基于驻波率原理的农药雾滴沉积量检测系统设计与试验

为实现施药后雾滴地面沉积量的快速获取,该文提出一种基于驻波率原理的叉指型雾滴采集极板结构。为验证该极板结构的合理性,应用三维电磁仿真软件HFSS对此系统进行电磁仿真。HFSS模型求解的结果表明,叉指型极板内部出现了静电屏蔽,极板间通过雾滴能够实现电磁耦合,可用于雾滴沉积量检测,系统灵敏程度将随着极板间距的增大而减小。通过标定试验,建立了检测系统输出电压与试剂溶液沉积量关系的回归方程,测试后2种不同介电常数的胭脂红溶液和丙三醇溶液决定系数R2分别为0.982 1和0.997 6。通过对3W-ZW10型温室自走式喷雾机应用测试,结果表明:该系统在采样点上沉积量的模拟值最大相对误差率不超过7.95%,且模拟值与实测值均方根误差RMSE最大为0.076 7 mg/cm~2,雾滴沉积检测准确率高,方便实用,可用于田间雾滴沉积率的快速测量。

Design and experiment of pesticide droplet deposition detection system based on principle of standing wave ratio

In order to realize the rapid acquisition of droplet deposition after application, this study proposed an interdigitated droplet collecting board structure based on standing wave ratio principle. The purpose of this study was to quickly and effectively obtain the characteristics and regularity of the droplet deposition distribution. On one hand, the system could reduce the experiment cost, the difficulty of operation and the complexity of the experiment. On the other hand, the system was important to evaluate the quality of pesticide application and improve the utilization rate of pesticide. Optimized droplet deposition detection technology could solve the problem of single measurement method and low efficiency of droplet deposition distribution in field, which was a goal pursued by scholars in this research field. Based on the principles of standing wave ratio and sensor network technology, the real-time detection system of droplet deposition on the ground was designed. The droplet distribution characteristics of the electric field were explored by the method of simulation, and then the optimal parameters of the interdigitated droplet collecting board were obtained. At the same time, combined with the greenhouse self-propelled sprayer system, the application test and verification test were carried out to obtain the distribution characteristics of droplet deposition accurately and quickly. The real-time detection system of droplet deposition in the greenhouse could be realized by using the method of standing wave ratio, and the reliability was very high. At the same time, the system had great practical significance in the field of droplet spray quality detection and regularity research. In order to verify the rationality of the interdigitated droplet collecting board structure, the electromagnetic simulation of the system was carried out by using the three-dimensional electromagnetic simulation software HFSS (high frequency structure simulator). The device took the STM32 single chip microcomputer as its core to build the ZigBee network, and the signal of the droplet collection sensor was transmitted to the remote terminal based on LabView2014 through the RS232 serial port, which realized the real-time monitoring of the droplet deposition. The results of the HFSS model showed that the electrostatic shielding appeared inside the interdigitated droplet collection board. The electromagnetic coupling could be realized by the droplets between the boards, which could be used to detect the droplet deposition. The sensitivity of the system would be decreased with the board spacing broadening. The regression equation of the relationship between the output voltage of the detection system and the deposition amount of the reagent solution was established through the calibration experiment. The determination coefficients under 2 different dielectric constants were 0.9821 and 0.9976 respectively. The 3W-ZW10 type self-propelled sprayer application test in greenhouse showed that the maximum relative error rate of the simulated value of the deposition amount of the system at the sampling point was not more than 7.95%. The RMSE (root mean square error) of the measured value was 0.0767 mg/cm2. The detection accuracy of droplet deposition was high. The droplet deposition amount detection system can be used for rapid measurement of field droplet deposition rate based on the principle of standing wave ratio. From the laboratory calibration and application test results, it can be concluded that the design of the interdigitated droplet collection system is feasible within the range of 300 μm particle size. The proposed real-time detection method of droplet deposition in greenhouse based on the standing wave ratio is suitable for the detection of the droplet spray quality and the characteristics of droplet distribution. This research can provide reference for the measurement of droplet deposition.