New Electronic Fruit Design And Dynamic Modeling Of Grape Cluster Vibration-Collision Coupling In Robotic Harvesting

The fresh table grapes in production must complete the "picking-clipping-clipping-laying" and postpartum sorting,packing,transportation and other operations in the form of clusters.The integrity of fruit bunches and the damage of fruit grains are the two major indicators for the quality evaluation of fresh table grapes.During the process of robot picking and transportation,the loss of grape clusters due to vibration and collision is as high as 20% to 30%.In this paper,aiming at the problems of vibration and collision in the process of grape cluster picking and transportation,the minimum vibration-collision unit named “dual stem fruit system” is defined,and a new vibration-collision coupling measurement electronic fruit is developed.A vibration-collision experiment is designed.Then the dynamic model of the dual stem fruit system is established,and finally the simulation analysis of vibration and collision is carried out based on the model.The main research and work content of this paper includes the following aspects:(1)A new electronic fruit that can measure the vibration-collision coupling motion of grape cluster is designed,and the accuracy check experiment of electronic fruit vibration signal acquisition and the collision detection calibration experiment are carried out.From the results of the vibration accuracy check experiment,it can be known that the vibration data detection relative errors of the X,Y,and Z axes are 2.92%,9.8%,and 5.79%,respectively.And through the collision signal calibration experiment,the relationship between the collision contact force and the induced voltage is determined,and it is finally determined that it can meet the requirements of agricultural production and use.(2)The minimum vibration-collision unit of grape cluster which named “dual stem fruit system” is proposed.Using electronic fruit to test the collision force of the dual stem fruit system.It can be seen from the experimental results that the first collision of the double fruit under the action of gravity excitation is the biggest,and the average peak collision force of the fruit measured at the declination angles of 30°,45°,60°,and 75° is 19.654 N,21.431 N,30.643 N,36.373 N respectively.The acceleration peak is positively correlated with the magnetic declination.The vibration-collision experiment of the double fruit pendulum is carried out by using the electronic fruit,and the average peak collision forces of the fruit at the declination angles of 30°,45°,60°and 75° were 14.052 N,15.146 N,17.266 N,20.671 N.In both experiments,the electronic fruit is used to analyze the influence of viscoelasticity on vibration-collision motion through elastic potential energy with the viscoelasticity between fruit stems as the control variable.(3)Based on the modeling method of grape cluster vibration model of "flexible rod-hinge-rigid rod-rigid ball",a vibration-collision coupling modeling method of "flexible rod-hinge-rigid rod-flexible ball" is proposed.Based on the idea of the vibration-collision coupling modeling method,the dynamic equation model of the dual stem fruit system is established by using the method of analytical mechanics.The two motion modes of the dual stem fruit system are analyzed,and the dual stem fruit system is given.The vibration-collision coupling dynamics equation of the granule system is obtained,and the solution program is given based on the Matlab platform to simulate the vibration-collision coupling process of the dual stem fruit system.(4)The verification and simulation analysis of the dynamic equation of the dual stem fruit system are carried out.The dynamic equation model of dual stem fruit system is used for simulation analysis.By comparing the results of previous experiments and vibration-collision coupling experiments of dual stem fruit system,it is found that the established dual stem fruit system model can indeed simulate the vibration-collision coupling movement process of grape cluster.The average peak collision force relative errors of fruit under deflection angles of 30 °,45 °,60 ° and 75 ° are 7.225%,6.864%,7.056% and 9.323%,The established model meets the needs of subsequent vibration-collision coupling experiments.Finally,the dynamic equation model of the dual stem fruit system is used for simulation analysis,and the vibration-collision motion law of the dual stem fruit system is analyzed.