erwan/phd-thesis
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

WIP related work

Browse Source
This commit is contained in:
Erwan Normand
2024-09-13 14:19:51 +02:00
parent eb71fd42ac
commit d576566c9c
6 changed files with 53 additions and 63 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
1-introduction/related-work/1-haptic-hand.tex
View File

@@ -29,6 +29,14 @@ In contrast, Merkel and Ruffini receptors, known as slow-adapting (SA), have a s
The \emph{size of the receptor} determines the area of skin that can be sensed by a single nerve ending.
Meissner and Merkel receptors have a small detection area (named Type I) and are sensitive to fine skin deformations, while Ruffini and Pacinian receptors have a larger detection area (named Type II).
The density of mechanoreceptors varies according to skin type and body region.
\emph{Glabrous skin}, especially on the face, feet, hands, and more importantly, the fingers, is particularly rich in cutaneous receptors, giving these regions great tactile sensitivity.
The density of the Meissner and Merkel receptors, which are the most sensitive, is notably high in the fingertips~\cite{johansson2009coding}.
Conversely, \emph{hairy skin} is less sensitive and does not contain Meissner receptors, but has additional receptors at the base of the hairs, as well as receptors known as C-tactile, which are involved in pleasantness and affective touch~\cite{ackerley2014touch}.
There are also two types of thermal receptors implanted in the skin, which respond to increases or decreases in skin temperature, respectively, providing sensations of warmth or cold~\cite{lederman2009haptic}.
Finally, free nerve endings (without specialized receptors) provide information about pain~\cite{mcglone2007discriminative}.
\begin{tab}{cutaneous_receptors}{Characteristics of the cutaneous mechanoreceptors.}[
Adaptation rate is the speed and duration of the receptor's response to a stimulus. Receptive size is the area of skin detectable by a single receptor. Sensitivities are the stimuli detected by the receptor. Adapted from \textcite{mcglone2007discriminative} and \textcite{johansson2009coding}.
]
@@ -44,14 +52,6 @@ Meissner and Merkel receptors have a small detection area (named Type I) and are
\end{tabularx}
\end{tab}
The density of mechanoreceptors varies according to skin type and body region.
\emph{Glabrous skin}, especially on the face, feet, hands, and more importantly, the fingers, is particularly rich in cutaneous receptors, giving these regions great tactile sensitivity.
The density of the Meissner and Merkel receptors, which are the most sensitive, is notably high in the fingertips~\cite{johansson2009coding}.
Conversely, \emph{hairy skin} is less sensitive and does not contain Meissner receptors, but has additional receptors at the base of the hairs, as well as receptors known as C-tactile, which are involved in pleasantness and affective touch~\cite{ackerley2014touch}.
There are also two types of thermal receptors implanted in the skin, which respond to increases or decreases in skin temperature, respectively, providing sensations of warmth or cold~\cite{lederman2009haptic}.
Finally, free nerve endings (without specialized receptors) provide information about pain~\cite{mcglone2007discriminative}.
\subsubsection{Kinesthetic Sensitivity}
\label{kinesthetic_sensitivity}
@@ -162,7 +162,7 @@ This can be explained by the sensitivity of the fingertips (see \secref{haptic_s
\subsection{Haptic Perception of Object Properties}
\label{object_properties}
The active exploration of an object with the hand is performed as a sensorimotor loop: The exploratory movements guide the search for and adapt to sensory information, allowing to construct a haptic perception of the object's properties.
The active exploration of an object with the hand is performed as a sensorimotor loop: The exploratory movements (see \secref{exploratory_procedures}) guide the search for and adapt to sensory information (see \secref{haptic_sense}), allowing to construct a haptic perception of the object's properties.
There are two main types of \emph{perceptual properties}.
The \emph{material properties} are the perception of the roughness, hardness, temperature and friction of the surface of the object~\cite{bergmanntiest2010tactual}.
The \emph{spatial properties} are the perception of the weight, shape and size of the object~\cite{lederman2009haptic}.
@@ -296,7 +296,9 @@ The amplitude of the frictional force $F_s$ is proportional to the normal force
\label{eq:friction}
F_s = \mu \, F_n
\end{equation}
The perceived intensity of friction is thus that of the friction coefficient $\mu$~\cite{smith1996subjective}.
The perceived intensity of friction is thus roughly related to the friction coefficient $\mu$~\cite{smith1996subjective}.
However, it is a complex perception because it is more determined by the micro-scale interactions between the surface and the skin: It depends on many factors such as the normal force applied, the speed of movement, the contact area and the moisture of the skin and the surface~\cite{adams2013finger,messaoud2016relation}.
In this sense, the perception of friction is still poorly understood~\cite{okamoto2013psychophysical}.
\begin{subfigs}{smith1996subjective}{Perceived intensity of friction of different materials by active exploration with the finger~\cite{smith1996subjective}. }[
\item Measurements of normal $F_n$ and tangential $F_t$ forces when exploring two surfaces: one smooth (glass) and one rough (nyloprint). The fluctuations in the tangential force are due to the stick-slip phenomenon. The coefficient of friction $\mu$ can be estimated as the slope of the relationship between the normal and tangential forces.
@@ -307,13 +309,10 @@ The perceived intensity of friction is thus that of the friction coefficient $\m
\subfig{smith1996subjective_2}
\end{subfigs}
Mais la perception de la friction est complexe car ce n'est pas seulement une propriété haptique de la surface.
Elle est, en effet, déterminée par les interactions à l'échelle micro entre la surface et la peau, et dépend donc de la force normale appliquée, de la vitesse du mouvement, de l'aire du contact et de l'humidité de la peau et de la surface~\cite{adams2013finger,messaoud2016relation}.
En ce sens, la perception de cette propriété est encore mal comprise~\cite{okamoto2013psychophysical}.
C'est pourtant une perception fondamentale pour la saisie et la manipulation d'objets : les forces de frottements permettent de tenir fermement l'objet en main pour éviter qu'il ne glisse, et la perception de la friction permet également d'ajuster automatiquement et très rapidement la force à appliquer à l'objet pour le saisir~\cite{johansson1984roles}.
Si le doigt est anesthésié, l'absence de sensations cutanées empêche d'ajuster efficacement la force de préhension: Les forces de l'objet sur le doigt ne sont plus correctement perçues et les doigts appuient alors plus fermement sur l'objet en compensation mais sans réaliser une bonne opposition des doigts~\cite{witney2004cutaneous}.
Yet, it is a fundamental perception for grasping and manipulating objects.
The forces of friction make it indeed possible to hold the object firmly in the hand and prevent it from slipping
The perception of friction also allows us to automatically and very quickly adjust the force we apply to the object in order to grasp it~\cite{johansson1984roles}.
If the finger is anaesthetized, the lack of cutaneous sensation prevents effective adjustment of the gripping force: the forces of the object on the finger are no longer correctly perceived, and the fingers then press harder on the object in compensation, but without achieving good opposition of the fingers~\cite{witney2004cutaneous}.
\subsubsection{Temperature}
\label{temperature}