Determination of UAV propellers speed with FMCW Radar: comparison with accelerometer data

Unmanned Aerial Vehicle (UAV) technology is rapidly spreading in different application fields. Unfortunately, UAVs may raise serious concerns regarding the safety of urban air space and nearby zones, either populated or densely industrialized ones, because of accidents or possible malicious intentions. Radar systems have been used to monitor the air space and detect flying targets since a long time, for both civil and military applications, but it could be possible to leverage their capability to measure vibrations by the micro-Doppler effect, to obtain additional information about a detected drone. In fact, as the rotation of drone propellers produces vibrations on its chassis, this work aims to investigate the possibility of determining the propellers’ rotational speed from drone chassis vibrations detected by a Frequency Modulated Continuous Wave (FMCW) Radar. The preliminary experiments here presented show promising results: the maximum difference in percentage between rotational speed values obtained by Radar and accelerometer signals is less than 6% in the two-blade configuration.