Design Of A Harvesting System For Leafy Vegetable Planting In Factory And Study Of Key Components

With the development of global agricultural science and technology,agricultural production methods are moving from open cultivation,facility cultivation to plant factories.One of the important characteristics of the plant factory is mechanization and automation.All kinds of machinery and equipment are important parts of factory agriculture systems.Based on R&D Key Project of Chongqing Technology Innovation and Application Demonstration called "Research,Development and Demonstration of Intelligent Equipment in Factory-cultivated Vegetable ",this paper studied the development of the cutting equipment for leafy vegetables in the harvesting line.After analyzing the cultivation characteristics of leafy vegetables produced in a factory,a design scheme of leafy vegetables harvesting system is put forward while the parameters of the cutting device are optimized.At present,harvesting machineries of leafy vegetables in open fields or facilities have 4 processes of R&D in most cases,called scheme design,prototype manufacturing,experiment and optimization.With the development of simulation theory and computer technology,computer modeling and simulation technology has been used in the process of product design extensively.During designing of this leafy vegetables harvesting system,it is hoped that the cutting device would be studied by means of simulation technology in order to predict its performance and reduce the design time.Based on analyzing the status of leafy vegetables harvesting machine,multi-domain co-simulation technology and the application of regression design method,this paper determines the main research contents as following:1)Design of factory leafy vegetables harvesting system.While the working flow of leafy vegetables producing in factory was analyzed,the structural parameters of cultivation plate and planting cup were determined.And a batch of leafy vegetable cultivated in water was sampled to collect their data of plant height,unfolding degree stem thickness and net weight.Then,the advantages of several different designs were analyzed about the conveying scheme,the cutting method and the transmission type.Finally,the overall scheme of continuous conveying-pneumatic driving-reciprocating cutting was determined.And the key components were designed and selected,including the conveying mechanism,the cutting mechanism,the transfer mechanism and the pneumatic system.2)Co-simulation modeling of cutting devices.The cutting device,including cutting mechanism and pneumatic system,was modeled by using ADAMS-AMESim co-simulation technology.Firstly,according to the schematic diagram of pneumatic system,the simulation sketch was established by selecting suitable components in AMESim.The co-simulation icon was created and the pneumatic system model was established.Then,the cutting mechanism was imported into ADAMS by SolidWorks,the constraint and drives were set to complete the dynamic modeling.Finally,the connection of two tools was set in ADAMS,and the co-simulation model was completed.3)The construction and experiment of the test platform.The physical test bench of the cutting device was constructed,including the assembly of the scaffold,the processing of the cutting mechanism,the connection of the pneumatic system and the installation of the tensile pressure acquisition system.Firstly,the leafy vegetables cutting test was carried out,and the results showed that the working process of the system was stable and the scheduled cutting task could be completed.Then,the influence test of air pressure on cutting force was carried out to get actual cylinder output force data.Finally,compared the simulation results with test results,it can be seen that there is relatively large deviation.The reasons are found through analysis,and the boundary conditions are improved.The modified simulation model is closer to the actual device and can be used for parameters optimization.4)Parameters optimization and simulation analysis of pneumatic system.Combined with the regression design method and the co-simulation virtual test,the working parameters of the cutting device were optimized.By taking the pressure and throttle valve opening as the influence factors,the cylinder output force,cutting speed and cylinder power as the evaluation indexes,the programming of bivariate quadratic regression orthogonal rotation combination design was carried out.By using the virtual test to collect data,three regression equations were obtained.The constraint optimization problem was constructed by combining the constraints of cutting force and speed.The optimal factor combination in the feasible domain was calculated by using MATLAB optimization function ‘fmincon'.The simulation results of the central test show that the power loss of the pneumatic system is reduced after optimization.