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Replace "immersive AR" with "AR headset"

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Erwan Normand
2025-04-11 22:51:10 +02:00
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2-related-work/4-visuo-haptic-ar.tex
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@@ -5,7 +5,7 @@ Perception and manipulation of objects with the hand typically involves both the
Each sense has unique capabilities for perceiving certain object properties, such as color for vision or temperature for touch, but they are equally capable for many properties, such as roughness, hardness, or geometry \cite{baumgartner2013visual}.
Both \AR and wearable haptic systems integrate virtual content into the user's perception as sensory illusions.
It is essential to understand how a visuo-haptic rendering of a virtual object is perceived as a coherent object property, and how wearable haptics have been integrated with immersive \AR.
It is essential to understand how a visuo-haptic rendering of a virtual object is perceived as a coherent object property, and how wearable haptics have been integrated with \AR headsets.
\subsection{Visuo-Haptic Perception of Virtual and Augmented Objects}
\label{vh_perception}
@@ -60,7 +60,7 @@ More precisely, when surfaces are evaluated by vision or touch alone, both sense
The overall perception can then be modified by changing one of the sensory modalities.
\textcite{yanagisawa2015effects} altered the perceived roughness, stiffness, and friction of real tactile materials touched by the finger by superimposing different real visual textures using a half-mirror.
In a similar setup, but in immersive \VST-\AR, \textcite{kitahara2010sensory} overlaid visual textures on real textured surfaces touched through a glove: many visual textures were found to match the real haptic textures.
In a similar setup, but in \VST-\AR, \textcite{kitahara2010sensory} overlaid visual textures on real textured surfaces touched through a glove: many visual textures were found to match the real haptic textures.
\textcite{degraen2019enhancing} and \textcite{gunther2022smooth} also combined multiple virtual objects in \VR with \ThreeD-printed hair structures or with everyday real surfaces, respectively.
They found that the visual perception of roughness and hardness influenced the haptic perception, and that only a few real objects seemed to be sufficient to match all the visual virtual objects (\figref{gunther2022smooth}).
@@ -85,7 +85,7 @@ For example, in a fixed \VST-\AR screen (\secref{ar_displays}), by visually defo
Some studies have investigated the visuo-haptic perception of virtual objects rendered with force-feedback and vibrotactile feedback in \AR and \VR.
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 \VST-\AR, \textcite{knorlein2009influence} rendered a virtual piston using force-feedback haptics that participants pressed directly with their hand (\figref{visuo-haptic-stiffness}).
In a \TIFC task (\secref{sensations_perception}), 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 (\figref{knorlein2009influence_2}).
@@ -114,7 +114,7 @@ The visuo-haptic simultaneity was varied by adding a visual delay or by triggeri
No participant (out of 19) was able to detect a \qty{50}{\ms} visual lag and a \qty{15}{\ms} haptic lead, and only half of them detected a \qty{100}{\ms} visual lag and a \qty{70}{\ms} haptic lead.
These studies have shown how the latency of the visual rendering of a virtual object or the type of environment (\VE or \RE) can affect the perceived haptic stiffness of the object, rendered with a grounded force-feedback device.
We describe in the next section how wearable haptics have been integrated with immersive \AR.
We describe in the next section how wearable haptics have been integrated with \AR.
\begin{subfigs}{gaffary2017ar}{Perception of haptic stiffness in \OST-\AR \vs \VR \cite{gaffary2017ar}. }[][
\item Experimental setup: a virtual piston was pressed with a force-feedback placed to the side of the participant.
@@ -129,7 +129,7 @@ We describe in the next section how wearable haptics have been integrated with i
\subsection{Wearable Haptics for Direct Hand Interaction in AR}
\label{vhar_haptics}
A few wearable haptic devices have been specifically designed or experimentally tested for direct hand interaction in immersive \AR.
A few wearable haptic devices have been specifically designed or experimentally tested for direct hand interaction in \AR.
Since virtual or augmented objects are naturally touched, grasped, and manipulated directly with the fingertips (\secref{exploratory_procedures} and \secref{grasp_types}), the main challenge of wearable haptics for \AR is to provide haptic sensations of these interactions while keeping the fingertips free to interact with the \RE.
Several approaches have been proposed to move the haptic actuator to a different location, on the outside of the finger or the hand, \eg the nail, the top of a phalanx, or the wrist.
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.
@@ -178,12 +178,12 @@ In a \VST-\AR setup, \textcite{scheggi2010shape} explored the effect of renderin
The middle phalanx of each of these fingers was equipped with a haptic ring of \textcite{minamizawa2007gravity}.
\textcite{scheggi2010shape} reported that 12 out of 15 participants found the weight haptic feedback essential to feeling the presence of the virtual cube.
In a pick-and-place task in non-immersive \VST-\AR involving direct hand manipulation of both virtual and real objects (\figref{maisto2017evaluation}), \textcite{maisto2017evaluation} and \textcite{meli2018combining} compared the effects of providing haptic or visual feedback about fingertip-object contacts.
In a pick-and-place task in \VST-\AR involving direct hand manipulation of both virtual and real objects (\figref{maisto2017evaluation}), \textcite{maisto2017evaluation} and \textcite{meli2018combining} compared the effects of providing haptic or visual feedback about fingertip-object contacts.
They compared the haptic ring of \textcite{pacchierotti2016hring} on the proximal phalanx, the moving platform of \textcite{chinello2020modular} on the fingertip, and a visual feedback of the tracked fingertips as virtual points.
They showed that the haptic feedback improved the completion time, reduced the force exerted on the cubes compared to the visual feedback (\figref{visual-hands}).
The haptic ring was also perceived as more effective than the moving platform.
However, the measured difference in performance could be due to either the device or the device position (proximal vs fingertip), or both.
These two studies were also conducted in non-immersive setups, where users viewed a screen displaying the visual interactions, and only compared the haptic and visual feedback of the hand-object contacts, but did not examine them together.
These two studies were also conducted in static setups, where users viewed a screen displaying the visual interactions, and only compared the haptic and visual feedback of the hand-object contacts, but did not examine them together.
\begin{subfigs}{ar_rings}{Wearable haptic ring devices for \AR. }[][
\item Rendering weight of a virtual cube placed on a real surface \cite{scheggi2010shape}.
@@ -200,7 +200,7 @@ A user study was conducted in \VR to compare the perception of visuo-haptic stif
\subsection{Conclusion}
\label{visuo_haptic_conclusion}
Providing coherent visuo-haptic feedback to enhance direct hand perception and manipulation with virtual objects in immersive \AR is challenging.
Providing coherent visuo-haptic feedback to enhance direct hand perception and manipulation with virtual objects in \AR is challenging.
While many wearable haptic devices have been developed and are capable of providing varied tactile feedback, few have be integrated or experimentally evaluated for direct hand interaction in \AR.
Their haptic end-effector must be moved away from the inside of the hand so as not to interfere with the user interaction with the \RE.
Different relocation strategies have been proposed for different parts of the hand, such as the nail, the index phalanges, or the wrist, but it remains unclear whether any of them are best suited for direct hand interaction in \AR.