Vision-Aided Measurement Level Integration of Multiple GPS Receivers for UAVs

Akshay Shetty and Grace Xingxin Gao

Abstract:	Robust and reliable navigation of Unmanned Aerial Vehicles (UAVs) is an upcoming and promising field of research. In this paper we describe tightly-coupled initialization procedure using a monocular camera to resolve the GPS carrier phase integer ambiguities. This helps us obtain heading estimates during flight, using the GPS receivers. Further, we describe a sensor fusion structure which uses the measurements from multiple GPS receivers and multiple sensors on-board a UAV. We implement an unscented Kalman filter (UKF) to fuse information from the GPS receivers, the monocular camera, the inertial measurement unit (IMU) and the motor tachometers. In the filter we use pseudoranges and carrier phases from the GPS receivers, as opposed to directly using the position updates. Experiments were conducted outdoors with an Ascending Technologies Firefly hexacopter. We validate the integer ambiguity resolution by our tightly coupled initialization, and the robust sensor fusion structure.
Published in:	Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015) September 14 - 18, 2015 Tampa Convention Center Tampa, Florida
Pages:	834 - 840
Cite this article:	Shetty, Akshay, Gao, Grace Xingxin, "Vision-Aided Measurement Level Integration of Multiple GPS Receivers for UAVs," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 834-840.
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