Design And Test Of Key Components Of Tracked Variable Rate Fertilizer Applicator Based On BDS

Orchard fertilization is an important link in agricultural production.The application of granular fertilizer can provide nutrients for fruit trees for a long time and improve the economic benefits of fruit trees.Variable rate fertilization combined with soil testing formula technology can effectively save the cost of fertilization and improve the utilization rate of fertilizer.In this paper,a crawler variable rate fertilizer applicator based on BDS is designed.Through the static analysis of ditching knife and the calculation of Fertilization Parameters of grooved wheel fertilizer ejector,the variable rate fertilizer system is applied to the crawler variable rate fertilizer applicator of BDS;The rate attenuation law of the trough wheel of the fertilizer applicator and the response speed of image processing and serial communication are studied to realize the accurate and variable control of the amount of fertilizer;Combined with the discrete element method,the grooved wheel fertilizer applicator is designed and simulated to explore the variation law of fertilizer amount under different rotating speed conditions.The density,water content,angle of repose,particle size distribution and other parameters of granular organic fertilizer were measured through experiments.The average value of 1000 grain weight measured by granular fertilizer is 50.36 g and the average moisture content is 4.32%.The variation diagram of the maximum and minimum force with time is obtained through the output of DS2 pressure tester.The maximum peak value in the 20 measurement results is 144 n.When testing the angle of repose,the average value of29.98 ° obtained by the injection method is similar to the average value of 27.85 ° obtained by the tilt method.According to the measurement and calculation results of 100 basic physical parameters of granular organic fertilizer,the average diameter is 4.28 mm,the average mass is 0.0648 g,and the average density is about1530 kg / m3.A crawler variable rate fertilizer applicator based on BDS is designed to calculate the working characteristics of trencher and grooved wheel fertilizer ejector.Selecting the row spacing parameters and fertilization amount of large-scale jujube garden in southern Xinjiang as the design basis,the single rotation fertilizer discharge amount of the fertilizer applicator is 100 g,which is more consistent with 97.47 g of the fertilization amount of the test-bed.The variable rate fertilization control system is designed through the regional fertilization prescription map.Using image processing and image segmentation to calculate the step data,57 step motor is selected to control the grooved wheel fertilizer ejector for precise fertilization.When EDEM discrete element analysis particle contact model,combined with the elastic modulus,shear modulus,Poisson’s ratio and other parameters of particles and fertilizer applicator,the best Hertz Mindlin(no slip)model is selected for simulation calculation,the particle velocity in the fertilizer plane and the moving speed trajectory of particles at the fertilizer inlet are analyzed,and the quality of organic fertilizer passing through the fertilizer inlet under five working conditions is simulated.The results show that the flow rate is similar under the two working conditions of 150 r/ min and 200 r/ min.in order to make the fertilization amount more accurate,the theoretical sheave speed should not exceed 150 r/ min;Moreover,the particle flow attenuation is obvious under the working conditions of 200 r/ min to 250 r/ min.The field experiment shows that the average time of furrow opening and fertilizing machine is 7.08 s;The average value of trenching depth is 409.90 mm;The average operating speed is 1.02 km / h;Under no-load condition,the speed loss of the fertilizer applicator is low,and the average accuracy rate is about 97%.Under the support of variable rate system,the comprehensive fertilization accuracy rate of grooved wheel fertilizer applicator is 99.27%.Under 60 r/ min condition,the fertilizer leakage accuracy rate is increased by 8.31%compared with the traditional DC motor fertilizer applicator.In the field experiment,the average fertilization accuracy rate of grooved wheel fertilizer applicator based on variable rate fertilization system is 96.07%,and when the variable rate fertilization system is lower than the limit speed,Rotational speed had little effect on the accuracy of fertilization.