The Design And Experiment Of The Control System For Picking And Throwing Seedlings Of The Plug Seedling Transplanter

At present,Xinjiang area is the largest production place for crops such as tomatoes and peppers in China.The transplanting of plug seedlings satisfy the climatic conditions in Xinjiang and meet the requirements for large-scale planting.At present,the crops’ seedlings such as tomatos and peppers are mainly manual transplanting and semi-automatic transplanting.The work efficiency is low and the labor intensity is high.Therefore,the fully-automatic transplanters have greater development potential and wider application prospects.Picking and sending seedlings automatically is the crucial technology to realize fully-automatic transplanting,and this also the main solution to improve the work efficiency of transplanting.Therefore,the research on the technology of automatic picking and sending of seedlings and its control strategy has become a research hotspot now.This article focuses on the key technology of fully-automatic transplanters.Especially in the aspect of picking,sending and throwing for the whole row seedlings.Design the control system to realize the picking and throwing motion for the whole row plug seedlings.The main research contents of this paper are as follows:(1)Analyze the typical working modes of transplanters in domestic and abroad machines.Propose a new working mode: pick seedlings at fixed points,release them alternately.This is the method that two seedling belts work alternately and throw seedlings in the shared hopper.We need to improve of the device for whole row seedlings picking and throwing,that is the way for optimization.In order to realize continuous and uninterrupted throwing procedure for seedlings,the double-rotating mechanism has been designed.And the scheme is based on whole row placing seedlings.(2)Analyze the overall structure and working principle of the devices,put forward the control requirements.Analyze the control requirements,clarify the control target,and propose a control system scheme based on the combination of mechanical and electric transmission.Analyze each part of the the device,to prove that the parts are relevant and sequential.Clarify the action flow of each implementing components and determine the work flow of the control system.(3)Design the hardware of the control system for whole row seedlings’ picking and throwing procedure.According to the overall design of the control system,determine the hardware system and complete the hardware selection.Carry out the hardware wiring design to meet the reliability and stability requirements of the control system hardware circuit.(4)Design the software of the control system for whole row seedlings’ picking and throwing procedure.GX Works2 has been used to develop lower computer control program,SFC(sequence function chart)has been used to design the main program and subprograms of the control system.Thus,the programming of the entire control program has been completed.GT Designer3 has been used to develop the host computer interface to complete the design of the control interface;Built communication between GX Works2 software and GT Designer3 software,carry on the joint simulation and complete the debugging of the system software.(5)Build a small simulation test platform to conduct test experiments.The accuracy of the control program and the feasibility of communication between the upper computer and the lower computer has been verified respectively.Build the test platform for the control system,carry out the displacement accuracy test of the manipulator movement and the seedling belt rotation.The results show that the positioning error of this two components is small,and the whole positioning accuracy is high.The variable speed control verification test of the seedling belt has been carried out and the setting value of seedling casting speed is in the range of 40～120 plants/min.The results showed that when the hopper in the position which the height difference(between the center of the seedling hopper and the seedling throwing point)is170 mm,the horizontal distance is 90 mm to 100 mm,the seedling casting speed is within the following two ranges: 60～80 plants/min and 100～120 plants/min.The success rate of seedling throwing is higher,and the variable speed control performance of the test device is better.