Journal of Bionic Engineering

, Volume 15, Issue 2, pp 220–235 | Cite as

A Soft Bionic Gripper with Variable Effective Length

  • Yufei Hao
  • Zheyuan Gong
  • Zhexin Xie
  • Shaoya Guan
  • Xingbang Yang
  • Tianmiao Wang
  • Li WenEmail author


This article presented a four-fingered soft bionic robotic gripper with variable effective actuator lengths. By combining approaches of finite element analysis, quasi-static analytical modeling, and experimental measurements, the deformation of the single soft actuator as a function of air pressure input in free space was analyzed. To investigate the effect of the effective actuator length on the gripping performance of the gripper, we conducted systematical experiments to evaluate the pull-off force, the actuation speed, the precision and error tolerance of the soft gripper while grasping objects of various sizes and shapes. A combination of depressurization and pressurization in actuation as well as applying variable effective actuator length enhanced the gripper’s performance significantly, with no sensors. For example, with tunable effective actuator length, the gripper was able to grasp objects ranging from 2 mm – 170 mm robustly. Under the optimal length, the gripper could generate the maximum pull-off force for the corresponding object size; the precision and the error tolerance of the gripper were also significantly improved compared to those of the gripper with full-length. Our soft robotic prototype exhibits a simple control and low-cost approach of gripping a wide range of objects and may have wide leverage for future industrial operations.


soft robotics pneumatic control soft bionic gripper variable effective actuator length 


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This work was supported by the National Science Foundation support projects, China (grant numbers 61633004, 61403012, and 61333016); the Open Research Fund of Key Laboratory Space Utilization, Chinese Academy of Sciences (No.6050000201607004). Many thanks to Ziyu Ren and Hui Wang for their kind help in implementing the experimental apparatus, conducting the force experiments and performing the data analysis. Thanks to Xi Fang for her kind help in revising the paper.

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Copyright information

© Jilin University 2018

Authors and Affiliations

  • Yufei Hao
    • 1
  • Zheyuan Gong
    • 1
  • Zhexin Xie
    • 1
  • Shaoya Guan
    • 1
  • Xingbang Yang
    • 1
    • 2
  • Tianmiao Wang
    • 1
  • Li Wen
    • 1
    • 3
    Email author
  1. 1.School of Mechanical Engineering and AutomationBeihang UniversityBeijingChina
  2. 2.School of Biological Science and Medical EngineeringBeihang UniversityBeijingChina
  3. 3.Beijing Advanced Innovation Center for Biomedical EngineeringBeihang UniversityBeijingChina

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