Study On Design And Control System Of Seedling Picking Claw Device For Transplanters

With the continuous development of seedling technology,the planting area of tomatoes and peppers in Xinjiang is expanding,so the degree of demand for automatic transplanting machinery is increasing year by year.At present,the technology of semi-automatic transplanters in Xinjiang is relatively mature,but the reliance on manual labour is still high,therefore,the development of seedling picking devices will occupy an important position in the whole process of developing automatic transplanters.This thesis analyses and compares the current research situation of seedling picking devices for transplanters at home and abroad,and designs a seedling picking claw device to meet the existing demand for cavity tray seedling transplanting in Xinjiang,taking into account the existing agronomic requirements in Xinjiang,The main studies are as follows:(1)The design of a seedling picking claw was initially designed using Solidworks software.The movement requirements of the picking claw were analysed,and the linear translation module was determined as its movement carrying device,completing the design of the overall scheme of the picking claw device.A theoretical analysis of the structure of the seedling picker was carried out,a mathematical model of the seedling picker was established,the seedling picking characteristics of the seedling picker were analysed,the optimisation objective function and constraints were determined,and the structural design of the seedling picker was optimised using a penalty function-based particle swarm optimisation algorithm in MATLAB.The design of the cam actuator mechanism for the picking jaws was completed according to the movement requirements of the picking jaws.(2)The results of the kinematic simulation using the Virtual Prototyping software show that the distance travelled by the push rod has a small deviation from the theoretical distance,and the optimisation of the cam parameters is completed.The results of the joint PID simulation using ADAMS and MATLAB/Simulink show that the trajectory of the picking jaw meets the requirements for picking seedlings and the step response is fast.(3)Theoretical analysis of the control requirements of the seedling picking claw device is carried out,and the overall scheme of the control system of the seedling picking claw device is completed.The STM32 microcontroller is determined as the controller,and the stepper motor is used as the power source of the seedling picking claw device to complete the overall wiring design.This paper proposes to use the positionvelocity PID double closed-loop control algorithm as the opening and closing precise positioning control system of the seedling picking claw,and the trapezoidal acceleration and deceleration control algorithm as the control system of the remaining three motors to complete the system software design.(4)After completing the construction of the test platform for the seedling picking claw device,in order to study the performance of the seedling picking claw device on the 72 and 128 hole cavity trays commonly used for processing tomatoes in Xinjiang,seedling picking and dropping tests were carried out at a frequency of 40 plants/min,50 plants/min and 60 plants/min.The results showed that the seedling picking claw device was well adapted to these two sizes of cavity trays and was able to complete the seedling picking and dropping operation.