Fully automatic taxiing, takeoff and landing of a UAV based on a single-antenna GNSS receiver

This paper presents fully automatic control of an unmanned aerial vehicle (UAV) from taxiing and takeoff to landing based on a single-antenna GPS receiver. In this paper, inertial sensors such as gyros and accelerometers are not used at all to show the full potential of a single-antenna GPS receiver based attitude determination system. DGPS is implemented to give high accuracy position information for automatic taxiing, landing and takeoff on the runway. For a fixed wing aircraft, under the assumption of coordinated flight, the attitude information called as pseudo-attitudes can be estimated from the measurements of a single-antenna GPS receiver. Therefore full state variables for the automatic control can be obtained from single-antenna GPS receiver. In addition to GPS receiver, only an airspeed sensor is added because the velocity relative to the air is very important during landing and takeoff. The forward velocity is replaced with the airspeed obtained from Pitot tube. From linearized equations of motions around the steady state, LQR controllers for takeoff and landing are built. In particular, the flare controller that controls the pitch, altitude and airspeed of a UAV is designed. During flight tests, the aircraft taxies and takes off the runway, follows the predefined waypoint path, and then lands on the runway along the curved approach path, all fully automatically. Based on flight test results, a single-antenna GPS receiver can be used as a main sensor for a backup or a low-cost control system of UAVs