| Target,variable,and contour spraying are important ways to increase the coverage of the droplets and reduce the waste of medicinal solution,which is of great significance to the realization of precision agriculture.Because most of the domestic and foreign spray research objects are spindle tree type,there is less research on the spray of banana tree type.The conventional sprayer structure cannot meet the spray requirements of banana trees,the coverage of the droplets on the reverse side of banana leaves cannot be effectively guaranteed,the medicinal solution is wasted.Aiming at the above problems,this paper combines the contour spray and variable spray to design and build a contour variable spray control system,and conducts a spray adaptation test research on banana trees to improve the control effect of banana trees’pests and diseases and reduce the waste of chemical liquid.The main contents of this article are as follows:(1)The overall scheme of the contour variable spray control system was determined,namely the variable spray control based on pulse width modulation and the contour control based on the stepper motor to control the air delivery angle and spray angle.(2)Designed and produced a hardware system for the spray control of the profile variable.Including the selection of components for the medicine supply circuit,spray control module and human-computer interaction module,the AT mega2560 single-chip microcomputer is used as the control core to complete the main controller and variable spray unit,variable air supply unit,contoured air supply unit,human-machine Hardware connection of the interaction module.(3)The software design of the upper and lower computer of the contour variable spray control system is completed.The host computer software design includes control interface design and communication module design.The lower computer software includes the single-chip microcomputer processing program,variable spray control program,variable air control program,contour air control program,and single-chip communication program design.(4)A PWM variable spray test platform was set up,and the experimental analysis of variable spray influencing factors was carried out.The test results show that the spray volume has a positive correlation with the spray pressure,is approximately linear with the duty cycle of the PWM signal,and has little relation with the frequency of the PWM signal.Excessive spray pressure and high PWM signal frequency will affect the variable control performance and service life of the solenoid valve.When the PWM signal duty is lower than 20%or higher than 90%,the solenoid valve responds abnormally and the spray effect is poor.A spray flow model based on PWM variable spray control was established,and the results showed that the linear fitting relationship was the best at a PWM frequency of 6 Hz at a spray pressure of 0.4 MPa,0.6 MPa,and 0.8 MPa;under the conditions of 0.4 MPa spray pressure and 6 Hz frequency The maximum adjustment of flow rate is 7.4 times.(5)A single-factor experimental study on the driving speed,spray angle,wind speed,and spray volume of banana plants was carried out.The results show that the spray angle,spray volume and wind speed have a greater impact on the coverage of the banana leaf droplets(the upper spray angle has a small effect on the coverage of the front droplets of the banana leaf,and the coverage ratio has reached more than 80%,while the lower spray angle has The coverage of the fog droplets on the reverse side of banana leaves has a great impact,with a maximum difference of about 30%;the coverage difference can vary up to20%when the spray volume changes;the coverage difference can vary up to about 47%when the wind speed changes),and the driving speed affects The influence of banana leaf fog drop coverage was not significant.(6)Response surface experiments were performed on banana plants with main stems of 1m,1.3m,and 1.6m.The test results show that the optimal spray angle for a banana tree with a main stem of 1 m(α,β)=(25~o,105.8~o),and the optimal spray angle for a banana plant with a main stem of 1.3 m(α,β)=(30~o,120.5~o),the optimum spray angle for a banana plant with a main stem of 1.6m(α,β)=(40~o,135~o).The ideal spray angle value of the test is close to the calculated value of the theoretical angle(the deviation is within 2~o).Spraying at the ideal spray angle can solve the problem of poor coverage of the droplets on the reverse side of the banana leaf,and at the same time,it can satisfy the droplets with less spray Coverage requirements,thereby increasing the utilization of medicinal solutions.To provide theoretical basis and reference for the realization of target profiled spray. |
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