Research On Discrete Variable Spray Model And Test

China is a great agricultural country, also a great country in pesticides application amount. Without considering the regional distribution characteristics of crop, pesticides were evenly sprayed in the field or row by ordinary pesticide spraying machinery,which not only wasted large number of pesticides, also polluted the ecological environment. On the other hand, pesticides in agricultural environment made contamination on agricultural and livestock products in different ways, and last seen in human body, which posed a potential threat to human survival and development, and even gave rise to the emergence of a variety of diseases. These problems are ultimately caused by backward of plant protection machinery and spray technology, so the adoption of advanced technology and development of advanced plant protection machinery has become a key link in the process of plant protection work and is of great significance. The precision and variable rate spray could effectively reduce pesticides application amount, improve the utilization rate of pesticides. The research contents and results are as follows.1. Overall design of the model. According to the design requirements of discrete variable spray model, schemes of the acquisition of spray target domain’s parameter,decision-making of variable rate spraying and implementation module are designed.The parallel binocular stereo vision system is used to obtain the spray target domain’s parameter. The whole scheme of variable spray is designed which includes spray domain control based on width adjustment and the uniform spray control based on flow adjusting.2. Acquisition of spray target domain’s parameters. The main parameters of the spraying domain include the equivalent circle radius and the edge position. In order to acquire the spray target domain’s parameters and solve the problem of "where to spray" and "how many to spray", the parallel binocular stereo vision system is used.The main parameters of the spray domain are acquired after the follow steps such as centric feature matching, coordinate transformation, 3D reconstruction and feature point positioning, an appropriate color space and channel selection, use of OTSU in foreground and background segmentation, combination with morphological operation and zone boundary operation steps.3. Variable spray decision analysis. In order to find the relationship between spray cone angle, flow and pressure, characteristics of the fan nozzle VP110-015 are considered in theoretical derivation and experiment. The spraying domain control based on width adjustment and the uniform spray control based on flow adjusting are fully analyzed and the diaphragm pump pulse width modulation technique is adopted.Variable spray decision is improved according to the step response analysis.4. Design of model display and control center. MATLAB GUI is used in the model display and control center design. The parameter information and spraying operation parameters are displayed and stored by the display control center, which make data monitoring more intuitive.5. Variable rate spray test in the laboratory. In order to verify the effect of variable spray model, test platform is set up in the laboratory based on sprayer frame. The test results show that compared with the contrast group, spray quality effective ratio increases by 10.25% under spray domain control based on width adjustment, control effect of spray field control is obvious. Variation coefficient of fog quantity distribution reduces by 6.83% under the uniform spray control based on flow adjusting, the effect of improving the distribution uniformity is obvious. The effect of variable spray model was obvious, which meets the design requirements.