Scanning LiDAR for telescope-based UAV localization

Abstract

In recent years, technological advancements have made Unmanned Aerial Vehicles (UAVs) more versatile, affordable, and accessible. However, alongside these benefits, growing safety concerns have emerged due to incidents that highlight their potential risks. The number of drone-related accidents near high-risk areas such as airports and industrial facilities has notably increased. To mitigate these threats, advanced detection and tracking systems are crucial. This challenge is typically addressed by multispectral systems, which integrate multiple sensors into a single holistic platform, utilizing various detection principles to provide complementary information. These systems commonly include sensors such as radar, radio frequency, acoustic, and electro-optical devices. Precise 3D localization of a target is critical when countermeasures are required. For this purpose, Light Detection and Ranging (LiDAR) sensors are highly effective, providing exceptional accuracy over distances of several kilometers. Integrating LiDAR with large receiver apertures, like optical telescopes, extends its range while allowing the use of cost-effective, low-power laser sources such as laser diode.This thesis focuses on the development of a telescope-based scanning LiDAR system to precisely localize small UAVs. The LiDAR measurement principle is based on the Time of Flight (ToF) method. The transmitter side consists of a laser diode with a peak power of 125 W and custom-designed collimation optics, while a Fast Steering Mirror (FSM) is used for beam scanning. The receiver consists of an Avalanche Photodiode (APD) detector integrated with a wide Field of View (FoV) telescope featuring a 300 mm aperture. Both the transmitter and receiver are mounted on a high-speed pan-tilt unit, enabling 360° coverage.The feasibility of the proposed system is demonstrated through a series of experiments targeting both static and dynamic objects. The system successfully localized small static targets measuring 0.35 × 0.15 m at a range of 286 m, achieving a localization uncertainty of 0.6 m. Additionally, the system is used to perform a 3D scan of the Freihaus building in the center of Vienna, achieving ranges exceeding 300 m. The system also proved effective in detecting a DJI Mini 2 UAV, with a diagonal size of 0.3 m. Furthermore, the system’s ability to track moving targets was validated, achieving over 70% localization probability at a maximum lateral relative speed of 67 m/s.