Abstract:
Seedling transplanting using paper chain pots is an efficient and sustainable crop cultivation technique, which has the advantages of reducing environmental impact, simple transplantation, and improving seedling survival rate. Simultaneously, it has the advantages of stronger seedling root systems and significant yield effects, which have significance for promoting multiple crop cultivations, improving land replanting index, increasing crop yield, and developing high-yield and efficient agriculture. However, existing paper chain pots seedling transplanting technologies adopt continuous automatic transplantation, which is only suitable for transplanting dense-planted crops with same plant spacing. In this study, a baffle-type conveyor belt seedling picking-throwing device and chain breaking device for chain pots automatic transplanter is designed to achieve automated transplanting operations such as seedling picking, transporting, chain breaking, seedling throwing, and planting. The developed device was mainly composed of various mechanisms for baffle-type conveyor belt seedling picking-throwing device, chain breaking device, driving system, posture correcting device, and planting device. The process of chain pots transplanting was as follows: The chain pots, which were in the appropriate planting period, were placed on the seedling storage tray before transplanting. The initial end of the chain pot seedling tray was pulled and placed on the seedling picking and throwing timing belt, ensuring that the chain pots remained engaged with the seedling transplanting baffles. Subsequently, the chain pots automatic transplanting device was started, and the chain pots were transplanted along a predetermined trajectory by the seedling picking-throwing timing belt. The chain pots were broken by the chain breaking device to form independent seedling pot. The planting device and the seedling picking-throwing timing belt operated in unison to ensure that the seedling pots were meticulously thrown into the seedling cups. Finally, the seedling pots were transported to the seedbed and planted vertically into the soil, thus completing the planting process. A single-factor bench test was conducted using the developed baffle-type conveyor belt seedling picking-throwing device and chain breaking device. Taking chain pot seedlings as the experiment object during their suitable planting period, the test aimed to clarify the influence of different parameters on the success rate of chain breaking and success rate of seedling throwing. Specifically, the optimal ranges were achieved, where the seedling age, the timing belt inclination angles, and transplanting frequencies were determined as 28~36 d, 0°~6°, and 50~60 plants/min, respectively. A three-factor, three-level orthogonal experiment was conducted to determine the interactive effects of different factors on the success rate of chain breaking and success rate of seedling throwing. The results showed that an optimal configuration was achieved when the seedling age was 29 d, the timing belt inclination angles was 4°, and the transplanting frequencies was 55 plants/min. Furthermore, the success rate of chain breaking and success rate of seedling throwing were 92.44 %, and 94.60 %, respectively, in optimal configuration. A field experiment was carried out under a optimal combination of working parameters, in order to verify the operation performance of the whole machine. It was found that the success rate of chain breaking and success rate of seedling throwing were 90.62 %, and 93.10 %, respectively, which fully met the performance requirements of the seedling transplanter. The research will provide novel insights into optimizing the operating parameters of fully automatic transplanters, as well as the intelligentization and unmanned operation of transplanting processes.