| With the so cial progress, the im provement on the comm ercial breeding of m aize, the great increase of labor cost and the high standards for the quality of trails make the traditional seeding methods beyond the requirements of trial breeding. Relying on the review of types of precision seed-metering device for m aize in China, this paper analyzed the advan tages and disadvantages of these different models and also summarized the seeding methods for maize trials performed by dom estic research institutions and m aize enterprises. Accordingly, it seems to be of critical importance to develop the autom atic seeding machine with the high degree of automation that can ef fectively promote the level and speed of trial seeding and reduce the labor cost.Based on the brief introduction to the m echanical structure and working principle of seed-metering device and the dem ands of supporting hardware of mechanical components of seed-metering device, this paper adopted the G5 S 4-axis m otion controller with S-type high-order accelerator that supports the federate linking and allows the smooth and coherent motion path. Meanwhile, it ca lculated the torque for the rotation of metering disc and also selected the m otor type. Besides, it proposed the application of s mall vacuum pump to produce the negative pressure on the metering disc. To promote the qualified rate of metering, it could adopt the technical solution with the high negative pressure and small suction port. It also performed the theoretical calculation for the air flow at the seed-suction port and selected the small vacuum pump(UV-180V) in line with the requirements of flow.To save the cost and resources, the reasonable design chose four sets of gear ratio that makes use of the anticlockwise and clockwise turning of stepping motor to solve the issues of seed-changing and seed-m etering in a sm art way; to enhance the degree of automation of seed-metering control component, it explained the modification for the motion parameters and seeding parameters and also performed the detailed calculation for the change of row spacing and density, in order to achieve the goal of automatic seed-changing and seed-metering.The paper specified the func tion and wiring method of mo tor command interface, DI digital input interface and system function interface of control com ponent. It also explain ed the system design, param eters setting, task m anagement and autom atic control process of control component in details. Furtherm ore, it presented the flow char t of control com ponent and wrote the management software for the automatic control to meet the control demands of automatic seed-changing, seed-metering and cl earance, which could effectively solve the problems of labor-consuming, time-consuming and poor quality of seeding of traditional maize trials.To verify the reliability of precision seed-metering device, the split-split plot design was employed to test the performance of seed-metering device. It studied the ef fect of parameters such as the diameter, speed and vacuum degree of seed-suction port on the qualified indicator of seed-metering. Besides, the analysis of variance was performed to test the reliability of trial process. Results showed that th e speed of seed-metering disc had th e greatest effect on the qualified indicator, with the m ean qualified indicator up to 96.71%. W hen the speed of seed-metering device was less than 22.5r/min, the mean qualified indicator was up to 98.38%. At such speed, it cou ld fully m eet the requ irements of precis ion and speed of precis ion seed-metering. |
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