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%&tex |
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\chapter{introduction} |
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\chapter{Introduction} |
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\label{introduction} |
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\section{Context of this Thesis} |
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\ac{cps} integrate computation and physical components as an engineered system. |
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Automobiles, robots, medical devices and even the smart grid are examples of \ac{cps}. |
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The complexity of \ac{cps} has gone from an embedded system that improved the fuel consumption of a car engine to a fully self-driving vehicle. |
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Although the complexity opens up more design possibilities, improved efficiency and safety, it has downsides. |
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The problem with the increasing complexity is the resulting increased developing cost and the decreasing reliability. |
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Within the research topics that focus on \ac{cps}, lies the development of new design methods that deal with this complexity problem. |
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The \emph{design method} by \textcite{broenink_rapid_2019} is one of these new design methods and focusses on the rapid development of embedded control software. |
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The rapid development is a design technique that splits the development into small individual steps, which can be implemented and tested separately. |
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Testing each individual step creates feedback on a short interval, with the goal to detect errors made during the development as early as possible. |
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As part of the research, Broenink and Broenink performed a small case study. |
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In this case study, they have designed a controller, and implemented the controller in software for a physical off-the-shelf system. |
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However, developing \ac{cps} incorporates both the computational software side, as well as the development of the physical dynamic side, although the latter is not covered by Broenink and Broenink. |
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For this design method to be suitable for a complete design of \ac{cps} it has to be applicable to the physical part as well. |
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%%In this thesis, the proposed design method is applied and evaluated in the context of the physical part of a \ac{cps}. |
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%%This is done in a case study, where a \ac{cps} is designed from scratch. |
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\section{Research Objective} |
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\textcite{broenink_rapid_2019} present a case study for software in their paper and state that "this [case study] does not mean that the same techniques cannot be applied to the physical part of the system." |
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In this thesis, I will research whether this design method applies to the physical part of a \ac{cps}, to come to a design method that can be applied on both the physical and cyber (software) part of a \ac{cps}. |
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From the start of this research, it was clear that a direct copy of the design method is not possible. |
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It is therefore necessary to analyse which design techniques cannot be used and thus how to replace or improve them. |
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The research is summarized in the following two research questions: |
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\begin{itemize} |
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\item Which design techniques of the design method by \textcite{broenink_rapid_2019} can be applied developing the physical part of \ac{cps}? |
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\item Which adaptations are required to make the design method by \textcite{broenink_rapid_2019} suitable for developing the computation and physical part of \ac{cps}? |
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\end{itemize} |
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\section{Approach} |
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Within this thesis, the design method by \textcite{broenink_rapid_2019} is evaluated in a case study. |
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The case study performs a development process according to the design method and will evaluate the result. |
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However, there are a couple of steps required prior to the start of the case study (see \autoref{fig:approach}). |
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The first step is to produce a concrete \emph{design plan} based on the design method. |
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The concrete design plan improves the evaluation of the design techniques. |
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The design method is presented in an abstract form which leaves room for interpretation. |
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This hampers the evaluation process, because it is impossible to point out flaws in something that was not specific in the first place. |
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Therefore, I will assess the design method and add detail to get a concrete design plan. |
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Because the design method focusses on the rapid development principles and modelling techniques, it does not cover the design steps outside of that focus. |
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These steps, like problem definition and system specifications, are a crucial part of the design process and are added to create the concrete design plan. |
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The added steps are based on the steps in a \ac{se} approach. |
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\begin{figure} |
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\centering |
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\includegraphics[width=9cm]{graphics/approach.pdf} |
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\caption{A graph that shows the interconnection of the different steps that are required to prior to the start of the case study.} |
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\label{fig:approach} |
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\end{figure} |
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With a design plan to use in the case study there are two steps of preparation left. |
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The first step is to develop an evaluation plan to ensure complete and consistent feedback during the case study. |
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The evaluation plan consists of a list of questions that have to be evaluated for each design step. |
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There are specific questions that evaluate the definition, or the execution of the design step. |
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The other step is to provide the \emph{subject of design} to develop in the case study. |
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Normally, the design process focusses on delivering the end product in the most effective manner. |
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However, the goal of this research is to use the design process to evaluate the design method, not to develop a product. |
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A possible pitfall is that during the design process a simple solution is found, such that the design techniques to deal with the increased complexity are left untouched. |
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Choosing to develop a very complex subject would ensure that all the design techniques are used, except that the limited time budget of a master's thesis does not allow that. |
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One of the requirements for the possible subjects is therefore a minimum level of complexity, forcing the developer to not go with the simplest solution. |
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Some other requirements, based on practical decisions like budget, tools, and time were defined as well. |
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Based on these requirements, the subject of choice is "Writing a tweet on a whiteboard". |
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With something to develop, a method to develop, and a method to evaluate, the case study is executed. |
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Even though the case study was terminated due to the limited amount of time available, it resulted in a partial prototype of a whiteboard writer and a significant amount of evaluation. |
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The results made it possible to propose improvements to the design method, not only for the physical part of \ac{cps} but also the cyber part. |
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\section{Notes on Terminology} |
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Design method is a commonly-used notion throughout the different papers and research used in this thesis. |
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\textcite{broenink_rapid_2019} refer to their design method as 'the methodology', which is to generic for this thesis. |
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To ensure distinct terminology throughout this thesis, their methodology is named \acl{ridm} and is abbreviated as \acs{ridm}. |
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The more concrete version of the design method that is tested in the case study, will be referred to as the 'design plan'. |
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The object or system that is going to be designed during the case study is referred as 'subject of design'. |
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\section{Structure} |
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The refinement of the design method and adding design steps is done in \autoref{analysis} to define a concrete design plan. |
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The evaluation plan and subject of design is defined in \autoref{case_method}. |
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The case study is executed in \autoref{case_experiment}, based on the design plan, evaluation plan and subject of design. |
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The execution of the case study is evaluated in \autoref{case_evaluation}. |
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In \autoref{reflection} the evaluation of the case study and the results are reflected back on the design plan. |
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Based on the reflection and the evaluation, an improved design method is proposed in \autoref{improved_design}. |
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And finally, the research is concluded in \autoref{conclusion}. |
Wouter Horlings
5 лет назад