| Wide-width boom sprayers are gradually applied to agricultural production due to their advantages of wide spray width,high operation efficiency,long battery life and low crop damage rate.Excitation,it is easy to cause body roll,pitch,etc.,resulting in irregular movement of the boom,reducing the stability of the boom and affecting the spraying effect.Only relying on the passive suspension of the sprayer itself cannot meet the requirements of modern agriculture for the uniformity of spraying in plant protection operations.At present,the domestic research on boom hangers lags behind that of European and American countries,and the technical level of high-end wide-width sprayers is difficult to meet the development of modern precision agriculture and green agriculture.In order to improve the stability of the boom and ensure the uniformity of liquid spraying,this thesis studies its attitude control system based on the 3WP-3000 trailing boom sprayer with a spray width of 24 m.The main research contents are as follows:(1)Analyze the mechanical structure of the sprayer,including the boom suspension,passive vibration damping mechanism,active trapezoidal mechanism of the lifting device and folding mechanism.Among them,the damper in passive suspension is deeply analyzed,the working principle of hydraulic damper and the relationship between damping force and displacement are analyzed.The height change stroke of the boom was obtained through mathematical calculation,and the force analysis of the lifting mechanism was carried out to obtain the maximum tensile force during operation,and based on this,the key parameters of the lifting cylinder were determined.The active trapezoidal mechanism is analyzed,and the relationship between the active action of the angle adjustment cylinder and the inclination of the spray rod is obtained,and the static test bench used for the preliminary test is briefly introduced.Finally,the static analysis of the boom is carried out using ANSYS software.(2)The basic working principle of the hydraulic system is expounded through the analysis of the working conditions of the hydraulic system of the boom hanger device.The overall hydraulic system of the sprayer is designed,and the design of the synchronous circuit and proportional control circuit in the hydraulic system of the boom hanger is introduced in detail,which ensures that the entire hydraulic system can meet the operating requirements of the hanger.The key hydraulic components in the system are introduced.(3)Design the attitude control system of the sprayer,describe the working principle of attitude control,and then introduce the height and angle adjustment hydraulic system and design the hardware,including the distance measuring sensor,angle sensor,proportional solenoid valve,selection of components such as conversion module and touch screen,and finally the design of software system,including data conversion,design of detection mode,selection of control method,and design of height adjustment,angle adjustment and alarm program.(4)Based on the above research,the relevant performance tests of the attitude control system are carried out.Through the actual data test of the ultrasonic sensor,it is concluded that the error between the detected value of the ultrasonic ranging sensor and the actual value is less than 0.5%,which meets the needs of the control system.The height adjustment test shows that when the height adjustment threshold is set to 30 mm,the accuracy and quick response of the boom height adjustment can be well guaranteed.The step response angle adjustment test shows that after the attitude control system is turned on,the stability of the boom increases compare with the state without the control system,and the recovery of the boom is significantly shortened,and the final state of the boom is closer to the horizontal state. |
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