Ultra-tightly coupled GNSS/INS for small UAVs

This paper describes an ultra-tight integration of a Global Navigation Satellite System (GNSS) receiver and an Inertial Navigation System (INS) for small Unmanned Aerial Vehicles (UAVs). The system is based on a low-cost and low-weight GNSS Intermediate Frequency (IF) sampler which has been fitted onto a small UAV. The storage of IF samples together with measurements from an Inertial Measurement Unit (IMU) has allowed the authors to process an Ultra-Tightly Coupled (U.T.C.) GNSS/INS solution from real data collected with a small UAV. The focus of this paper has been to investigate the potential benefits in signal tracking during flights below dense foliage and tree canopies by using the developed U.T.C. system. The obtained results have been compared to a scalar GNSS receiver and a high-grade commercial reference receiver and have showed significant improvements in tracking capabilities.