From 8e23adbdb836463cc6281320babd16a0d12673f4 Mon Sep 17 00:00:00 2001 From: Thomas Pietrzak Date: Wed, 8 Sep 2021 11:41:08 +0200 Subject: [PATCH] Vibrotactile widgets --- tex/2-output.tex | 54 ++++++++++++++++++++++++++++++++++-------------- 1 file changed, 38 insertions(+), 16 deletions(-) diff --git a/tex/2-output.tex b/tex/2-output.tex index daa968c..f86262c 100644 --- a/tex/2-output.tex +++ b/tex/2-output.tex @@ -1735,7 +1735,7 @@ It means that results about perception made with research prototypes are hard to 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. +We are however 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. @@ -1765,7 +1765,7 @@ We prototyped the driving electronics and clamping system, designed tactile widg \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.} + \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 and the driving electronics.} \label{fig:mojave} \end{figure} @@ -1776,16 +1776,17 @@ We prototyped the driving electronics and clamping system, designed tactile widg %Leverage vibrotactile feedback to restore haptic properties on touchscreens \subsubsection{Experimental platform} +\label{sec:printgetsplatform} 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}. +Our colleagues who designed and implemented these actuators, performed FEM simulations, and measured the response to signal with laser vibrometers~\cite{poncet17,poncet16}. 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 first prototype (top of~\reffig{fig:printedslider}) had six buttons embedded in a molded plastic dashboard part. The clamping area was a circle around each actuator. -A clamping area defines the area on which the vibration propagates. +It defines the area on which the vibration propagates, therefore this vibrotactile feedback is localized. 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. +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}. @@ -1799,7 +1800,7 @@ The setup is depicted at the bottom of~\reffig{fig:printedslider}. \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}}. +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/CAP1188}{Microchip CAP1188} for buttons and \href{http://www.microchip.com/wwwproducts/en/CAP1214}{Microchip CAP1214} for sliders}. 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. @@ -1810,15 +1811,25 @@ 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} +The idea of using vibrations to simulate button clicks on touch surfaces started with vibrotactile actuators attached to PDAs~\cite{fukumoto01,nashel03,poupyrev02}, then mobile phones~\cite{brewster07,hoggan08}. +This was before phone manufacturers included vibrotactile actuators to mobile phone. +And even now mobile phones do have one, it is low quality (ERM or LRA) and mostly used for message or call notifications. +They sometimes propose vibrations for button presses, but the quality of this feedback is poor. +Indeed other actuators provide a sharper vibrotactile feedback, we discussed this at the beginning of this chapter. +Voice coil actuators provide precise and strong vibrations~\cite{yao10}, and piezo actuators have a smaller form factors, and convenient for implementing buttons~\cite{tashiro09,lylykangas11}. +Our challenge is that printed actuators are thin (between $4\mu m$ and $10\mu m$). +Therefore the vibration propagation requires a careful design as discussed in the previous page. + +%Designing better tactile buttons requires knowing how people operate buttons, and what they perceive. +%Neuromechanics button press ~\cite{oulasvirta18} +Kim and Lee analyzed force-displacement curves of physical buttons and designed high quality vibrotactile feedback that emulates button presses~\cite{kim13}. +They split force-displacement curves into two types of sections: slopes and jumps, which are delimited by tactile points (\reffig{fig:buttonfeedback}). +Slopes are spring-like sensations that corresponds to the material resistance. +When pressing a button we feel a first resistance before the click, then another one when the button reaches its end. +When releasing a button we feel another resistance before the click sensation. +The tactile points (1) and (3) represent the click sensations when the button physically switches, and the bottom-out (2) represents the end of the button. +We adapted and simplified these curves for the design and implementation of our buttons. +We describe further our implementation of buttons, sliders and touchpads in~\cite{frisson20,frisson17}. \begin{figure}[htb] \definecolor{cellred}{rgb} {0.98,0.17,0.15} @@ -1849,6 +1860,7 @@ Neuromechanics button press ~\cite{oulasvirta18} \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, ultra thick, dashed] (three) -- (threeb); \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}; @@ -1868,11 +1880,21 @@ Neuromechanics button press ~\cite{oulasvirta18} \label{fig:buttonfeedback} \end{figure} +The design of the tactile feedback for slopes and points we described in the previous paragraph requires an iterative process. +Several tools were designed to support the design of vibrotactile animations~\cite{schneider15,schneider16} +As we discussed in section~\ref{sec:printgetsplatform}, the haptic drivers provide an audio mode in which we can provide an audio signal to drive the actuators. +We leveraged this feature with Purr Data, a web-based audio synthesis programming language that we used to design vibrotactile feedback~\cite{frisson16}. +We describe the design of the vibrotactile feedback for tactile buttons in~\cite{frisson20}. %Leverages vibrotactile feedback for touch surfaces. \subsubsection{Discussion and conclusion} +put together existing building blocks to design a whole system + +interdisciplinary skills and knowledge + +low vibration amplitude => clamping arrea => localized haptic feedback \subsection{Actuated computer peripherals} \label{sec:metamorphe-livingdesktop} -- 2.30.2