High-Speed Magnetic Surveying for Unexploded Ordnance Using UAV Systems

• Published in: Remote sensing (Basel, Switzerland) Vol. 14; no. 5; p. 1134
• Main Authors: Kolster, Mick Emil, Wigh, Mark David, Lima Simões da Silva, Eduardo, Bjerg Vilhelmsen, Tobias, Døssing, Arne
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.03.2022
• Subjects: Aerial surveys; Airframes; Altitude; Birds; Coasts; Configuration management; Data collection; detection; Detonation; Explosives; Explosives detection; Gradiometers; inverse problem; inversion; Magnetic disturbances; Magnetic measurement; magnetism; Magnetometers; Model testing; Planning; Remote sensing; Sensors; Software; surveys; uncrewed aerial vehicle; Unexploded ordnance; Unmanned aerial vehicles; UXO; Denmark
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs14051134

Using Uncrewed Aerial vehicles (UAVs) to rapidly scan areas for potential unexploded ordnance (UXO) can provide an efficiency increase while minimizing detonation risks. We present a complete overview of how such mappings can be performed using scalar magnetometers, including initial sensor testing, time stamping validation, data positioning, noise removal, and source model inversion. A test survey was performed across disarmed UXO targets, during which three scalar magnetometers were towed in an airframe (“bird”) 10 m below a small (<25 kg) high speed (∼10 m/s) UAV to avoid magnetic disturbances from the UAV itself. Data were collected across ∼58 min of flight, with each sensor traversing ∼31.7 km to acquire dense data coverage across a 600 m × 100 m area. By using three individual magnetometers in the bird, UXO detection results across single-sensor data and several different multi-sensor configurations can be compared. The data obtained exhibited low apparent noise floors (on the order of tens of picoTesla) and retained a precision that enabled targeted modelling and removal of high-frequency noise with amplitudes of ±5 picoTesla. All of the different gradiometer configurations tested enabled recovery of most targets (including all major targets), although the horizontal configuration performed significantly worse in comparison.