Seedling transplanting is an essential step in vegetable cultivation. Although vegetable transplanting can be automated and mechanized, mostly is still performed manually, which is laborious, time-consuming, and inefficient. The objective of this study was to conduct a review of the existing vegetable transplanters used for seedling transplanting, and of kinematic analyses of their major mechanisms. Generally, vegetable transplanters are classified into three main categories: handheld, semi-automated, and fully automated. Researchers described mechanisms involved in the overall transplanting process, which included seedling picking from the nursery tray, conveyance to the planting unit, and planting in the soil. The main mechanisms involved are picking and dibbling, which both include bar-based and gear-based mechanisms. For successful seedling transplanting, analytical techniques, CAD systems, and computer methods are used to evaluate the operating characteristics of transplanter components, and to determine the number of link bars and gears required to achieve the appropriate seedling transplanting trajectory. The effective field efficiency and transplanting efficiency of transplanters were evaluated based on seedling pick-up, feeding, planting rates, and operational speed. Recent studies reported that seedling transplanting methods using clamp-type and sliding-type picking mechanisms with 4 and 5-bar-based linkages, and 1 to 2 degrees of freedom, were effective at holding and releasing seedlings without damaging them. In addition, gear-driven rotating dibbling mechanisms were recommended for their capacity to plant 45 seedlings per minute at a sufficient rate. Scientific trends highlight the performance capabilities of each type of transplanter, which could guide the manufacturers to enhance vegetable-transplanter designs.
Figures & Tables
Fig. 1. Classification of vegetable transplanters.