Design and Experiment of a Control System for the Oblique Seedling Picking-and-Release Device of Vegetable Transplanters

At present, the oblique seedling picking-and-release device of vegetable transplanters has low positioning accuracy and poor stability, which easily leads to issues such as failing to pick, damaging seedlings, and breaking seedling grippers during operation. Conventional PID control is difficult to meet the positioning control requirements. A step positioning control system based on fuzzy PID was designed, the transfer function of the control system was determined, and a fuzzy PID controller was established. Simulation analysis shows that with the displacement of the seedling picking-and-release frame as the system input, under optimal parameters, the times to reach steady state taken for conventional PID control and for fuzzy PID control are 1.2 s and 0.5 s, respectively. Field test results show that under fuzzy PID control, the maximum displacement error is reduced to 2.6 mm, with a relative error of 1.24%, which is less than the maximum relative error allowed for the displacement of the seedling picking-and-release frame. Fuzzy PID control has a shorter adjustment time, enabling rapid and precise positioning of grippers, and improving the success rate of seedling picking. The research results can provide reference and basis for the development of the control system for seedling picking-and-release device.