A georeferencing of the collected data is required for many unmanned aerial vehicle (UAV)-based remote sensing applications in the fields of surveying, precision farming, infrastructure inspection or geography. This georeferencing can generally be done indirectly using ground control points, or directly using an on-board sensor system. Since an indirect georeferencing is very time consuming and also not available in real time many users would prefer a direct georeferencing. However, UAVs do mostly only have a C/A code GPS and a low-cost IMU on board. Even if this sensor combination enables a rough navigation of the UAV it does not allow for a precise direct georeferencing. Thus, the development of a precise direct georeferencing system for lightweight unmanned aerial vehicles is currently in great demand. In this contribution a new developed direct georeferencing system for lightweight UAVs is presented, which is designed to (1) enable a precise position and attitude determination (position accuracy Ï〈5cm, attitude accuracy Ï〈1deg), (2) to be applicable on lightweight UAVs and (3) to be real-time capable for sampling rates 〉10 Hz. Generally, the system combines a dual-frequency GPS receiver, a tactical grade IMU, a single-frequency GPS receiver and a real-time processing unit on one board. Both, the RTK-GPS (real-time kinematic) and the attitude determination software are in-house developed and show good performances in first flight tests.
550 Earth sciences