Optimal Design And Experiment Of Vegetable Plug Seedlings Pick-up Mechanism For Exploring And Picking-pushing Plugs

Being a kind of important agricultural products,vegetables are vital to the survival of Human.According to the national vegetable industry development plan from 2011 to 2020,adding comprehensive support of science and technology for the development of vegetable industry will be vegetable industry’s primary task.Domestic vegetable transplanting machines are mostly semi-automatic types which use manual seedlings picking,most of which have problems such as seedlings’ low picking efficiency and poor pushing accuracy.So,it is very important to develop an automatic seedlings pick-up mechanism without destroying existing types in domestic market.Aiming at the problems mentioned,a vegetable potted seedlings pick-up mechanism for exploring and picking-pushing plugs is developed to use the new picking and pushing combination seedlings pick-up terminal actuator(potent number: 201910229874.7)to replace old ones which can only do one job.The mechanism uses a non-circular gear with a variable speed rotary transmission method to transmit power,and use of a straight line trajectory,replacing the old beak like trajectory,which can reduce the secondary damage to the seedlings caused by seedlings picking needles in the seedlings picking procedure.This mechanism can achieve fast seedlings picking movement and seedlings pushing movement,and has a batter fit degree with seedlings transplanting mechanism,making it able to do accurate seedlings putting job.The main research contents of this paper are as follows:(1)Studying the design and technology of seedlings pick-up mechanism at home and abroad and the development of them as well as stating the main research contents of this paper and technology tree.Large fruit and pepper cultivated by Northeast Agricultural University is chosen as the test subject for the seedlings pick-up experiments.The design requirements of the vegetable seedlings pick-up mechanism are put forward in combination with the agronomic requirements of test subjects.The composition and operating principle of the seedlings pick-up mechanism are analyzed,after which the kinematic model are set up,changing abstract issues into concrete ones.Parameters such as location coordinates and rotation angles of critical components of the seedlings pick-up mechanism while operating are shown in digitized form.According to the theoretical model of the seedlings pick-up mechanism,seven optimization design goals are determined.Visual Basic 6.0 is used to develop a visual optimization design software(register number: 2019SR0053063)in order to set up a function relationship between the parameters and the optimization design goals.A group of applicable parameters and theoretical trajectory of the seedlings pick-up mechanism are determined by means of adjusting the input parameters and optimizing the trajectory and shape of the seedlings pick-up mechanism.(3)According to the operating principle of the seedlings pick-up mechanism,the structure is designed and parameters are determined by visual optimization design software.Using Auto CAD2016,a two-dimensional graphics software,the design of the integral structure of the seedlings pick-up mechanism is accomplished.Using NX 8.0,three-dimensional models of parts of the seedlings pick-up mechanism are built and the virtual prototype of the seedlings pick-up mechanism is assembled.(4)According to the motion principle of the seedlings pick-up mechanism,the virtual prototype is imported into the simulation software Adams,in which the motion of the mechanism is simulated and analyzed.The design of the mechanism is verified by contrasting the simulated trajectory and theoretical trajectory.Using Abaqus,a finite element analysis software,and through the operating frequencies of the non-circular gears are measured by means of virtual simulation,model analysis of the non-circular gears suggests that the operating frequencies of them are not related to their natural frequencies,making sure there will be no resonance while the gears are operating.(5)Experimental prototype is built using 3D print technology,and the actual trajectory is extracted using high-speed photography technology,verifying the consistency of actual,theoretic al and simulated trajectory.The maximum soil entering force of the prototype is calculated using similarity theory.The matrix ratio of soil is set at 0.4,which proves to be comparatively excellent according to the calculation.With the test bench built,seedling pick-up test are performed on the prototype.The success rate of the prototype is 96.87%,which satisfies the requirement of vegetable seedlings pick-up and verifies the feasibility of the seedlings pick-up mechanism.