Review for UAV Acoustic Positioning

In recent years, the rapid growth of “low, small and slow” UAVs (Unmanned Aerial Vehicles) and their uncontrolled flying have posed a serious threat to urban security and public safety. How to effectively locate “low, small and slow” UAVs in complex low-altitude situations has become an urgent social problem. Due to the blind spot and weak radiation intensity of radar and photoelectric detection, the effect of close range positioning is not ideal. Acoustic positioning, effectively compensates for the disadvantages of radar and photoelectric positioning methods due to its low sensor cost, flexible array placement and small positioning error. This paper summarized the acoustic positioning methods for UAVs. The spectrum of UAV noise was analyzed and it found that these noise signals have a strong line spectrum structure. These line spectra are rich in harmonic frequency components, have a high signal-to-noise ratio and are highly resistant to interference. Firstly, the acoustic characteristics of rotor noise were integrated to derive the capability of locating the UAV from both time and frequency domain perspectives. Secondly the principles of acoustic localization methods were introduced and the algorithm simulation results were given. It also compared the root mean square error of the time domain and frequency domain localization methods. Next, the implementation methods of acoustic-based localization of low-altitude UAVs in universities at home and abroad in recent years were counted, and it found that the planar array based on time difference of arrival (TDOA) is most widely used and has better localization effect. Finally, acoustic localization of low-altitude UAVs in the future was prospected.