| Land area information is very important data.It is not only widely used in crop yield estimation,land transfer,real estate,etc.,but also widely used in agricultural machinery operation,land survey,livestock industry and other fields.Monitoring of agricultural resources is of great significance.At present,research in the field of land area measurement is mainly based on GPS satellite positioning technology.my country’s self-developed Beidou navigation system has matured.In order to promote and further improve the application of my country’s Beidou satellite system in the civilian field and reduce the dependence on GPS satellites,this study designed a dual-mode positioning system based on GPS and Beidou for the agricultural field.land area measurement system.The system can realize area measurement using GPS and Beidou positioning information.This system consists of two parts,the first part is a land area measuring instrument composed of single chip microcomputer,positioning module and other devices,the second part is a computer land information management system,the system can add,delete,modify,check and other operations on the measurement information.And realized the function of displaying the traveling track on the map.The main research contents include the following four parts:(1)The trapezoidal method,a commonly used method for calculating land area using navigation satellites,is analyzed,and several commonly used coordinate systems and corresponding coordinate system conversion methods are described in detail.Choose from three measurement modes:land area measurement based on GPS signal,Beidou signal,and land area measurement based on GPS+Beidou dual-mode positioning signal.(2)Hardware instrument design.There are three main hardware instruments used in this research,namely Beidou/GPS area measuring instrument,GPS area measuring instrument,and Beidou area measuring instrument.Each instrument is developed based on STM32 single-chip microcomputer.On the basis of single-chip microcomputer,hardware such as dual-mode positioning module and display module is added.The difference between the three instruments is only the difference in the received signal.The main functions of the hardware instrument include receiving the positioning information of the area to be measured,extracting the positioning information,converting the positioning information,wireless data communication with the computer management system,land area calculation and area calculation result display.(3)Design of computer management system.The computer management system includes two parts:land information management system and travel track display.The land information management system in this study is developed based on Python language,the development environment used is pycharm,and the database used is MySQL.The land information management system is established based on the MySQL database,including land information such as measurement results,errors,measuring instruments,and regions.The database is used to manage the measurement results of the hardware part;the GUI interface of the land information management system is designed based on the wxPython library in Python,and the Establish a connection with MySQL,and control a series of operations on the database through GUI interface buttons.The travel trajectory display is designed and implemented by the folium library in Python,and the travel trajectory display is realized according to the positioning information obtained by measurement.(4)System operation test.The GPS area measuring instrument,the Beidou area measuring instrument,and the Beidou/GPS area measuring instrument were tested for positioning function,positioning information acquisition,and wireless data transmission respectively.Area measurement was carried out in the surrounding area and the area enclosed by the inner ring runway,and area measurement experiments were carried out with different sample points.When dual-mode,GPS,and Beidou area measuring instruments measure the area surrounded by the outer runway,the lowest errors are 0.658%,1.026%,and 1.048%,respectively,and the highest errors are 4.014%,4.679%,and 4.928%.In the region,the lowest errors are 0.747%,1.068%,1.106%,and the highest errors are 3.924%,4.92%,and 4.793%,respectively.After the experiment is completed,the computer management system is functionally tested,and the functions of adding,deleting,modifying and checking the land information management system and the display function of the driving track are tested.The area measuring instrument and computer management system can stably realize the functions of each part in the testing process,and the measurement accuracy can meet the requirements and can be put into use. |
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