Research On Inline-mixing And Variable-rate Spray Coordination Control Of Intelligent Sprayer

In precision agriculture,inline mixing and precision spray are two important means to promote the reduction and efficiency of pesticide application.The integrated coordination of inline mixing and variable-rate spray can further improve the utilization rate of pesticides,protect operators’ safety and reduce pesticide pollution.In this paper,a real-time coordinated control system based on the requirement of spraying quantity for plant target is designed,which can achieve real-time inline mixing and variable-rate spraying.The main contents of this paper are as follows,(1)Aiming at the requirements of high-precision mixing ratio and low mixing residue in inline mixing operation,a real-time inline mixing system based on synchronous control of water and chemicals flow was developed.The system is composed of decision model and control system.The mixture quantity decision model calculates the mixing quantity of water and chemicals in real-time according to the flow control cycle determined by the information acquisition frequency in variable spray.The mixed dose control unit is composed of a computer for communications between the operator and the mixing system,a microcontroller unit(MCU)for processing the system operation,a dual circuit for generating pulse width modulation(PWM)signals and two DC motor pumps.It can adjust the working voltage of diaphragm pump and peristaltic metering pump periodically and timely,and then adjust the water and chemicals flow synchronously.(2)A real-time inline mixing system based on the synchronous control of water and chemicals flow is built.The target information collection unit and the spray quantity control unit are set up,and the mixture model is converted according to the3 D data of the target,and a linear regression equation between the duty ratio of the electromagnetic valve and the nozzle flow is established.The delay time composition and data conversion of the coordinated control system are analyzed,and the mathematical model of the coordinated control system is optimized.After calculating the duty cycle of each nozzle according to the volume data,the voltage regulation duty cycle of the corresponding DC pump motor is directly calculated through the quantitative relationship.(3)In order to avoid overexposure to chemicals,an intelligent spray vehicle experimental platform was built based on the Ackerman chassis trolley.The man-machine communication module and the air delivery system were designed to realize the real-time observation of the spray vehicle’s operation status and precision spraying.The delay time of the coordination system was calculated by the delay detection module,and the spray experiment,the mixing ratio experiment and the dose test were carried out.The results showed that the number of droplets deposition was within the range of 34.8～63.5.The maximum relative error of the mixture was 7.56%and the maximum relative error of the spray volume was 7.17% when the expected mixing amount and mixing ratio of 139 m L were 100～500.