An electric-driven maize seeding system: improving the quality of accelerate seeding using Tracking Differential Filtering-Optimal Tracking Control (TDF-OTC) method

In light of the growing conflicts between human activities and land use, enhancing the precision of seeding control throughout the entire maize seeding process is crucial for ensuring seeding quality and increasing yield per unit area. However, current research on maize seeding control methods has predominantly focused on the uniform speed seeding stage. Little attention has been paid to the acceleration stage, where speed variations are more complex and impose higher requirements for speed measurement and real-time control. To address this issue, this paper develops a maize seeding control system based on the Tracking Differentiator Filter-Optimal Tracking Control (TDF-OTC) method, aiming to improve the seeding quality during the acceleration stage from both input and output perspectives of the control system. An electric-driven seeding system was built on a pneumatic precision high-speed maize planter to provide the hardware platform for implementing the TDF-OTC method. A nonlinear tracking differentiator (NLTD) based on TDF was designed to address the filtering problem of oscillatory speed measurement signals, leveraging its ability to balance tracking speed and noise reduction. This ensures accurate forward speed input for the control system. Additionally, a linear quadratic tracker (LQT) based on OTC was designed to minimize error performance metrics and compel the system’s actual output to track the target output trajectory. This resolved the rapid tracking of the drastically changing target rotational speed of seed metering drive motor, ensuring accurate motor speed output for the control system. Considering the real-world conditions of accelerated seeding operations, the parameters of NLTD and LQT were determined using MATLAB Simulink to ensure optimal performance. A series of tests was conducted to evaluate the performance of the proposed method. The TDF test results demonstrated that the NLTD effectively filtered and reduced noise from oscillatory speed input signals. The accelerated response test results of OTC showed that the designed LQT outperformed PID controllers in acceleration tracking capability. Accelerated seeding test in the field, where the planter accelerated from a standstill to approximately 3.5–4.0 m/s, revealed that the TDF-OTC method achieved an average seeding qualification rate (ASQR) of 90.63% and an average coefficient of variation of seeding spacing (ACVSP) of 21.66%. Compared to the PID method, these results represented a year-on-year improvement of 12.28% in ASQR and a reduction of 14.99% in ACVSP, affirming the effectiveness of the proposed method in improving seeding quality during the acceleration stage. This study provides a valuable reference for advancements in precision seeding.