Design and implementation of an autonomous landing control system of unmanned aerial vehicle for power line inspection

UAVs (Unmanned Aerial Vehicles) have been widely used in power line inspections, but low autonomous cruise capacity of UAVs requires strict condition for operators and site while landing during UAV power line inspections. This paper presents an autonomous landing control technique for UAVs when charging at the electric towers based on vision positioning method. The proposed system consists of three modules: visual processing, positioning estimation and landing control. The desired position and direction can be obtained by ellipse fitting and Shi-Tomasi corner detection method after the landing pad was identified by affine constant moment and Support Vector Machine (SVM) in visual processing module. Extended Kalman Filter (EKF) is used for the fusion of inertial measurement with the position data estimated by camera imaging principle in positioning estimation module. A control strategy is designed to enable the UAV to land safely and reliably. The experimental results show that the position error of the landing is within 20cm, and the direction error is within 20 degrees, which basically meets the demand for autonomous landing.