\chapter{Related Work}
\mainlabel{related_work}

\chaptertoc

This chapter reviews previous work on the perception and manipulation with virtual and augmented objects, directly with the hand, using either wearable haptics, \AR, or their combination.
%Experiencing a visual, haptic, or visuo-haptic \AE relies on one to many interaction loops between a user and the environment, as shown in \figref[introduction]{interaction-loop}, and each main step must be addressed and understood: the tracking and modelling of the \RE into a \VE, the interaction techniques to act on the \VE, the rendering of the \VE to the user through visual and haptic user interfaces, and, finally, the user's perception and actions on the overall \AE.
We first overview how the hand senses and acts on its environment to perceive and manipulate the haptic properties of real everyday objects.
Second, we present how wearable haptic devices and renderings have been used to augment the haptic perception of roughness and hardness of real objects.
Third, we introduce the principles and user experience of \AR, and overview the main interaction techniques used to manipulate virtual objects directly with the hand.
Finally, we describe how visual and haptic feedback have been combined to augment direct hand interaction in \AR, in particular using wearable haptics.

\input{1-haptic-hand}
\input{2-wearable-haptics}
\input{3-augmented-reality}
\input{4-visuo-haptic-ar}
\input{5-conclusion}
