The limited load capacity and power resources of small-scale fixed-wing drones mean that it is difficult to employ internal high-precision inertial navigation devices to assist with the landing procedure. As an alternative, this paper proposes an attitude measurement system based on a monocular camera. The attitude angles are obtained from a single captured image containing five coded landmark points using the radial constraint method and three-dimensional coordinate transformations. The landing procedure is simulated for pitch angles from -15 ∘ to -40 ∘ , roll angles from -15 ∘ to +15 ∘ and yaw angles from -15 ∘ to +15 ∘ . For roll and pitch angles of approximately 0 ∘ and -25 ∘ , respectively, the accuracy of the method reaches 0.01 ∘ and 0.04 ∘ . This UAV attitude measurement system obtains an attitude angle by a single captured image, which has great potential for assisting with the landing of small-scale fixed-wing UAVs.
Keywords: UAV; attitude angle; coded target; coordinate transformation; monocular vision; optical measurement.