The transplanting arm of two-arm transplanting mechanism is easy to cause seedlings injury and missing due to its faster speed relative to the seedlings. In order to solve the existed problems, a three-arm transplanting mechanism for rice potted seedlings was developed in this study. The developed three-arm transplanting mechanism for rice potted seedling can make the transplanting arm realize special trajectory and attitude through the unequal planetary gear transmission. The kinematic model of three-arm transplanting mechanism for rice potted seedling was established, and the optimal design software was developed. Based on the heuristic optimization algorithm named "parameter guide", a set of satisfied mechanism parameters required by the rice potted seedling transplanting were obtained. The trajectory and attitude of three-arm transplanting mechanism used for the rice potted seedling were analyzed. Besides, the virtual simulation results were basically consistent with the optimization software results, and the correctness of theoretical analysis and virtual simulation were also verified by each other. When the developed transplanting mechanism picked up the seedling, the velocity of transplanting arm relative to the seedling was reduced by about 30%. The results showed that the injury rate of rice potted seedling transplanting mechanism was 0.04%, the missing rate of seedling was 1.4%, the integrity rate of seedling pot matrix was 96%, and the success rate of picking seedling was 99.92%.

A non-circular gear train has the advantages of compact structure, easy to achieve dynamic balance, and is often used to drive an end-effector to achieve complex trajectory and attitude. The gearbox is the key component of non-circular gear train, which has complex structure, and requires high precision of each wheel shaft hole and its relative position. Conventional methods often use numerical control process tools to process the gearbox with non-circular gear train. The processing cost is too high, and there are some problems, such as shaft hole deflection and it can be difficult to ensure the phase position. This research has proposed a processing method of the gearbox with non-circular gear train and developed the corresponding combination tool. Taking the gearbox of a rice potted seedling transplanting mechanism as an example, a special cutting tool with five boring tools was designed which can process five holes at one clamping, and greatly improve the efficiency and accuracy of gearbox processing. The processed gearbox and other parts were assembled into a rice potted seedling transplanting mechanism and assembled into a rice potted seedling transplanting process to conduct a seedling transplanting performance experiment. The results show that the processing of the gearbox with non-circular gear train satisfies the requirement of processing accuracy, and the transplanting mechanism can accurately complete seedling picking, transporting, planting, and other series of actions. The processing method is suitable for the large-scale manufacturing of transplanting mechanism. In this research, aiming at the double arm transplanting mechanism of high-speed rice potted seedling transplanting, the gearbox was analyzed, and a processing method of the gearbox was proposed.