| Rice field weeds are an important part of the agricultural paddy ecosystem.T hey compete with rice for growth space,fertilizer nutrients,light,water and heat,resulting in a decline in rice yield and quality,directly affecting national food security capacity.According to the data of FAO,the loss rate of rice yield caused by weed damage in China has reached about 13%,and ten billion kilograms of grain have been lost per year.Scientific and effective prevention and control of weed damage is an important guarantee for achieving high,stable and high-quality rice production.Mechanical weeding is favored because it can loosen the soil during the weeding process and enhance the soil's ability to absorb nutrients.At present,the paddy field weed er is still mainly used for tractors or manual push-pull operations,there are some problems,such as low efficiency,high labor intensity,high rate of seedling injury,difficulty in field turning,and unable to work continuously for a long time.The development of intelligent automation machine is still in progress and it mostly acts on dry-land crops.In view of the low degree of automation and lack of equipment in the paddy field weeder,this paper developed a crawler-type controlled paddy field weeder with light soil damage,good vehicle maneuverability,compact structure,small turning radius,etc.The weeding wheel with adjustable pitch,height and speed in order to carry out effective high-speed weeding work in paddy fields with different line spacing and mud depth.The performance of the machine is verified by tests.The main contents of the research are as follows:(1)According to the agronomic requirement of rice planting in Northeast China,considering the factors such as operation time,field operation efficiency,seedling injury rate and weeding rate during operation,field walking subsidence and soil damage degree,the overall structure scheme of remotely-controlled double row paddy field inter-row weeder was determined.The plane motion model of the turning machine was established,and the maximum power of the chassis motor was deduced.The remote control system of the machine was designed according to the principle of radio receiving and sending,which realized the remote control of the forward,backward,turning of the machine,the swing and pitch of the camera steering gear,t he rotation of the weeding wheel.(2)Designed the key components of the whole machine,designed the transmission system of the machine,designed the propulsion device such as the driving wheel and the supporting wheel reference to the relevant formula,supporting wheel was checked by the finite element analysis software.The statics research was carried out on the weed wheel at a constant speed to determine the main parameters of the weeding wheel,established the static model of the weeding device,derive the maximum power required of the weeding device motor,and selected the electrical components of the machine.(3)The paper established 3D modeling by Pro/ENGINEER Wildfire 5.0,and the performance of the machine was analyzed.The maximum grounding pressure was 9872 Pa,and the minimum ground pressure was 7836 Pa when the center of gravity was shifted.By analyzing the lateral and vertical stability of the machine,the vertical ultimate tilt angle was 42.8° and 28.7° when the machine gone uphill and gone downhill,the vertical limit slip angle was 31°,the lateral limit tilt angle was 33.9°,and the lateral limit slip angle was 31°.(4)Workbench 14.0 software was used to solve the modal frequency and mode shape of the non 0 first 4th order of the weeding device frame,and the accuracy of theoretical calculation and modal test was tested.Comparing and analyzing the relationship between the natural frequency of the frame and the external excitation frequency,the natural frequency of the frame avoided the external excitation frequency.When the weeding device worked,the resonance can be effectively avoided,and the reliability of the frame structure design was verified.(5)The field running speed,turning radius and height of the machine chassis were teste d respectively.The chassis running speed ranged from 0 to 0.9 m/s,the minimum turning radius was 435 mm,and the maximum height of the field crossing was 162 mm,it can realize the operation of unimpeded driving in the low ridge paddy field.(6)The field weeding test was carried out,the forward speed and depth of the machine were selected as the tested factors,and the weeding rate and seedling injury rate were selected as the tested indicators.The field single factor and multi-factor tests were carried out respectively.The paper analyzed the test data by data processing software,determined the order of the factors affecting the performance of the operation.Field tests showed that the interaction between the forward speed and the weeding depth had a significant effect on the weeding rate.The primary and secondary factors affecting the weeding rate were: weeding depth and forward speed.The interaction between the forward speed and the weeding depth had a significant effect on the injury rate.The pri mary and secondary factors affecting the injury rate were: forward speed and weeding depth.When the forward speed of the implement was 0.45 m/s and the weeding depth was 74 mm,the weeding performance was the best,the weeding rate and the injury rate were 82.73% and 2.63%,respectively,which satisfied the agronomic requirements of weeding in paddy fields. |
PDF Full Text Request