Beamforming-Based Acoustic Source Localization and Enhancement for Multirotor UAVs

The problem of acoustic source localization and signal enhancement through beamforming techniques is especially challenging when the acoustic recording is performed using microphone arrays installed on multirotor unmanned aerial vehicles (UAVs), The principal source of disturbances in this class of devices is given by the high frequency, narrowband noise originated by the electrical engines, and by the broadband aerodynamic noise induced by the propellers. A solution to this problem is investigated, which employs an efficient beamforming-based spectral distance response algorithm for both localization and enhancement of the source. The beamforming relies on a diagonal unloading (DU) transformation. The proposed algorithm was tested on a multirotor micro aerial vehicle (MAV) equipped with a compact uniform linear array (ULA) of four microphones, perpendicular to the rear-front axis of the drone. The array is positioned slightly above the plane of propellers, and centered with respect to the drone body. The experimental results conducted in stable hovering conditions are illustrated, and the localization and signal enhancing performances are reported under various noise conditions and source characteristics.