Design and experiment of a control system for sweet potato seedling-feeding and planting device based on a pre-treatment seedling belt

Although existing sweet potato transplanters require automatic seedling feeding instead of manual seedling feeding, this causes seedling leakage and low efficiency. In this work, a control system for automatic seedling feeding of sweet potatoes was designed based on a pre-treatment seedling belt. The system uses STM32 as the main controller and obtains the running speed of the machine through the encoder. The speed of the planting motor can be adjusted in real-time according to the running speed to keep the planting distance stable. The speed control model and linkage control strategy of seedling-feeding and planting motors are investigated to keep the system feeding frequency and planting frequency consistent under running speed changes. In order to verify the performance of this control system, a test bench was built, and some experiments were conducted. The test results show that the average error of seedling-feeding motor speed is 4.04%, and that of planting motor speed is 3.28%. At medium and low operating speed levels, the stability of the seedling-feeding mechanism is good, and the relative errors of automatic seedling-feeding operation are 7.8% and 5.1%, respectively. The variation coefficients of plant spacing were 9.34% and 7.42%, respectively, indicating that the system could meet the seedling-feeding and planting device control requirements based on the seedling belt and realise continuous automatic seedling feeding in the process of sweet potato seedling transplanting.