Research On The Design And Control System Of Vegetable Plug Seedling Picking And Throwing Device

In recent years,with the acceleration of urbanization and the migration of rural labor force to cities,the problem of difficult employment in vegetable industry has become increasingly serious.In order to alleviate the problem of labor shortage,various types of vegetable transplanting machines come into being.However,most of the vegetable transplanting machines on the market in China are semi-automatic.In this way,vegetable transplanting still requires the assistance of multiple people,and its transplanting efficiency is limited by human work efficiency.Moreover,the transplanting efficiency of the semi-automatic transplanting machine is not high,but the labor intensity is still very high.On the contrary,the fully automatic transplanting machine adopts a mechanical automatic method of picking and throwing seedlings,which has high efficiency and low labor intensity.With the advancement of agricultural mechanization,the vegetable industry has an even more urgent demand for fully automatic vegetable transplanting machines.As the key device of the fully automatic transplanter,the seedling picking and throwing device has been widely concerned by researchers around the world.Therefore,a simple structure and high efficiency seedling picking and throwing device is proposed,which is beneficial to the development of fully automated vegetable transplanting.In this paper,referring to the existing domestic and foreign seedling picking and throwing devices,by analyzing its characteristics,a new type of vegetable plug seedling picking and throwing device is proposed,the corresponding national patent has been applied,and the research is carried out.The specific research content is as follows:1)According to the research status of domestic and foreign plug seedling picking and throwing devices,combined with the existing picking and throwing device,a vegetable plug seedling picking and throwing device is designed,which includes a seedling picking mechanism,a tray moving mechanism and a seedling feeding mechanism.Moreover,the working principle of the device is described,and the cooperation mode of each mechanism is designed.At last,kinematics theory model is established for the seedling picking mechanism.2)Based on the kinematic model of the seedling picking mechanism,the auxiliary optimization software of the seedling picking mechanism is developed.The effects of different structural parameters on the trajectory and motion characteristics of seedling pick-up point are analyzed,and the optimization direction of each structural parameter is summarized And taking the requirements of the trajectory of the plug seedlings and throwing seedlings as the goal,using the optimization method of human-computer interaction,a series of better parameters is selected through the software:γ=40°,l₁=94mm,l₂=278mm,l₄=45mm,r=130mm,x_d=-326mm3)According to the better structural parameters of the seedling picking mechanism,the seedling picking mechanism,the tray moving mechanism and the seedling feeding mechanism in the plug seedling picking and throwing device are designed.Moreover,the three-dimensional modeling and virtual assembly are completed in PTC Creo.At the same time,the kinematics simulation of the seedling picking mechanism is carried out.The simulation results show that the simulation trajectory of the seedling clip tip is basically consistent with the theoretical trajectory,which shows the correctness of the theoretical design.4)The system is designed for the device,including hardware design,motion control algorithm design and software design.In terms of hardware,PLC is selected as the core controller,and the selection of stepping motor,sensor and other hardware is completed,and the wiring diagram is designed;In the aspect of motion control,a double closed-loop incremental PID control algorithm is designed for the stepper motor of the tray moving mechanism,and the simulation is completed in Matlab/Simulink.The simulation results show that the algorithm can reach the requirements of tray positioning.Meanwhile,for the DC motor of seedling picking mechanism,a control algorithm of trapezoidal curve acceleration and deceleration is designed,and the mechanism test is completed in PTC Creo.The test results show that the algorithm can reduce the start-stop impact;In the aspect of software,the control program of the device is completed in GX works2.5)The prototype is manufactured,and the test bench is built.On this basis,the trajectory verification test and the seedling performance test are carried out,which verifie the correctness and feasibility of the theoretical design of the vegetable plug seedling taking and throwing device.Meanwhile,the results show that the highest success rate of picking seedlings is 92.44%,the average success rate of picking seedlings is more than 89%,the highest success rate of throwing seedlings is 98%,the average success rate of throwing seedlings is more than 90%,the lowest injury rate was 1.4%,and the average injury rate is less than 3%.Moreover,the test shows that the device can complete the seedling picking and throwing operations well,and the seedling picking efficiency can reach 80 plants/min.