Optimal Design of an Onion Planting Mechanism Based on a Denatured Pascal Limacon Gear

Abstract

Mechanized onion planting is crucial for improving efficiency and reducing labor costs. However, traditional elliptical gear-driven planting mechanisms often exhibit issues such as unstable trajectories and excessively high velocities and accelerations. To address this, this paper proposes a parallelogram planting mechanism based on a denatured Pascal limacon gear drive. By analyzing the mechanism’s operating principle and the transmission characteristics of the denatured Pascal limacon gear, a kinematic model was established. The effects of parameters such as gear denaturation coefficient, drive speed, and link dimensions on the planting point trajectory and motion velocity were investigated. Results indicate that the denaturation coefficient, crank length, and initial mounting angle significantly influence the mechanism’s performance. Based on these findings, multi-objective optimization using a genetic algorithm was conducted to meet agronomic requirements. The optimized mechanism achieves a planting depth of 27 mm at a forward speed of 0.3 m/s and a gear angular velocity of 2π rad/s. Horizontal velocities at soil entry and exit approach zero, acceleration changes gradually during the planting phase, and operational stability is significantly enhanced. Compared to the elliptical gear drive configuration, it demonstrates superior overall performance.