Abstract
To obtain the optimal seedling taking trajectory, this study proposed the adjustment of the total transmission ratio curve by using human-computer interaction. On the basis of this design method, a planetary non-circular gear mechanism was designed that can realize the twice unequal amplitude transmission ratio to meet the seedling harvesting requirements. The cubic non-uniform B-spline curve was used to fit the twice unequal amplitude transmission ratio curve, and the transmission ratio was freely distributed in two levels. The seedling pick-up mechanism was designed by controlling the seedling taking track and the corresponding attitude directly through the local section of the total transmission ratio, and the gear pitch curve was directly controlled by the transmission ratio. The kinematics model of the seedling pick-up mechanism was also established. Furthermore, the influence of the total transmission ratio on the seedling picking track, the ratio of the wave crest to the amplitude, and the mechanism parameters were discussed. A human-computer interactive optimization software was developed using Matlab, and a set of optimal parameters for the seedling pick-up mechanism was obtained to meet the transplanting requirements. By using the Adams software, the virtual prototype simulation of the seedling pick-up mechanism was completed, and the idle experiment for the track and attitude of the prototype was conducted through high-speed camera technology. The theoretical, simulated, and experimental trajectories were consistent with each other. Results revealed that the success rate of the seedling picking exceeded 90% when the rotation speeds were 40 r/min, 50 r/min, and 60 r/min, and the qualified rate of the matrix decreased with the increase in rotating speed. Moreover, the number of damaged plants increased with the increase in rotating speed. The experimental results showed that the seedling pick-up mechanism designed using the proposed method demonstrated a good effect and met the required seedling picking performance. Keywords: seedling pick-up mechanism, second unequal amplitude, planetary gear train, seedling picking experiment DOI: 10.25165/j.ijabe.20221501.6168 Citation: Liu J G, Yu G H, Tong Z P, Hua Y. Design and experimental study of a planetary gearing mechanism based on twice unequal amplitude transmission ratio. Int J Agric & Biol Eng, 2022; 15(1): 155–163.
Highlights
The establishment of a reasonable structure, stable performance, and high efficiency of the seedling pick-up mechanism is the premise for realizing the automation of vegetable production[3-5]
The type value points of the total transmission ratio are continuously adjusted in accordance with the design requirements of the seedling pick-up mechanism, influence of the mechanism parameters on the seedling picking track, and human-computer interaction software developed by the author until a group of non-inferior solutions of parameters for the planetary gear train seedling pick-up mechanism are obtained (a1= 58 mm, a2= 57 mm, φ0= 20°, and δ0= 4°)
A design method for obtaining the optimal seedling taking track was proposed by adjusting the total transmission ratio curve via human-computer interaction
Summary
Mechanical transplanting can overcome the problem of crops not being continuously planted due to seasonal limitations. Iqbal[8] from South Korea developed a single-arm seedling pick-up mechanism with a connecting rod, which collects seedlings by installing a clamping-type needle on the single arm. This tool has a slow speed and low efficiency and is difficult to improve. This method is suitable for transplanting rice with an “8” shaped seedling track but not for transplanting potted vegetable seedlings. Jia et al.[23] proposed a seedling pick-up mechanism with a cam-connecting rod This mechanism achieves low seedling picking efficiency and is difficult to improve. The prototype produced using the seedling pick-up mechanism was verified through experiments
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