French researchers are developing a kind of balloon that will explore the room hidden deep inside.
For more context, see The robot explores the pyramid.
Airship robot.
Unmanned aircraft are designed to squeeze through 4cm wide holes before expanding and bulging on racks.
The team chose a balloon model instead of the conventional multi-engine unmanned aircraft, because this design is safer for the surrounding environment while exploring.
Unmanned aircraft can access obstacles without damaging the building.