UAVs low-altitude visual tracking of unburied pipeline by the designed variant PID controller and position controller

This paper presents a control mechanism based on the actual distance between the Unmanned Aerial Vehicles (UAV) and the tracking structure for UAV visual tracking of pipeline on the ground in a low altitude. The technique includes two parts: structure identification and navigation control. The unburied pipeline is considered as a simple line in 2D image, then the Canny Edge Detector (CED) and Probabilistic Hough Transformation (PHT) are used in image processing to detect edges, identify the pipeline and extract useful parameters (angle and distance in image). For autonomous tracking, the response time, flight stability and tracing accuracy are influenced by the navigation and control performance severely. Thus in this paper the position controller is designed which can calculate the actual distance between the UAV body frame and the detected structure, and the UAV position is regulated by the variant PID controller until the UAV is flying exactly over the pipeline on ground.