An Innovative Positioning-Based Precision Landing System for Unmanned Aerial Vehicles Operating in Complex Rugged Terrain

Abstract

The growing demand for safe autonomous landing of unmanned aerial vehicles (UAVs) in complex terrain requires reliable guidance throughout the final descent, even under degraded Global Navigation Satellite System (GNSS) conditions, where intentional interference, signal obstruction, and residual positioning errors reduce navigation continuity. This paper presents a complementary navigation system combining a ground-based and an onboard MIMO Frequency-Modulated Continuous-Wave (FMCW) radar, providing estimation of slant range, relative velocity, and angular deviation independently of GNSS signal quality. Navigation errors and trajectory corrections are modeled in simulation, and the radar signal processing and localization algorithms are supported by laboratory measurements in an anechoic chamber and by UAV flight tests. The results show that the range, velocity and angular parameters of the radar are sufficient for guidance throughout the descent and that the slant range and height to the landing site are obtained directly, without reliance on satellite geometry. The system is designed around commercially available automotive radar modules, enabling cost-effective implementation with technologically mature hardware. The proposed concept is designed to support autonomous guidance of multirotor UAVs, fixed-wing platforms, and helicopters to a predefined landing site from stand-off distances of several hundred meters and establishes a foundation for mobile take-off and landing stations and hybrid navigation systems.