Design And Implementation Of Data Collector For Filar Suspended Soil Lysimeter

Field water balance is an important basis of the research of crop growth and water-saving irrigation. And lysimeter is the direct measuring device of the field water balance. Generally, the measuring result is the data support for the research of crop growth and water-saving irrigation. At present, lysimeter has low degree of automation for data collection, low precision, slow processing speed and poor stability. Consequently, on the basis of the research on the model and working principle of the filar suspended soil lysimeter, a data collector is developed based on ARM9+Linux embedded system in order to realize functions of automatic collection, analysis, output and other functions for the data of soil evaporation, leakage, light, temperature, etc. In terms of collector, it behaves better advantage of both the real-time dynamic monitoring for soil data and management of data collection. Meanwhile, the collector also provides the data support for the water saving irrigation, which is significant for the modern agriculture and relevant research practice. The main research work and contributions of this thesis can be summarized as follows:(1) Through the analysis of the realization approach to lysimeter, the filar suspended soil lysimeter model is studied and the working principles for data collector of lysimeter are described based on the LVDT sensor, weighting sensor, soil body, the steel, shock absorbing cup and other equipments. Meanwhile, the function of collector and the analysis of demand are proposed. Moreover, the processor for the colloector is also selected according to the investigation and research. And the overall design of the collector is carried out.(2) The peripheral circuit of systemtic hardware is designed by S3C2240 microprocessor of Mini2440, which is involve in the system power, interface circuit for sensor, interface circuit for electric valve and interface based on RS232 protocol. It is to finish the collection of soil evaporation, leakage, light, temperature, moisture and rainfall.(3) The systemtic software can be divided into driver for hardware circuit and Delta touch screen. For hardware driver, C language is used to design and program so as to achieve driver module based on linux operating system. In terms of software design of touch screen man-machine interface, the Modbus protocol and control board of S3C2440 are applied to communicate and complete the data real-time display, valves control and data download functions.(4) Starting with the following three parts including the serial communication of delta touch screen, sensor data error and the performance of shock absorbing, the data collector of filar suspended soil was tested and analyzed. The test results and the demonstration application show that the data acquisition system of the collector is stable and meets the requirements of automatic collection and management for the data of soil evaporation, leakage, light, temperature, moisture and rainfall.