Passive Retroreflector-Based Optical Multilateration for Three-Dimensional UAV Localization
This paper presents a three-dimensional (3D) unmanned aerial vehicle (UAV) localization framework based on optical round-trip time (RTT) ranging and multilateration. Multiple fixed optical transmitters estimate distances via laser reflections from a UAV equipped with passive retroreflectors, enabling infrastructure-assisted localization without active onboard hardware or additional energy consumption. The system model incorporates additive Gaussian ranging noise, and the localization problem is formulated as a non-linear least-squares estimation problem. Monte Carlo simulations demonstrate a median localization error of approximately 0.055 m, with 90% and 95% of errors below 0.11 m and 0.14 m, respectively, under centimeter-level ranging noise. The results show that localization accuracy depends on transmitter geometry and UAV altitude, with errors increasing at higher altitudes and under larger noise levels. Furthermore, increasing the number of transmitters improves accuracy through enhanced measurement redundancy. The results provide practical design guidelines for optical UAV tracking systems.