| High-clearance sprayers have the advantages of efficient application operation such as wide spraying width,spraying precision and uniformity of spraying volume,and they are more and more widely used in field plant protection operation.Due to the ground surface is uneven in the field,which affect the uniformity of distribution of spray volume,resulting in a decline in the quality of application.the body of the high-clearance sprayer is prone to tilt in the rolling direction during operation and the spray beam tends to incline and even touches the crop or the ground,which is potential of accident.Considering this problem,this paper adopted theoretical analysis,simulation analysis,experimental testing,and other methods to integrate automatic control technology to design a spray beam attitude adjustment system of high-clearance sprayers,which can realize the function of manual and automatic adjustment of the spray beam attitude.The main research contents of this thesis are as follows:(1)Researched and designed the general structure of the spray beam attitude adjustment system and the adjustment scheme.Based on the 3WP-500 G three-stage beam sprayer,the overall structure was mainly composed of travel control system,spraying operation parts,beam leveling and lifting mechanism,electro-hydraulic control system,etc.According to the pendulum-type suspension operation mode,took the sprayer body as the benchmark,the posture of the sprayer was set as the left-down,right-up,and the inclination angle of the spray-beam was negative.The relationship between the inclination angle of the spray beam relative to the sprayer when the spray beam suspension is driven by the hydraulic cylinder is studied.According to the common working posture of the sprayer with high ground clearance,an adjustment scheme of four groups of basic combined actions was designed: overall rise,overall fall,left rise and right fall,left fall and right rise.According to the adjustment method of the beam,an automatic sprayer-leveling scheme based on the inclination sensor,hydraulic system and electronic control system was designed.(2)Researched and designed the key components of the beam attitude adjustment system.The spray beam leveling mechanism of the high ground clearance sprayer was a pendulum structure.By analyzing the working principle of leveling,the response time required for every1° rotation of the spray beam was calculated.The beam lift was realized by the double parallel four-bar mechanism,and the beam lift mechanism was designed,included the upper lift beam,the middle section of the beam suspension,the lower lift beam,the lift cylinder,and the T-shaped fixed beam.The effective lifting range of the beam was 600 ～2000mm.The three-section beam suspension adopted a foldable structure.The beam was connected to the beam suspension through a pipe clamp.The suspension was hinged to the beam through a leveling hydraulic cylinder,which realized the left and right swing relative to the body of the sprayer.According to the adjustment method selected the key parameters of the spray bar suspension and installation location,the hydraulic system was built,and the hydraulic components were selected in accordance with the operational requirements.(3)Researched and designed the control system for the attitude adjustment of the beam.The control system hardware mainly consists of spray bar attitude controller,information acquisition module,control execution module,and power supply module.Self-developed controller main board circuit,with PIC microcontroller as the core design of the spray beam attitude controller,through programming software development spray beam leveling control software system.The controller can read the output signal of the inclination sensor in real time,used the average filtering algorithm to process the collected signal,and used the PID algorithm to calculate the spray beam inclination and leveling hydraulic cylinder flow direction,it controlled the solenoid reversing valve switching state so as to achieve the flow direction and expansion control,to achieve the purpose of spray beam adjustment.(4)Researched and analyzed the rationality of the spray beam attitude adjustment system.Using ANSYS Workbench,the static analysis of the lifting mechanism and the spray beam suspension was carried out,the maximum stress value and maximum strain value during the working process,and the modal analysis was carried out to obtain the natural frequencies and mode shapes of the 1st to 6th orders.The comparison between the frequency and the natural frequency confirms that there would be no resonance phenomenon;the joint simulation analysis of the spray beam leveling mechanism and the hydraulic control system was carried out.The static simulation test results showed that the horizontal adjustment range of the spray beam was-17°～17°,the maximum external load of the hydraulic cylinder was 1.45 k N,and the maximum pressure in the hydraulic cylinder cavity was 160 bar.The dynamic simulation test results showed that the maximum inclination angle of the spray beam was 1.8°,the average value of the spray beam angle during the leveling process was 0.31°,the root mean square error value was 0.629°,and the average absolute error was 0.52°,it indicated that the spray beam adjustment Institutional rationality and feasibility.(5)In order to check the working performance of the automatic adjustment beam,the test evaluation index was designed,and the field test were carried out.The field test drove through a10° step road at a speed of 2.5km/h.By changing the response threshold and the average filter parameters,the system response speed stability and control error were compared and analyzed,and the optimum beam automatic leveling parameters were determined.The best combination,the maximum test leveling error was 1.84°,the average leveling error of the beam suspension inclination angle change no more than 0.05°,the average absolute error no more than 0.59°,and the root mean square error was no more than 0.689°.The field test results showed that the maximum leveling error was 1.53°,the average was 0.135°,the root mean square error was0.454°,the angle of the beam after leveling was kept within 1°,and the angle was no more than0.5°,which indicated that the automatic spray beam leveling system meet requirements of automatic beam leveling control.This research improved the operation quality and safety of the sprayer and provided a reference for the automatic leveling of the spray beam. |
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