Development of automatic single pendulum vegetable pot seedling picking and feeding system

Abstract: Plug seedlings can be used to alleviate the negative effect of severe weather on crops production, further to achieve high and stable yield, and improve land utilization. At present in China, semi-automatic transplanting machines are mainly used with low degree of automation and high labor intensity. The mechanized operation of automatic transplanter can reduce the influence of human factors, and improve the overall benefits, indicating a main trend in current development of agricultural planting mechanization. The seedling feeding system is the crucial part of an automatic transplanter. Most previous studies focused on various schemes, such as clamping, ejection, insertion, and pneumatic type. Different types of automatic transplanting machines have also been developed, however, there are still some problems, including the high seedling damage rate, low seedling retrieval efficiency, and relatively low adaptability to seedling plants. This study proposed an automatic symmetrical simple pendulum-type seedling system, mainly composed of the seedling plate conveying, longitudinal moving, rotating, reciprocating, seedling mechanism, and power control system. Kinematics analysis was performed on the reciprocating, rotating and seedling mechanism, and the structural parameters of each key mechanism were determined. The key mechanisms of seedling retrieval system were driven by stepping motors and cylinders that controlled by FN 2N-32MT. In order to explore the effects of various parameters on the performance of seedlings in the design of test plan, the seedling efficiency was tested at 90 plants/min, and the test parameters were selected, including the seedling species, substrate moisture content, seedling depth and working pressure. A multi-objective orthogonal test was carried out, where the success rate and the seedling integrity rate, were taken as the evaluation indicators of seedling transplanter system. The experimental results showed that the moisture content had the greatest influence on the seedling success rate of seedling extraction, and the seedling integrity rate of seedling plants, reached 58.92% and 50.58%, respectively, followed by the insertion depth. The optimal system was achieved with the best seedling effect, when the seedling type was peper seedling, where the moisture content was 35%, the depth was 40 mm, and the air pressure was 0.6 MPa. The success rate of seedling removal, and the intact rate of seedling plants were 98.61% and 97.22%, respectively. This finding can provide a sound reference for automatic seedling removal and mechanism design of transplanting machine.