Study On Low Damage Picking Pattern Based On Tomato Biomechanical Properties

Picking pattern is a very important part in the research of picking robots.In this paper,the picking pattern was taken as the research object,and the local mechanical damage assessment model was taken as the standard to establish the finite element model of tomato.The finite element analysis of the tomato picking process was carried out to obtain the picking pattern with the lowest damage.The feasibility was verified by the tomato picking test.The main contents of this paper are as follows:Firstly,the mechanical properties of Breaker,Turn,Pink tomato stem and its components were studied.The tensile,compression,shear and bending tests of tomato stem,epidermis,peel and colloid were carried out by texture analyzer,and the force-displacement curves of each maturity sample were obtained.The mechanical parameters such as tensile/compressive elastic modulus,tensile strength,compressive strength and shear strength were calculated to analyze the influence of maturity on the mechanical properties of tomato stem and its components.Secondly,the effects of local compression on mechanical damage of Breaker,Turn,Pink tomatoes were studied.The tomatoes were pressed by fruit hardness tester,and the microstructure changes of tomatoes were observed by scanning electron microscope.The four damage levels of decay,wrinkle,indentation and no indentation and the days of damage could be observed were used as evaluation criteria.The influence of local compression pressure on damage at all levels was analyzed by compression test.The pressure distribution area of different damage levels of tomatoes with different maturity was obtained,and the local mechanical damage assessment model of tomato was established.Then,the effects of picking pattern on the damage of Breaker,Turn,Pink tomato were studied.The finite element model of tomato fruit-stem was established by reverse engineering method,and a method to evaluate the damage level of tomato based on finite element simulation was proposed.Through the finite element simulation of three picking patterns of tension,bending and bending-tension combination,the force-time curve of three fingers on the surface of tomato and the stress of tomato components were obtained.The influence of picking pattern and maturity on the mechanical damage of tomato was analyzed.Finally,tomato picking information collection system was used to collect the pressure of fingers on tomato in artificial picking test,and the damage degree of each picking pattern of Breaker,Turn,Pink tomato was obtained.Compared with the finite element simulation results,a picking pattern with the lowest damage to tomato was obtained.The robot picking test was carried out through the tomato picking test platform to analyze the feasibility of lowdamage picking pattern applied to the robot.