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chap2/literature_review.tex
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% To better understand which metrics and methods are meaningful in the domain of keyboards and especially when % To better understand which metrics and methods are meaningful in the domain of keyboards and especially when
% To investigate whether or not solely the actuation force of individual keys can make a difference in terms of efficiency or satisfaction an .... % To investigate whether or not solely the actuation force of individual keys can make a difference in terms of efficiency or satisfaction an ....
\subsection{Keyboards and key switches} \subsection{Keyboards and Keyswitches}
\subsubsection{Keyboard Models and Layouts}
\label{sec:kb_layout}
\begin{figure}[ht] \begin{figure}[ht]
\centering \centering
@ -15,12 +17,12 @@ Keyboards are well known input devices used to operate a computer. There are a
variety of keyboard types and models available on the market, some of which can variety of keyboard types and models available on the market, some of which can
be seen in Figure \ref{fig:keyboard_models}. The obvious difference between be seen in Figure \ref{fig:keyboard_models}. The obvious difference between
those keyboards in Figure \ref{fig:keyboard_models} is their general those keyboards in Figure \ref{fig:keyboard_models} is their general
appearance. What we see is mainly the shape of the enclosure and the keycaps, appearance. The keyboards feature different enclosures and keycaps, which are
which are the rectangular pieces of plastic on top of the actual keyswitches the rectangular pieces of plastic on top of the actual keyswitches that
which sometimes indicate which letter, number or symbol, also known as sometimes indicate what letter, number or symbol, also known as characters, a
characters, a keypress should send to the computer. These keycaps are mainly keypress should send to the computer. These keycaps are mainly made out of the
made out of the two plastics \gls{ABS} and \gls{PBT} which primarily differ in two plastics \gls{ABS} and \gls{PBT} which primarily differ in feel, durability,
feel, durability, cost and sound \parencite[8]{bassett_keycap}. cost and sound \parencite[8]{bassett_keycap}.
\begin{figure}[ht] \begin{figure}[ht]
\centering \centering
@ -31,16 +33,16 @@ feel, durability, cost and sound \parencite[8]{bassett_keycap}.
\label{fig:keyboard_layouts} \label{fig:keyboard_layouts}
\end{figure} \end{figure}
Nowadays, there are three main standards for the physical layout of keyboards Nowadays, there are three main standards that define the physical layout of a
namely ISO/IEC 9995 \cite{iso9995-2}, ANSI-INCITS 154-1988 keyboard―ISO/IEC 9995 \cite{iso9995-2}, ANSI-INCITS 154-1988
\cite{ansi-incits-154-1988} and JIS X 6002-1980 \cite{jis-x-6002-1980}, that \cite{ansi-incits-154-1988} and JIS X 6002-1980 \cite{jis-x-6002-1980}. These
propose slightly different arrangements of the keys and some even alter the layouts propose slightly different arrangements of the keys and some even alter
shape of a few keys. Figure TODO\ref{fig:keyboard_layouts} shows the layouts the shape of a few keys entirely. Figure \ref{fig:keyboard_layouts} shows the
defined by the three standards mentioned and shows the main differences. In layouts defined by the three standards mentioned and shows the main
addition to the physical layout, there are also various layouts concerning the differences. In addition to the physical layout, there are also various layouts
mapping of the physical key to a character that is displayed by the concerning the mapping of the physical key to a character that is displayed by
computer. Most of the time, the mapping happens on the computer via software and the computer. Most of the time, the mapping happens on the computer via software
therefore the choice of layout is not necessarily restricted by the physical and therefore the choice of layout is not necessarily restricted by the physical
layout of the keyboard but rather a personal preference. As seen in Figure layout of the keyboard but rather a personal preference. As seen in Figure
\ref{fig:keyboard_models}, there are also non standard physical layouts \ref{fig:keyboard_models}, there are also non standard physical layouts
available which are often designed to improve the posture of the upper extremity available which are often designed to improve the posture of the upper extremity
@ -48,28 +50,36 @@ while typing to reduce the risk of injury or even assist in recovering from
previous \gls{WRUED} \cite{ripat_ergo}. Those designs often split the keyboard previous \gls{WRUED} \cite{ripat_ergo}. Those designs often split the keyboard
in two halves to reduce ulnar deviation and some designs also allow tenting of in two halves to reduce ulnar deviation and some designs also allow tenting of
the halves or provide a fixed tent which also reduces forearm pronation the halves or provide a fixed tent which also reduces forearm pronation
\cite{baker_ergo, rempel_ergo}. Besides the exterior design of the keyboard, \cite{baker_ergo, rempel_ergo}.
there is another part of interest—the keyswitch. This component of a keyboard
actually sends the signal that a key is pressed. There are different types of \subsubsection{Membrane Keyswitch}
keyswitches available to date. The more commonly available ones are scissor \label{sec:mem_switch}
switches and rubber dome switches which are both subsets of the membrane
switches. Scissor switches are often found in keyboards that are integrated into Besides the exterior design of the keyboard, there is another part of
notebooks while rubber dome switches are mostly used in workplace interest—the keyswitch. This component of a keyboard actually sends the signal
keyboards. Both variants use a rubber membrane with small domes underneath each that a key is pressed. There are different types of keyswitches available to
key. When a key is pressed, the corresponding dome collapses and because the date. The more commonly available ones are scissor switches and rubber dome
dome's inner wall is coated with a conductive material, closes an electrical switches which are both subsets of the membrane switches. Scissor switches are
circuit \cite{ergopedia_keyswitch, peery_3d_keyswitch}. Another type of switches often found in keyboards that are integrated into notebooks while rubber dome
are mechanical keyswitches. These switches are frequently used in gaming and switches are mostly used in workplace keyboards. Both variants use a rubber
high quality workplace keyboards as well as by enthusiast along with prosumers membrane with small domes underneath each key. When a key is pressed, the
which build and then sell custom made keyboards to the latter audience corresponding dome collapses and because the dome's inner wall is coated with a
\cite{bassett_keycap, ergopedia_keyswitch}. These keyswitches are composed of conductive material, closes an electrical circuit \cite{ergopedia_keyswitch,
several mechanical parts which can be examined in Figure peery_3d_keyswitch}.
\ref{fig:mech_keyswitches_dissas}. The housing is made up of two parts, the
bottom and top shell. The actual mechanism consists of two conductive plates, \subsubsection{Mechanical Keyswitch}
which when connected trigger a keypress, a stainless steel spring which defines \label{sec:mech_switch}
how much force has to be applied to the switch to activate it and a stem which Another type of switches are mechanical keyswitches. These switches are
sits on top of the spring and separates the two plates. The shape of the stem, frequently used in gaming and high quality workplace keyboards as well as by
represented by the enlarged red lines in Figure enthusiast along with prosumers which build and then sell custom made keyboards
to the latter audience \cite{bassett_keycap, ergopedia_keyswitch}. These
keyswitches are composed of several mechanical parts which can be examined in
Figure \ref{fig:mech_keyswitches_dissas}. The housing is made up of two parts,
the bottom and top shell. The actual mechanism consists of two conductive
plates, which when connected trigger a keypress, a stainless steel spring which
defines how much force has to be applied to the switch to activate it and a stem
which sits on top of the spring and separates the two plates. The shape of the
stem, represented by the enlarged red lines in Figure
\ref{fig:mech_keyswitches_dissas}, defines the haptic feedback produced by the \ref{fig:mech_keyswitches_dissas}, defines the haptic feedback produced by the
keyswitch. When pressure is applied to the keycap, which is connected to the keyswitch. When pressure is applied to the keycap, which is connected to the
stem, the spring gets contracted and the stem moves downwards and thereby stops stem, the spring gets contracted and the stem moves downwards and thereby stops
@ -154,7 +164,7 @@ typing speed, which could be more significant with greater variation of
actuation force across tested keyboards \cite{loricchio_force_speed}. actuation force across tested keyboards \cite{loricchio_force_speed}.
\subsubsection{Relevance for this thesis} \subsubsection{Relevance for this Thesis}
Since this thesis is focused around keyboards and especially the relation Since this thesis is focused around keyboards and especially the relation
between the actuation force of the keyswitch and efficiency (speed, error rate) between the actuation force of the keyswitch and efficiency (speed, error rate)
and also the differences in satisfaction while using keyswitches with varying and also the differences in satisfaction while using keyswitches with varying
@ -186,7 +196,7 @@ capabilities for our experiment to reduce the effort required to equip each
keyboard with the required keyswitches and in case a keyswitch fails during keyboard with the required keyswitches and in case a keyswitch fails during
the experiment, decrease the time required to replace the faulty switch. the experiment, decrease the time required to replace the faulty switch.
\subsection{Measurement of typing related metrics} \subsection{Measurement of Typing Related Metrics}
\label{sec:metrics} \label{sec:metrics}
Nowadays, a common way to compare different methods concerning alphanumeric Nowadays, a common way to compare different methods concerning alphanumeric
input in terms of efficiency is to use one of many typing test or word input in terms of efficiency is to use one of many typing test or word
@ -195,7 +205,12 @@ software used and the experimental setup, users have to input different kinds of
text, either for a predefined time or the time is measured till the whole text text, either for a predefined time or the time is measured till the whole text
is transcribed \cite{chen_typing_test, hoffmann_typeright, is transcribed \cite{chen_typing_test, hoffmann_typeright,
fagarasanu_force_training, akagi_keyswitch, kim_typingforces, fagarasanu_force_training, akagi_keyswitch, kim_typingforces,
pereira_typing_test}. Text used should be easy to read for typists pereira_typing_test}.
\subsubsection{Readability of Text}
\label{sec:meas_fre}
Text used should be easy to read for typists
participating in studies that evaluate their performance and are therefore is participating in studies that evaluate their performance and are therefore is
chosen based on a metric called the \gls{FRE} which indicates the chosen based on a metric called the \gls{FRE} which indicates the
understandability of text \cite{fagarasanu_force_training, understandability of text \cite{fagarasanu_force_training,
@ -232,6 +247,9 @@ classified according to the ranges given in Table \ref{tbl:fre_ranges} \cite{fle
\end{tabular} \end{tabular}
\end{table} \end{table}
\subsubsection{Performance Metrics}
\label{sec:meas_perf}
There are several metrics to measure the performance of typists. Typical methods There are several metrics to measure the performance of typists. Typical methods
to measure speed are to measure speed are
\begin{enumerate} \begin{enumerate}
@ -280,6 +298,9 @@ following two methods
\end{equation} \end{equation}
\end{enumerate} \end{enumerate}
\subsubsection{Electromyography}
\label{sec:meas_emg}
In several other studies, in addition to the metrics mentioned so far, \gls{EMG} In several other studies, in addition to the metrics mentioned so far, \gls{EMG}
data was captured to evaluate the muscle activity or applied force while typing data was captured to evaluate the muscle activity or applied force while typing
on completely different or modified hardware \cite{kim_typingforces, on completely different or modified hardware \cite{kim_typingforces,
@ -312,29 +333,31 @@ convert applied force to an electrical signal. This signal usually gets
amplified by specialized circuits and then further processed by a micro amplified by specialized circuits and then further processed by a micro
controller, computer or other hardware \cite{johnson_loadcell}. controller, computer or other hardware \cite{johnson_loadcell}.
\subsubsection{Subjective Metrics}
\label{sec:meas_sub}
Lastly, subjective metrics e.g., comfort, usability, user experience, fatigue Lastly, subjective metrics e.g., comfort, usability, user experience, fatigue
and satisfaction, are evaluated based on survey data collected after and satisfaction, are evaluated based on survey data collected after
participants used different input methods \cite{kim_typingforces, participants used different input methods \cite{kim_typingforces,
bell_pauseboard, bufton_typingforces, pereira_typing_test, iso9241-411}. In bell_pauseboard, bufton_typingforces, pereira_typing_test, iso9241-411}. In
their study, Kim et al. used a survey provided by the \gls{ISO} which is their study, Kim et al. used a modified version of the \gls{KCQ} provided by the
specifically designed to evaluate different keyboards in terms of user \gls{ISO} which is specifically designed to evaluate different keyboards in
satisfaction, comfort and usability \cite{kim_typingforces, iso9241-411}. This terms of user satisfaction, comfort and usability \cite{kim_typingforces,
survey poses a total of twelve questions concerning e.g., fatigue of specific iso9241-411}. This survey poses a total of twelve questions concerning e.g.,
regions of the upper extremity, general satisfaction with the keyboard, fatigue of specific regions of the upper extremity, general satisfaction with
perceived precision and uniformity while typing, etc., which are presented on a the keyboard, perceived precision and uniformity while typing, etc., which are
seven-point Likert-scale \cite{iso9241-411}. Further, studies concerning the presented on a seven-point Likert-scale \cite{iso9241-411}. Further, studies
usability and user experience of different text entry methods used the \gls{UEQ} concerning the usability and user experience of different text entry methods
or \gls{UEQ-S} to evaluate the differences in those categories \cite{nguyen_ueq, used the \gls{UEQ} or \gls{UEQ-S} to evaluate the differences in those
olshevsky_ueq, gkoumas_ueq}. While the full \gls{UEQ} provides a total of 26 categories \cite{nguyen_ueq, olshevsky_ueq, gkoumas_ueq}. While the full
questions divided into six scales (attractiveness, perspicuity, efficiency, \gls{UEQ} provides a total of 26 questions divided into six scales
dependability, stimulation and novelty), the \gls{UEQ-S} only features 8 (attractiveness, perspicuity, efficiency, dependability, stimulation and
questions and two scales (pragmatic and hedonic quality). Because of the limited novelty), the \gls{UEQ-S} only features 8 questions and two scales (pragmatic
explanatory power of the \gls{UEQ-S}, it is recommended to only use it, if there and hedonic quality). Because of the limited explanatory power of the
is not enough time to complete the full \gls{UEQ} or if the participants of a \gls{UEQ-S}, it is recommended to only use it, if there is not enough time to
study are required to rate several products in one session complete the full \gls{UEQ} or if the participants of a study are required to
\cite{schrepp_ueq_handbook}. rate several products in one session \cite{schrepp_ueq_handbook}.
\subsubsection{Relevance for this thesis} \subsubsection{Relevance for this Thesis}
Measuring metrics related to data entry tasks can be performed with the help Measuring metrics related to data entry tasks can be performed with the help
several commercially available tools and equipment. Especially muscle activity several commercially available tools and equipment. Especially muscle activity
has to be measured with appropriate tools and accurate placement of the has to be measured with appropriate tools and accurate placement of the
@ -348,38 +371,85 @@ thereby reveal differences that cannot be easily acquired by a device or formula
\cite{rowley_surveys}. \cite{rowley_surveys}.
\subsection{Crowdsourcing / Observer Bias} \subsection{Observer Bias and a Possible Solution}
As shown by the previous research in Section \ref{sec:metrics}, it is common As already discussed in Section \ref{sec:metrics}, it is common practice in
practice in research related to typing to present a text that has to be research related to typing to present a text that has to be transcribed by the
transcribed by the participant. Usually, the text was chosen by the researcher participant. Usually, the text was chosen by the researcher or already available
or already available through the used typing test software. If the through the used typing test software. If the understandability of text is of
understandability of text is of concern, the binary choice of, is understandable concern, the binary choice of, is understandable or not, made by the researcher
or not, made by the researcher could lead to a phenomenon called the observer could lead to a phenomenon called the observer bias \cite{hrob_observer,
bias \cite{hrob_observer, berger_observer}. Thus, the text could potentially be berger_observer, angrosino_observer}. Thus, the text could potentially be to
to difficult to understand for the participants if not evaluated with e.g. the difficult to understand for the participants if not evaluated with e.g. the
\gls{FRE} or other adequate formulas. Further, if there is previous knowledge \gls{FRE} or other adequate formulas. Further, if there is previous knowledge
about the requested participants, the researcher could subconsciously select about the requested participants, the researcher could subconsciously select
text that is familiar to, or well received by some of the subjects and could text that is familiar to, or well received by some of the subjects and could
thereby conceivably influence the outcome \cite{hrob_observer, berger_observer}. thereby conceivably influence the outcome of the study\cite{hrob_observer,
The same problem arises, if the typing test software already provides such texts berger_observer}. The same problem arises, if the typing test software already
but the researcher has to select some of them for the experiment. Further, the provides such texts but the researcher has to select some of them for the
difficulty of the provided texts should be verified to ensure accurate results experiment. Furthermore, the difficulty of the provided texts should be verified
across multiple treatments. A possible solution for this problem is to ensure accurate results across multiple treatments. A possible solution to
crowdsourcing. this problem is crowdsourcing. Howe describes crowdsourcing as the act of
outsourcing a problem to a group of individuals that are voluntarily working
Howe CONTINUE together to solve it \parencite[1-11]{howe_crowd_book} \&
\cite{howe_crowdsource, schenk_crowdsource}.
\cite{howe_crowdsource}. If there are automated checks for text Observer bias can also occur while conducting the experiment when the researcher
difficulty in place, this method completely excludes the researcher from the has to give instructions to the subject. Therefore, it is important to treat
text selection process. every participant equally by following a predefined procedure and minimize
unnecessary interaction where possible to further minimize the risk of bias
\parencite[674]{angrosino_observer}.
\subsubsection{Relevance for this thesis}
% \subsection{Keyboard usage} \subsubsection{Relevance for this Thesis}
% \subsection{Finger strength} Summarizing, even seemingly arbitrary decisions or actions can have a potential
% \subsection{Traditional methods} undesirable impact on the results of a study. If it is possible to implement
% \subsection{Alternative methodology} automated checks for the suitability of text e.g., a platform that verifies
% - Available Methods (Impact vs load) submitted text based on \gls{FRE} scores, crowdsourcing could be used to
% - Load cells completely exclude the researcher from the text selection process and therefore
mitigate the risk of unwanted bias. In addition, the aspect of time in the
preparation phase of a study could be another factor to consider crowdsourcing
to acquire larger amounts of text with equal difficulty.
\subsection{Strength of Individual Fingers}
As already mentioned in Section \ref{sec:metrics}, the force applied to a
keyswitch is the concern of multiple studies that evaluate the relation between
keyboarding and \gls{WRUED}. Further, multiple studies came to the conclusion,
that there is a significant discrepancy in strength between individual fingers
\cite{bretz_finger, martin_force, baker_kinematics, dickson_finger}. Bretz et
al. found, that when participants squeezed an object between thumb and finger,
differences in applicable force between different fingers ranged from 1.6
\gls{N} up to 25.9 \gls{N} (n=16) \cite{bretz_finger}. Dickson and Nicolle
observed the effects of surgery on patients with rheumatoid hands. The pre and
post surgery force of finger flexion was recorded and the post surgery results
yielded a difference in flexion force, which is similar to the force required to
actuate a keyswitch, that ranged from 1 \gls{N} to 4 \gls{N}
\cite{dickson_finger}. Martin et al. measured applied average and peak force of
individual digits while typing on a keyboard (n=10). The measured differences
ranged from 0.10 \gls{N} to 1.49 \gls{N} for peak force and 0.01 \gls{N} to 0.08
\gls{N} for mean force \cite{martin_force}.
\subsubsection{Relevance for this Thesis}
The goal of this thesis is to evaluate the possible advantages of keyboards with
non-uniform actuation forces. The fairly small difference of only 0.08 \gls{N} in mean
force applied to keyboards recorded by Martin et al. \cite{martin_force} but
rather big difference in finger strength measured by Bretz et
al. \cite{bretz_finger} could indicate, that albeit the difference in strength,
all fingers have to apply equal force to generate a keypress because of the
uniform actuation force used in commercially available keyboards.
\subsection{Summary}
Since keyboards are still the most commonly used input method for data entry to
date and so far all efforts to convince the mainstream to move from the
standard, less ergonomic, physical layouts to split keyboards failed, further
alternatives that could be easily implemented into manufacturing processes have
to be explored, to counteract the rising risks for \gls{WRUED}. One factor
related to \gls{WRUED} is the actuation force of the keyswitches
\cite{bufton_typingforces, rempel_ergo, rempel_force,
gerard_keyswitch}. Especially higher actuation forces have shown to be the
reason for discomfort in the upper extremity. On the other hand, higher
actuation forces also led to lower error rates while typing and therefore
enhance user satisfaction and performance \cite{gerard_keyswitch}. With the help
of several methods to measure typing relate metrics such as muscle activity
(\gls{EMG}), error rates (\gls{CER} and \gls{UER}), typing speed (\gls{WPM}) and
user satisfaction {\gls{UEQ} and \gls{KCQ}} it is feasible to evaluate possible
alternative input methods to the more traditional keyboard.

4
glossary.tex
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@ -27,6 +27,10 @@
\newglossaryentry{N}{
name={N},
description={Newton: 1 N $ \approx $ 101.97 g}
}
\newglossaryentry{cN}{ \newglossaryentry{cN}{
name={cN}, name={cN},

60
ref_shelf.bib
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@ -344,6 +344,17 @@ urldate = {2021-06-28}
publisher = {Elsevier} publisher = {Elsevier}
} }
@article{rempel_force,
title={The effect of keyboard keyswitch make force on applied force and finger flexor muscle activity},
author={Rempel, David and Serina, Elaine and Klinenberg, Edward and Martin, Bernard J and Armstrong, Thomas J and Foulke, James A and Natarajan, Sivakumaran},
journal={Ergonomics},
volume={40},
number={8},
pages={800--808},
year={1997},
publisher={Taylor \& Francis}
}
@article{peery_3d_keyswitch, @article{peery_3d_keyswitch,
title = {3D Printed Composite Keyboard Switches}, title = {3D Printed Composite Keyboard Switches},
journal = {Procedia Manufacturing}, journal = {Procedia Manufacturing},
@ -717,3 +728,52 @@ title = {Crowdsourcing: What can be Outsourced to the Crowd, and Why ?}
pages={1--4}, pages={1--4},
year={2006} year={2006}
} }
@book{howe_crowd_book,
title = {Crowdsourcing: How the Power of the Crowd is Driving the Future of Business},
author = {Jeff Howe},
publisher = {Random House Business},
isbn = {1905211155, 9781905211159},
year = {2006},
}
@article{angrosino_observer,
title={Rethinking observation: From method to context},
author={Angrosino, Michael V and Mays de P{\'e}rez, Kimberly A},
journal={Handbook of qualitative research},
volume={2},
pages={673--702},
year={2000}
}
@article{bretz_finger,
title={Force measurement of hand and fingers},
author={K{\'a}roly J{\'a}nos, Bretz and {\'A}kos, Jobb{\'a}gy and K{\'a}roly, Bretz},
journal={Biomechanica Hungarica},
volume={3},
number={1},
year={2010}
}
@article{baker_kinematics,
title={Kinematics of the fingers and hands during computer keyboard use},
author={Baker, Nancy A and Cham, Raki{\'e} and Cidboy, Erin Hale and Cook, James and Redfern, Mark S},
journal={Clinical Biomechanics},
volume={22},
number={1},
pages={34--43},
year={2007},
publisher={Elsevier}
}
@article{dickson_finger,
title={The assessment of hand function: Part 1—Measurement of Individual Digits},
author={Dickson, RA and Nicolle, FV},
journal={The Hand},
volume={4},
number={3},
pages={207--214},
year={1972},
publisher={Elsevier}
}

2
thesis.tex
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@ -18,6 +18,8 @@
\usepackage[UKenglish]{babel} \usepackage[UKenglish]{babel}
\usepackage[T1]{fontenc} \usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc} \usepackage[utf8]{inputenc}
\usepackage{kpfonts}
% \usepackage{mathpazo}
% verbesserter Randausgleich % verbesserter Randausgleich
\usepackage{microtype} \usepackage{microtype}

2
titlepage.tex
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@ -25,7 +25,7 @@
Faculty of Computer Science\\ [7em] Faculty of Computer Science\\ [7em]
\Large\textbf{ \Large\textbf{
Impact of adjusted, per key, actuation force on efficiency and satisfaction while using mechanical keyboards} \\ Impact of Adjusted, per Key, Actuation Force on Efficiency and Satisfaction While Using Mechanical Keyboards} \\
\end{center} \end{center}
\vfill \vfill

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