Automatic Landing without GPS
Abstract: Sagem Défense et Sécurité (now Safran Electronics & Defense), a French space and defense company of the SAFRAN group, is working on the next generation of Unmanned Aerial System (UAS). This UAS features a fully automatic Unmanned Aerial Vehicle (UAV) equipped with a state-of-the-art navigation system. This navigation system relies mainly on a high-accuracy Inertial Measurement Unit (IMU) coupled with a GPS receiver. But the GPS is known to be easy to jam, either naturally (solar flare for example) or intentionally. In the event of a loss of GPS signal, the navigation system is not able anymore to provide accurate position and speed information to the Flight Controller (FC). Deprived of reliable position and speed information the FC is not able to guide the UAV safely to the ground. So the goal of the project detailed in this report is to add to the existing UAS the ability to land safely in case of a GPS loss. At the core of the solution described in this report is a sensor fusion algorithm taking as input inertial, vision based, barometric, laser and azimuthal measurements. The filter is using all these measurements to establish reliable position and speed estimates. Even if very reliable systems enabling automatic landing without GPS exist today; they all require heavy and expensive ground equipment. This is why SAGEM decided to develop its own solution using more embedded sensors and less ground equipment. This is a first step toward a fully embedded automatic landing system nondependent on GPS availability, a very active field of research today. All the tests done during the thesis and presented in this report shows the efficiency and robustness of this solution.
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