Design and experiment of a flexible end effector for seedling picking with adjustable clamping diameter

Authors

  • Zhaoyang Ren 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China; 2. Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
  • Minjuan Hu 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
  • Kun Li
  • Wei Yan 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
  • Yao Ji 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
  • Youfu Yang 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
  • Peichao Yuan 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China
  • Wenyi Zhang 1. Nanjing Institute of Agricultural Mechanization, Ministry of Agriculture and Rural Affairs, Nanjing 210014, China

Keywords:

adjustable clamping diameter, end-effector for seedling picking, seedling picking mechanism, stem clamping, non-circular gear, automated transplanting, experimental design

Abstract

To improve the adaptability of the stem-clamping end effector to variations in pepper plug seedling stem diameter, a flexible seedling-picking end effector with an adjustable gripping diameter was developed. The closing clearance between the two gripper plates was preset by replacing the miniature cam-follower bearing with bearings of different outer diameters, while rubber-covered gripping surfaces provided passive compliance and reduced the risk of stem damage and slippage. Based on the geometric relationship among the claw, connecting rod, push rod, and cam, the maximum claw opening and push-rod stroke were determined to be 32 and 4.7 mm, respectively, and the cam profile was designed to coordinate the opening, closing, holding, and releasing actions of the gripper. Mechanical tests showed that the average maximum pull-out resistance at picking angles of 0°, 20°, and 40° were 1.20, 1.18, and 1.29 N, respectively, which were substantially lower than the maximum tensile load of the seedling stems. Compared with rigid aluminum gripping surfaces, the rubber-covered gripper plates reduced the stem breakage rate from 66.67%-80.00% to 3.33%-6.67% and increased the transfer success rate from 76.67%-86.67% to 83.33%-93.33%. A three-factor Box-Behnken experiment was conducted using the rotational speed of the seedling-picking mechanism, stem diameter, and miniature-bearing outer diameter as experimental factors. Response surface optimization identified an optimal parameter combination of 66.1785 r/min for the rotational speed of the seedling pick-up mechanism, 2.1991 mm for the seedling stem diameter, and 10.0811 mm for the micro-bearing outer diameter. Under these conditions, the predicted seedling pick-up success rate and seedling injury rate were 93.1296% and 2.2087%, respectively, with an overall desirability of 0.976. The results demonstrate that the proposed end effector can preset the gripping diameter and reduce stem damage and slippage risks under the tested conditions, providing a practical design for automatic seedling picking.      

Key words: adjustable clamping diameter; end effector for seedling picking; seedling picking mechanism; stem clamping; non-circular gear; automated transplanting; experimental design

DOI: 10.25165/j.ijabe.20261904.10235

Citation: Ren Z Y, Hu M J, Li K, Yan W, Ji Y, Yang Y F, et al. Design and experiment of a flexible end effector for seedlingpicking with adjustable clamping diameter. Int J Agric & Biol Eng, 2026; 19(4): 123–132.

References

[1] Yang Q Z, Xu L, Shi X Y, Ibrar A, Mao H P, Hu J P, et al. Design of seedlings separation device with reciprocating movement seedling cups and its controlling system of the full-automatic plug seedling transplanter. Computers and Electronics in Agriculture, 2018; 147: 131–145.

[2] Li M Y, Zhu X W, Ji J T, Jin X, Li B M, Chen K K, et al. Visual perception enabled agriculture intelligence: A selective seedling picking transplanting robot. Computers and Electronics in Agriculture, 2025; 229: 109821.

[3] Li Y T, Wei H, Tong J H, Qiu Z, Wu C Y. Evaluation of health identification method for plug seedling transplantation robots in greenhouse environment. Biosystems Engineering, 2024; 240: 33–45.

[4] Hu S Y, Hu M J, Yan W, Zhang W Y. Design and experiment of an integrated automatic transplanting mechanism for picking and planting pepper hole tray seedlings. Agriculture, 2022; 12(4): 557.

[5] Han C J, Hu X W, Zhang J, You J, Li H L. Design and testing of the mechanical picking function of a high-speed seedling auto-transplanter. Artificial Intelligence in Agriculture, 2021; 5: 64–71.

[6] Ren Z Y, Hu M J, Ji Y, Yan W, Li K, Zhou X Z, et al. Dynamic analysis and experiment of seedling picking and throwing process of pepper hole tray seedlings. Int J Agric Biol Eng, 2025; 18(1): 134–142.

[7] Shen T H, Feng J A, Wang W B, Yu J Z. Virtual design and parameter optimization of the transplanter’s end-effector based on ADAMS. Journal of Machine Design, 2019; 36(10): 46–51. (in Chinese)

[8] Hu J P, Pan J, Chen F, Yue R C, Yao M J, Li J. Simulation optimization and experiment of finger-clamping seedling picking claw based on EDEM Recurdyn. Transactions of the CSAM, 2022; 53(5): 75–85, 301.

[9] Yang Q Z, Huang G L, Shi X Y, He M S, Ahmad I, Zhao X Q, et al. Design of a control system for a mini-automatic transplanting machine of plug seedling. Computers and Electronics in Agriculture, 2020; 169: 105226.

[10] Sun G X, Wang X C, He G M, Zhou T, Wang C, Qiao X J. Design of the end-effector for plug seedlings transplanter and analysis on virtual prototype. Transactions of the CSAM, 2010; 41(10): 48–53, 47. (in Chinese)

[11] Zhao X, Guo J L, Li K W, Dai L, Chen J N. Optimal design and experiment of 2-DoF five-bar mechanism for flower seedling transplanting. Computers and Electronics in Agriculture, 2020; 178: 105746.

[12] Han L H, Zhang M J, Wang Y, Ma G X, Yang Q Z, Liu Y. Design and tests of a large-opening flexible seedling pick-up gripper with multiple grasping pins. Agronomy, 2025; 15(7): 1634.

[13] Peng Z H, Yang F Z, Li Y H, Li X, Li B G, Xu G L. Design and testing of a whole-row top-loosening stem-clamping seedling extraction device for hole tray seedlings. Agriculture, 2025; 15(2): 165.

[14] Jin X, Li R S, Tang Q, Wu J, Jiang L, Wu C Y. Low-damage transplanting method for leafy vegetable seedlings based on machine vision. Biosystems Engineering, 2022; 220: 159–171.

[15] Ren Z Y, Hu M J, Yan W, Li K. Research status on seedling picking‐up mechanism of dryland hole tray seedling transplanting machine. Journal of Chinese Agricultural Mechanization, 2025; 46(2): 41–47. (in Chinese)

[16] Sharma A, Khar S. Design and development of a vegetable plug seedling transplanting mechanism for a semi-automatic transplanter. Scientia Horticulturae, 2024; 326: 112773.

[17] Zhang X D, Liu L J, Ning Y C, Kong D H, Liu Y Q, Wu H H. Design and experiment of end effector of seedling taking by jacking and clampling of vegetable transplanter. Transactions of the CSAM, 2023; 54(S1): 115–124, 134. (in Chinese)

[18] Chen J N, Zhang X W, Liu L M, Ma X X, Yao K, Cheng D. Design and experiments of the clipping-stem type non-circular gear transplanting mechanism for corn pot seedlings. Transactions of the CSAE, 2023; 39(18): 30–40. (in Chinese)

[19] Ren Z Y, Yan W, Ji Y, Li K, Zhou X Z, Zhang W Y, Hu M J. Optimized design and experiment of the seedling picking mechanism for stem-clipping for pepper hole tray seedlings. Transactions of the CSAE, 2025; 41(1): 55–64. (in Chinese)

[20] Ma X X, Li H, Ge Y, Li S F, Zhao Y M, Yu S Y. Experimental study on mechanical properties of tomato seedling stem. Chinese Agriculture Mechanization, 2020; 42(8): 161–167. (in Chinese)

[21] Cui Y J, Wei Y Z, Ding X T, Cui G P, He Z, Wang M H. Design and experiment of adjustable spacing end-effector based on cylindrical cam. Transactions of the CSAM, 2022; 53(1): 104–114, 122. (in Chinese)

[22] Hu S Y, Hu M J, Zhang W Y, Jiang Z. Experimental and simulation study on mechanical properties of stem of pepper hole seedlings. Journal of Chinese Agricultural Mechanization, 2022; 43(3): 09–18. (in Chinese)

[23] Wen Y S, Zhang J X, Zhang Y, Tian J Y, Yuan T, Tan Y Z, et al. Development of insertion and ejection type seedling taking device for vegetable plug seedlings. Transactions of the CSAE, 2020; 36(22): 96–104. (in Chinese)

[24] Han L H, Mao H P, Yan L, Hu J P, Huang W Y, Dong L L. Pincette-type end-effector using two fingers and four pins for picking up seedlings. Transactions of the CSAM, 2015; 46(7): 23–30. (in Chinese)

[25] Jin X, Suo H B, Zhang H Y, Ji J T, Zhang B, Lin C. Development and experiment of integrated vegetable pot seedling picking jaw clamping force detection sensor. Transactions of the CSAM, 2023; 54(7): 175–183. (in Chinese)

[26] Yu W F, Tian Y F, Liu H B, Cui Y J. Design study on the end-effector of fetch seedling. Chinese Agriculture Mechanization, 2016; 38(5): 87–91. (in Chinese)

[27] Ye B L, Li L, Yu G H, Liu A, Cai D. Design and test on cam mechanism of seedling pick-up arm for vegetable transplanter for pot seedling. Transactions of the CSAE, 2014; 30: 21–29. (in Chinese)

[28] Hu S Y, Hu M J, Zhang W Y, Ge X Y. Dynamic analysis and experiment of seedling taking and planting process of pepper hole tray. Journal of Chinese Agricultural Mechanization, 2023; 44(7): 40–47, 54. (in Chinese)

[29] Ministry of Industry and Information Technology of the People’s Republic of China. JB/T 10291-2013. Transplanter of dry land plant, Beijing: China Machine Press, 2013. (in Chinese)

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Published

2026-09-03

How to Cite

(1)
Ren, Z.; Hu, M.; Li, K.; Yan, W.; Ji, Y.; Yang, Y.; Yuan, P.; Zhang, W. Design and Experiment of a Flexible End Effector for Seedling Picking With Adjustable Clamping Diameter. Int J Agric & Biol Eng 2026, 19, 123-132.

Issue

Vol. 19 No. 4 (2026): IJABE

Section

Power and Machinery Systems

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