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Better figures

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Erwan Normand
2024-09-24 15:07:13 +02:00
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1-introduction/related-work/2-wearable-haptics.tex
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@@ -17,7 +17,7 @@ An increasing wearability resulting in the loss of the system's kinesthetic feed
\begin{subfigs}{pacchierotti2017wearable}{
Schematic wearability level of haptic devices for the hand \cite{pacchierotti2017wearable}.
}[
}[][
\item World-grounded haptic devices are fixed on the environment to provide kinesthetic feedback to the user.
\item Exoskeletons are body-grounded kinesthetic devices.
\item Wearable haptic devices are grounded on the point of application of the tactile stimulus.
@@ -41,9 +41,7 @@ Such \emph{body-grounded} devices are often heavy and bulky and cannot be consid
An approach is then to move the grounding point very close to the end-effector (\figref{pacchierotti2017wearable_3}): the interface is limited to cutaneous haptic feedback, but its design is more compact, lightweight, comfortable and portable, \eg in \figref{grounded_to_wearable}.
Moreover, as detailed in \secref{object_properties}, cutaneous sensations are necessary and often sufficient for the perception of the haptic properties of an object explored with the hand, as also argued by \textcite{pacchierotti2017wearable}.
\begin{subfigs}{grounded_to_wearable}{
Haptic devices for the hand with different wearability levels.
}[
\begin{subfigs}{grounded_to_wearable}{Haptic devices for the hand with different wearability levels. }[][
\item Teleoperation of a virtual cube grasped with the thumb and index fingers each attached to a grounded haptic device \cite{pacchierotti2015cutaneous}.
\item A passive exoskeleton for fingers simulating stiffness of a trumpet's pistons \cite{achibet2017flexifingers}.
\item Manipulation of a virtual cube with the thumb and index fingers each attached with the 3-RSR wearable haptic device \cite{leonardis20173rsr}.
@@ -84,7 +82,7 @@ Although these two types of effector can be considered wearable, their actuation
\begin{subfigs}{normal_actuators}{
Normal indentation actuators for the fingertip.
}[
}[][
\item A moving platform actuated with cables \cite{gabardi2016new}.
\item A moving platform actuated by articulated limbs \cite{perez2017optimizationbased}.
\item Diagram of a pin-array of tactors \cite{sarakoglou2012high}.
@@ -112,7 +110,7 @@ By turning in opposite directions, the motors shorten the belt and create a sens
Conversely, by turning simultaneously in the same direction, the belt pulls on the skin, creating a shearing sensation.
The simplicity of this approach allows the belt to be placed anywhere on the hand, leaving the fingertip free to interact with the \RE, \eg the hRing on the proximal phalanx in \figref{pacchierotti2016hring} \cite{pacchierotti2016hring} or Tasbi on the wrist in \figref{pezent2022design} \cite{pezent2022design}.
\begin{subfigs}{tangential_belts}{Tangential motion actuators and compression belts. }[
\begin{subfigs}{tangential_belts}{Tangential motion actuators and compression belts. }[][
\item A skin strech actuator for the fingertip \cite{leonardis2015wearable}.
\item A 3 \DoF actuator capable of normal and tangential motion on the fingertip \cite{schorr2017fingertip}.
%\item A shearing belt actuator for the fingertip \cite{minamizawa2007gravity}.
@@ -137,7 +135,7 @@ Several types of vibrotactile actuators are used in haptics, with different trad
An \ERM is a \DC motor that rotates an off-center mass when a voltage or current is applied (\figref{precisionmicrodrives_erm}). \ERMs are easy to control, inexpensive and can be encapsulated in a few millimeters cylinder or coin form factor. However, they have only one \DoF because both the frequency and amplitude of the vibration are coupled to the speed of the rotation, \eg low (high) frequencies output at low (high) amplitudes, as shown on \figref{precisionmicrodrives_erm_performances}.
\begin{subfigs}{erm}{Diagram and performance of \ERMs. }[
\begin{subfigs}{erm}{Diagram and performance of \ERMs. }[][
\item Diagram of a cylindrical encapsulated \ERM. From Precision Microdrives~\footnotemark.
\item Amplitude and frequency output of an \ERM as a function of the input voltage.
]
@@ -158,7 +156,7 @@ Piezoelectric actuators deform a solid material when a voltage is applied.
They are very small and thin and provide two \DoFs of amplitude and frequency control.
However, they require high voltages to operate, limiting their use in wearable devices.
\begin{subfigs}{lra}{Diagram and performance of \LRAs. }[
\begin{subfigs}{lra}{Diagram and performance of \LRAs. }[][
\item Diagram. From Precision Microdrives~\footnotemarkrepeat.
\item Force generated by two \LRAs as a function of sinusoidal wave input with different frequencies: both their maximum force and resonant frequency are different \cite{azadi2014vibrotactile}.
]
@@ -238,7 +236,7 @@ Alternative models have been proposed to both render both isotropic and patterne
When comparing real textures felt through a stylus with their virtual models rendered with a voice-coil actuator attached to the stylus (\figref{culbertson2012refined}), the virtual textures were found to accurately reproduce the perception of roughness, but hardness and friction were not rendered properly \cite{culbertson2014modeling}.
\textcite{culbertson2015should} further showed that the perceived realism of the virtual textures, and similarity to the real textures, depended mostly on the user's speed but not on the user's force as inputs to the model, \ie responding to speed is sufficient to render isotropic virtual textures.
\begin{subfigs}{textures_rendering_data}{Augmentating haptic texture perception with voice-coil actuators. }[
\begin{subfigs}{textures_rendering_data}{Augmentating haptic texture perception with voice-coil actuators. }[][
\item Increasing and decreasing the perceived roughness of a real patterned texture in direct touch \cite{asano2015vibrotactile}.
\item Comparing real patterned texture with virtual texture augmentation in direct touch \cite{friesen2024perceived}.
\item Rendering virtual contacts in direct touch with the virtual texture \cite{ando2007fingernailmounted}.
@@ -270,7 +268,9 @@ The displacement $x_r(t)$ is estimated with the reaction force and the tapping v
As shown in \figref{jeon2009haptic_2}, the force $\tilde{f_r}(t)$ perceived by the user is modulated, but not the displacement $x_r(t)$, hence the perceived stiffness is $\tilde{k}(t)$.
This stiffness augmentation technique was then extended to allow tapping and pressing with 3 \DoFs \cite{jeon2010stiffness}, to render friction and weight augmentations \cite{jeon2011extensions}, and to grasp and squeez the real object with two contact points \cite{jeon2012extending}.
\begin{subfigs}{stiffness_rendering_grounded}{Augmenting the perceived stiffness of a real surface with a hand-held force-feedback device. }[%
\begin{subfigs}{stiffness_rendering_grounded}{
Augmenting the perceived stiffness of a real surface with a hand-held force-feedback device.
}[][
\item Diagram of a user tapping the surface \cite{jeon2009haptic}.
\item Displacement-force curves of a real rubber ball (dashed line) and when its perceived stiffness $\tilde{k}$ is modulated \cite{jeon2009haptic}.
]
@@ -283,7 +283,9 @@ More importantly, the augmentation proved to be robust to the placement of the d
Conversely, the technique allowed to \emph{decrease} the perceived stiffness by compressing the phalanx before the contact and reducing the pressure when the user pressed the piston \cite{salazar2020altering}.
\textcite{tao2021altering} proposed instead to restrict the deformation of the fingerpad by pulling a hollow frame around it to decrease perceived stiffness (\figref{tao2021altering}): it augments the finger contact area and thus the perceived Young's modulus of the object (\secref{hardness}).
\begin{subfigs}{stiffness_rendering_wearable}{Modifying the perceived stiffness with wearable pressure devices. }[%
\begin{subfigs}{stiffness_rendering_wearable}{
Modifying the perceived stiffness with wearable pressure devices.
}[][
\item Modify the perceived stiffness of a piston by pressing the finger during or prior the contact \cite{detinguy2018enhancing,salazar2020altering}.
\item Decrease perceived stiffness of hard object by restricting the fingerpad deformation \cite{tao2021altering}.
]
@@ -303,12 +305,12 @@ It has been shown that these material properties perceptually express the stiffn
Therefore, when contacting or tapping a real object through an indirect feel-through interface that provides such vibrations (\figref{choi2021augmenting_control}) using a voice-coil (\secref{vibrotactile_actuators}), the perceived stiffness can be increased or decreased \cite{kuchenbecker2006improving,hachisu2012augmentation,choi2021augmenting}, \eg sponge feels stiffer or wood feels softer (\figref{choi2021augmenting_results}).
A challenge with this technique is to provide the vibration feedback at the right time to be felt simultaneously with the real contact \cite{park2023perceptual}.
\begin{subfigs}{contact_vibrations}{Augmenting perceived stiffness using vibrations when touching a real surface \cite{choi2021augmenting}. }[%
%\item Experimental setup with a voice-coil actuator attached to a touch-through interface.
\begin{subfigs}{contact_vibrations}{
Augmenting perceived stiffness using vibrations when touching a real surface \cite{choi2021augmenting}.
}[][
\item Voltage inputs (top) to the voice-coil for soft, medium, and hard vibrations, with the corresponding displacement (middle) and force (bottom) outputs of the actuator.
\item Perceived stiffness intensity of real sponge ("Sp") and wood ("Wd") surfaces without added vibrations ("N") and modified by soft ("S"), medium ("M") and hard ("H") vibrations.
]
%\subfig[.15]{choi2021augmenting_demo}
\subfigsheight{50mm}
\subfig{choi2021augmenting_control}
\subfig{choi2021augmenting_results}