Design Of Orchard Target Variable Spraying System Based On Ultrasonic Detection

The output and quality of agricultural products have always been the basis of China's national economy.However,due to the technology level of plant protection machinery is not advanced enough and the accuracy is poor,the dosage of pesticide will exceed the standard when applying pesticide.This results in a large amount of pesticide residues in crops such as grain,fruits and vegetables,which is inconsistent with the concept of agricultural green development in China.The application of the target variable is an important technical means for achieving accurate application of pesticides,and is the direction of development of pesticide application equipment.In order to precisely target the fruit trees with pesticides,a set of ultrasound-target variable application systems for orchards was designed.The system uses ultrasonic sensors to detect the canopy information of fruit tree targets in real time.Based on this,the system decides the target application amount,and according to the real-time speed,flow and other information,it can achieve variable application control of fruit trees.The main research content of this article is as follows:1.Analyze and determine the overall design of the system.According to the purpose and requirements of the system design,the current contour profile detection scheme and variable application control scheme for fruit trees were elaborated.After comparative analysis,the ultrasonic sensor was used to detect fruit tree target information and the calculation method of the fruit tree shape volume used in this paper was introduced.The PWM control technology was used to control the target application amount in real time and the corresponding flow control algorithm was introduced.2.The target variable application system hardware design.A hardware system for target variable application with ATmega16 as the control core was proposed.The main functional modules of the contour detection subsystem and the variable application subsystem of the fruit tree were analyzed and designed in detail.3.Application software design for target variable application system.Using MODBUS communication protocol and based on RS-485 bus to build the communication network of the system.The upper computer man-machine interaction interface was developed using C#,which is more intuitive for the user to observe the system parameters and set it.Through the MCU software program,functions such as tree detection,variable application,speed and flow detection were implemented.4.System debugging and experimental verification.A fruit tree shape detection platform based on an ultrasonic sensor was built,and the effectivemeasurement range and start-up interval time of the ultrasonic sensor were calibrated through experiments.Through the fruit tree model and fruit tree entity detection experiments,the feasibility and universality of detecting the shape of fruit trees based on ultrasonic sensors were proved.Based on the volume of fruit trees,a variable control experiment based on PWM control was conducted.The relationship between the PWM duty cycle and the application flow rate was tested at 0.2,0.3 and 0.4 MPa pressure.Experiments have shown that when the pressure fluctuations are kept within a certain range,the greater the flow rate of application,the smaller the influence of pressure fluctuations on it.