Analysis and Design of a Spatial Planetary Noncircular Gear Train for Rice Seedling Transplanting Based on Three Given Positions

摘要

This study proposes a method ofsolving the parameters of a spatial planetary gear train mth noncircular gears t0 meet the requirements of wde-narrow row pot seedling transplanting (WPST). First, the planetary gear train was simplified to a spatial open-chain 2R mechanism (planetary carrier). A kinematic model of the 2R mechanism was derived from the three given homogeneous matrices describing the spatial position and attitude information of grasping, extracting, and planting seedlings. Second, the length of each link, attitude of each rotation axis, and relative initial angles were calculated. The model for solving the transmission ratio was deduced. A spatial planetary gear train configuration with a single planet carrier and two-stage driving wasderived, in which the middle axis could be determined by combining the selected configuration, represented trajectory, and transmission ratio of each gear pair. Finally, a planetary gear train combining a noncircular gear pair and a helical gear pair wasused in the WPST mechanism design. Simulations and tests conducted on a prototype confirmed the correctness of the theoretical model and the practicality of the design.