Design Of End Effector For Citrus Nondestructive Picking Mechanism

As a characteristic crop in the Three Gorges Reservoir area,citrus has a wide planting area and high yield.It is the main economic source of local farmers.Its picking method is mainly through manual picking,accounting for40% of the total production.Citrus picking is time-consuming and labor-consuming.The hilly terrain further increases the difficulty and risk of picking.The citrus picking end effector generally picks Citrus by clamping,and puts the fruit into the collecting basket through the mechanical arm,which not only causes mechanical damage to citrus,but also reduces the picking efficiency.Therefore,it is of great significance to design a citrus non-destructive picking end effector.Taking Ponkan and guhongju in Wanzhou citrus orchard as the research objects,the citrus picking end effector was designed.The main contents of this paper are as follows(1)Physical properties of citrus.Based on the investigation of Ponkan and guhongju,the basic parameters of the two kinds of fruits were obtained,and the mechanical properties of the fruit stem were analyzed.The maximum cutting resistance of the fruit stem was 79.2n,and the minimum pulling force was 22 n.(2)Design of end effector for citrus nondestructive picking.According to the physical characteristics of citrus,the distance between the blade of the cutting mechanism and the knife groove in the transverse and longitudinal directions was determined.In order to make the citrus stem can be cut by the blade at any position,the branch holding rod was designed.Considering that the citrus is easy to be mechanically damaged when it is clamped,the adsorption device was set to absorb the citrus,and the pulling force on the citrus during the adsorption is not more than 22 n,A transmission frame is arranged on the side of the end effector close to the suction cup,which is connected with the transmission channel to reduce the single fruit picking time of the mechanical arm.(3)Simulation analysis.The kinematics simulation of the cutting mechanism is carried out,and the motion trajectory,velocity and acceleration curves of the blade and cylinder are obtained.The kinematics simulation results show that the speed and acceleration of the blade and cylinder are a smooth curve,without obvious instantaneous impact,good stress,no motion interference and reasonable layout.Through the finite element simulation analysis of the shear mechanism,the stress nephogram and strain nephogram of the shear mechanism are obtained.The maximum stress of the blade is11.34 mpa.According to the calculation of the strength check formula,the strain and strain of each part of the shear mechanism are within the allowable stress range,and the deformation is small,which can be ignored,It can meet the design requirements of the end effector of Citrus nondestructive picking.pla is used as the material of some parts of the prototype,and the finite element simulation of the shear mechanism is carried out again.Through the calculation of the strength check formula,the material meets the design requirements of the end effector.(4)Prototype assembly test.The cylinder selection,design of Citrus picking end effector system schematic diagram,assembly of prototype,experimental verification,shear mechanism to meet the shear requirements,and adsorption mechanism for further improvement and optimization,so that it can meet the test requirements.