The U.S. Army’s “Lumberjack” drone completed flight testing and verified GPS-free magnetic field navigation for the first time

The "Lumberjack" drone has completed flight testing. (Picture taken from Northrop Grumman official website)

If the GPS signal is severely interfered with in modern battlefields, how should the drone continue to navigate? The "Lumberjack" drone developed by Northrop Grumman (hereinafter referred to as Northrop Grumman) in the United States has completed flight testing recently and was equipped with the AQNav magnetic field navigation system of the start-up company SandboxAQ for the first time to verify the feasibility of using the earth's magnetic field for navigation in a GPS-denied environment.

According to the American aviation and military website "The Aviationist", this test is not to allow AQNav to replace the existing navigation system, but to add an independent positioning source. AQNav uses quantum sensing technology to detect changes in the earth's magnetic field, and then compares the magnetic field data to determine the location. It does not need to rely on GPS or ground navigation facilities, and can also be used with inertial navigation and visual navigation systems.

"Lumberjack" belongs to the "Group 3" unmanned aerial vehicle system (UAS) in the U.S. military classification. According to this classification standard, such drones must weigh less than 600 kilograms, fly at an altitude less than 5,500 meters, and have a speed between 185 and 462 kilometers per hour. This type of drone adopts a modular design and can be equipped with different equipment according to the mission. Northrop Grumman's public missions include electronic warfare, intelligence, surveillance and reconnaissance, tactical data link and precision strike.

It took less than 14 months for the drone to develop from concept to first flight, and the AQNav integration test was completed about one month after the test goal was established.

During the test, AQNav operated independently of the Lumberjack's original GPS system to simulate a situation where GPS was denied. SandboxAQ stated that AQNav’s navigation performance in relevant tests was better than relying solely on inertial navigation. This is because position errors will continue to accumulate after inertial navigation loses external correction for a long time, and magnetic navigation can provide another positioning reference to help correct such drifts.

The core of AQNav is not a "quantum computer", but the use of quantum sensing technology to detect the earth's magnetic field. SandboxAQ said this system can provide additional positioning information in open oceans, environments with few terrain features or limited visual navigation. However, the specific flight location and performance data of this test have not been made public.

Northrop Grumman said that the "Lumberjack" will have follow-up flight tests later this year and next year to continue to verify its autonomous flight and navigation capabilities. This test is an actual flight verification of AQNav on an unmanned vehicle. Whether it will be further used in the future still depends on the results of subsequent tests.