  Current approaches in human-aware or social robot navigation address the
humans that are visible to the robot. However, it is also important to address
the possible emergences of humans to avoid shocks or surprises to humans and
erratic behavior of the robot planner. In this paper, we propose a novel
approach to detect and address these human emergences called `invisible
humans'. We determine the places from which a human, currently not visible to
the robot, can appear suddenly and then adapt the path and speed of the robot
with the anticipation of potential collisions. This is done while still
considering and adapting humans present in the robot's field of view. We also
show how this detection can be exploited to identify and address the doorways
or narrow passages. Finally, the effectiveness of the proposed methodology is
shown through several simulated and real-world experiments.
