Development Of The Picking End-effector Of Kiwi Fruit Harvesting Robot Based On Linkage

The kiwi fruit of Shanxi province has become the China and world's largest plant area and producer.Kiwi fruit has been using artificial pick harvest because there is no machine using in harvest and it is high labor intensity and low efficiency harvest method at present.It has been the obstacle of the development of agriculture productive forces.In recent decades with the advance of science and technology especially the emergence of agriculture picking robots provides a better idea to kiwi fruit harvest.In the agricultural robot parts,fruit end-effector plays an important role,because its located at the end of the mechanical arm,directly picking the kiwi fruit,therefore the end–effector need ensure nondestructive picking and high efficiency when it is working.Due to the agricultural production environment compared with the industrial production environment is complicated and picking robot in the face of the target object has its own impact on the work environment and physical characteristics,the end–effector compared with industrial robot mechanical hand has its own technical requirements and particularity.So the research of kiwi fruit fast picking end–effector not only increases the productivity but also has important research value.The research object of this thesis is “Hayward”kiwi fruit which grows in natural conditions under the scaffold.The development of the rapid picking end-effector of the harvest robot is based on the previous studies.The major contents are as follows:(1)The physical and mechanical of the fruit were studied.Kiwi fruit physical and mechanical properties provide theoretical basis and the parameter design for the end-effector.This paper research the kiwi experiment station and analyzing the distribution of fruit growth state,It is concluded that the vertical hang fall fruit stem length is 58 mm on average.The fruit rotate twist off experiment results showed that twist of the kiwi fruit need 16.1 circles and rotating twist off is not well to harvest the fruit.Put out the end-effector requirements and performance indicators,requireing the picking time less than 5 seconds Determined the fruit harvest way to begin from the bottom of the " grabbing-picking-unloading " way of harvest.The end-effector project were compared and determined.(2)Based on the " grabbing-picking-unloading " way of harvest and the the characteristics of linkage mechanical,design the mechanical of the end-effector.According to the characteristics of the overgrown kiwi fruit and scaffolding cultivation mode,based on the parameter of the theoretical basis provided by physical and mechanical properties,design the picking mechanism and the unloading fruit mechanism,design of three-dimensional bionic fingers radius of curvature is 32.5mm,unloading finger blank wideh is 55 mm,and length is 70 mm.Based on the inverse cam design the rapidly picking end-effector track groove.The inverse cam mechanism can converts linear motion to swing.Based on geometry theory,mathematics method is used to design the cam mechanism.Through the track groove design achieve the whole machine "grabbing-picking-unloading" integration movement.This paper established the 3d parametric model of the end –effector by using Pro/E 3d modeling software.Using the finite element software ANSYS WORKBENCH dynamic simulation to simulate the whole machine movement,and determine the end-effector trajectory and the structural parameters.(3)Design of the end-effector control system.End-effector control system integrated the single-chip microcomputer and sensor system and motor technology.The 51 microcontroller and motorcontroller control the whole machine.The hall position sensor,photoelectric position sensor and pressure sensor consist of the sensor system to detect fruit information and provide motor control signals and realize the automatic machine operation.(4)Trial-manufacture and picking experiment of end-effector prototype.Using the prototype did the picking experiment and evaluated the efficiency of the end-effector.The experiment of the robot movement was did at first and then the experiment did in the laboratory and field and evaluated the efficiency of the end-effector and did the quality of the kiwi fruit aging experimentafter harvest.The results showed that the picking success rate is 80%,average time to harvest is 4.5±0.5s,damage rate is 14.6,the end-effector increase the harvesting efficiency than Zhang fa nian in China.