initialization and pairing reduced the error frequency a
+lot.
+
+\paragraph{Techniques}
+Using the combination of all tools such as DSL, XText, XTend and eclipse went
+surprisingly well. In the beginning there were some technical difficulties
+setting everything up and there was quite some overhead since the tools
+required a lot of computing power. But when everything was set up correctly it
+worked like a charm.
+
+Creating our solution was a bit difficult at the beginning due to extra works
+designing the DSL to accomodate the robot's missions and behaviours. However
+when the DSL was created appropriately the generation of different missions and
+behaviours for the robot became very easy.
+
+\paragraph{General lessons learned}
+From our experience, the most important thing in the development process was to
+work iteratively in small building blocks. Another lesson learned was the fact
+that robots are not always reliable and can behave in unexpected ways.
+
+Another lesson learned was that plans mostly take longer than expected. Our
+planning was very generous but still we did not have time to implement some
+extra functionality. If we would have more time we would have tried to make the
+robots autonomous in start up. The current robot needs to have a button pressed
+when the bricks can pair. We have experimented with autonomous pairing but we
+never got it stable but with more time we could make it stable. Another option
+is to try to get more requirements. For example the mapping and internal
+representation of the locations of the lakes. This problem is not trivial at
+all and because of the lack of time we could unfortunately not spend time on
+it.
repositories / des2015.git / blobdiff