| Facility agriculture is a hot spot of agricultural research in China.Hydroponic technology of providing nutrients and water directly to plug seedlings in facility agriculture has been popularized and applied by many domestic research institutions.In order to transplant the plug seedlings into the cultivation hole,the hydroponic transplanting operation needs manual operation.The strong labor and low efficiency seriously restrict the need of large-scale production.In this paper,the core component of a greenhouse hydroponic transplanter is developed,which is mainly composed of the multi-transplanting-hands transplanting part and the variable spacing seedling cup part.Combined with the working object,a small space operation spring-tooth insertion transplanting hand is developed.The theoretical analysis of the seedling claw is carried out to optimize its structure.The transplanting components of multi-transplanters hands part and the variable spacing seedling cup part were developed to realize the whole row of transplanters clamping plug seedlings,and the variable spacing transplanting operation of seedling cup,and the parameters were optimized.The optimal parameter combination of transplanter is determined,and the main research contents are as follows :(1)Design of small space operation spring-tooth insertion transplanting hand.Taking a single seedling claw piece as the research object,the two working conditions of seedling pick-up and seedling release of transplanter is analyzed,and the bending deformation model of seedling claw was established.The force analysis of the transplanting hand is carried out to determine the specific size of the transplanting hand.Rigid-flexible coupling simulation analysis is carried out on the release process of transplanted hand to determine the fitting curve of seedling claw.(2)Design and parameter optimization of the multi-transplanting-hands transplanting part and the variable spacing seedling-cup part.The multiple-transplanting hands transplanting part and the variable spacing seedling-cup part are developed to optimize the design and dynamic selection of key components.The collision simulation was carried out for the longitudinal variable spacing design and transverse variable spacing of the variable spacing seedling cup part;the theoretical model of opening and closing mechanism is established and the parameters are optimized.The orthogonal experiment is carried out on the factors related to seedling pick-up and seedling release of multi-transplanting-hands transplanting part.The optimal combination of parameters is obtained as follows: seedling pick-up depth is 48 mm,substrate moisture content is70 %,lifting speed is 0.24 m/s,and horizontal traverse speed is 0.35 m/s.The test verification is carried out,and the success rate of seedling pick-up and release was 98 %.The test results meet the requirements of transplanting design.(3)Control system and electrical system design of the transplanting.According to the circular transplanting requirements of each mechanism,the electrical system design and related components selection are carried out to determine the overall control scheme.Mitsubishi FX3U-64MT-ESS PLC is selected as the controller,The double closed loop PID synchronous coupling control system is established by the double stepper motors on the variable spacing components of the butt seedling cup,and the PLC control program is written to realize the synchronous control of the longitudinal variable spacing of the seedling cup,improve overall transplanting efficiency.(4)Repeat positioning accuracy test and the variable spacing seedling cup part parameter optimization test.The three-dimensional model is established by Solid Works,and the prototype debugging was carried out to realize the cyclic action.The repeated positioning and grasping experiment of the multi-transplanting-hands transplanting part is carried out,and the optimized positioning and grasping accuracy is 0.11 mm by changing the acceleration and deceleration.The orthogonal test of five factors and three levels was used.Under the condition of optimal parameter combination of multitransplanted-hands part.In order to improve the transplanting efficiency and transplanting success rate as the optimization goal,the seedling-cup variable spacing part is optimized and analyzed.The optimal parameters were as follows : the elastic coefficient of the buffer belt is 0.66 N/m,the longitudinal equidistant separation speed of the seedling cup is 0.24 m/s,the overall lateral movement speed of the seedling cup is 0.32 m/s,the opening and closing speed of the seedling cup is 0.20 m/s,and the energy absorption of the overall lateral is 30 J.The verification test is carried out.The transplanting success rate is 97.2 % and the transplanting efficiency is 9600 plants/h. |
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