  Recent technological advancements in small-scale unmanned aerial vehicles
(UAVs) have led to the development of companion UAVs. Similar to conventional
companion robots, companion UAVs have the potential to assist us in our daily
lives and to help alleviating social loneliness issue. In contrast to ground
companion robots, companion UAVs have the capability to fly and possess unique
interaction characteristics. Our goals in this work are to have a bird's-eye
view of the companion UAV works and to identify lessons learned and guidelines
for the design of companion UAVs. We tackle two major challenges towards these
goals, where we first use a coordinated way to gather top-quality human-drone
interaction (HDI) papers from three sources, and then propose to use a
perceptual map of UAVs to summarize current research efforts in HDI. While
being simple, the proposed perceptual map can cover the efforts have been made
to realize companion UAVs in a comprehensive manner and lead our discussion
coherently. We also discuss patterns we noticed in the literature and some
lessons learned throughout the review. In addition, we recommend several areas
that are worth exploring and suggest a few guidelines to enhance HDI researches
with companion UAVs.
