| With a dramatic increase in the world's population and decrease in the plantation, the foodstuff and safety problem has come to front of people in the world. Variable rate fertilization technology is one of the main elements in precision agriculture, which can realize on-demand variable rate fertilization based on the differences of the soil and the crop expected to yield in each plot (operation unit). At present, applying fertilizers improperly has become a serious problem. Popularization and application of variable rate fertilization technology can significantly increase crop production significantly and improve the entironment effectively.At present, in applying of variable rate fertilization techniques home and abroad, data and control signals are transmitted by cables. It is a point-to-point mode in signal connection from controller to variable rate fertilization applicator. In applying of variable rate fertilization technology, some particularities are involved in agricultural machinery operating environment, point-to-point connections exist many problems, such as complex wiring, cabling problems, poor anti-jamming capability and instability, and so on.Bluetooth is one special kind of internet short-range wireless communication ways. Bluetooth uses microwave technology replace of complicated cable of the traditional network and complete interconnection from a fixed equipment to a mobile. Bluetooth wireless communication technology can carry out data and control signals transmission within 10 meters(by increasing the Bluetooth module's transmission power, transmission distance can be expanded to 100 meters). Bluetooth communication is primarily used in LAN, home network, industrial control, and other fields. With the development and improvement of Bluetooth wireless technology continuously, more and more applications of Bluetooth have also been used in the agricultural intelligent monitoring and control filed. This paper integrates miniaturized, low-power Bluetooth wireless technology with embedded system, which meets real-time data acquisition and wireless control requirements in variable rate fertilization well.This paper has done some researches on variable rate fertilization test and control system applying Bluetooth under the program of " Study on Variable Rate Fertilization, Spraying and Intelligent Yield Monitor Technology for Corn" (2006AA10A309-6), belonging to the state's 863 Program "Research and Application of Precision Operating System for Ccorn" The main works and results are as follows:[1] A variable rate fertilization monitoring and short-distance wireless control system was designed using Bluetooth to carry out data transmission. In this paper, Bluetooth was used as a communication carrier to transmit data and control signals. It taken LK-D101A Bluetooth USB adapter and KC111 Serial Adapter as Bluetooth communications equipment after comparing of a variety of wireless communications technology and equipments.[2] Developed a displacement signal acquiring system based on ARM microprocessor. The paper designed a external circuit to read the pulse signals coming from the displacement sensor using S3C44BOX microprocessor timer 4 and 5 and fulfilled fertilizing applicator ranging function through programming.[3] Using the C language and the assembly language programming to establish ARM development system's ports and the memory, ect. Using the simulator to carry out the designed software online debugging. Both manual and automatic control modes can be realized in the variable rate fertilization, the upper machine can select automatic or manual fertilization mode. Under automatic mode, fertilization information can be displayed in the upper device in real-time. At the same time, the upper machine can wireless control the variable rate fertilizer applicator. Under manual fertilization mode, through the upper machine select manual mode and inputs the quantity of fertilizer needed in the plot.[4] Completed the wireless communications distance test and anti-jamming test in order to confirm Bluetooth wireless technology's communications distance and capability of anti-jamming. Field work environment were imitated in laboratory. When multiple machines and equipment were working simultaneously, Bluetooth communications distance was able to reach over 30m with better real-time performance. The anti-jamming test results showed that the system which used the Bluetooth communications technology had not only anti-interference capability, but also (had) reliable communications data.[5] Fulfiled an experiment on the system in laboratory with different distances and speeds(1.8km/h-5.4km/h). The experiment data proved Bluetooth data signals transmission method is feasible and can decrease ranging error effectively. From the test data and graphs, we can see that Bluetooth communications data transmission error has not obviously risen with the increase in distance and speed. And most of the time Bluetooth communications' error is less than cable's. After the system was working continuously more than four hours', the error of system was still little(less than 5%). So Bluetooth transmission is feasible and can decrease ranging error effectively.The innovation work can be summarized as follows:[1] Taking ARM microprocessor S3C44B0X as a center unit to design and develop a displacement signal acquisition system. It realize the variable rate fertilizer applicator displacement and speed signal's acquisition and wireless signal transmission through KC111 Bluetooth serial adapter.[2] Designed and implemented variable rate fertilization monitoring system using Bluetooth. The system controls the motor's speed to realize the variable rate fertilization by signals wireless transmission. At the same time, the applying of Bluetooth in the agriculture control domain has also expanded its application scope.The current variable rate fertilization system exists the problem of data transmitting insufficiency. In this paper, we designed and produced effective communication, convenient implementation's variable rate fertilization wireless monitoring system based on Bluetooth. According to the results of experimentation tests about communications distance, data transmission and anti-jamming capabilities, the paper proved that Bluetooth transfer accurate data with small error. So Bluetooth can replace communications cables to realize wireless monitoring. Through analyzing data and error of the experimentation, the paper advances practical improving programmer. The experimentation has provided a good reference value to the later research work, and built the good foundation for the further research works. |
PDF Full Text Request