Optimal design and experiment of variable spacing intra-row cultivation and weeding mechanism based on non-circular planetary gears

Abstract

To overcome the limitations of existing intra-row weeding mechanisms, which often suffer from structural complexity and poor adaptability to variable plant spacing, this study proposes a novel cashew-shaped weeding blade designed according to agronomic requirements and the principle of rotational seedling avoidance. This intra-row weeding mechanism is capable of operating under various crop spacings without requiring structural modification or component replacement. By exploiting the non-uniform transmission characteristics of non-circular gears, an intra-row micro-tillage weeding mechanism based on a planetary gear train was developed. A kinematic model was established by integrating the blade geometry with the pitch curve of the non-circular gear. Two performance indices—the coverage rate of the intra-row area and the intrusion rate into the crop protection zone—were defined as optimization objectives. Fifteen structural parameters were initially considered, and ten were retained based on symmetry. A custom analysis and optimization program was developed to evaluate parameter effects and identify optimal configurations. Both virtual and physical prototypes were constructed, and their performance was validated through simulations and field experiments. The results show that the optimized mechanism achieved a weeding rate exceeding 92.2% at plant spacings of 200, 250, and 300 mm, while maintaining a zero crop injury rate. The proposed design provides an effective and adaptable solution for high-efficiency, environmentally friendly intra-row weeding.