Development Of Mobile Platform For Tea Garden Management Machine In Hilly And Mountainous Areas

China has the largest planting area of tea gardens in the world,with more than 60%of tea gardens distributed in hilly and mountainous areas.The unique topography of hilly and mountainous areas limits the automatic management of tea gardens.The protection of tea plant diseases and insect pests is particularly important in the daily management of tea gardens.Nowadays,the spraying operation in the automatic management of tea gardens is basically completed by manpower,which makes the labor force tense and the operation cost increase.Traditional spray rod spraying device can’t realize high efficiency,precision and low pollution spraying.In order to realize automatic spraying in tea gardens in hilly and mountainous areas and solve the problems of poor spraying quality,low spraying efficiency,high labor intensity,serious pollution of pesticides to soil and environment,and inability of large and medium-sized tractors to enter tea gardens in hilly and mountainous areas in China,this paper analyzes and compares the performance characteristics of different types of sprayers at home and abroad by consulting a large number of relevant literatures,and combines with the actual situation of tea garden management in hilly and mountainous areas in China at present,deeply investigates and understands the actual needs of tea garden managers.An automatic spraying device for tea garden with compact mechanical structure and self-adaptive ability is developed,which can be used in hilly and mountainous areas and based on small and medium-sized mobile platforms.The main research contents are as follows:(1)Design of key components of automatic spraying device for tea gardens in hilly and mountainous areas.According to the characteristics that tea garden pests like to feed on the back of mature old leaves in the middle and lower parts of tea trees,the spraying mode of horizontal spraying and 45 angle spraying is adopted The ultrasonic ranging module is used to automatically target,and the position between the nozzle and the surface layer of tea crown is located.Combined with the actual conditions,design requirements and agronomic requirements of tea gardens in hilly and mountainous areas,and taking into account the factors such as the passability and adaptability of the automatic spraying device between tea ridges,the mechanical structure of the automatic spraying device was designed.Three-dimensional model of automatic spraying system of tea garden was drawn by Solid Wor ks software.The movable range of spray bar bracket of automatic spraying device in vertical direction was 0～700 mm.The length of spray bar was measured and calculated to be1100mm,and the distance between spray heads was 500 mm.According to the spray performance requirements of automatic spraying device,the service pressure and maximum flow rate of electric pump,solenoid valve and fan nozzle are analyzed and calculated,the energy loss of fluid flow resistance and local water flow loss in pipeline are quantitatively calculated and pressure compensation is carried out,and the performance parameters of spraying loop system are determined.(2)Hardware design of control system.The hardware circuit of the main control system is designed,and the automatic control program is written.Using ultrasonic sensor ranging module,the spatial position of tea crown surface layer and nozzle is detected,and the accuracy of data and targeting accuracy are improved.The vehicle speed detection module is used to detect the running speed of the automatic spraying device,so as to study the influence of walking speed on spraying quality.(3)Spray performance comprehensive test platform test.The parameters,droplet size and spray uniformity of the fan-shaped nozzle are tested by using the spray performance comprehensive test platform.The experimental results show that the air resistance has no effect on the nozzle parameters when the pressure of the liquid medicine power unit is0.30MPa and the distance from the nozzle to the surface layer of tea crown is 400mm;Under this spraying condition,the spray angle is 102.6,the droplet size is 89.784μm,which is easily absorbed by plant leaves when it is less than 100μm,and the variation coefficient of liquid volume distribution is less than 50%specified in the standard,which meets the operation quality requirements of mobile sprayer in the national standard.Field experiment of tea garden.When the driving speed of automatic spraying device in tea garden is in the range of 1～3m/s and the distance from spraying rod to tea crown is in the range of 300～500mm,the average coverage rate of droplets is taken as the main evaluation index,and the deposition density is taken as the auxiliary index.The orthogonal test design method is adopted to carry out the experimental study,and the orthogonal test of three factors and three levels is carried out to test the influence of spraying height,driving speed and canopy gradient on spraying quality.The experimental results show that the average deposition density of droplets at different points under different canopy gradients of tea trees is more than 26/cm~2,which is higher than the requirement of JB/T9782—2014"General Test Method for Plant Protection Machinery"of 20/cm~2for spray width in air-driven spray.The influence degree of spraying parameters on the deposition density of droplets in the experiment is canopy gradient,spray height and driving speed.Among them,the deposition density of different canopy gradients is the largest in the surface layer,and the difference of droplet deposition density between the middle and lower canopy is relatively small and not significant.The higher the spray height,the less the number of droplets deposited,and the number of droplets at the height of 30cm is significantly higher than that at the height of 50 cm.