Several studies have indicated that potted vegetable seedling transplanting technology can greatly improve the ability of vegetable seedlings to resist cold, flood, drought, saline-alkali and pests. The existing transplanting equipment mostly adopts mechanical, electrical and hydraulic integration technologies with a complex structure and a high cost. To address the problems of the complex structure and low efficiency of existing transplanting equipment, a rotary transplanting mechanism for potted vegetable seedlings was developed through configuration analysis and optimization design. Through kinematic analysis of the transplanting mechanism, optimization design software was developed, and the parameters were optimized. A mechanism was developed for picking, transporting, hole punching and transplanting potted vegetable seedlings. The virtual simulation results showed that the maximum error of attitudes of the transplanting arm is less than 1.19° and that of the hole punching shovel is less than 1.7°. In this study, perforation, seedling harvesting and transplanting experiments were conducted through a bench test. The results showed that the specific trajectory and attitude of the potted vegetable seedlings transplanting mechanism conformed to the requirements of potted vegetable seedling transplantation and the success rate of seedling picking was 92.4%, which verified the correctness and feasibility of the rotary potted vegetable seedling transplanting mechanism. Keywords: planting machinery, transplanting mechanism, potted vegetable seedling, punching device, trajectory and attitude DOI: 10.25165/j.ijabe.20201304.5404 Citation: Zhou M L, Shan Y Y, Xue X L, Yin D Q. Theoretical analysis and development of a mechanism with punching device for transplanting potted vegetable seedlings. Int J Agric & Biol Eng, 2020; 13(4): 85–92.

Optimized design and experiment of the three-arm transplanting mechanism for rice potted seedlings

To better meet the requirements of mechanized transplanting of pepper plug seedlings, this study explores the seedling picking mechanism of a fully automatic pepper transplanting machine. It introduces a novel “eagle beak” type trajectory for seedling picking and designs a probe-type mechanism for pepper plug seedling retrieval. We establish a kinematic theoretical model and delineate the composition and operational principles of this probe-type mechanism. Additionally, we develop an auxiliary optimization software tailored based on Visual Basic 6.0 visual programming software for this mechanism. It employs a blend of manual fine-tuning and a “parameter guidance” optimization algorithm, enabling the determination of 11 optimal target parameters. Our comparative analysis between the theoretical model, optimization software, and high-speed camera experiments reveals a strong correlation in the motion trajectories, and the maximum error of the pose angle is 1.2°. To validate the mechanism’s design, we conducted a seedling retrieval experiment. In this test, the success rates of the seedling harvesting mechanism at speeds of 30, 40, and 50 r/min were 96.4%, 94.3%, and 91.4%, respectively, thus demonstrating its practical feasibility.

Super rice contains a variety of advantageous characteristics. However, current rice seedling transplanting machines fail to achieve the necessary trajectory and distance required for super rice mechanized transplanting. To address this issue, this study introduces a differential-speed rotary mechanism for transplanting super rice pot seedlings. The developed mechanism operates using a non-uniform speed differential gear train, which enables the transplanting arm components to mimic the specific trajectory and posture necessary for transplanting super rice pot seedlings. The kinematic model of the differential-speed rotary super rice pot seedling transplanting mechanism (PSTM) was established, and optimization design software was developed. This software facilitated the determination of a set of mechanism parameters optimized for super rice pot seedling transplantation. The results obtained from virtual simulations were found to be in alignment with those from the optimization software, thereby verifying the accuracy of the theoretical analysis and simulation. A testing bench for the rice PSTM was also developed and used for pot seedling pickup experiments. The bench tests demonstrated that the designed super rice PSTM yielded a seedling pickup success rate of 97% and a seedling injury rate of 1.8% when operating at an efficiency of 200 times/min.

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.

Bale density is one of the main performance indicators to measure the quality of baler operation. In this study, a real-time baler bale density monitoring system was designed for the problem of difficult real-time measurement of bale density on round balers. Firstly, a weighing calculation model for the rolling and sliding stage of the bale was established, and the dynamic characteristics during the contact between the bale and the inclined surface were analyzed based on ADAMS dynamics simulation. Then, a real-time monitoring system for the bale density based on the contact pressure of the inclined surface, attitude angle measurement and hydraulic monitoring of the cylinder was constructed, and the accuracy of the weighing model was confirmed. The system was used to observe and analyze the changes in the pitch angle of the carrier table and the oil pressure in the rod chamber of the backpack cylinder during the operation of the round baler. Finally, the monitoring system was calibrated and the dynamic calibration equations were obtained. The results show that the maximum error between the calculated value of the original weighing model and the actual weight was 3.63%, the maximum error of the calculated value of the weighing model corrected by the calibration equations was 3.40% and the measurement accuracy could be satisfied. The results show that the system was highly accurate and met the practical needs of bale weighing in the field.