High-Precision Fixated Hovering and Pinpoint Landing of Quadrotors by Visual Navigation

One of the key requirements in many UAV applications is the capability of precise positioning and pinpoint landing. Precise positioning is essential for maintaining task-advantageous positions of UAV relative to a ground object with minimum deviation, and is crucial for task actions, such as geo-referencing, image capturing, and payload delivery. Pinpoint landing helps assure successful task conclusion and machine safety. In this paper, we present a technical approach to achieve precise positioning, fixated hovering, and pinpoint landing by autonomous visual navigation. Different visual processing methods, such as fiducial detection, object tracking, and visual odometry, are combined and integrated with navigation control. A visual-based autonomous control system has been developed and field tested with successful performance. The system is capable of achieving high-precision positioning with visual navigation in the process of changing altitude. The average lateral deviation at 100-meter altitude by a drone product with better flight stability is only 0.25 meter.