Abstract
Currently, transplanting mechanisms for dryland plug seedlings in China are mainly semiautomatic and have low efficiency. The rotary seedling pick-up mechanism with a planetary gear train for non-uniform intermittent transmission, and a concave and convex locking arc device, has a large rigid impact. To solve these problems, according to the design requirements for a dryland plug seedling transplanting mechanism, a rotary seedling pick-up mechanism of a planetary gear train with combined non-circular gear transmission of incomplete eccentric circular and non-circular gears was proposed. This has the characteristics of two-times greater fluctuation of the transmission ratio in a cycle, and can achieve a non-uniform continuous drive. Through analysis of the working principle of the seedling pick-up mechanism, its kinematics model was established. The human–computer interaction optimization method and self-developed computer-aided analysis and optimization software were used to obtain a set of parameters that satisfy the operation requirements of the seedling pick-up mechanism. According to the optimized parameters, the structure of the seedling pick-up mechanism was designed, a virtual prototype of the mechanism was created, and a physical prototype was manufactured. A virtual motion simulation of the mechanism was performed, high-speed photographic kinematics tests were conducted, and the kinematic properties of the physical prototype were investigated, whereby the correctness of the theoretical model and the optimized design of the mechanism were verified. Further, laboratory seedling pick-up tests were conducted. The success ratio of seedling pick-up was 93.8% when the seedling pick-up efficiency of the mechanism was 60 plants per minute per row, indicating that the mechanism has a high efficiency and success ratio for seedling pick-up and can be applied to a dryland plug seedling transplanter.
Highlights
1 Introduction The dryland plug seedling transplanter is a type of agricultural machinery for transplanting crops such as cultivated vegetables and rape plug seedlings into fields
Semiautomatic and automatic transplanting machines have been employed for dryland plug seedling transplanting in China and other countries
For automatically transplanting dryland plug seedlings, the automatic transplanting operation scheme shown in Figure 1 was adopted, in which the rotary seedling pickup mechanism (Figure 1(a)) matches the duckbill-type planting mechanism (Figure 1(b)) developed at our institute to ensure a high success ratio, low seedling-damage
Summary
The dryland plug seedling transplanter is a type of agricultural machinery for transplanting crops such as cultivated vegetables and rape plug seedlings into fields. Korean Choi et al [7] designed a vegetable plug seedling pickup mechanism of the crank-guide rod-slideway type composed of five rods, seedling pick-up claws, and their respective drives It has a relatively simple structure, but the seedling pick-up efficiency is low (only 30 plants per minute), the slideway is prone to wear, and significant vibration occurs during operation. The aim of this work was to solve the problems of seedling pick-up mechanisms, such as the complex structures, high costs, low efficiency of seedling pick-up, large vibration during operation, and unsuitability for transplanting plug seedlings in China In this system, two seedling pick-up arms are arranged symmetrically on the rotary box, and two seedlings are extracted in a working cycle. Studies on the seedling pick-up mechanism were performed, including kinematics modeling and analysis, structure design, virtual motion simulation, prototype tests, and seedling pick-up tests
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