In recent years, China has made a series of achievements in the development of agricultural aviation application technology. However, compared with agricultural aviation applications in developed countries, China still has shortcomings in the basic theories of aviation application, low-altitude spray deposition, aviation electrostatic spray technology, and aviation variable application technology. In this issue, I will talk about the development status of agricultural aviation application in China from the key technologies of aviation application and aviation application equipment, and hope to provide reference for the research and application of domestic scientific research institutions and enterprises.
Development of key technologies for drone application
At this stage, drones have developed in China due to their high efficiency, superior performance, and strong ability to cope with sudden disasters. Especially in recent years, technologies such as low-altitude low-volume spraying and remote control application of drones have made breakthroughs in China.
In the prevention and control of agricultural pests and diseases, the working height of the drone and the airflow field have a great influence on the uniformity of the droplets, droplet deposition and drift. For example, in order to clarify the working parameters of small drones and to explore the dosage forms suitable for their application, the researchers applied drones to spray corn mites with different dosage forms of chlorpyrifos. Tests have shown that at a flight speed of 5 m/s, the control effect is best when the height of the top of the plant is 2.5 m. Excessive flight affects the control effect, and too low affects the work efficiency.
For example, in the control of wheat midge, a small UAV is used for low-altitude spraying. Different nozzles are used to spray different agents, different dosage forms and additives with different additives. After analyzing the control effect, it was found that the droplet atomization density of the centrifugal atomizing nozzle was better than that of the liquid atomizing nozzle compared with the two atomization methods.
Centrifugal nozzle working diagram
Development of equipment and technology for drone application
Test and improvement of aviation nozzle
At present, the civil aviation aircraft operations in developed countries in the world mainly use hydraulic atomizing nozzles and rotary centrifugal atomizing nozzles. The purpose is to realize the controllable droplets, large spraying flow, not easy to block, few nozzles, and low-volume spraying. It can reduce the environmental pollution while improving the effectiveness of aviation operations.
China's large-scale agricultural pesticide spraying aircraft is directly purchased from abroad, and most of them use rotary centrifugal atomizing nozzles. For the effect of this type of nozzle, whether it needs to be upgraded and developed for actual production, a series of test verification is needed.
To achieve low-altitude, low-volume, uniform spray, and high-efficiency spray requirements, drones must be optimized and selected for their atomized components. Researchers in China have started testing and researching the structure, performance and application effects of UAV nozzles, and have made some progress.
However, the nozzles currently developed in China often have insufficient fogging spectrum, large drift, and uncontrollable atomization effects. In the future, it is necessary to increase the research intensity from the nozzle structure design. For example, focusing on the application experience of ultra-low-capacity application technology used in developed countries, special-purpose controlled atomization nozzles suitable for large-scale agricultural aircraft and different types of agricultural drones are developed to improve the utilization rate of liquid medicine.
Development and application of advanced sensors
At present, the development and use of sensors such as fog drift monitoring, fog droplet deposition evaluation, and droplet image processing system are hot research topics in the field of aviation application.
For example, some researchers have developed a telemetry system for aerosol distribution and drifting trend of aerospace application, using a near-infrared imager to obtain a cloud image of aerospace application at a certain distance, and analyzing its infrared imaging spectrum characteristics. Identification is carried out to invert the concentration image of the drug mist cloud to predict the trend of the drug mist drift.
The Nanjing Agricultural Mechanization Research Institute of the Ministry of Agriculture carried out a series of tests on the rotor wind field test and the airborne drift prediction model. South China Agricultural University successfully developed a wind farm wireless sensor network measurement system, which provides a basis for the optimization of operational parameters such as aviation spraying.
In addition, the researchers developed a set of detection devices and systems for the distribution of aerosol spray droplets. By processing the scanned image of the water sensitive test paper, the distribution index of the droplets was obtained, and the measurement error of the droplet distribution index was reduced to improve the measurement error. Droplet deposition measurement efficiency.
Prospects for the application of agricultural aviation in China
China has a large gap with major foreign countries in terms of the number of fixed-wing aircraft and rotary-wing drones and the operating area. At the same time, it also shows that agricultural application aircraft and drones have great development and application prospects in China.
We should base on the actual production needs of domestic agriculture, and learn from the deployment experience of agricultural application models in countries with mature applications such as the United States, Russia, Japan, South Korea and Brazil. For example, large-scale agricultural aircraft production services can refer to European and American standards, small and no The man-machine can refer to the Japanese and Korean standards; the agricultural application aircraft with independent intellectual property rights should be vigorously developed (mainly with drones with high degree of openness and low capital investment), and then establish a sound agricultural aviation application aircraft operation industry. standard.
China and developed countries air application technology comparison _ Yu Chen network _ let the world read the drone _ global professional drone service information platform China and developed countries aviation application technology comparison / map source network
In recent years, China has made a series of achievements in the development of agricultural aviation application technology. However, compared with agricultural aviation applications in developed countries, China still has shortcomings in the basic theories of aviation application, low-altitude spray deposition, ultra-low-volume spray technology, and aviation variable application technology.
It can be seen from Table 2 that the latest technologies for airborne application in the world, such as low- and medium-speed wind tunnel wind field simulation, aviation drift prediction model construction, electrostatic spray technology, prescription map variable spray, wireless sensor monitoring fog drop deposition, etc. The Beijing Agricultural Intelligent Equipment Technology Research Center, Nanjing Agricultural Mechanization Research Institute, South China Agricultural University, and China Agricultural University all have research teams conducting follow-up studies. However, due to the lack of supporting equipment and special fund support, there are still large gaps in the application of some theoretical research results.
With the development needs of hot areas such as green plant protection, precision agriculture and food safety, the state has given priority support to the field of agricultural aviation application. China's scientific research institutions and scientific and technological workers should seize this strategic development period, and focus on the following aspects according to national conditions and practical application needs:
1. Establish and use a professional wind tunnel wind farm research base to further deepen the theoretical study of aviation application;
2. According to the regional characteristics of the country and the division of planting areas, carry out targeted drug application technology exploration, and form a production service system for multi-type operation such as large-scale agricultural aircraft, unmanned helicopters and multi-rotor UAVs;
3. Break through the cutting-edge technology of fog droplet drift prediction, electrostatic spray, variable application, etc., and form a practical and feasible technical system.
In the next 5 to 10 years, with the strengthening of the formulation and in-depth publicity of the agricultural aviation development policy and the cultivation and development of specialized aviation aerobic equipment, China will obtain the basic theoretical research and related equipment research and development of aviation precision spray. Breakthrough, this will effectively promote the rapid development and application of aviation precision drug application technology, and truly achieve high-efficiency, environmentally friendly and safe agricultural plant protection requirements.
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