A review of GNSS-independent UAV navigation techniques

Application of UAVs (Unmanned Aerial Vehicles) in environments devoid of GNSS (Global Navigation Satellite System) service has motivated research into GNSS-independent navigation solutions. This paper presents an account of such solutions proposed within the last decade. Unlike most literature that abstract UAV navigation to mere localization, this work takes a bottom-up approach by assessing the navigation components namely perception, localization and motion planning presented in the selected literature. The review results indicate that only 16% of the research presented full navigation solutions, while the rest present one or several components thereof. Besides the account of navigation solutions, our other contributions include an adapted MTOW-based (Maximum Take-Off Weight) UAV classification scheme incorporating a nano-sized UAV class, technology maturity assessment of the reviewed GNSS-independent navigation solutions and analysis of integrity monitoring frameworks.