• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2022, Vol. 58 ›› Issue (21): 1-15.doi: 10.3901/JME.2022.21.001

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Review of Variable Stiffness Mechanisms in Minimally Invasive Surgical Manipulators

SHANG Zufeng1, MA Jiayao2,3, WANG Shuxin2,3   

  1. 1. School of Mechanical Engineering, Zhejiang Sci-Tech University, Hangzhou 310018;
    2. Key Laboratory of Mechanism Theory and Equipment Design of the Ministry of Education, Tianjin University, Tianjin 300350;
    3. School of Mechanical Engineering, Tianjin University, Tianjin 300350
  • Received:2021-11-18 Revised:2022-05-07 Online:2022-11-05 Published:2022-12-23

Abstract: Taking one or several small cuts on skin or a body orifice as the path, minimally invasive surgery can significantly reduce the tissue damage, thus representing the future trend of the surgery. To reach a lesion far away from the path, slender and flexible device should be adopted for its adaptability to the complicated body-cavity condition. A surgical manipulator with variable stiffness can fulfill stiffening-softening function of the flexible device, and it thus becomes the key to ensure a safe human-machine interaction, a good precision, and an enough force output of manipulation during the surgery. Focused on the field of minimally invasive surgical manipulator, the current variable stiffness mechanisms are reviewed and classified as those based on jamming, thermally responsive material, shape-locking, antagonistic actuation force, reconfigurable cantilever, and combinations of them. Under the consideration of the application requirements, performances of manipulators in stiffening capability, response time, and space consumption, are firstly compared and discussed under different variable stiffness mechanisms. Next, potential variable stiffness mechanisms that could be applied in manipulators are reviewed, and the prospects and challenges are also analyzed. Finally, the field is summarized and forecasted. It is pointed out that developing new variable-stiffness material and carrying out integrated design of structures and functions based on biomimetic concepts are the main future directions.

Key words: minimally invasive surgery, manipulator, rigidity and flexibility, variable stiffness, bending stiffness

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