  In this paper, we present a path planner for low-altitude terrain coverage in
known environments with unmanned rotary-wing micro aerial vehicles (MAVs).
Airborne systems can assist humanitarian demining by surveying suspected
hazardous areas (SHAs) with cameras, ground-penetrating synthetic aperture
radar (GPSAR), and metal detectors. Most available coverage planner
implementations for MAVs do not consider obstacles and thus cannot be deployed
in obstructed environments. We describe an open source framework to perform
coverage planning in polygon flight corridors with obstacles. Our planner
extends boustrophedon coverage planning by optimizing over different sweep
combinations to find the optimal sweep path, and considers obstacles during
transition flights between cells. We evaluate the path planner on 320 synthetic
maps and show that it is able to solve realistic planning instances fast enough
to run in the field. The planner achieves 14% lower path costs than a
conventional coverage planner. We validate the planner on a real platform where
we show low-altitude coverage over a sloped terrain with trees.
