Analysis of operating speed and power consumption of a gear-driven rotary planting mechanism for a 12-kW six-row self-propelled onion transplanter

Aim of study: To determine the optimal working speed of a gear-driven rotary planting mechanism for a self-propelled riding-type onion transplanter in order to choose an adequate forward speed for effective onion (Allium cepa L.) seedling planting. Area of study: Daejeon, Korea.Material and methods: The gear-driven rotary planting mechanism was composed of six planting hoppers that received free-falling onion seedlings through the supply mechanism and deposited them into the soil. To determine the optimal working speed for accurate transplantation of the seedlings, mathematical working trajectory modelling of the planting mechanism, virtual simulations, and validation field experiments were carried out.Main results: According to the model simulation, a forward speed of 0.15 m s-1 of the transplanter and a rotating speed of 60 rpm of the planting mechanism were favourable for seedling uprightness and minimum mulch film damage. For the proposed transplanting mechanism, the free-falling distance was calculated as 0.08 m, and the accuracy for the seedling deposition into the hopper was demonstrated as 97.16% through the validation test. From the field tests, a forward speed of 0.15 m s-1 combined with a transplanting frequency of 60 seedlings min-1 was found to be optimum for obtaining a high seedling uprightness (90o), a low misplant rate (7.66%), a low damage area on mulch film, and low power consumption (36.53 W). Research highlights: The findings of this research might be helpful in improving the design of the onion transplanting mechanism and accelerating the automation process for seedling transplantation.