Validation of a UAV-mounted GPR system for landmine and IED detection under operational conditions

In this contribution, the performance of a Ground Penetrating Radar (GPR) system mounted on board an Unmanned Aerial Vehicle (UAV) is analyzed. The ultimate goal of the system is to enable a safe, fast, and autonomous inspection of the subsoil to detect buried landmines and Improvised Explosive Devices (IEDs). Thanks to the integration of highly-accurate positioning sensors, the radar measurements are coherently combined using a Synthetic Aperture Radar (SAR) algorithm. Moreover, the SAR processing is complemented with several clutter mitigation techniques and, as a result, 3D high-resolution radar images of the subsurface with enhanced signal-to-clutter-ratio are retrieved. Several prototypes and different GPR architectures (conventional Down-Looking and distributed Forward-Looking/Down-Looking configurations) have been extensively tested in realistic scenarios (similar to operational conditions). In order to properly assess the detection capabilities of the prototypes, numerous metallic and non-metallic targets (antipersonnel and antitank landmines, and IEDs such as jugs and pressure plates) have been buried under different conditions (dry and wet fields, dirt roads, sloped terrains). The results of these experiments show that a high probability of detection can be achieved for targets with a diameter larger than 10 cm, either metallic or non-metallic, even under challenging operational conditions. In addition, analyzing the retrieved 3D radar images, it can be also concluded that the proposed clutter mitigation techniques are essential to achieve such high detection capabilities, especially when dealing with low-metal content devices. These techniques also allow to infer the shape of the buried targets, paving the way towards automatic target recognition.