A low cost GPS/INS sensor for small UAVs augmented with multiple GPS antennas

In this paper, a tightly coupled GPS/INS based on low cost MEMS sensors with multiple GPS antennas providing highly accurate attitude of a small UAV is proposed. The attitude accuracy of the typical GPS/INS sensor is limited to 1 deg-3 deg because of the instability of MEMS inertial sensors. The higher attitude accuracy can be obtained by a GPS compass using the carrier phase measurements. However, the fast and reliable ambiguity resolution using the low cost GPS L1 receiver modules is highly challenging for the highly maneuverable small UAV. For the proposed method, a tightly coupled GPS/INS is also tightly integrated with the GPS compass. The effective and reliable ambiguity search can be performed based on the estimated attitude by GPS/INS with a couple of constraints for the base line vector. The performance of the GPS/INS sensor on the flight is evaluated by the hardware-in-the-loop simulations using GPS RF simulator, and the field test. The heading accuracy better than 0.12 deg (ls) was confirmed.