Performance evaluation of low cost multi-antenna GPS/INS for small UAVs

This paper examines in-flight performance of a low-cost tightly coupled multi-antenna GPS/INS capable of producing highly accurate attitude of 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 LI 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 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. The verification of attitude accuracy for the small UAV is highly difficult because the weight of the high-performance reference GPS/INS exceeds the loading capabilities of the small UAV. In this paper, a photogrammetry based attitude verification technique is used for the performance evaluation.