Research On Uav Gimbal System Of Small-Sized Multispectral Camera

In recent years,due to the rapid development of small-sized unmanned aerial vehicle(UAV)technology,more and more UAV remote sensing technology is used in agricultural information monitoring and access.The method of obtaining image data of farmland by carrying a camera sensor(such as visible light,multispectral,hyperspectral,thermal infrared imager,etc.)on a small-sized UAV is widely used because of its high efficiency,high timeliness and low cost application.However,due to poor versatility of the existing gimbal and high environment requirements of camera operation and other reasons,the promotion of the camera sensor in agricultural application is seriously limited.This thesis,aimed to small-sized multispectral camera,will develop a set of UAV gimbal system,which can realize the function of stabilizing the multispectral camera's visual axis in the normal operation of gimbal,ensure the image quality of the camera,and accept the remote control instruction from the ground to change the background of the gimbal.The main research contents include the following aspects:(1)The overall scheme of the gimbal system for small-sized multispectral unmanned aerial vehicles is determined.According to the size and working environment of the multispectral camera studied by the gimbal system,the function and main performance indexes of the gimbal system are determined.Based on the above performance requirements,firstly,the thesis analyzes the frame of the UAV gimbal and adopts the structure of three-axis framework in the studies of the gimbal system.Then,after the analysis of the gimbal damping system of UAV,the scheme of using rubber damping ball is made.At last,the thesis discusses the main implementation plan of the control part of the gimbal system.(2)The structure of three-axis gimbal of unmanned aerial vehicles is designed.According to the parameters of small multispectral camera and the function of gimbal,the thesis chooses the type from the materials used to design the gimbal.By using Solidworks software,three-dimensional structure of the UAV three-axis gimbal is designed,including the design of the three-axis gimbal,pitch axis,the roll axis and yaw axis.Moreover,in order to verify the intensity of the gimbal structure,the thesis uses finite element analysis software——ANSYS Workbench to make a static analysis of the key components of the three-axis gimbal from the bottom to the top.Finally,the dynamic analysis of the whole three-axis gimbal structure is carried out to determine the influence of the vibration of the UAV transmitted to the gimbal on the three-axis gimbal.(3)The control system of three-axis gimbal of unmanned aerial vehicles is designed.Using the Storm32 gimbal controller as the main control board,MPU6050 sensor as a gimbal attitude acquisition module,using brushless DC motor and motor driver as power output,receiver and remote control as a wireless transmission module,each part of the gimbal control system is designed.And then the gimbal is set,gimbal motor PID is tuned,ultimately to achieve self-stabilization function and remote control of the UAV gimbal.Finally,photoelectric isolation trigger control design of the multispectral camera is completed.(4)Measurements and installed tests of UAV platform are conducted.The self-stabilization function of the gimbal is simulated by the different interference of the UAV gimbal.In combination with practical applications,the field tests by which the completed gimbal is installed in UAV are performed.Then the acquisition and splicing of farmland multispectral image are carried out and a comparative test is conducted to verify the importance of UAV gimbal.