A Low-Cost Tightly Coupled GPS/INS for Small UAVs Augmented with Multiple GPS Antennas

In this paper, we design and evaluate a low-cost multi-antenna GPS/INS capable of producing highly accurate attitude for small UAVs. The main disadvantage of low-cost GPS/INS based on MEMS inertial sensors is that the typical yaw angle accuracy is limited to 0.5-2 deg. In this regard, a GPS compass using carrier phase measurements can achieve higher attitude accuracy. However, fast and reliable ambiguity resolution using low-cost GPS L1 receiver modules is a challenging task for small and highly maneuverable UAVs. In the proposed method, a tightly coupled GPS/INS is tightly integrated with a GPS compass, which allows for an effective and reliable ambiguity search to be performed on the basis of the attitude as estimated by GPS/INS with a couple of constraints for the base line vectors. The in-flight performance of the proposed GPS/INS was verified through hardware-in-the-loop simulations and experimental flights.