\paragraph{Prototypes}
-We built two series of prototypes, the first one being FlexStylus~\cite{fellion16,fellion17} (\reffig{fig:penprototypes}, up).
+We built two series of prototypes, the first one being \emph{FlexStylus}~\cite{fellion16,fellion17} (\reffig{fig:penprototypes}, up).
It used a custom flexion sensor made with 4 eroded fiber optics, with an infrared LED on one end and phototransistors on the other end each.
By measuring the amount of light sensed by the phototransistors we could infer two angles and a degree of absolute bending.
Full length flexible early prototypes shown to be unconvenient for precise manipulation.
Therefore we chose to limit the flexible part to a few centimeters with a rigid part on both size to keep the benefits of both flexible and rigid pens.
-The second series of prototypes, called HyperBrush~\cite{guerrero21} (\reffig{fig:penprototypes}, down), used a consumer electronics bend sensor\footnote{\href{https://www.bendlabs.com/}{https://www.bendlabs.com/}}.
-It provided more precise and reliable inputs.
-However, the interesting new property of these prototypes was the ability to change the flexural stiffness with interchangeable components.
-Both the rigid and flexible parts of the pen are 3D printed, and the flexible part is threaded so that it is screwed to the rigid parts.
-The end sensor slips inside the 3D printed stylus.
-
-The FlexStylus prototypes had an orientation issue.
-Users had no cues on where to hold the stylus.
-Therefore the angles inputs were relative rather than absolute.
-This is the same issue Buxton reports with the iMac Round Mouse\footnote{\href{https://www.microsoft.com/buxtoncollection/detail.aspx?id=109}{https://www.microsoft.com/buxtoncollection/detail.aspx?id=109}}.
-We addressed this issue with the HyperBrush prototypes be adding a fake button that users were encouraged to keep under their index finger.
-
\begin{figure}[htb]
\centering
\def\protosize{.7\columnwidth}
\node[anchor=south west] (flexstylus) at (0,0) {\includegraphics[width=\protosize]{figures/flexstylus}};
\node[anchor=south west] (hyperbrush) at (0,0) {FlexStylus};
- \node[below=5mm of flexstylus.south] (hyperbrush) {\scalebox{-1}[1]{\includegraphics[width=\protosize]{figures/hyperbrush}}};
+ \node[below=2mm of flexstylus.south] (hyperbrush) {\scalebox{-1}[1]{\includegraphics[width=\protosize]{figures/hyperbrush}}};
\node[anchor=south west] (hyperbrush) at ($(hyperbrush.south west) - (0,5)$) {HyperBrush};
\end{tikzpicture}
\label{fig:penprototypes}
\caption[Flexible pen prototypes]{Two series of flexible pen prototypes. On the top: FlexStylus with a custom bend sensor made of eroded fiber optics. On the bottom: HyperBrush with a consumer electronics bend sensors, and interchangeable flexible components.}
\end{figure}
+The second series of prototypes, called \emph{HyperBrush}~\cite{guerrero21} (\reffig{fig:penprototypes}, down), used a consumer electronics bend sensor\footnote{\href{https://www.bendlabs.com/}{https://www.bendlabs.com/}}.
+It provided more precise and reliable inputs.
+However, the interesting new property of these prototypes was the ability to change the flexural stiffness with interchangeable components.
+Both the rigid and flexible parts of the pen are 3D printed, and the flexible part is threaded so that it is screwed to the rigid parts.
+The end sensor slips inside the 3D printed stylus.
-\paragraph{Pen grips}
-grip~\cite{song11,hinckley13}
-
-\fixme{Studies show there is a close relationship between how users hold a stylus and their intended purpose~\cite{song11,hinckley13}, and that users often change grips in relation to the task at hand.}
-
-Pen grip: like writing, thumb for bending the pen
+The FlexStylus prototypes had an orientation issue.
+Users had no cues on where to hold the stylus.
+Therefore the angles inputs were relative rather than absolute.
+This is the same issue Buxton reports with the iMac Round Mouse\footnote{\href{https://www.microsoft.com/buxtoncollection/detail.aspx?id=109}{https://www.microsoft.com/buxtoncollection/detail.aspx?id=109}}.
+We addressed this issue with the HyperBrush prototypes be adding a fake button that users were encouraged to keep under their index finger.
+The relief of this button helped users keeping the stylus in a consistent orientation eyes-free.
-joystick grip: hold from the top, tip fixed to the surface, rotation movement
-roll grip: in the air between the fingers
+\paragraph{Pen grips}
-brush grip: pen grip but the hand is higher, feels like brush bristles, hence Hyperbrush
+Studies in the literature show that there is a strong connection betweeen the way users hold a stylus and the way they use the stylus~\cite{song11,hinckley13}.
+They noticed that participants in their user studies often changed the way they gripped the stylus depending on the task they were performing.
+We took inspiration from this work, and we designed our prototypes for three kinds of grips.
+
+\begin{itemize}
+\item \textbf{Tool grip}: users hold the stylus the same was they hold a pen.
+ This is actually a family of grips, but the idea is that users hold the rigid part of the pen close to the tip.
+ They can press the pen with their thumb to bend it.
+\item \textbf{Menu grip}: users hold the stylus from the rigid part on the other side of the flexible part.
+ The tip remains still on the surface thanks to friction.
+ This way, users can control an orientation vector around the contact point.
+\item \textbf{In-air grip}: users hold the stylus in the air between their fingers.
+ They can bend the stylus by squeezing their fingers, or roll the pen.
+\end{itemize}
+
+When we evaluated our second series of prototypes some participants reported drawing with the menu grip, after the flexible part.
+Drawing this way gave them the impression of painting with a brush, hence the name \emph{Hyperbrush}.
+%This kind of serendipitous behaviour is typically what we hope we will get with such a research project.
+This is a difficulty with this type of work.
+We need a design rationale to guide the implemention before we evaluate the device.
+However, we want to let such serendipitous behaviour happening because it makes interaction with the device richer.
\begin{figure}[htb]
\includegraphics[height=5cm]{figures/flexstylus-pengrip}
projects / hdr.git / commitdiff