Structural Design And Simulation Analysis Of The End Effector Of The Cherry Tomato Picking Robo

In the production process of cherry tomatoes,the harvesting of cherry tomatoes is the largest proportion of labor,accounting for more than 40%of the total production work,the development of cherry tomato picking robots,to achieve automatic harvesting of cherry tomatoes,for reducing manual labor intensity and cost,improve the efficiency of picking operations has a very practical significance.The direct contact between the picking end effector and the fruit and vegetable is the key to successful fruit and vegetable picking,and it is also one of the core technologies of agricultural picking robot research.Therefore,the research on the end effector of cherry tomatoes is of great significance to improve the picking robot to realize the automatic harvesting of cherry tomatoes.According to the biological characteristics and geometric distribution of cherry tomatoes,a shear model of cherry tomato stalks was established,and the shearing effect of various parameters under the model was studied,and a picking scheme of first clamping and then cutting was proposed.A self-compensating structure is designed to realize the integrated action of end effector clamping and shearing and improve the picking efficiency.And an experimental platform was built indoors,and the end effector was experimentally verified,which basically realized the picking of cherry tomatoes in the indoor environment of the picking robot.The specific research content of this paper is as follows:(1)According to the biological characteristics of cherry tomatoes,a shear model of cherry tomatoes was established,and the parameters affecting the effect of cutting cherry tomato stalks were analyzed,such as solid weight,stem diameter,stem declination angle and inclination angle.The experimental results show that the shear resistance force increases with the increase of the diameter of the stalk.The study of these physical properties of cherry tomatoes provides theoretical parameters for the design of the later clamping shear mechanism.(2)According to the separation characteristics of cherry tomato stalks,the basic scheme of picking cherry tomatoes was determined,and the basic idea of clamping and then cutting was adopted.In order to realize this process,the clamping and shearing mechanisms were studied and designed separately: first,the clamping mechanism was designed based on the principle of a planar four-link linkage,and a preliminary model of the end effector was determined.Based on this model,the self-compensating clamping mechanism is designed,the force state and process are analyzed,the spring selection is determined,and the clamping contact parts are redesigned based on the principle of clamping closure.Secondly,the influence of simple support beam and cantilever shear models on the shear effect is analyzed,and the cantilever shear method is selected,the motor is selected as the power source on the basis of completing the mechanical body of the end actuator,and the power of the selected motor is calculated on the basis of the principle of virtual work.(3)The designed end effector is modeled in Solidworks in three dimensions,and the kinematics of the clamping linkage are solved.The simplified model is imported into Adams software for kinematics simulation,and whether there is motion viscosity,transient impact and whether the motion process meets the design goals during the overall transmission process.In order to obtain the force state of the overall mechanism of the shear process,the transient analysis of the shear mechanism was carried out,and the simulation results showed that the axial force response of the shear fruit stem and the separation force of the fruit stem were relatively close,and then the blade and V-shaped connecting rod with larger force were optimized,and the strength formula was used to check the strong height.(4)The designed end effector is processed and assembled,and the prototype,mobile chassis,robotic arm and vision camera are assembled into an experimental platform for cherry tomato picking robots,and the picking experiment of the prototype is carried out in an indoor environment.