update: methodolody, finger forces

chap2/literature_review.tex

@@ -256,7 +256,6 @@ easy to comprehend \cite{flesch_fre}. Immel proposed an adjusted formula of the
 According to Flesch, the values retrieved by applying the formula to text can be
 classified according to the ranges given in Table \ref{tbl:fre_ranges} \cite{flesch_fre}.
 \begin{table}
-
   \centering
   \caption{Categories for different FRE scores to classify the understandability
     of text \cite{flesch_fre}}

chap4/methodology.tex

@@ -63,6 +63,7 @@ Desktop\footnote{\url{https://signal.org/download/}}, Telegram
 Desktop\footnote{\url{https://desktop.telegram.org/}}).
 
 \subsection{Market analysis of available mechanical keyswitches}
+\label{sec:market_forces}
 To gather information about available actuation forces, we collected the product
 lines of keyswitches for all well known manufacturers, namely
 Cherry\footnote{\url{https://www.cherrymx.de/en/mx-original/mx-red.html}},
@@ -83,7 +84,7 @@ actuation force is 35 g ($\approx$ 0.34 \gls{N}) the most common one is 50 g
 
 \begin{figure}[ht]
   \centering
-  \includegraphics[width=1.0\textwidth]{images/keyswitches_brands}
+  \includegraphics[width=0.8\textwidth]{images/keyswitches_brands}
   \caption{Available actuation forces for keyswitches of major keyswitch manufacturers}
   \label{fig:keyswitches_brands}
 \end{figure}
@@ -105,5 +106,100 @@ subjects were all personal contacts. Subjects professions were distributed as
 follows: computer science students (3/6), physiotherapist (1/6), user experience
 consultant (1/6) and retail (1/6). All Participants were given instructions to
 exert maximum force for approximately one second onto the key mounted to the
-measuring device described in Section \ref{sec:force_meas_dev}. The order of
-positions in which the participants had to press the key was complete counterbalanced
+measuring device described in Section \ref{sec:force_meas_dev}. We also used a
+timer to announced when to press and when to stop. We provided a keyboard to
+every participant, which was used as a reference for the finger position before
+every measurement. To reduce order effects, we used a balanced latin square to
+specify the sequence of rows (top, home, bottom) in which the participants had
+to press the keys \cite{bradley_latin_square}. Additionally, because there were
+only six people available, we alternated the direction from which participants
+had to start in such a way, that every second subject started with the little
+finger instead of the index finger. An example of four different positions of
+the finger while performing the measurements for the keys \textit{Shift, L, I}
+and \textit{Z} can be observed in Figure \ref{fig:FM_example}.
+
+\begin{figure}[ht]
+  \centering
+  \includegraphics[width=1.0\textwidth]{images/FM_example}
+  \caption{Prototype of the force measuring device used to gather data about the
+    maximum applicable force to a key with different finger positions. The
+    positions for certain keys are simulated by aligning the wrist pad (left
+    picture) to the scale of the device. The four different positions for the
+    keys \textit{Shift, L, I, Z} (right pictures) are color coded according to
+    the keys on the scale}
+  \label{fig:FM_example}
+\end{figure}
+
+The results of the measurements are given in Table \ref{tbl:finger_force}. The
+median of the means (15.47 N) of all measurements was used to calculate the
+actuation forces in gram for the keyswitches later incorporated in the layout
+for adjusted keyboard. We used Eq. (\ref{eq:N_to_g}) and
+Eq. (\ref{eg:actuation_forces}) to calculate the gram values for each measured
+keyswitch.
+
+\begin{equation}
+  \label{eq:N_to_g}
+  GFR = \frac{50 g}{M_{maf}} = \frac{50 g}{14.47 N} = 3.23 \frac{g}{N}
+\end{equation}
+
+\begin{equation}
+  \label{eq:actuation_forces}
+  AF_{key} = GFR * MAF_{key}
+\end{equation}
+
+With $M_{maf}$ the median of the means of applicable forces, $50 g$ the most
+commonly found actuation force on the market (Section \ref{sec:market_forces}),
+$GFR_{key}$ the gram to force ratio, $MAF_{key}$ the median of applicable force
+for a specific key and $AF_{key}$ the actuation force for that specific key in
+grams.
+
+An example where we calculated the theoretical actuation force for the \textit{P}
+key can be seen in Eq. (\ref{eq:force_example}).
+
+\begin{equation}
+  \label{eq:force_example}
+  AF_{P} = GFR * MAF_{P} = 3.23 \frac{g}{N} * 10.45 N \approx 33.75 g
+\end{equation}
+
+Because there are only certain spring
+
+% Custom spring stiffness
+% https://www.engineersedge.com/spring_comp_calc_k.htm
+
+
+\begin{table*}[]
+  \centering
+  \ra{1.3}
+  \begin{tabularx}{13cm}{?l^l^l^l^l^l^l^l}
+    \toprule
+    \multicolumn{8}{c}{\textbf{Bottom Row}}\\
+    \rowstyle{\itshape}
+    \emph{Key}                 & ↑     & -     & :     & ;     & M     & N     & B    \\
+    \midrule
+    \emph{Mean Force (N)}      & 11.23 & 10.84 & 14.22 & 15.34 & 16.38 & 15.6  & 14.36\\
+    \emph{Actuation Force (g)} & 36.05 & 34.8  & 45.65 & 49.24 & 52.58 & 50.08 & 46.1\\
+  \end{tabularx}
+  \begin{tabularx}{13cm}{?l^l^l^l^l^l^l^X}
+    \multicolumn{8}{c}{\textbf{Home Row}}\\
+    \rowstyle{\itshape}
+    \emph{Key}                 & Ä     & Ö     & L     & K     & J     & H     &\\
+    \midrule
+    \emph{Mean Force (N)}      & 11.88 & 12.27 & 15.84 & 18.56 & 17.78 & 18.43 &\\
+    \emph{Actuation Force (g)} & 38.13 & 39.39 & 50.85 & 59.58 & 57.07 & 59.16 &\\
+  \end{tabularx}
+  \begin{tabularx}{13cm}{?l^l^l^l^l^l^l^l}
+    \multicolumn{8}{c}{\textbf{Top Row}}\\
+    \rowstyle{\itshape}
+    \emph{Key}                 & +     & Ü     & P     & O     & I     & U     & Z    \\
+    \midrule
+    \emph{Mean Force (N)}      & 10.8  & 10.7  & 10.45 & 14.34 & 17.95 & 17.0  & 16.8 \\
+    \emph{Actuation Force (g)} & 34.67 & 34.35 & 33.54 & 46.03 & 57.62 & 54.57 & 53.93\\
+    \bottomrule
+  \end{tabularx}
+  \caption{Maximum force measurements for all digits of the right hand in
+    different positions. The mean force of six participants is shown in the
+    first row of each table and the resulting actuation force for the
+    corresponding keyswitch in the following row. The columns indicate the label
+    of the scale on the measuring device which can be seen in Figure
+    \ref{fig:FM_example}. \textit{↑} stands for the shift key.}
+\end{table*}

ref_shelf.bib

@@ -861,4 +861,15 @@ urldate = {2021-07-06}
   pages={541--547},
   year={2007},
   publisher={BMJ Publishing Group Ltd}
+}
+
+@article{bradley_latin_square,
+  title={Complete counterbalancing of immediate sequential effects in a Latin square design},
+  author={Bradley, James V},
+  journal={Journal of the American Statistical Association},
+  volume={53},
+  number={282},
+  pages={525--528},
+  year={1958},
+  publisher={Taylor \& Francis}
 }

thesis.tex

@@ -23,6 +23,15 @@
 \usepackage{mdframed}
 \BeforeBeginEnvironment{minted}{\begin{mdframed}}
 \AfterEndEnvironment{minted}{\end{mdframed}}
+\usepackage{booktabs}
+\usepackage{tabularx}
+\newcommand{\ra}[1]{\renewcommand{\arraystretch}{#1}}
+\usepackage{array}
+\newcolumntype{?}{>{\global\let\currentrowstyle\relax}}
+\newcolumntype{^}{>{\currentrowstyle}}
+\newcommand{\rowstyle}[1]{\gdef\currentrowstyle{#1}%
+  #1\ignorespaces
+}
 % \usepackage{mathpazo}
 
 % verbesserter Randausgleich