Design And Test Of Electric Seedling Taking Device For Tobacco Transplanter

Since the foam seedling tray suitable for the floating tray of tobacco pot seedlings cannot be bent,it is difficult to automatically take seedlings for transplanting,the speed is slow,and the efficiency is low.In order to solve the above problems,this paper designed a double seedling tray horizontal conveying and automatic seedling picking device.Under the control of the designed STM32 control system,the two sets of automatic seedling picking mechanisms alternately reciprocate and accurately pick and drop seedlings according to the transplanting operation sequence.The horizontal movement of the seedling picking mechanism adopts the control strategy of T-shaped acceleration and deceleration,which can effectively reduce the grasping time of the farthest pot seedlings and reduce the time interval of the connected pot seedlings,thereby improving the speed of automatic seedling picking and transportation of tobacco pot seedlings..The specific research contents are as follows:1)The physical properties of the tobacco pot seedlings,the three-dimensional size of the floating seedling tray,and the centering of the pot seedlings were measured;the stalks of the tobacco pot seedlings were compressed by the universal testing machine.The average plant height is 125.9mm,the seedling weight is 16.5g,the diameter of the seedling stem is4.18 mm,the range of the opening degree of the seedling clip is 16-28 mm,the critical force for damage is 4.7N,and the force for pulling out the seedling is 1.75N;it is a non-destructive seedling removal plan Design provides reference.2)According to the characteristics of 10×20 floating seedling trays in tobacco seedling raising and the requirements for picking and throwing seedlings from tobacco pots,a seedling picking process of horizontal tray feeding,bilateral seedling feeding and variable distance seedling feeding was proposed.Through the analysis of the process of taking seedlings from tobacco pots,the overall structure of the device for taking seedlings is determined.The dynamic modeling analysis of the key components of the seedling picking mechanism is carried out.The calculation results show that the time for removing seedlings is 195 ms and the time for putting seedlings is 142 ms when the system air pressure is0.42 MPa.3)The hardware circuit,control logic,control algorithm and program software of the control system of the seedling picking device are designed.At the hardware level,STM32IGT6 is selected as the core controller,and its model is determined by calculating the power of the stepper motor;in the aspect of motion control logic,the wiring principle of components and the logic of information interaction between various mechanisms and sensors are expounded;In terms of control,a trapezoidal control algorithm is designed.When the program setting value is 28.2mm/s2,the acceleration of the first half of the plant spacing is 28.2mm/s2,and the distance acceleration of the second half of the plant spacing is970mm/s2,which takes 1.354 s.The maximum acceleration of seedling picking is 952mm/s2,the maximum speed is 596mm/s,and it takes 3s to take seedlings per plant.It can meet the seedling picking efficiency of 40 plants/min.In terms of software,the main program and the motion control program of each mechanism are partially and integrally designed.4)The prototype was processed and trial-manufactured,and the tests of tray feeding,seedling picking and loadability were carried out.The average error of a single line is1.79 mm,and the average cumulative error of the position error of 20 times of intermittent feeding is 2.89 mm,which can fully meet the needs of accurate seedling picking.The last row and the 10 th seedling in each row are most seriously affected by distance,running speed and cumulative error;the lateral seedling transport actuator can run stably when the load is less than 29 g,and when the transport mass is 30 g,the average error reaches 2.93 mm,The maximum error reaches 3.64 mm.5)The performance test of seedling picking was carried out on the device.The 6 groups of test data showed that the success rate of seedling picking of the device was up to 93.62%.The rate of damage to seedlings was as high as 90%,the lowest rate of damage to seedlings was 2.88%,and the average rate of damage to seedlings was less than 4%,indicating that the device could well fulfill the job requirements,and the maximum efficiency of the bilateral seedling picking device could reach 40 plants/min.