\chapter{Introduction}
\mainlabel{introduction}

\sectionstarbookmark{Wearable Haptics and Augmented Reality}

\subsectionstarbookmark{The Senses of Vision and Touch}

Touch is the only sense that allows not only to perceive the environment, but also to interact with it. Explain how both vision and touch are complementary and important for combined perception and interaction with the environment.


\subsectionstarbookmark{Wearable Haptics and the Augmentation of Touch}

Present what is wearable haptics, how they can be used to augment the sense of touch~\autocite{pacchierotti2017wearable}. Detail then how they have been used with virtual reality, but how little they have been used with augmented reality.


\subsectionstarbookmark{Augmented Reality is Mostly Visual}

Explain what is augmented reality, and why it is important to use wearable haptics with it.


\sectionstarbookmark{Research Challenges}

Explain what are the challenges of using wearable haptics with immersive augmented reality.


\sectionstarbookmark{Approach and Contributions}

The objective of this thesis is to understand how augmented visual and wearable haptic feedback compare and complement each other in the context of hand interaction with augmented and virtual objects.
%
Our approach is to
%
\begin{enumerate*}[label=(\arabic*)]
    \item design immersive and wearable multimodal visuo-haptic renderings that augment both the objects being interacted with and the hand interacting with them, and
    \item evaluate experimentally in user studies how these renderings affect the perception and manipulation of these objects using psychophysical, performance, and user experience methods.
\end{enumerate*}
%
We consider two main axes of research:
%
\begin{enumerate*}[label=(\Roman*)]
    \item augmenting the visuo-haptic texture perception of tangible surfaces, and
    \item improving virtual object manipulation with visuo-haptic augmentations of the hand.
\end{enumerate*}
%
Our contributions in these two axes are summarized in \figref{xxx}.

% TODO: Add figure with the two axes of research and the contributions


\subsectionstarbookmark{Augmenting the Visuo-Haptic Texture Perception of Tangible Surfaces}



\subsectionstarbookmark{Improving Virtual Object Manipulation with Visuo-Haptic Augmentations of the Hand}

% Touch allows to perceive the environment and interact with it, thus it motivates these two axes of research.

% it's a mix of augmented reality, virtual reality, vibrotactile feedback for visuo-tactile augmentation of the real world. Such multimodal rendering raise many questions on how to design, how renderings interact and complete each other, to give one perception

\sectionstarbookmark{Overview}

%Present the contributions and structure of the thesis.

This thesis is structured in four parts:
%
\begin{itemize}
    \item \partref{context} describes the context and background of our research.
          \begin{itemize}
              \item This first current \textit{Introduction} chapter presents the research challenges, and the objective, approach, and contributions of this thesis.
              \item \chapref{related_work} provides an overview of related work on the visuo-haptic perception of surfaces and the manipulation of objects. First, it presents how vision and touch senses allow us to perceive and interact with everyday objects. Second, it details how haptic and AR/VR devices can render virtual touch and vision sensations, respectively, with a focus on vibrotactile feedback, immersive AR headsets, and their combination. Finally, it shows how visual, haptic and visuo-haptic feedback can be leveraged to improve the manipulation of virtual objects.
          \end{itemize}
    \item \partref{perception} describes our contributions to the first axis of research, augmenting the visuo-haptic texture perception of tangible surfaces. \chapref{xr_perception} first details a system for rendering visuo-haptic virtual textures on tangible surfaces using an immersive AR/VR headset and a wearable vibrotactile device. It then presents a user study that evaluates how different the perception of these textures is in AR \vs VR and when touched by a virtual hand \vs one's own hand.
\end{itemize}
