Design And Implementation Of Irrigation Controller Based On AT89S52Single-chip Microcomputer

Reasonable irrigation, scientific and efficient water usage is the essence of agricultural water-saving irrigation. Especially in the current, our country and other countries of the world are facing the situation of increasingly shortage of water resources. Therefore, vigorously promote and apply new water-saving irrigation techniques, and develop matched irrigation device, have great significance to save water and improve the quality of field irrigation, and relieve the poignant contradictions between development of agricultural irrigation and shortage of water resources.Water-saving automatic irrigation system in general can achieve a simple pipe constant pressure feedback control, less taking into account the nonlinear, time-varying, large delay of plant irrigation characteristics, and there are a variety of methods in the water-saving irrigation system of measurement the soil water content, but can be achieved quickly and accurately measured have a certain difficulty, and whether or not accurate measurements will directly affect the quality of subsequent irrigation control.This research is the related extension by National Natural Science Fund Project (60971115)"Modeling and Dynamic Simulation of Soil Compaction Effect on Plant Underground Tissue Architecture". In summing up the previous study on the basis of the irrigation control, based on the methods of soil moisture measurement and characteristics of fuzzy control, designed an irrigation controller based on AT89S52microcontroller and through verification test to verify the performance of the controller. System uses the dielectric properties of the soil, and according to the frequency domain reflectometry measurement principle to obtain soil moisture, control unit constituted by the AT89S52microcontroller make the fuzzy processing on the error and error change between measured soil moisture and fixed soil moisture for plant and make fuzzy decision to judge irrigation or not.The overall scheme of the irrigation controller was designed in this paper. Hardware parts of the irrigation controller based on AT89S52microcontroller were designed and production.According to the fuzzy control theory, the fuzzy controller of the irrigation controller was designed. Select the error and error change between measured soil moisture and fixed soil moisture of plant for the input, irrigation time for the output, and set up the fuzzy control rules to obtain fuzzy control table and use look-up table to achieve fuzzy control algorithm.Software program of the irrigation controller was compiled by C language, and the monitoring software was developed by C#. Use MATLAB Simulink simulation software to simulate the fuzzy controller. Simulation results show that:the fuzzy control has better dynamic quality, long time stability, etc., showing a good steady performance.After linear calibration and measurement accuracy test found that this sensor has good linearity, high measurement accuracy and relative error control within10%, the measurement accuracy to meet the requirements of the irrigation controller. Through crop growing experiments validate the performance of the irrigation controller. With plotted monstera deliciosa and upland rice as experiment object to carry out the relevant test, the test results show that the irrigation controller is running in a good condition, works stably, controls accurately and responsives to change, and meets the requirements of automatic water-saving irrigation.