The objective of this research was to enhance the stability and consistency of seed distribution during carrot planting. The impact of the seed guide tube’s structure on seeding quality was examined, leading to the design of a cycloidal seed guide system augmented by positive pressure airflow. By conducting kinematic modeling of the collision position of the seeds within the seed guiding system, as well as considering the seed guiding process and the seed drop position, the significant parameters influencing the final velocity of the seeds were determined. Employing a coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) simulation, the effects of different structural and operating parameters of the seed guide tube on the seed trajectory and airflow field were analyzed. A three-factor five-level orthogonal test was then utilized to examine the influence of each factor on each index, with the optimal conditions identified as an inlet airflow velocity of 0.077 m/s, a 45° tilt angle for the airflow branch tube, and a seed initial velocity of 0.1 m/s. Under these parameters, the qualification index was recorded as 94.1%, with a coefficient of variation of 3.2%. Bench testing conducted under the same conditions showed a decrease of 0.07% in the qualification index, and an increase of 1.875% in the coefficient of variation, with errors relative to the simulation results within acceptable bounds. These findings enhance the stability and reliability of the seed guiding system during carrot sowing operations, aligning with the demands of precision sowing.

Large high clearance self-propelled sprayers were widely used in field plant protection due to their high-efficiency operation capabilities. Influenced by the characteristics of field operations such as high power, heavy weight, high ground clearance, and fast operation speed, the comprehensive requirements for the ride comfort, handling stability and road friendliness of the sprayer were increasingly strong. At the present stage, the chassis structure of the high clearance self-propelled sprayer that attaches great importance to the improvement of comprehensive performance still has the problems of severe bumps, weak handling performance and serious road damage in complex field environments. Therefore, this paper proposes an optimization design method for hydro-pneumatic suspension system of a high clearance self-propelled sprayer based on the improved MOPSO (Multi-Objective Particle Swarm Optimization) algorithm, covering the entire process of configuration design, parameter intelligent optimization, and system verification of the high clearance self-propelled sprayer chassis. Specifically, chassis structure of the hydro-pneumatic suspension suitable for the high clearance self-propelled sprayer was designed, and a design method combining the improved MOPSO algorithm based on time-varying fusion strategy and adaptive update with the parameter optimization of hydro-pneumatic suspension based on this algorithm was proposed, and finally the software simulation and bench performance verification were carried out. The results show that the optimized hydro-pneumatic suspension has excellent vibration reduction effect, and the body acceleration, suspension dynamic deflection and tire deflection were increased by 16.5%, 9.9% and 0.9% respectively, compared with those before optimization. The comprehensive performance of the hydro-pneumatic suspension designed in this study is better than that of the traditional suspension.