KINEMATIC ANALYSIS OF ROTARY TRANSPLANTING MECHANISM FOR WIDE-NARROW ROW POT SEEDLINGS

摘要

Wide-narrow row pot seedling transplanting (WPST) could obtain high rice yield and quality. In this study, a new type of mechanism for WPST is designed based on analysis of recent advances at home and abroad. The WPST mechanism, which consists of planetary gear trains with seven noncircular bevel gears, is used in an automatic rice pot seedling transplanter. The working trajectory and attitude properties are analyzed according to the agronomy requirements of rice WPST. To establish the kinematics, a non-uniform B-spline curve is used to fit and control the outer pitch curve of the noncircular bevel gears, and D-H transformation matrices are introduced to express the trajectory and attitude of the planting paw in the world frame of the WPST mechanism. Computer-aided analysis and an optimization program of the WPST mechanism are developed. Based on the program, the effects of various parameters on transplanting trajectory and attitude are analyzed. By human-machine interaction, the structural parameters that meet the demands of the WPST mechanism are optimized. Using these parameters, a 3D model of the mechanism is built, and virtual simulation and physical prototype tests are carried out. The simulation and experimental results agree with the theoretical analysis, which validates the theoretical model of the WPST mechanism.