Design And Experiment Of Automatic Separating And Gathering Devices For Bare Root Welsh Onion Seedlings

The transplanting technology of bare root seedling of welsh onion is one of the key technologies of welsh onion production,and the automatic seedling separation technology is the key to realize the automatic operation of welsh onion transplanting machine.At present,the transplanting methods of bare root seedlings of welsh onion are mainly divided into manual transplanting and semi-manual mechanical transplanting,and the low efficiency and high labor intensity restrict the development of welsh onion industry.With the adjustment of agricultural and rural industrial structure and the transfer of labor force to cities,the demand for automatic and intelligent onion transplanting machinery is becoming more and more urgent.However,at this stage,the domestic research on the automation of scallion transplanter is still in the preliminary exploration stage.Studying the orderly collection of bare root seedlings of welsh onion in the indoor environment is conducive to providing prerequisites for automatic seedling delivery in the subsequent bare root seedling transplanting operation.Therefore,based on the research status of welsh onion transplanting machine and its supporting mechanism at home and abroad,this paper proposes an automatic seedling separation and seedling collection device for bare root seedlings of welsh onion,which is mainly composed of seedling separation device,seedling collection device,end seedling clamper,Delta robot,conveyor belt and so on.In this paper,the bare root seedlings of welsh onion were taken as the research object to realize the separation,identification,grasping and collection of bare root seedlings of welsh onion.The main contents of this paper are as follows:(1)The structure design and optimization of seedling system.Through the mechanical properties test of the bare root seedlings of welsh onion,the test results were analyzed.Based on this,the end clamping device was designed and the clamping force was analyzed,which provided a basis for cylinder selection.Based on the analysis of the agronomic requirements and technical specifications related to the transplanting of welsh onion,two vibration seedling separation devices suitable for bare root seedlings of welsh onion were proposed,and the oblique throwing seedling separation device was selected and optimized.At the same time,this paper also proposes a collection belt for bare roots of welsh onion,aiming to place the separated bare roots of welsh onion on the collection belt in an orderly manner,which can be used as a supporting device to support the rapid transplanting of welsh onion transplanter.(2)An image acquisition system for bare root seedlings of scallion was established.The center of gravity position and axial angle of the bare root seedling of welsh onion were obtained and located by threshold segmentation and geometric moment method.On this basis,the positional relationship between the devices is calibrated,and the accuracy of the two visual calibration methods based on the robot and the conveyor belt is compared.The visual calibration method based on the conveyor belt is selected.Based on this method,a software for identification and pose determination of bare root seedlings of scallion based on conveyor belt is developed.(3)Delta robot analysis and motion planning.The kinematics model of Delta robot is established,and the displacement and maximum acceleration are given as constraints to plan the motion trajectory of the robot end moving platform,so that the robot moving platform is in a relatively stable state during the movement.According to the actual movement of the Delta robot,the motion path of the end is planned,and the virtual prototype model of the Delta robot is established.The rationality of the trajectory planning and the correctness of the mathematical model are verified by ADAMS modeling and MATLAB simulation analysis.(4)The physical prototype construction and prototype test of the bare root seedling separation and collection mechanism of scallion.By establishing the communication connection between the host computer and the terminal seedling clipper,conveyor belt,Delta robot,seedling separating device and seedling collecting device,the system integration is realized.The physical prototype was built and debugged,the working sequence was distributed,the workflow was introduced,the seedling separation and seedling collection test was carried out.The average seedling separation rate was 72.344%.The average single collection time of the seedling collection device was about 5.9 s.The theoretical collection efficiency was about 610.169 seedlings per hour,and the rate of seedling collection was 87.5%,which verified the feasibility of the device and met the actual collection requirements of bare root seedlings of welsh onion.