In the 2012 sci-fi film Prometheus, scientists release small drones into a mysterious tunnel complex to create a detailed 3D map of the caverns in minutes. Australian researchers plan to use a similar approach to explore parts of old mines that are unsafe to visit.
The drones, which are controlled by a pilot, will be able to carry out safety checks by monitoring the build-up of water and checking the extent of roof collapses, and search for valuable mineral deposits that may have been missed. They are being developed by Craig Lindley and his colleagues at the Commonwealth Scientific and Industrial Research Organisation, Australia’s government research agency.
The researchers’ model is based on a commercial quadcopter. It has powerful LED lights, cameras and sonar. Initially, they tried flying it using the drone’s on-board camera to guide them, an approach known as first-person-view (FPV) piloting. But this isn’t ideal for long journeys navigating labyrinthine mines without hitting the walls.
“FPV makes operating really difficult, since the space is confined and seeing in just one direction doesn’t give you good situational awareness in terms of distance to anything in other directions,” says Lindley.
So the team developed computer software called VoxelNet, which creates a 3D model of the surrounding area based on video imagery sent from the drone to a laptop. This gives the navigator a virtual view of the drone in its environment, so they can see where it is in relation to floors and walls while also looking for minerals and safety hazards.
It currently takes 20 minutes to map a 10-metre stretch of tunnel using the video data – but there may be a more efficient way.