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Improve development phase

tags/0.4.3-reflection
Wouter Horlings 4 vuotta sitten
vanhempi
commit
6de418b97e
3 muutettua tiedostoa jossa 12 lisäystä ja 10 poistoa
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      content/case_experiment_end-effector.tex
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      content/case_experiment_scara.tex
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      include

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content/case_experiment_end-effector.tex Näytä tiedosto

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With the preparation phase completed, the development cycle is next.
This consists of three steps: Feature selection, Rapid Development and Variable Approach.
The current section explains the first development cycle during the design.
The end-effector is the feature that is selected in the first cycle.
For this first cycle of the design process, I will develop the end-effector.
The implementation of the end-effector was not successful, as the design was too complex.
Fortunately, this failure did give valuable insight on the design method.

@@ -30,11 +30,11 @@ Fortunately, this failure did give valuable insight on the design method.
Upgrading the motor torque is a minor parametric change and the dependency is therefore insignificant.

The testing number is directly the number of tests that can be completed by implementing that single component.
For the risk and time it was an engineering judgement and no specific protocol to determine the values.
The risk and time values are not determined with a specific protocol, but with simple engineering judgement.
The estimated risk is high for the end-effector due to the collision dynamics of the operation.
It has to grab something and that is difficult to model. Furthermore, it was not known if that design would work.
The SCARA has the most moving parts, but no difficult dynamics and has therefore an estimated risk of medium.
For the carriage the there was no real risks and got therefore a low risk indication.
For the carriage there was no real risks and got therefore a low risk indication.
The SCARA would be implemented first based on number of tests, but is dependent on the end-effector.
Beginning with the end-effector is an obvious choices.
@@ -44,7 +44,7 @@ Fortunately, this failure did give valuable insight on the design method.
This first step of the detail design phase did go well.
A more refined method for this step could be very useful.
But the risk and time assessment will probably always be a engineering judgement from the developer.
Within a design team a form of planning poker\footnote{\url{https://en.wikipedia.org/wiki/Planning_poker}{Wikipedia entry: Planning Poker}} could be a good option.
Within a design team a form of planning poker \autocite{grenning_planning_2002} could be a good option.
\begin{figure}
\centering


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content/case_experiment_scara.tex Näytä tiedosto

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As the previous development cycle was aborted prematurely, the development cycle is repeated for the next feature.

\subsection{Feature Selection}
The implementation of the end-effector proofed to be impractical.
The implementation of the end-effector proved to be impractical.
This means that only two features are left.
\autoref{tab:featurestab2} shows an updated feature comparison.
Compared with the previous feature selection in \autoref{tab:firstfeatureselection}, the number of tests for the SCARA decreased and the Risk/Time increased.
@@ -77,7 +77,7 @@
It consists of the forward and inverse kinematics of the design.
With this kinematics model it was easy to find a good configuration of the SCARA.
I tested if the SCARA could reach the required operating area, to be able to satisfy specification \ref{threecharspec}.
The operating area is not a couple of centimeters away from the base of the SCARA.
The operating area is a couple of centimeters away from the base of the SCARA.
This is to avoid the singularity point that lies at the base of the SCARA.
Resulting in longer arms than strictly necessary but this reduces the operating angles of the joints allowing for simpler construction.
@@ -131,9 +131,9 @@

Due to the aborted implementation of the end-effector, the SCARA must also lift the marker of the board.
The chosen configuration of the SCARA makes it possible to add an extra joint in the linkage.
As the marker only needs to be moved a couple of millimeters from the board, a simple servo suffices.
As the marker only needs to be moved a couple of millimeters from the board, a simple hobby servo suffices.

\subsubsection{Implementing details}
\subsubsection{Advanced Detail Design}
The new concrete design decisions, make it possible to plan the next steps of adding detail.
The following steps are an addition to the steps as described in the previous section:
\begin{enumerate}
@@ -186,7 +186,9 @@
\subsubsection{Evaluation}
The complete development was rather smooth.
However, this was not without deviating from the original design plan.
The different levels of detail could not be defined before the start of the development but had to be updated midway.
It was not feasible to define all different levels of detail before the start of the development.
Prior to the design, it was possible to plan 4 levels of detail.
After these steps, the design decisions taken made it possible to define the following levels of detail.

In total there are seven predefined levels of detail in the design.
Meaning that there must also be seven test cycles.


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Subproject commit d67b00ea55a6274f292704af4eb068cc501d4f59
Subproject commit 23887547caf9e84215373493f0c49ccd51d0f9de

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