In the context of activity monitoring, the distance between the correct value and the user answer matters.
Indeed, interpreting a $60\%$ progression instead of $70\%$ is a lesser concern than interpreting $20\%$ instead of $70\%$.
-Therefore we analyzed this prrecision as a measure of distance between the input and the actual answer.
+Therefore we analyzed this precision as a measure of distance between the input and the actual answer.
We observed differences in terms of precision across pattern sets.
For example with sets A and B, the precision gets worse as the number is high.
However, the proportions are larger with set B, which confirms the idea that counting short vibrations is easier than estimating the duration of long vibrations.
\subsection{Vibrotactile widgets}
\label{sec:printgets}
-Replacing physical controls with touchscreens have advantages: updates, reconfigurable, visual feedback, but most of haptic properties are lost: click sensations of buttons, detents on slides. Impact on interaction. Technologies to restore haptic feedback.
+In the previous section we investigated the output vocabulary for a new device providing a new type of haptic feedback.
+We did not explore a particular context or application, but rather studied the possibilities and limitations of the technology.
+In this project we are interested in vibrotactile feedback, which is well covered in the literature.
+We are interested in a particular case: restoring haptic feedback on touchscreens.
+Indeed touchscreens have many advantages compares to physical interfaces.
+They can be updated.
+They have no mechanical parts that wear over time.
+They are flat, so they are easy to clean.
+However, physical interfaces such as buttons and sliders have interesting interactive properties.
+They have a relief that enable people to locate them with touch.
+They provide haptic feedback when they are operated: click sensation, detents, stops.
+These properties guarantee invaluable usability benefits, such as giving a continuous feedback of users actions and the discoverability of interactive elements.
+
+%Haptic properties of physical objects
+
+%Replacing physical controls with touchscreens have advantages: updates, reconfigurable, visual feedback, but most of haptic properties are lost: click sensations of buttons, detents on slides. Impact on interaction. Technologies to restore haptic feedback.
+
+The manufacturing process of touch interfaces such as dashboards augmented with haptic feedback is complex.
+Mechanical actuators must be attached underneath such that the vibration transmits to the interactive places of the surfaces.
+In this project we investigate a new kind of actuators.
+%However, the originality of this work is that we used a new type of vibrotactile actuator.
+They are printed on a flexible substrate with a piezo electric ink.
+Therefore, these actuators can be embedded in plastic injection molds when dashboard barts are produced.
+They can even be integrated in curved interactive surfaces.
+%This is convenient for dashboards with tactile input.
+%Manufacturers are interested in this solution because it simplifies the fabrication process because they can include a flexible actuator sheet in their plastic injection molds.
+Our colleagues at CEA LITEN\footnote{\href{https://www.cea.fr/cea-tech/liten/english/Pages/Work-with-us/Technology-platforms/Large-Surface-Printed-Electronics.aspx}{Pictic platform}} designed and implemented the actuators and Walterpack\footnote{\href{http://www.walterpack.com/}{http://www.walterpack.com/}} worked on the integration of actuators in the plastic mold.
+We prototyped the driving electronics and clamping system, designed tactile widgets, and implemented a dashboard prototype that was showcased at the Geneva Motor Show 2017\footnote{\href{https://www.carscoops.com/2017/03/this-is-what-sbarro-mojave-really-looks/}{Mojave} concept car, produced by the \href{http://www.e-sbarro.fr/}{Esperra Sbarro} school} (\reffig{fig:mojave}).
-Vibrotactile widgets~\cite{frisson17,frisson20}
+\begin{figure}[htb]
+ \centering
+ \includegraphics[height=5.2cm]{figures/mojave}%
+ \includegraphics[height=5.2cm]{figures/mojavedashboard}
+ \caption[Mojave concept car.]{The Mojave concept car designed by the Esperra Sbarro school, showcased at the Geneva Motor Show 2017. We implemented the software of the dashboard.}
+ \label{fig:mojave}
+\end{figure}
+
+%We worked on the driving electronics, a clamping system, and the signal for simulating button clicks and slider detents.
+
+%Inform the design of actuators
+
+%Leverage vibrotactile feedback to restore haptic properties on touchscreens
+
+\subsubsection{Experimental platform}
+
+The design of the actuators is a trade-off between their size and thickess, the number of layers and the signal voltage.
+Our colleagues who designed and implemented these actuators, performed FEM simulations, and measured the response to signal with laser vibrometers~\cite{poncet16,poncet17}.
+They gave us several prototypes that we could use to design vibrotactile widgets.
+The first prototype (top of~\reffig{fig:printedslider}) had six buttons embedded in amolded plastic dashboard part.
+The clamping area was a circle around each actuator.
+A clamping area defines the area on which the vibration propagates.
+The second prototype was a bare flexible substrate with seven actuators.
+We designed a clamping frame around the actuators so that the vibration could propagate on the whole length of the slider.
+we added tension strings to tighten the frame so that the clamping area could resonate.
+This is the same approach than a drum head on a drum shell.
+The capactitive touch sensor, printed with silver ink, is under the actuators.
+The setup is depicted at the bottom of~\reffig{fig:printedslider}.
+
+\begin{figure}[htb]
+ \centering
+ \includegraphics[width=.55\textwidth]{figures/printedbuttons}%
+
+ \includegraphics[width=.55\textwidth]{figures/printedslider2}%
+ \caption[Printed buttons and slider.]{Top: Printed buttons. They are clamped individually. Bottom: Printed slider on a clamping frame. The slider is made of 7 piezo actuators. Tension strings make sure the substrate is tight.}
+ \label{fig:printedslider}
+\end{figure}
+
+We built a custom PCB with piezo drivers\footnote{\href{http://www.ti.com/product/DRV2667.}{TI DRV2667}} (one per actuator), and the capacitive sensing chip~\footnote{\href{http://www.microchip.com/wwwproducts/en/CAP1214.}{Microchip CAP1214}}.
+The chips communicate with the main board that runs the application\footnote{\href{https://www.raspberrypi.org/products/raspberry-pi-3-model-b/}{Raspberry Pi 3B}} through an I2C bus.
+The drivers have two mode of operation. Either we play pre-recorded signals, or we provide an audio signal in the tactile frequency-range.
+The pre-recorded signal solution is easier because it does not require additional hardware.
+The audio solution requires a sound generation hardware (typically a sound card with one channel per driver), but the signal generation is more flexible.
+We chose to use the audio mode for designing iteratively the tactile signals.
+We generated the audio signals with Purr-Data~\cite{bukvic16}.
+Then when used the other mode when the tactile signals were validated.
+
+\subsubsection{Vibrotactile widgets}
+
+
+\cite{lylykangas11}
+
+
+\cite{schneider16,seifi17}
+
+~\cite{frisson20,frisson17}
+
+Neuromechanics button press ~\cite{oulasvirta18}
+
+\begin{figure}[htb]
+ \definecolor{cellred}{rgb} {0.98,0.17,0.15}
+ \definecolor{cellblue}{rgb} {0.17,0.60,0.99}
+ \def\scale{1mm}
+
+ \newcommand{\nodec}[3]{\node[x=1mm,y=1mm, draw, fill=white, circle, align=center, text width=4mm, minimum size=1mm] (#3) at (#1) {\small #2};}
+ \newcommand{\nodes}[3]{\node[x=1mm,y=1mm, draw, fill=white, rectangle, minimum size=6mm] (#3) at (#1) {\small #2};}
+
+ \centering
+
+ \tikzexternalenable
+ \begin{tikzpicture} %v lines
+ \draw[x=\scale, y=\scale, <->] (0,40) -- (0,0) -- (85,0) node [anchor=north east] {Displacement (mm)};
+ \node[x=\scale, y=\scale, anchor=south, rotate=90] () at (0,30){Force (N)};
+
+ \nodec{15,30}{$1$}{one};
+ \nodec{60,30}{$1'$}{oneb};
+ \nodes{80,40}{$2$}{two};
+ \nodec{45,10}{$3$}{three};
+ \nodec{0,10}{$3'$}{threeb};
+
+ \draw[x=\scale, y=\scale, ->, -stealth', draw=cellred, ultra thick] (0,20) -- (one);
+ \draw[x=\scale, y=\scale, ->, -stealth', draw=cellred, ultra thick] (one) -- (45,20) -- (oneb);
+ \draw[x=\scale, y=\scale, ->, -stealth', draw=cellred, ultra thick] (oneb) -- (two);
+
+ \draw[x=\scale, y=\scale, ->, -stealth', draw=cellblue, ultra thick] (two) -- (three);
+ \draw[x=\scale, y=\scale, ->, -stealth', draw=cellblue, ultra thick] (three) -- (15,20) -- (threeb);
+
+ \draw[x=\scale, y=\scale, draw, ultra thick, dashed] (one) -- (oneb);
+
+ \draw[x=\scale, y=\scale, draw=cellred, ultra thick] (90,40) -- (98,40);
+ \node[x=\scale, y=\scale, anchor=west] () at (100,40){Press curve};
+ \draw[x=\scale, y=\scale, draw=cellblue, ultra thick] (90,32) -- (98,32);
+ \node[x=\scale, y=\scale, anchor=west] () at (100,32){Release curve};
+ \draw[x=\scale, y=\scale, draw, ultra thick, dashed] (90,24) -- (98,24);
+ \node[x=\scale, y=\scale, anchor=west] () at (100,24){Jump};
+ \nodec{94,16}{$x$}{}
+ \node[x=\scale, y=\scale, anchor=west] () at (100,16){Tactile point};
+ \nodes{94,8}{$y$}{}
+ \node[x=\scale, y=\scale, anchor=west] () at (100,8){Bottom-out};
+
+% \node[x=\scale,y=\scale, align=right, text width=1.8cm, anchor=east] () at (0,20){circles};
+ \end{tikzpicture}
+ \tikzexternaldisable
+ \caption[.]{Force-displacement curve for a tactile button, adapted and simplified from~\cite{kim13}.}
+ \label{fig:buttonfeedback}
+\end{figure}
+
+
+%Leverages vibrotactile feedback for touch surfaces.
+
+\subsubsection{Discussion and conclusion}
-Leverages vibrotactile feedback for touch surfaces.
\subsection{Actuated computer peripherals}
\label{sec:metamorphe-livingdesktop}
projects / hdr.git / commitdiff
