Singapore’s Indoor Drones Can Now Look Through Walls

You’ve seen the movies where special forces storm an apartment, swiftly clearing rooms one by one and taking down all the bad guys.

In reality, it is a lot more complex than it seems.

Even if commanders have the floor plan, it does not reveal the number of armed assailants in the quarters. And what if the layout has changed?

This is where indoor mapping comes in. Using just two drones, a team of DSO engineers have constructed a 3D map of a previously uncharted area in
real time.

Working simultaneously, their indoor mapping drones have successfully mapped DSO’s library — around the size of a 5-room flat — in just 1min 30s.
Taking the First Step

These drones can explore and navigate autonomously without any prior set-up or the use of the Global Positioning System.

With their indoor drone (top right), the team from the Singapore Ministry of Defence has successfully mapped the DSO library (above), an area roughly equivalent to a 5-room flat. (Photo courtesy: SPore MoD.)

This is an impressive technological leap, considering that most indoor mapping drones require operators to set up beacons in the room for the drone to locate where it is. “But this is not practical for us; we cannot expect soldiers to go into a hostile area and set up (equipment),” said flight control engineer and project lead Poh Yze Yang.

Instead, DSO’s indoor drone uses a smart navigation algorithm that allows it to map in real time and track its own location based on its distance to the walls and objects it is mapping. The team’s algorithm also allows multiple drones to work in tandem and contribute to the same mapping image so that they can map faster.
Information from both drones are then consolidated and sent to a command post in real time. The result is a precise 3D model of the apartment’s interior, rendered in a true-to-scale grid.

“We want to use unmanned assets to mitigate risks for our soldiers, especially in urban fighting where the casualty rate can be quite high,” said Mr Poh, 31.

With this remote surveillance capability, commanders can make better decisions on their next course of action and even the number of soldiers to deploy.

The drones also have a “smart command and control” mode for commanders to direct it to areas of interest when needed. For example, the drones can be instructed to inspect the corner of a room where terrorists are suspected to be hiding at.

Mapping Faster

With their indoor drone (top right), the team has successfully mapped the DSO library (above), an area roughly equivalent to a 5-room flat.

In order to improve the drone’s speed and accuracy, the DSO team will enhance the system with stereo cameras — using two cameras to give the depth between objects and thus form a 3D image.

This replaced the Time of Flight sensors which the team initially used — these sensors emit infrared light in order to measure its distance from an object. While the concept worked, mapping was slower and enemy forces could detect the infrared emissions.

“We’re trying to map faster because time is critical when it comes to operations, (such as) counter-terrorism missions. This upgrade brings us closer to it being applied for military use,” noted Mr Poh.

The stereo camera can also be switched to use low- light sensors, should there be
a need to enter a dark room.

The project is part of a DSO initiative to get young engineers to brainstorm simple and effective solutions to complex problems, explained Mr Poh. The team is then led by senior engineers like him to explore the feasibility and cost-saving applications of these ideas.

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