FMCW Radar-Aided Navigation for Unmanned Aircraft Approach and Landing in AAM Scenarios: System Requirements and Processing Pipeline.

This paper focuses on the use of Frequency-Modulated Continuous Wave radars as an aiding source to provide precision navigation during approach and landing operations in Advanced Air Mobility scenarios. Specifically, the radar system requirements are delineated through an analysis of operational constraints defined by regulatory guidelines, including approach trajectories and vertiport infrastructure to ensure compatibility with Urban Air Mobility scenarios. A preliminary radar design is proposed which is integrated within a multi-sensor navigation architecture including a GNSS receiver, an inertial measurement unit, and two cameras. The radar is designed to detect high-reflectivity targets placed in the landing area and uses a matching algorithm to associate these detections with their known positions, enabling reliable corrections to the aircraft navigation state. Radar measurements are tightly integrated into an Extended Kalman Filter alongside data from other sensors, refining the vehicle navigation state estimate and ensuring seamless transitions between long-range and short-range sensing modalities. A high-fidelity simulation environment validates the proposed multi-sensor architecture under different visibility conditions and accordingly disactivating the radar to validate its contribution. The results demonstrate significant improvements in navigation performance when the radar is integrated within the multi-sensor architecture thanks to its important role in providing accurate estimates at high ranges from the landing pattern and during low-visibility operations. The reported statistics of the multi-sensor architecture performance are compared with the assumed required navigation performance in the scenarios of interest, demonstrating the radar contribution and showing the effects of designed radar angular resolution on the multi-sensor architecture.