Design And Experiment Of The End-effector For Seeding Pick-up Based On The Mechanical Properties Of Cabbage Seedlings

China is a big vegetable country,and cabbage is one of the main vegetable growing crops in China.It ranks third in China's vegetable planting area and ranks first in the world.Seedling transplanting is the main way of planting vegetables at present,but there are few studies on automatic transplanting machinery for cabbage seedlings.The end-effector is a key component of the fully automatic transplanting machine and has an important impact on the quality of the seedlings.At present,many scholars have carried out targeted research on the end-effector,but mainly applied to a specification of the plugs,which is not easy to meet the requirements of various specifications of the plugs.In the view of fixed spacing and poor adaptability of the existing seedling needle,and the difficulty of ensuring the on-demand adjustment to adapt to different plugs of seedlings in the transplanting process,a needle-type seeding end-effector with adjustable insertion pitch is designed.A systematic study of the end-effector of the seedling was conducted by consulting the literature,growth characteristics and mechanical properties of cabbage seedlings,mechanism design,EDEM single factor simulated test,orthogonal experiment,etc.The main research contents and results are as follows.(1)The seedling experiment was carried out on the seedlings of cabbage,and the growth characteristics were analyzed.The diameters,plant heights and the formation of root mites of the72,128 and 200 points seedlings of different seedling ages were obtained,and the situation in which the seedlings are falling down is obtained.The seedlings of the experiment were determined to be the seedlings of 128 plugs,the seedling age was 40 days;the seedlings of 128 plugs were seedlings for 30 days;the seedlings of 200 plugs were seedlings for 20 days,and the seedling experiment was carried out under the premise that roots were formed.(2)The experimental study on the mechanical properties of cabbage seedlings was carried out.Through the insertion and extraction resistance experiment of the seedling needle,the maximum insertion and extraction resistance at different water content levels and different insertion and extraction speeds were obtained.The maximum force of the taking seedling at different water contents was obtained by the force experiment of the taking seedling.Through the extraction destruction experiment of the seedlings of cabbage,the extraction force at differentwater content levels was obtained.Through the compression experiment of cabbage root,the compression characteristics under three water contents were obtained,and the root destruction characteristics were obtained by compression destruction experiment.(3)Structural design and parameter determination were made for the end-effector.Analyze three common driving forms of pneumatic,electric and electromagnetic,and determining that the drive component of the end-effector is an electric putter.The adaptability experiment of needle was carried out on the seedlings of different size plugs,and the diameter of the needle corresponding to the seedlings of different plugs was determined.The comparative analysis of the needles under the two operation modes confirmed that the operation mode was a four-needle centripetal type.The structural parameters of the end-effector were designed,and the force analysis was carried out on the extraction of the seedlings for the roots,and the parameter relationship between the various mechanisms was determined.(4)The root integrity rate and the failure rate of the seedling picking were regarded as evaluation indexes.The specifications of plugs,the acceleration of seedling picking,the insertion ratio of the needle and the moisture content of root were regarded as the test factors.Single factor simulation was conducted for the seedling picking by EDEM,The optimal range of the acceleration of seedling picking was 0.1-0.5 m/s2,and the optimal range of the insertion ratio of the needle was 10%-20%,The single factor simulation results of The specifications of plugs are not much different.(5)Performance experiment were carried out on the end-effector of the seedlings of cabbage.The results of the range analysis show that the optimal level combination of factors affecting the integrity of roots is 0.1 m/s2 for acceleration,15% for margin ratio,56.2% for the moisture content of root and 72 points for the specification of plugs,and the optimal level combination of factors affecting the failure rate of the seedling picking is 72 points for the specification of plugs,0.1 m/s2 for acceleration,56.2% for the moisture content of root,and 10%for margin ratio.Through the comprehensive weighting method,the optimal combination of parameters for the evaluation indexes is 0.1 m/s2 for the acceleration of seedling picking,the moisture content of root was 56.2%,the specification of plugs was 128 and the insertion ratio was15%,and the verification experiment is carried out.The experiment results showed that the root integrity rate was 97.93%,the failure rate of the seedling picking was 0.81%.