Research On Autonomous Landing Technology Of Four-rotor UAV Mobile Platform Based On Visual Positioning

In recent years,with the continuous development of drones and related technologies,more and more drones are being used.The four-rotor is widely used in all aspects of life due to its small size and flexibility,and the extremely low requirements for the take-off site,such as the sprayed pesticide quadrotor drone in agriculture,the aerial quadrotor drone in life and Power inspection quadrotor drones and so on.As the most important landing process,it has always been the most concerned issue.Therefore,the research on the autonomous landing technology of the quadrotor UAV is particularly important.The autonomous landing of the four-rotor can reduce the difficulty of man-made control,and the identification and positioning of the landing target through the visual aided quadrotor avoids the problem of inaccurate positioning caused by GPS signal failure due to occlusion.This topic is taken from the unmanned aerial vehicle coordination project.The project requires that the four-rotor UAV can take off on its own,and enter the mission mode to perform the outbound operation after autonomous takeoff.At low power,the quadrotor can return spontaneously and land on a specific target for charging.In the project,it is considered that there may be a weak GPS signal or even a terminal in the work area,and a visual aided drone is required for visual positioning,and then landing is performed.The main research contents of the thesis are as follows:Firstly,according to the task requirements,the visually detected target position is designed as the feedback amount,and then the control signal of the four-rotor is calculated by the controller to control the overall structure of the four-rotor flight system.Then according to the overall structure of the system,considering the system accuracy requirements and the limitation of the calculation amount,the model of the main control computer and the model of the camera are selected.Secondly,according to the limitation of the amount of calculation,the target recognition and visual positioning method based on the marker is selected,and the corresponding marker generation and recognition algorithm research is carried out.In addition,the ROI is optimized for the algorithm by analyzing the target recognition algorithm.Then,the relative pose calculation is performed according to the identified target feature points,thereby obtaining the input signals of the quadrotor position and attitude controller.Finally,according to the mathematical model of the four-rotor UAV,the control structure diagram of the four-rotor is established.The controllers all use the PID controller,and then the simulation simulation is performed according to the controlstructure diagram.By analyzing the simulation results,the membership function and fuzzy control rate are designed.The fuzzy control rules are used to correct the PID control parameters and verify the simulation.At the same time,according to the task requirements,the design of the independent landing strategy and experimental verification.