Research Of Automatic Variable Spraying Control System Based On GPS

In recent years precision agriculture has been a hot field in the international agricultural scientific research. The definition of precision agriculture is to arrange the managements of soil and crop precisely according to the certain condition of every single operation unit in the field which can optimize the use of agricultural inputs to get the highest output and most significant benefits and protect the environment, soil and some other agriculture resources.The major research content of this paper is to research and study the variable precision agriculture spraying theories and techniques, and use GPS and automatic control unit into spraying machine.The related technology and research are as followed:(1) Global Positioning System (GPS);(2) S3C44B0X control centre;(3) Spatial data acquisition and data processing, including sampling and analysis of pest information, the field operations division and code modules, the merger principle of the variables spraying unit operations;(4) To building the pest information database and the decision-making fertilizer of the field;(5) The storage and transmission of the decision-making data;(6) Establishment of control model;(7) Construction a spraying control system , which involves the application of the integration technical data, the identification of the operation unit, extraction the spraying decision-making information and building an export control module;(8) The field trial of the variable spraying application and the economic analysis to the spraying.the technical line of this study is to combine the introduction with the self-development, in other words, we need to digest the advanced ideas of management and technology from others, and to depend on ourselves to develop a feasible, less expensive technology and equipment strive to reduce the costs and adapt to the local farming mode.This research is based on prescription maps to implement variable spraying , use GPS systems to give the positioning and navigation information to spraying machine, use the pressure sensors, flow sensors and electric control valve as the executing agency, use S3C44B0X as a core devices of the control centre t, use ADS1.2 to develop and debug system's software and use a module with T6963c LCD display inside system to show the main body of relevant information.The principles of the main module are as followed:Prescription Analysis System: We use DACS system to plot the farmland into mesh, sample the pest extent of each grid and analysis the plant diseases, then insect pests information correspondingly, at last, we store of these information into a prescription map. Unlike single attribute data and spatial data, prescription plans is integrated the spatial data and attribute data and the file format of a prescription map document is "shp". In order to improve the inquire speed and maintain the accuracy of the prescription map, we use a certain algorithm to divide a prescription map, at the same time , in order to locate the map and increase the inquiry for the prescription , we must make the data of coordinate system in prescription map and GPS positioning system data are consistency . As the GPS positioning system is under WGS-84coordinates, in order to improve the performance of the system, here the prescription map is initiated in the WGS-84 system.Control Center: Control Center is the "brain" of the variable spraying system, it is a application software. It conjoint analysis the decision-making prescription maps which is produced according with the basis information of the plots and positioning information field from the Agricultural Mechanization GPS, and provide the ultimate decision-making prescription plan, such as the real-time spraying information of the agricultural machinery.GPS receiver system: In this system, the main function of GPS receiver is to locatedthe positioning information of agricultural machinery in order to generate the decision-making variables spraying prescription map. The spraying process GPS positioning is used twice: First, the location identification of the field insect pest , production variables spraying prescription map; second, when the machinery is spraying, we measured field location by GPS and then read the pest information correspondingly, at last, sent the spray command. GPS via the RS-232 serial interface sent the positioning information to the variable controller.Variable spraying implementing agency: variable spraying devices is the core parts implementation of variables spraying machine. For spraying operations, the host computer is accordance with GPS signal to judge of the spraying machine grid position, combined with information stored in the control center to calculate out the current value of the spraying; then via the RS-232 interface to transmit into the controller, the controller accord to equipment location, spraying machine-speed, loop pressure, as well as the control signals which is made by the preparatory work in order to meet variable spraying machine running speed and conditioning block spraying of information requirements.Under existing conditions, the study proposed two steps for the implementation of variable precision agriculture spraying, namely, the implementation of this research program:Step 1, production spraying decision-making data files. That is, conduct field data collection, and then deal with the spatial data processing has been collected in the laboratory. At last, in accordance with the pests and diseases test results, spraying history of every past year and the production, the expert system decide a appropriate spraying quantity in different plots of this quarter, then writes the data into the EEPROM.Step 2, the spraying machine is spraying under the control of control center in the field. In other words, when spraying machine is operating in the field, with the GPS positioning system, via the control system to read the spraying data in the EEPROM, then location data which has combine the spraying information to control the pharmaceutical output.After the establishment of a single module, software tested, we built the overall structures of spraying system, and complete the corresponded software debugging and simulation. In the entire system design and debugging process, we could record of all the problems in the design and propose reasonable solutions and implemented, the entire design process in an orderly, tensed and relaxed to a degree. At last, we completed the design task.The design of this system achieved the target of precise control of spraying. A preliminary experiment showed that when the system pressure remains between 0.2Mpa and 0.4Mpa, the nozzle can be achieved better atomizing effect. When the pressure changed the system can control the regulation of electric valve which will lead to the change of the system flow, in order to maintain the dynamic balance of the system pressure, to optimize the objectives of allocation of resources to reduce waste, increase revenue and protect agricultural resources and environmental quality.Of course, because of the restriction of the design level and the lack of consideration, the system will appear some problems in the practical application in the future. We will activate for the improvements of the system in order to meet the evolving needs of the actual system variables.