Research On Multi-rotors UAV Multi-spectral Image Acquisition System

Agricultural production information is related to China’s food security supply and the rapid and sustainable development of agriculture.Timely and effectively access to agricultural production information is particularly important.As a new efficient,fast and non-destructive method to obtain the information ofground objects,UAV remote sensing technology can obtain high flux and multi-scale agricultural production information.There are still some problems in the existingUAV remote sensing image acquisition system.Therefore,it has great significance to develop multi-spectral remote sensing image acquisition system for multi-rotors unmanned aerial vehicle(UAV).In order to solve these problems,the development of UAV multispectral remote sensing image acquisition system has important significance.In this paper,we developed a UAV multi-spectral remote sensing image acquisition system which integrated gimbal,could control the acquisition of multi-spectral remote sensing image and obtain the corresponding POS data.The main contents of this paper are as follows:1.Due to the fixed wing UAV has the characteristics of fast flight speed,inconvenient landing,and can’t hover,high cost and high maintenance cost of single wing UAV,we chose multi-rotors unmanned aerial vehicle(UAV)to development remote sensing image acquisitionsystem.By analyzingthe relationship betweenforce,main body parameters andparameters of power system,the parameters of HEXA UAV were determined.And the rationality of the parameters has been verified by using the multi-rotors UAV performance evaluation software xcopterCalc.Based on the analysisthe change of battery voltage during the load hovering flight test,it was found that when the payload of HEXA UAV was 800 g,the hover time under the condition of breeze was 24 min.By analyzingthe relationship between desired attitude and actual attitude,and IMU vibration of the UAV during the flight,we found that the HEXA UAV developed in this paper had nice stability,and could meet the requirements of multi-spectral camera and its gimbal.2.In order to fix the problem thatexisting unmanned aerial vehicle remote sensing image acquisition system has no camera gimbal,and can’t obtain remote sensing image without distortion,the stable gimbal of multi-spectral camera has been developed.Based on the analysis of gimbal principle,the selection,structure modification and adjustment of controller parameters had been accomplished.And for the purpose of improving the stability,the attitude compensation of Pixhawk flight controller had been accomplished.3.In view of the existing remote sensing image acquisition system acquiring redundant images and can’t mosaic easily,the controlof multi-spectral images acquisition byflight controller and the obtain ofcorresponding POS data had been achieved.Based on the analysis of the Pixhawk flight controller and shutter of ADC Lite,the optical switch circuit using to tiggercamera has been designed.And the POS GENERATION tool to obtain POS data was writed by using the MATLAB software writed.4.In order to obtain high quality multi-spectral remote sensing images,the influence of multi spectral camera’s photosensitive parameters on the quality of multi-spectral remote sensing image was analyzed.The results showed that,in the case ofother camera parameters were reasonable,in order to obtain the image with uniform brightness,the fixed shutter should be used.In order to meet the blur requirements of UAV remote sensing image,it was necessary to ensure that the altitude of the system was high enough.In order to ensure that all the objects in the remote sensing images had enough definition,the flight height of the system should be guaranteed to be high enough.Finally,several experiments were carried out,and obtained a total of 3740 multi-spectral remote sensing images and corresponding POS data.And high resolution multi-spectral orthophoto data was acquired by using Pix4 Dmapper.The results showed that multi-rotors UAV remote sensing image acquisition system developed in this paper could be used to obtain multi-spectral orthophoto data of regional crop,and then provide technical support for acquiring agricultural production information.