Kinematic analysis and virtual experiment of rotary pick-up mechanism on cotton transplanter

Abstract: Picking seeding tache in plug seedings of cotton transplanting is completed manually at present. As a result, the efficiency of cotton transplanting is limited. In order to realize automatic pick-up in seedlings in cotton transplanting, a new kind of seedling pick-up mechanism was designed which adapts with the characteristics of the stems' matrix tensile force of the cotton seedlings in nursery medium which is much larger than the fetching seedling force. A new form of planetary gearing system that is composed with blended high-order deformed elliptic gears was introduced. Mechanism kinematics mathematical model was established, the objective of clipping seedling type working with seeding pick-up mechanism were set according to the demand of the clipping seedling type. Working and the demand of coordination between the seeding pick-up mechanism and seeding box, seeding transplanting mechanism, and optimize analysis of software were compiled to determine the parameters of institutions: the center distance of the meshing gear is 58 mm, the eccentricity ratio of first stage second order deformation elliptical gear is 0.2, the major deformation coefficient of first stage second order deformation elliptical gear is 0.9, the eccentricity ratio of second stage single deformation elliptical gear is 0.14, and the major deformation coefficient of second stage single deformation elliptical gear is 0.18. The installation angle of the mark line on the fixed sun gear 1 is 13π/18, the angle of planetary carrier OA and the mark line on the sun gear 1 is/2, the first middle gear and the second middle gear are installed on the middle shaft A, the first middle gear that the meshing with sun gear, the angle of mark lines on the second middle gear and the first middle gear is 7π/18. At the initial position, the angle of the planetary carrier AB and the mark line of the second middle gear is 35π/36, the first planetary gear that the meshing with the second middle gear, the first planetary gear and the picking-up seedling claw are installed on the planetary shaft B, the angle of picking-up seedling claw BE and the mark line of the first planetary gear is π/6, the angle of BT to BE which on the picking-up seedling claw is 7π/18 and the BT length is 150 mm, the angle between the fetching seedling section of the trajectory to the seedlings box is 91°, the rotational angle of the planetary carrier is 36° and no interference between the seedling and the potting during the process of fetching seedlings, picking-up the seedling claw swing angle is 5°, and the angle between the fetching seedling section to the claw approach seedlings section is 85°, pushing the seedlings angle is 76°, the minimum distance between two pick-up seedling claws is 48.6 mm. The virtual experiment indicated that the mechanism's work trajectory is in agreement with theoretical calculations, well meets the demand of the seedling fetching process, the seedlings claws have a rapid fetching speed in fetching the seedling section which is beneficial to rapid fetching seedlings, cycle speed curve smoothing, and provides a viable solution for automatic fetching of cotton seedling in nursery medium.