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| %&tex | |||
| \chapter{Case Study: Evaluation} | |||
| \label{chap:case_evaluation} | |||
| \section{Time Investment} | |||
| Prior to each step in the development I made an estimation on the workload of that particular step. | |||
| Prior to each step in the development, I made an estimation on the workload of that particular step. | |||
| In \autoref{fig:time_spend} the planned and spend time on each step is plotted next to each other. | |||
| Five of these steps were completed in the planned number of days. | |||
| However, three steps required more time than expected. | |||
| @@ -18,20 +16,26 @@ | |||
| \caption{Overview of the planned and spend number of days for each step during the case study.} | |||
| \label{fig:time_spend} | |||
| \end{figure} | |||
| Furthermore, there is a significant difference between the planned number of days of the between the development cycles. | |||
| Furthermore, there is a significant difference between the planned number of days for both development cycles. | |||
| Prior to the first development cycle I was not confident about the feasibility of the end-effector implementation. | |||
| Based on that, I decided to spend about three days on basic model of the end-effector to gain more information. | |||
| These three days let me to the conclusion that the end-effector was not feasible for this case study. | |||
| The second development cycle was significantly more feasible so I planned to spend two and a half week on the development. | |||
| This development was also three days for the basic model and another two weeks for the additional levels of detail. | |||
| Based on that, I decided to spend about three days on the basic model of the end-effector to collect more information. | |||
| This let me to the conclusion that the end-effector was too time-consuming for this case study. | |||
| For the second cycle, I also planned three days to create the basic model. | |||
| This time, the basic model was finished within a couple of hours. | |||
| Based this early success and prior experience, I planned an additional two weeks of development time for this cycle. | |||
| To create a functional prototype, writing software was unavoidable, even though it was not part of the design plan. | |||
| However, the time required to get to a basic software implementation too substantial to keep it out of the evaluation. | |||
| Especially when I take the quality and evaluation overhead in account. | |||
| The dynamic model was build up with different levels of detail including documentation for each level. | |||
| Furthermore, between the levels I also did the evaluation of the design process. | |||
| For the software, I skipped documentation and evaluation, as it would not contribute to the case study. | |||
| The code quality of the software is decent in my opinion but significantly lower than the quality of the dynamic models. | |||
| Although not directly part of the design method, I did build a prototype. | |||
| This consisted of acquiring and assembling the hardware, and writing software. | |||
| Acquiring and assembling the hardware took about two days. | |||
| This was mainly due to CoViD-19 restrictions which made part ordering and printing more challenging. | |||
| Without these restrictions I think it would it would be a day of work. | |||
| However, the time required to get the software to a viable state was four weeks. | |||
| Even though, the focus was not on the software, this timespan of four weeks is too significant to ignore. | |||
| Especially when the software is compared to the developed models. | |||
| In total I build eight competent models: a CAD drawing, one kinematics model, three 2D models and three 3D models. | |||
| Each of these models includes documentation and an evaluation of the design process. | |||
| The software, on the other hand, is in a bare minimum state; I skipped documentation and evaluation; and the code quality relatively low. | |||
| Still, the software was more time consuming than the hardware modeling and development. | |||
| \section{One-man development team} | |||
| The case study was performed by me, as a single developer. | |||
| @@ -46,3 +50,14 @@ | |||
| The social interaction within a design team stimulates this documenting process as it improves the recall and interpretation of information. | |||
| It also improves the judgement and selection between design alternatives \autocite{lamb_221_2008}. | |||
| \section{Switching Modelling Language} | |||
| The initial idea of the development was to start with a basic model and extend that model by adding more detail. | |||
| Meaning that one design and one model would develop in parallel with each other. | |||
| However, the development of the SCARA resulted in four major model versions. | |||
| The basic model started with a kinematics model. | |||
| To take the physics of the design into account, a 2D dynamics model was created. | |||
| Multiple steps of detail into the development, the 2D model was not adequate anymore. | |||
| Therefore, the design was remodeled with 3D physics. | |||
| Although this 3D physics model was able to implement the dynamic behavior, the modeling language was not suitable to design the shape of the mechanical components. | |||
| Resulting in a fourth model which represents the mechanical component design, in the form of a CAD drawing. | |||