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Remove "see" before section or figure reference

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Erwan Normand
2024-09-16 12:57:05 +02:00
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34
1-introduction/related-work/4-visuo-haptic-ar.tex
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@@ -67,10 +67,10 @@ Some studies have investigated the visuo-haptic perception of virtual objects in
They have shown how the latency of the visual rendering of an object with haptic feedback or the type of environment (\VE or \RE) can affect the perception of an identical haptic rendering.
Indeed, there are indeed inherent and unavoidable latencies in the visual and haptic rendering of virtual objects, and the visual-haptic feedback may not appear to be simultaneous.
In an immersive \VST-\AR setup, \textcite{knorlein2009influence} rendered a virtual piston using force-feedback haptics that participants pressed directly with their hand (see \figref{visuo-haptic-stiffness}).
In an immersive \VST-\AR setup, \textcite{knorlein2009influence} rendered a virtual piston using force-feedback haptics that participants pressed directly with their hand (\figref{visuo-haptic-stiffness}).
In a \TAFC task, participants pressed two pistons and indicated which was stiffer.
One had a reference stiffness but an additional visual or haptic delay, while the other varied with a comparison stiffness but had no delay. \footnote{Participants were not told about the delays and stiffness tested, nor which piston was the reference or comparison. The order of the pistons (which one was pressed first) was also randomized.}%
Adding a visual delay increased the perceived stiffness of the reference piston, while adding a haptic delay decreased it, and adding both delays cancelled each other out (see \figref{knorlein2009influence_2}).
Adding a visual delay increased the perceived stiffness of the reference piston, while adding a haptic delay decreased it, and adding both delays cancelled each other out (\figref{knorlein2009influence_2}).
\begin{subfigs}{visuo-haptic-stiffness}{Perception of haptic stiffness in \VST-\AR ~\cite{knorlein2009influence}. }[
\item Participant pressing a virtual piston rendered by a force-feedback device with their hand.
@@ -91,7 +91,7 @@ where $t_B = t_A + \Delta t$.
Therefore, a haptic delay (positive $\Delta t$) increases the perceived stiffness $k$, while a visual delay in displacement (negative $\Delta t$) decreases perceived $k$~\cite{diluca2011effects}.
In a similar \TAFC user study, participants compared perceived stiffness of virtual pistons in \OST-\AR and \VR~\cite{gaffary2017ar}.
However, the force-feedback device and the participant's hand were not visible (see \figref{gaffary2017ar}).
However, the force-feedback device and the participant's hand were not visible (\figref{gaffary2017ar}).
The reference piston was judged to be stiffer when seen in \VR than in \AR, without participants noticing this difference, and more force was exerted on the piston overall in \VR.
This suggests that the haptic stiffness of virtual objects feels \enquote{softer} in an \AE than in a full \VE.
%Two differences that could be worth investigating with the two previous studies are the type of \AR (visuo or optical) and to see the hand touching the virtual object.
@@ -118,7 +118,7 @@ No participant (out of 19) was able to detect a \qty{50}{\ms} visual lag and a \
A few wearable haptic devices have been specifically designed or experimentally tested for direct hand interaction in immersive \AR.
The main challenge of wearable haptics for \AR is to provide haptic sensations of virtual or augmented objects that are touched and manipulated directly with the fingers while keeping the fingertips free to interact with the \RE.
Several approaches have been proposed to move the actuator away to another location on the hand.
Yet, they differ greatly in the actuators used (see \secref{wearable_haptic_devices}) thus the haptic feedback (see \secref{tactile_rendering}), and the placement of the haptic rendering.
Yet, they differ greatly in the actuators used (\secref{wearable_haptic_devices}) thus the haptic feedback (\secref{tactile_rendering}), and the placement of the haptic rendering.
Other wearable haptic actuators have been proposed for \AR but are not detailed here.
A first reason is that they permanently cover the fingertip and affect the interaction with the \RE, such as thin-skin tactile interfaces~\cite{withana2018tacttoo,teng2024haptic} or fluid-based interfaces~\cite{han2018hydroring}.
@@ -126,12 +126,12 @@ Another category of actuators relies on systems that cannot be considered as por
\subsubsection{Nail-Mounted Devices}
\textcite{ando2007fingernailmounted} were the first to propose this approach that they experimented with a voice-coil mounted on the index nail (see \figref{ando2007fingernailmounted}).
The sensation of crossing edges of a virtual patterned texture (see \secref{texture_rendering}) on a real sheet of paper were rendered with \qty{20}{\ms} vibration impulses at \qty{130}{\Hz}.
\textcite{ando2007fingernailmounted} were the first to propose this approach that they experimented with a voice-coil mounted on the index nail (\figref{ando2007fingernailmounted}).
The sensation of crossing edges of a virtual patterned texture (\secref{texture_rendering}) on a real sheet of paper were rendered with \qty{20}{\ms} vibration impulses at \qty{130}{\Hz}.
Participants were able to match the virtual patterns to their real counterparts of height \qty{0.25}{\mm} and width \qtyrange{1}{10}{\mm}, but systematically overestimated the virtual width to be \qty{4}{\mm} longer.
This approach was later extended by \textcite{teng2021touch} with Touch\&Fold, a haptic device mounted on the nail but able to unfold its end-effector on demand to make contact with the fingertip when touching virtual objects (see \figref{teng2021touch}).
This moving platform also contains a \LRA (see \secref{moving_platforms}) and provides contact pressure (\qty{0.34}{\N} force) and texture (\qtyrange{150}{190}{\Hz} bandwidth) sensations.
This approach was later extended by \textcite{teng2021touch} with Touch\&Fold, a haptic device mounted on the nail but able to unfold its end-effector on demand to make contact with the fingertip when touching virtual objects (\figref{teng2021touch}).
This moving platform also contains a \LRA (\secref{moving_platforms}) and provides contact pressure (\qty{0.34}{\N} force) and texture (\qtyrange{150}{190}{\Hz} bandwidth) sensations.
%The whole system is very compact (\qtyproduct{24 x 24 x 41}{\mm}), lightweight (\qty{9.5}{\g}), and fully portable by including a battery and Bluetooth wireless communication. \qty{20}{\ms} for the Bluetooth
When touching virtual objects in \OST-\AR with the index finger, this device was found to be more realistic overall (5/7) than vibrations with a \LRA at \qty{170}{\Hz} on the nail (3/7).
Still, there is a high (\qty{92}{\ms}) latency for the folding mechanism and this design is not suitable for augmenting real tangible objects.
@@ -139,12 +139,12 @@ Still, there is a high (\qty{92}{\ms}) latency for the folding mechanism and thi
% teng2021touch: (5.27+3.03+5.23+5.5+5.47)/5 = 4.9
% ando2007fingernailmounted: (2.4+2.63+3.63+2.57+3.2)/5 = 2.9
To always keep the fingertip, \textcite{maeda2022fingeret} with Fingeret proposed to adapt the belt actuators (see \secref{belt_actuators}) to design a \enquote{finger-side actuator} instead (see \figref{maeda2022fingeret}).
To always keep the fingertip, \textcite{maeda2022fingeret} with Fingeret proposed to adapt the belt actuators (\secref{belt_actuators}) to design a \enquote{finger-side actuator} instead (\figref{maeda2022fingeret}).
Mounted on the nail, the device actuates two rollers, one on each side of the fingertip, to deform the skin: When the rollers both rotate inwards (towards the pad) they pull the skin, simulating a contact sensation, and when they both rotate outwards (towards the nail) they push the skin, simulating a release sensation.
By doing quick rotations, the rollers can also simulate a texture sensation.
%The device is also very compact (\qty{60 x 25 x 36}{\mm}), lightweight (\qty{18}{\g}), and portable with a battery and Bluetooth wireless communication with \qty{83}{\ms} latency.
In a user study not in \AR, but involving touching different images on a tablet, Fingeret was found to be more realistic (4/7) than a \LRA at \qty{100}{\Hz} on the nail (3/7) for rendering buttons and a patterned texture (see \secref{texture_rendering}), but not different from vibrations for rendering high-frequency textures (3.5/7 for both).
However, as for \textcite{teng2021touch}, finger speed was not taken into account for rendering vibrations, which may have been detrimental to texture perception (see \secref{texture_rendering}).
In a user study not in \AR, but involving touching different images on a tablet, Fingeret was found to be more realistic (4/7) than a \LRA at \qty{100}{\Hz} on the nail (3/7) for rendering buttons and a patterned texture (\secref{texture_rendering}), but not different from vibrations for rendering high-frequency textures (3.5/7 for both).
However, as for \textcite{teng2021touch}, finger speed was not taken into account for rendering vibrations, which may have been detrimental to texture perception (\secref{texture_rendering}).
\begin{subfigs}{ar_wearable}{Nail-mounted wearable haptic devices designed for \AR. }[
\item A voice-coil rendering a virtual haptic texture on a real sheet of paper~\cite{ando2007fingernailmounted}.
@@ -161,14 +161,14 @@ However, as for \textcite{teng2021touch}, finger speed was not taken into accoun
The haptic ring belt devices of \textcite{minamizawa2007gravity} and \textcite{pacchierotti2016hring}, presented in \secref{belt_actuators}, have been employed to improve the manipulation of real and virtual objects in \AR.
In a \VST-\AR setup, \textcite{scheggi2010shape} explored the effect of rendering the weight (see \secref{weight_rendering}) of a virtual cube placed on a real surface hold with the thumb, index, and middle fingers (see \figref{scheggi2010shape}).
In a \VST-\AR setup, \textcite{scheggi2010shape} explored the effect of rendering the weight (\secref{weight_rendering}) of a virtual cube placed on a real surface hold with the thumb, index, and middle fingers (\figref{scheggi2010shape}).
The middle phalanx of each of these fingers was equipped with a haptic ring of \textcite{minamizawa2007gravity}.
However, no proper user study was conducted to evaluate this feedback.% on the manipulation of the cube.
%that simulated the weight of the cube.
%A virtual cube that could push on the cube was manipulated with the other hand through a force-feedback device.
%\textcite{scheggi2010shape} report that \percent{80} of the participants appreciated the weight feedback.
In pick-and-place tasks in non-immersive \VST-\AR involving both virtual and real objects (see \figref{maisto2017evaluation}), \textcite{maisto2017evaluation} and \textcite{meli2018combining} compared the effects of providing haptic feedback about contacts at the fingertips using either the haptic ring of \textcite{pacchierotti2016hring}, or on the proximal phalanx, the moving platform of \textcite{chinello2020modular} on the fingertip.
In pick-and-place tasks in non-immersive \VST-\AR involving both virtual and real objects (\figref{maisto2017evaluation}), \textcite{maisto2017evaluation} and \textcite{meli2018combining} compared the effects of providing haptic feedback about contacts at the fingertips using either the haptic ring of \textcite{pacchierotti2016hring}, or on the proximal phalanx, the moving platform of \textcite{chinello2020modular} on the fingertip.
They showed that the haptic feedback improved the performance (completion time), reduced the exerted force on the cubes over a visual feedback alone.
The haptic ring was also perceived by users to be more effective than the moving platform.
However, the measured difference in performance could be attributed to either the device or the device position (proximal vs fingertip), or both.
@@ -188,10 +188,10 @@ These two studies were also conducted in non-immersive setups, where users looke
With their \enquote{Tactile And Squeeze Bracelet Interface} (Tasbi), already mentioned in \secref{belt_actuators}, \textcite{pezent2019tasbi} and \textcite{pezent2022design} explored the use of a wrist-worn bracelet actuator.
It is capable of providing a uniform pressure sensation (up to \qty{15}{\N} and \qty{10}{\Hz}) and vibration with six \LRAs (\qtyrange{150}{200}{\Hz} bandwidth).
A user study was conducted in \VR to compare the perception of visuo-haptic stiffness rendering~\cite{pezent2019tasbi}.
In a \TAFC task, participants pressed a virtual button with different levels of stiffness via a virtual hand constrained by the \VE (see \figref{pezent2019tasbi_2}).
In a \TAFC task, participants pressed a virtual button with different levels of stiffness via a virtual hand constrained by the \VE (\figref{pezent2019tasbi_2}).
A higher visual stiffness required a larger physical displacement to press the button (C/D ratio, see \secref{pseudo_haptic}), while the haptic stiffness control the rate of the pressure feedback when pressing.
When the visual and haptic stiffness were coherent or when only the haptic stiffness changed, participants easily discriminated two buttons with different stiffness levels (see \figref{pezent2019tasbi_3}).
However, if only the visual stiffness changed, participants were not able to discriminate the different stiffness levels (see \figref{pezent2019tasbi_4}).
When the visual and haptic stiffness were coherent or when only the haptic stiffness changed, participants easily discriminated two buttons with different stiffness levels (\figref{pezent2019tasbi_3}).
However, if only the visual stiffness changed, participants were not able to discriminate the different stiffness levels (\figref{pezent2019tasbi_4}).
This suggests that in \VR, the haptic pressure is more important perceptual cue than the visual displacement to render stiffness.
A short vibration (\qty{25}{\ms} \qty{175}{\Hz} square-wave) was also rendered when contacting the button, but kept constant across all conditions: It may have affected the overall perception when only the visual stiffness changed.
@@ -211,5 +211,5 @@ A short vibration (\qty{25}{\ms} \qty{175}{\Hz} square-wave) was also rendered w
\label{visuo_haptic_conclusion}
% the type of rendered object (real or virtual), the rendered haptic property (contact, hardness, texture, see \secref{tactile_rendering}), and .
%In this context of integrating \WHs with \AR to create a \vh-\AE (see \chapref{introduction}), the definition of \textcite{pacchierotti2017wearable} can be extended to an additional criterion: The wearable haptic interface should not impair the interaction with the \RE, \ie the user should be able to touch and manipulate objects in the real world while wearing the haptic device.
%In this context of integrating \WHs with \AR to create a \vh-\AE (\chapref{introduction}), the definition of \textcite{pacchierotti2017wearable} can be extended to an additional criterion: The wearable haptic interface should not impair the interaction with the \RE, \ie the user should be able to touch and manipulate objects in the real world while wearing the haptic device.
% The haptic feedback is thus rendered de-localized from the point of contact of the finger on the rendered object.