Flight demonstration of multi-UAV CDGPS and vision-based sensing for high accuracy attitude estimation

This paper presents a cooperative navigation technique which exploits relative vision-based sensing and carrier-phase differential GPS (CDGPS) between antennas embarked on different flying platforms, to improve UAV attitude estimation in real time or in post-processing phase. The focus is set on outdoor environments, hence it is assumed that all vehicles are under nominal GPS coverage. The logical architecture and the main processing steps are highlighted with particular focus on the CDGPS processing. The experimental setup used to evaluate the proposed approach comprises two multi-rotors and two ground antennas. Results from flight tests are presented in which both code-based differential GPS (DGPS) and CDGPS solutions are analyzed. In addition, the attitude solution obtained by integrating CDGPS and vision (CDGPS/Vision) is compared with attitude estimates provided by the onboard autopilot system and with those obtained by adopting a DGPS/Vision approach.