\chapter{Related Work}
\mainlabel{related_work}

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This chapter reviews previous work on the perception and manipulation of virtual and augmented objects directly with the hand, using either wearable haptics, \AR, or their combination.
First, we review how the hand senses and interacts with 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 review 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}