Research On Control System Of Orchard Variable Rate Spray Based On LiDAR Detection Technology

Spraying plant protection is an important technology in forestry production.At present,there are some problems in the traditional spray machinery in China,such as pesticide waste and environmental pollution,and spray technology needs to be improved.Because the LiDAR has the advantages of simple detection device,small environment influence and more accurate target detection,this paper combines the variable rate spray system for the target with traditional orchard sprayer to study the orchard variable rate spray system for target based on LiDAR detection technol ogy.The specific research contents are as follows:(1)The application model of the orchard variable rate spray system for the target was determined,orchard sprayer spray device was optimized to be a multi-out let spray device that was evenly distributed at a vertical height compare to the traditional spray device;The hardware platform of the orchard variable-rate spray system for target was built.(2)Researching the information acquisition methods of the orchard variable rate spray system for the target.Recognizing the distance between the target trunk and the LiDAR by exploring the method of vertical distribution of trunks.Calculating the discrete canopy volume of the nozzle spray area based on the measured distance.The methods were verified by experiments.The test results showed that the method based on the vertical distribution of trunks can accurately detect the trunk distance,the absolute error satisfies the accuracy of LiDAR detection.The relative error of the canopy volume calculation is within 10%.With the increase of detection speed and distance,the error of canopy volume calculation increases,but the detection speed difference too small to be ignored.In the actual environment,the trunk distance can be detected and the canopy volume in the corresponding area can be represented by a small rectangular body.Moreover,calculating the trunk distance by measuring the trunk distance can reduce the influence of factors such as the walking route of the sprayer and ground on the test.(3)Studying the real-time control method of the variable spray system for the target.The method of transforming the canopy volume into the PWM was studi ed.The relationship between the nozzle flow velocity and the PWM duty cycle was obtained through experiments.The experiment results showed that the curve fitti ng was linear,the goodness of fit is up to 0.97,as the pump voltage increases,the linear relationship error becomes larger.The time delay of each part of the system was analyzed.The solenoid valve response test was used to study the delay of the solenoid valve.The test result showed that the mechanical response of the solenoid valve was behind the signal response and there was a 20 ms time gap between the two.The system delay compensation method is studied,and the delay compensation time is converted to the length of the FIFO buffer area which saved the data.(4)System software development was performed.The upper computer softw are was developed by MFC multithreading.The interface thread implements spray displ ay,spray parameter input,and start-stop control of the spray system.The work thread realizes initialization of system parameters,information collection and real-t ime control of the variable-rate target spray system,the transformation of the corresponding crown volume to the PWM,and the communication with the slave computer.he software of the slave computer is developed by Keil C51,and the communication format between the upper and slave computers was determined.The message sent by the upper computer was received in real time by using the interrupt mode.The upper computer and the slave computer were debugged respectively,and the debugging results showed that the upper and slave computer all achieved their functions.