X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=marsrover%2Fdocument%2Fevaluation.tex;h=9d3924011a77d0074ba315de5652d96e39c29c1e;hb=HEAD;hp=a9aa80ced0394c5cb6f716f316826b462753dc1f;hpb=8bccaab629058956e02945978df7fc500a69bd4d;p=des2015.git diff --git a/marsrover/document/evaluation.tex b/marsrover/document/evaluation.tex index a9aa80c..9d39240 100644 --- a/marsrover/document/evaluation.tex +++ b/marsrover/document/evaluation.tex @@ -73,7 +73,7 @@ and if they are we try to complete as many iterations as possible. \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 @@ -84,6 +84,7 @@ of that mapping and localization was not implemented. In the end of the process 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 @@ -91,25 +92,72 @@ interruptible at all times. Together with the rudimentary variable storage we 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.