Design And Experiment On Eight-linkage Planting Mechanism

China’s vegetable transplanting land area is wide,the number of transplanting machines is relatively small,and most of them are still semi-automatic transplanting machines,and the transplanting efficiency is low,so it is urgent to research and manufacture a high-speed transplanting machine.The planting drive mechanism is a key part of planting pot seedlings,which is related to the planting performance of pot seedlings such as uprightness,plant spacing,planting depth,planting frequency and so on.Although the existing planting mechanism in our country can carry out high-speed seedling planting,the uprightness and other conditions are good,but it is mostly a planting mechanism with a fixed plant spacing,which cannot meet the needs of vegetable seedlings with different plant spacings.This paper proposes a new type of eight-linkage planting mechanism,which can ensure the uprightness of pot seedlings by using the reaction force of the soil,and can expand the variety of vegetables transplanted by the planting mechanism.It can be gradually approached by mathematical modeling analysis and GUI human-computer interaction.The rod length is optimized,and three-dimensional modeling,etc.,is made into a prototype,and field experiments are carried out to verify the planting performance.The main research work is as follows:1.The composition and working principle of the eight-linkage planting mechanism.An eight-linkage planting mechanism of four parts is proposed:a crank rocker mechanism,a parallelogram mechanism,a return mechanism,and a hanging cup opening and closing mechanism.The principle of zero-speed planting is:the hanging cup has the characteristics of being stationary relative to the ground under the action of the reaction force of the soil,which can ensure the uprightness of pot seedlings,and can be planted at different plant spacings.It is suitable for transplanting a variety of vegetables and has strong flexibility.2.The rod length of the eight-linkage planting mechanism is optimized.By establishing the mathematical model of the eight-linkage planting mechanism,the position equations,trajectory equations,velocity equations,acceleration equations,extreme angles,rocker swing angle equations of key points are obtained.Using MATLAB programming,obtain the change curve of the above equation when the key rod length changes.Through the establishment of GUI human-computer interaction interface,according to the above change law,through a stepwise approach,a set of rod length combinations with quick return characteristics and optimal force transmission characteristics,planting strokes and other requirements are obtained.3.Three-dimensional modeling of eight-linkage planting mechanism was established.The planting mechanism adopts a symmetrical layout as a whole,which is beneficial to increase the stability of the mechanism;the three-dimensional design of the frame,the rod,the cup assembly,the crank sleeve,the slider,the collar,and the crank shaft are described in detail.4.The field test verified the planting performance of the eight-linkage planting mechanism.Test preparations were carried out:motor selection and speed adjustment,tractor forward speed determination,arable land preparation,pepper seedling model preparation,etc.four sets of tests were carried out,each group of test plants The data of 100 plants in the middle is collected for 120 plants.By analysis,it shows that the planting good rate at two forward speeds and two planting frequencies is more than 94%,the total pass rate is more than 96%,and the coefficient of variation of plant spacing can be It reaches about 3.25%.The test results show that the designed eightlinkage planting mechanism has the characteristics of stable plant spacing and high yield,and has good planting performance,which can meet the agronomic requirements of transplanting operations.