The variable application technology aims to improve the utilization rate of pesticides, reduce agricultural costs, appropriately reduce the amount of pesticides, reduce pesticide residues, and reduce environmental pollution. It is an important topic in precision agriculture and the development direction of pesticide application technology. This paper summarizes the field information collection method, the variable application control method, and the variable application control algorithm in the key technology of variable application. Firstly, the field information acquisition technology based on geographic information technology and realtime sensor technology is explained. The second analysis includes variable pressure regulation, chemical concentration regulation, and pulse width modulation variable application control methods and analyzes the advantages and disadvantages of each control method. Pulse width modulation has broad application prospects because of its better dynamic response characteristics and flow regulation performance. Finally, the most important variable application control algorithms (fuzzy control algorithm, PID control algorithm, and BP neural network) are summarized and researched. It is understood that the combination and improvement of different algorithms improve the variable application control performance. Aiming at the problems of domestic variable application technology, suggestions are made to provide a certain reference for the development and promotion of variable application technology in my country.

In order to meet the needs of variable spray technology for boom sprayers, a variable spray control and test bench for boom sprayers were designed to realize real-time control and performance testing of existing variable spray devices. The variable spray control and test bench are composed of a control system and a data acquisition system. The control system is based on Siemens S7-200 series PLC, which is composed of a power system, drive system, flow system, and variable control system. The data acquisition system uses data acquisition modules and sensors to obtain pipeline flow, pressure, torque, driving speed and other parameters. Real-time display and storage of the collected parameters can be achieved through LabVIEW software. The flow accuracy test under the speed condition shows that the average flow error is 4.0%, which can be used as a technical reference for judging the performance of the variable spray device. The test shows that the test bench can effectively control the variable spray control components of the boom sprayer in real-time to meet the requirements of the boom sprayer. The performance test requirements of variable spray control components of sprayers provide technical reference for the formulation of technical specifications for variable spray quality evaluation.