% Chapter 0 - Proposal
% Section 1 - Motivation, problem statement and thesis objectives
\section{Bachelor Thesis Proposal - Philip Gaber}
{\huge Impact of adjusted, per key, actuation force on efficiency and satisfaction while using mechanical keyboards}
\subsection{Motivation}
In recent years, computers are used to some extend in almost every industry in
Europe \cite{eurostat_ent_w_comp} and China \cite{iresearch_ent_w_comp}. This
leads to the conclusion, that also other countries must have a high usage of
computers in corporations. Furthermore, according to a statistic published by
\citeauthor{itu_hh_w_comp} in 2019, nearly half of the worldwide households have
access to at least one computer \cite{itu_hh_w_comp}. One of the most used
devices for data input while operating a computer is the keyboard
\parencite[22]{handbook_chi}. Therefore, people who use a computer, either at
home or to fulfill certain tasks at work, are also likely to use a keyboard. An
important part of a keyboard is the keyswitch also called keyboard key or
key. Those keyswitches use, depending on the manufacturer or keyboard type,
different mechanisms to actuate a keypress. More commonly used mechanism to date
are scissor switches, mostly used in laptop keyboards, dome/membrane switches,
often used in low- to mid-priced keyboards, and mechanical switches which are
the main switch type for high-priced and gaming keyboards
\cite{ergopedia_keyswitch}. Depending on the mechanism and type of key used, it
is possible that different force has to be applied to the key to activate
it. Normally, the force required to activate a key is identical for each key
across the keyboard. However, previous research has shown, that there is a
disparity in force generated by different fingers
\cite{bretz_finger_force}. This raises the question, why there are no keyboards
for personal or work related use cases with adjusted actuation forces per finger
or even customizable keyboards, where an individual can select the actuation
force for each keyswitch individually.

\subsection{Proposed Objective, Research Question and Hypothesis}

% This thesis is intended to provide an overview of already conducted research in
% the domain of keyboards, especially in connection with actuation force and the
% impact of different keyswitches on keyboard users.

% Because there is no previous research in the particular field of per finger/key
% actuation force for (mechanical) keyboards and the impact of such customization
% on efficiency and comfort, this thesis is also intended to research if this is a
% viable option in comparison to the classic keyboard with uniform actuation
% force. Therefore the author proposes to answer the question:

This thesis is intended to research if a keyboard with zones of keys, which have
adjusted actuation force depending on the assigned finger for that zone and the
position on the keyboard, is a viable option compared to the standard keyboard
with uniform actuation force across all keyswitches.

\begin{tabular}{p{0.3cm} p{0.5cm} p{13cm} p{0.5cm}}
  & \textbf{\large RQ}	& {\Large Does an adjusted actuation force per key have a positive impact on efficiency and overall satisfaction while using a mechanical keyboard?} & \\
\end{tabular}
\vspace{1em}

% TODO: Dissatisfied statt comfort da hohe error rate und dadurch frustriert
% TODO: Bei hypothesen noch error rate bei geschwindigkeit mit einbeziehen
% ASK: Doch noch comfort mit einbeziehen?
\begin{longtable}{p{0.3cm} p{0.5cm} p{13cm} p{0.5cm}}
  & \textbf{H1}	& Lower key actuation force improves typing speed over higher key actuation force (efficiency - speed). & \\
  & & & \\
  & \textbf{H2}	& Higher key actuation force decreases typing errors compared to lower key actuation force (efficiency - error rate). & \\
  & & & \\
  & \textbf{H3}	& Keys with lower actuation force are perceived as more satisfactory to write with than keys with higher actuation force. & \\
  & & & \\
  & \textbf{H4}	& Users perform better and feel more satisfied while using Keyboards with adjusted key actuation force than without the adjustment. & \\
\end{longtable}


\section{Proposed Method}

\subsection{Subjects}

It is planned to recruit 20 participants in total. Main target group to recruit
participants for the research study from are personal contacts and fellow
students. Participants are required to type with more than just one finger per
hand. Thus, touch typing is not a mandatory but helpful skill to
participate. The age distribution for the subjects is estimated to be between 18
and 56 years. The average typing speed should be known prior to the main
experiment. Therefore, a typing speed test should be performed on the subject's
own keyboard in beginning of the experiment. This typing test has to be
performed within the standardized test environment consisting of an adjustable
chair, desk, monitor and the typing test software used within the main
experiment. Also, all subjects have to give their written consent to
participate in the study.

\subsection{Study design}

Participants must complete several typing tests using four different keyboards.

The experiment should consist of a experimental group and a control group. The
control group will perform all typing tests with the same keyboard. The text
used for the typing test should be easily understandable. Therefore, the text
has to be evaluated with the help of a \gls{FRE} \cite{flesch_fre}
adjusted for German language \cite{immel_fre}.

\begin{equation}\label{fre_german}
  FRE_{deutsch} = 180 - \underbrace{ASL}_{\mathclap{\text{Average Sentence Length}}} - (58,5 * \overbrace{ASW}^{\mathclap{\text{Average Syllables per Word}}})
\end{equation}

The adjusted formula (\ref{fre_german}) to estimate the understandability of the
texts used in this experiment usually yields a number in the range of
\([0;100]\) called the \gls{FRE}. Higher \gls{FRE}s refer to better
understandability and thus the texts used in this experiment all have to fulfill
the requirement of a \gls{FRE} \(> 70\), which represents a fairly easy text
\cite{immel_fre} and \cite{flesch_fre}.

One typing test will consist of several smaller, randomly chosen, texts
snippets. The length of the snippets has to be between 100 and 400 characters
and a snippet has to meet the \gls{FRE} requirement. The snippets are generated by
volunteers via the web interface of the platform used in this experiment which
can be seen in appendix \ref{app:gott}.

% ASK: Should there be a control group at all, if so should they use their own keyboard or always the same random keyboard while they think they are testing different keyswitches?
After each typing test, the participant has to fill out an adjusted CEN ISO/TS
9241-411:2014 keyboard comfort questionnaire \cite{iso9241-411}. One additional
question was added to this questionnaire: ``How satisfied have you been with
this keyboard?'' The answer for this question can be selected with the help of a
\gls{VAS} ranging from 0 to 100 \cite{lewis_vas}.

\textbf{Planned experiment procedure: (Total time requirement: 120 min)}

\begin{enumerate}
  \item Pre-Test questionnaire to gather demographic and other relevant
  information e.g., touch typist, average \gls{KB} usage per day, predominantly
  used keyboard type, previous medical conditions affecting the result of the
  study e.g., \gls{RSI}, \gls{CTS}, etc. The full questionnaire can be observed
  in the appendix \ref{app:gott}. (5 min)

  \item Adjustment of the test environment (Chair height, monitor height, etc.) (2 min)
  \item Prepare subject for \gls{EMG} measurements: Electrodes are placed on the
  \gls{FDS}/\gls{FDP} and \gls{ED} of both forearms. The main function of the
  \gls{FDS} and \gls{FDP} is the flexion of the medial four digits, while the
  \gls{ED} mainly extends the medial four digits. Therefore, these muscles are
  primarily involved in the finger movements required for typing on a keyboard
  \cite{netter_anatomy}. (8 min)
  \item Familiarization with the typing test and keyboard model used in the experiment. All participants use the same keyboard with 50g actuation force for this step. (5 min)
  \item Initial typing test with own keyboard. (5 min) \\
        Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
        Pause with light stretching exercises. (3 min)
        % SUBTOTAL: 30 min

        \item \textbf{Main Test (H1-H4):} In this part the subject has to
        take two, 5 minute, typing tests per keyboard, with a total of 4
        keyboards (\gls{KB} A, \gls{KB} B, \gls{KB} C, \gls{KB} D). After each
        typing test, the subject has to fill out the post typing test keyboard
        comfort questionnaire. Keyboards A, B and C are equipped with one set of
        keyswitches and therefore each of the keyboards provides one of the
        following, uniform, actuation forces across all keyswitches: 35 \gls{g},
        50 \gls{g} or 80 \gls{g}. These specific values are the results of a
        self conducted comparison between the product lines of most major
        keyswitch manufacturers. The results shown in appendix
        \ref{app:keyswitch} yield, that the lowest broadly available force for
        keyswitches is 35 \gls{g}, the highest broadly available force is 80
        \gls{g}, and the most common offered force is 50 \gls{g}. Keyboard D is
        equipped with different zones of keyswitches that use appropriate
        actuation forces according to finger strength differences and key
        position. The keyboards used in this experiment are visually identical,
        ISO/IEC 9995-1 conform \cite{iso9995-1} and provide a \gls{QWERTZ}
        layout to resemble the subjects day-to-day layout and keyboard format as
        close as possible. All keyboards are equipped with linear mechanical
        keyswitches from one manufacturer to minimize differences in haptic and
        sound while typing. To mitigate order effects, the order of the
        keyboards is counterbalanced with the help of the latin square method
        and the text snippets for the individual tests are randomized
        \cite{statist_counterbalancing}. \textbf{(total: 80 min)}

  \begin{enumerate}
    \item \textbf{\gls{KB} A, Part 1:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} A, Part 2:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} C, Part 1:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} C, Part 2:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} B, Part 1:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} B, Part 2:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} D, Part 1:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
    \item \textbf{\gls{KB} D, Part 2:} Typing test. (5min) \\
    Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
    Pause with light stretching exercises. (3 min)
  \end{enumerate}

  \item Post-Test semi-structured interview: The participant has to draw three
  different UX curves \cite{kujala_ux_curve} to evaluate how fatigue,
  performance and overall usability of the individual keyboards were perceived
  during the experiment. While drawing the UX curve, participants should
  describe their thought process. To reduce errors in the later evaluation of
  the UX curves, the entire interview is recorded. (10 min)

\end{enumerate}

The \gls{EMG} data for all muscles is captured using the Flexvolt Chrome app and Flexvolt 8-Channel
biosensor device in combination with TIGA-MED ECD-Electrodes. The captured data is then processed and
plotted using Python. Hardware and plots can be observed in Figure \ref{fig:emg_setup}.

\begin{figure}[h]
  \centering
  \includegraphics[width=1.0\textwidth]{images/emg_setup.jpg}
  \caption{Flexvolt 8-Channel Biosensor and example plots of \gls{EMG} data}
  \label{fig:emg_setup}
\end{figure}

This test scenario is inspired by the tests conducted in \cite{kim_typingforces}.