Acoustic-enhanced local bearing estimation using low-cost microphones for Micro Air Vehicle swarms

Abstract

Micro Air Vehicle (MAV) swarms are often constrained by limited onboard processing capabilities and payload capacity, restricting the use of sophisticated localization systems. Lightweight ultra-wideband (UWB) ranging techniques are commonly used to estimate inter-vehicle distances, but they do not provide local bearing information—essential for precise relative positioning. Inspired by bat echolocation in low-visibility environments, we propose an acoustic-enhanced method for local bearing estimation designed for low-cost MAVs. Our approach leverages ambient acoustic signals naturally emitted by a target MAV in flight, combined with UWB distance measurements. The acoustic data is processed using the Frequency-Sliding Generalized Cross-Correlation (FS-GCC) method, enhanced with our analytical formulation that compensates for inter-channel switching delays in asynchronous, high-frequency sampling. This enables accurate Time Difference of Arrival (TDOA) estimation, even with compact microphone arrays. These TDOA values, along with known microphone geometry and UWB data, are integrated into our geometric model to estimate the bearing of the target MAV. We validate our approach in a controlled indoor hall across two experimental scenarios: static-bearing estimation, where the target MAV hovers at predefined angular positions (0°, ±30°, ±45°, ±60°), and dynamic-bearing estimation, where it flies across angles at varying velocities. The results show that our method yields reliable TDOA measurements compared to classical and machine learning baselines, and produces accurate bearing estimates in both static and dynamic settings. This demonstrates the feasibility of our low-cost acoustic-enhanced solution for local bearing estimation in MAV swarms, supporting improved relative navigation and decentralized perception in GPS-denied or visually degraded environments.

Keywords

Local bearing estimation / MAV swarms / Sound source localization / Microphone array

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