“…We consider the problem of autonomously driving a mobile robot through an unknown and unstructured 3D tunnel-like environment. This task is elemental for many applications of mobile robotics such as inspection and servicing of storm runoff networks, channelized aquifers, mines, bypass tunnels for dams, pipelines in sewer networks, power plants, factories, petrochemical, water supply and fluid transportation industries [8,16,[18][19][20]24,28], underwater environmental studies and archeology, exploring flooded cenotes and ancient cisterns [7,14,27], indoor and city exploration, rescue, and surveillance by micro air vehicles (MAV) [3,21], to name just a few.…”