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Erwan Normand
2024-09-30 11:47:29 +02:00
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1-background/related-work/1-haptic-hand.tex
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@@ -76,7 +76,7 @@ These receptors give the hand its great tactile sensitivity and great dexterity
\label{sensorimotor_continuum}
\textcite{jones2006human} have proposed a sensorimotor continuum of hand functions, from mainly sensory activities to activities with a more important motor component.
As illustrated in the \figref{sensorimotor_continuum}, \Citeauthor{jones2006human} propose to delineate four categories of hand function on this continuum:
As illustrated in \figref{sensorimotor_continuum}, \Citeauthor{jones2006human} propose to delineate four categories of hand function on this continuum:
\begin{itemize}
\item \emph{Passive touch}, or tactile sensing, is the ability to perceive an object through cutaneous sensations with a static hand contact. The object may be moving, but the hand remains static. It allows for relatively good surface perception, \eg in \textcite{gunther2022smooth}.
\item \emph{Exploration}, or active haptic sensing, is the manual and voluntary exploration of an object with the hand, involving all cutaneous and kinesthetic sensations. It enables a more precise perception than passive touch \cite{lederman2009haptic}.
@@ -100,13 +100,13 @@ In this thesis, we are interested in exploring visuo-haptic augmentations (\part
Before we describe how the hand is used to explore and grasp objects, we need to look at its anatomy.
Underneath the skin, muscles and tendons can actually move because they are anchored to the bones.
As shown in the \figref{blausen2014medical_hand}, the skeleton of the hand is formed of 27 articulated bones.
As shown in \figref{blausen2014medical_hand}, the skeleton of the hand is formed of 27 articulated bones.
The wrist, comprising 8 carpal bones, connects the hand to the arm and is the base for the 5 metacarpal bones of the palm, one for each finger.
Each finger is formed by a chain of 3 phalanges, proximal, middle and distal, except for the thumb which has only two phalanges, proximal and distal.
The joints at the base of each phalanx allow flexion and extension, \ie folding and unfolding movements relative to the preceding bone.
The proximal phalanges can also adduct and abduct, \ie move the fingers towards and away from each other.
Finally, the metacarpal of the thumb is capable of flexion/extension and adduction/abduction, which allows the thumb to oppose the other fingers.
These axes of movement are called DoFs and can be represented by a \emph{kinematic model} of the hand with 27 DoFs as shown in the \figref{blausen2014medical_hand}.
These axes of movement are called DoFs and can be represented by a \emph{kinematic model} of the hand with 27 DoFs as shown in \figref{blausen2014medical_hand}.
Thus the thumb has 5 DoFs, each of the other four fingers has 4 DoFs and the wrist has 6 DoFs and can take any position (3 DoFs) or orientation (3 DoFs) in space \cite{erol2007visionbased}.
This complex structure enables the hand to perform a wide range of movements and gestures. However, the way we explore and grasp objects follows simpler patterns, depending on the object being touched and the aim of the interaction.
@@ -124,7 +124,7 @@ This complex structure enables the hand to perform a wide range of movements and
\label{exploratory_procedures}
The exploration of an object by the hand follows patterns of movement, called exploratory procedures \cite{lederman1987hand}.
As illustrated in the \figref{exploratory_procedures}, a specific and optimal movement of the hand is performed for a given property of the object being explored to acquire the most relevant sensory information for that property.
As illustrated in \figref{exploratory_procedures}, a specific and optimal movement of the hand is performed for a given property of the object being explored to acquire the most relevant sensory information for that property.
For example, a \emph{lateral movement} of the fingers on the surface to identify its texture, a \emph{pressure} with the finger to perceive its hardness, or a \emph{contour following} of the object to infer its shape.
These three procedures involve only the fingertips and in particular the index finger \cite{gonzalez2014analysis}.
For the other procedures, the whole hand is used: for example, approaching or posing the palm to feel the temperature (\emph{static contact}), holding the object in the hand to estimate its weight (\emph{unsupported holding}).
@@ -149,7 +149,7 @@ In \emph{power grasps}, the object is held firmly and follows the movements of t
In \emph{precision grasps}, the fingers can move the object within the hand but without moving the arm.
\emph{Intermediate grasps} combine strength and precision in equal proportions \cite{feix2016grasp}.
For all possible objects and tasks, the number of grasp types can be reduced to 34 and classified as the taxonomy on \figref{gonzalez2014analysis} \cite{gonzalez2014analysis}.\footnote{An updated taxonomy was then proposed by \textcite{feix2016grasp}: it is more complete but harder to present.}
For all possible objects and tasks, the number of grasp types can be reduced to 34 and classified as the taxonomy in \figref{gonzalez2014analysis} \cite{gonzalez2014analysis}.\footnote{An updated taxonomy was then proposed by \textcite{feix2016grasp}: it is more complete but harder to present.}
For everyday objects, this number is even smaller, with between 5 and 10 grasp types depending on the activity \cite{bullock2013grasp}.
Furthermore, the fingertips are the most involved areas of the hand, both in terms of frequency of use and time spent in contact: In particular, the thumb is almost always used, as well as the index and middle fingers, but the other fingers are used less frequently \cite{gonzalez2014analysis}.
This can be explained by the sensitivity of the fingertips (\secref{haptic_sense}) and the ease with which the thumb can be opposed to the index and middle fingers compared to the other fingers.