Eye on the sky: new drone detection technology advances national security

- Ottawa, Ontario

Aerial view of the team's basecamp.

Valcartier test range, Interconnect Bravo-Bravo basecamp. Credit: Michel Guitard, science visual documentation at DRDC.

Drones take up a lot of airspace around the world these days—filming movie scenes, delivering goods, gathering agricultural data, supporting search-and-rescue operations as well as conducting military surveillance, targeting and attack. Their sizes can range from small recreational units that fit into the palm of your hand to military drones weighing upwards of 600 kilograms. And the commercial drone market is expected to grow from over US$20 billion today to US$500 billion by 2028.

As their numbers surge, uncrewed aerial systems (UASs), commonly known as drones, will pose more hazards than ever, whether planned or unplanned. When photographing weddings and events, they could encroach on the public's privacy. While flying over airports, prisons or military facilities, they could compromise security. And in war zones, they can pose danger to lives, homes and infrastructure.

"Over the past year, we've seen a rapid evolution of UAS use on the battlefield in Ukraine," says Andrew Scheidl, Program Lead of the Multimedia Analytics Tools for Security program at the National Research Council of Canada (NRC). "Those developments will affect future deployments of the Canadian Armed Forces, but they will also migrate to other threat actors. Reliable detection and countermeasure systems will be increasingly important for military and public safety applications."

Orange drone being tested in the sky.

Autel Evo II FLIR drone. Credit: Michel Guitard, science visual documentation at DRDC.

In other high-profile incidents, the world has seen a drone crash onto the White House lawn, several circle around a nuclear power plant in France and others bomb a Ukrainian army weapons warehouse.

With the number of scenarios for illegal drone activities growing every day, the need for innovative drone-detection systems is intensifying. And in combat zones, having the ability to identify and counter enemy drones is particularly important.

A longstanding collaboration between the NRC and Defence Research and Development Canada (DRDC) sparked the development of a new approach to drone detection that disrupted the status quo, one that uses AI and classifies drones by their propeller speeds. The highly skilled team has brought all the necessary expertise to the table: optics, physics, signal processing, machine learning and vision, and neuromorphic systems.

AI helps dodge the perils and pitfalls of drone detection

Aerial view of a drone flying over the team's basecamp.

Matrice 200 drone carrying NRC prototype visual frequency detection system that was tested at Interconnect Bravo-Bravo basecamp. Credit: Michel Guitard, science visual documentation at DRDC.

While several methods of detecting drones have been in use for a long time, none are totally dependable, particularly in dense urban areas and forests. This is because radio frequency, acoustic and optical detection systems can be misled by noise in complex environments and cause false or missed detections. For example, tall buildings and trees can with interfere with the ability of visible-light and infrared cameras to match the appearance of a live drone to images in a large database of UAS models. As well, while ground-based radars detect drones efficiently, their reliability can be affected by the environment and geography. Using these radar systems is also an expensive approach that requires bulky equipment and a lot of power. In addition, some of them transmit an active signal, thus exposing the devices.

Controller being used to test and fly a drone.

Close-up Autel Evo II drone controller. Credit: Michel Guitard, science visual documentation at DRDC.

Over the past 4 years, an R&D team of engineers and scientists from the NRC's Digital Technologies Research Centre and the DRDC have developed an innovative technological solution for passively spotting drones in cluttered settings. It incorporates AI to accurately detect, track and characterize drones on the basis of the signal generated by their rotating propellers rather than by using an image bank. This method generates very few false alarms and accurately detects low-flying drones that use topography to evade discovery. The "signature" of a drone propeller can also be used to discriminate or classify aircraft by type, such as identifying it as a helicopter and not a drone.

The DRDC team initially lab-tested the feasibility of passive detection using drone characteristics. The next step was to develop energy-efficient detection algorithms and predict the performance of systems using different hardware. After some ground testing, the team built the first prototypes by combining the hardware and software and replacing some of the physical modelling of sensor responses with machine learning and AI technologies.

Changing the drone-detection game

For a week in October 2022, the team assessed the first 2 prototypes at the Valcartier, Quebec, military base.

"Our results clearly disrupted the status quo, which depended on image banks to identify drones," says Guillaume Gagné, Defence Scientist at the DRDC Valcartier Research Centre. "The test showed that this lightweight technology can be housed in a small box, consume very little power and—most importantly—guarantee excellent accuracy in a visually congested environment."

While the technology is not yet scalable for commercial use, the multi-talented research team is working on modifications that will take it to the next level.

"We're developing the next generation of the prototype that has recently been tested in collaboration with the DRDC and the Canadian Armed Forces," says Marc-Antoine Drouin, Senior Research Officer with the NRC's Computer Vision and Graphics team. "We expect to double the detection range, add a radio link to communicate detection and connect the system to command and control software—allowing full integration into the drone-detection ecosystem." The tests will pinpoint missing features or limitations that need to be addressed before it can be market-ready.

This success aligns with the DRDC's mandate to develop technology in support of the CAF's operational needs. "We are crafting a road map for a multi-year project with the NRC's Digital Technologies Research Centre to continue advancing the current prototype using emerging approaches and technologies," adds Guillaume.

He also points out that the 3-year project builds on the collaboration between these two government entities that goes back more than 75 years. This history creates the ideal partnership to support national defence and align military and civil security. Their continuing inventiveness will contribute to Canada's national security well into the future.

For a more in-depth look at the research behind the story, read the team's recent article, A Virtual Fence for Drones: Efficiently Detecting Propeller Blades with a DVXplorer Event Camera.

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