  Robot navigation in crowded public spaces is a complex task that requires
addressing a variety of engineering and human factors challenges. These
challenges have motivated a great amount of research resulting in important
developments for the fields of robotics and human-robot interaction over the
past three decades. Despite the significant progress and the massive recent
interest, we observe a number of significant remaining challenges that prohibit
the seamless deployment of autonomous robots in public pedestrian environments.
In this survey article, we organize existing challenges into a set of
categories related to broader open problems in motion planning, behavior
design, and evaluation methodologies. Within these categories, we review past
work, and offer directions for future research. Our work builds upon and
extends earlier survey efforts by a) taking a critical perspective and
diagnosing fundamental limitations of adopted practices in the field and b)
offering constructive feedback and ideas that we aspire will drive research in
the field over the coming decade.
