  When does a robot planner need a map? Reactive methods that use only the
robot's current sensor data and local information are fast and flexible, but
prone to getting stuck in local minima. Is there a middle-ground between fully
reactive methods and map-based path planners? In this paper, we investigate
feed forward and recurrent networks to augment a purely reactive sensor-based
planner, which should give the robot geometric intuition about how to escape
local minima. We train on a large number of extremely cluttered worlds
auto-generated from primitive shapes, and show that our system zero-shot
transfers to real 3D man-made environments, and can handle up to 30% sensor
noise without degeneration of performance. We also offer a discussion of what
role network memory plays in our final system, and what insights can be drawn
about the nature of reactive vs. map-based navigation.
