Dimensional synthesis and kinematics simulation of a high-speed plug seedling transplanting robot

• The optimum mechanism dimension parameters are obtained by dimension synthesis.
• The motion trajectory planning is carried out to meet the transplanting demands.
• The rationality of structure design and trajectory planning is validated by kinematic simulation.
• Kinematic parameters are obtained by kinematic simulation to provide basis for prototype control.

To improve the automation and efficiency of plug seedlings transplanting in greenhouse, a high-speed plug seedling transplanting robot was designed by making use of a 2-DOF parallel translation mechanism with a pneumatic manipulator. According to the coordinates of healthy seedlings, the manipulator was driven by the mechanism to fetch and plant seedlings in a planned path. Based on the inverse kinematics of parallel mechanism, a global comprehensive performance index was proposed to synthesize a set of optimized dimension parameters for a good dynamic performance throughout the entire workspace. In accordance with the motion demand of transplanting robot, trajectory planning was carried out and quintic polynomial motion law was taken as the principle of operation for the manipulator. Based on the mechanism dimensions and assembly mode, a virtual prototype model was built, and kinematics simulation carried out. The simulation results were identical to the planed trajectory and a single transplanting cycle took 1.08 s, verifying the rationality of the structure design and trajectory planning. Also, the kinematic parameters were obtained to provide a theoretical basis for optimization design and practical control of the physical prototype.