INVESTIGATION OF THE CONTROL SYSTEM FOR MAIZE SEEDER SOWING DEPTH BASED ON SOIL MOISTURE CONTENT

To ensure the stability of seeding depth for a corn planter unit under different soil moisture conditions, a control system was designed to adjust the seeding depth of the unit based on soil moisture content. Using a PLC controller as the control foundation, the system employs a hydraulic system as its actuator. Soil moisture content is detected by moisture sensors, and the PLC controller processes the analog signals from the sensors. The controller then adjusts the forward and reverse rotation and speed of the motor via a variable frequency drive, thereby controlling the vertical displacement of the depth-limiting wheel to regulate the seeding depth. At the same time, a pressure sensor provides feedback to the PLC controller to control the switching time of the solenoid directional valve, driving the hydraulic cylinder stroke. The profiling mechanism connected to the hydraulic system moves the depth-limiting wheel accordingly, achieving stability in the planter's seeding depth. The control system is further optimized using the Mamdani fuzzy PID algorithm. Experimental results demonstrate that the designed seeding depth control system is stable and reliable, accurately adjusting the seeding depth according to different soil moisture levels. When the unit operates at speeds of 8 ~10 km/h, the stability of the seeding depth reaches 90%, significantly improving the stability of the unit's seeding depth.