Kim, Jongwoo Choi, Woo-Young Kang, Sungchul Kim, Chunwoo Cho, Kyu-Jin 2024-01-19T18:34:12Z 2024-01-19T18:34:12Z 2021-09-04 2019-12 1552-3098 https://pubs.kist.re.kr/handle/201004/119298 Variable stiffness enables the safe and effective operation of the minimally invasive surgical instruments. In this article, we propose a continuously variable stiffness mechanism of the scalable tubular structure. The mechanism consists of multiple coaxial nitinol tubes, and each tube has an anisotropic distribution of flexural stiffness created by nonuniform through-hole patterning. The stiffness of the mechanism is varied by relative rotation and translation among the tubes, resulting in flexural stiffness difference up to 7.2 times in the direction of load. Its flexural stiffnesses along principal axes are independently controlled by the suggested counterrotation algorithm. The stiffness change is validated through analytical modeling, FEM simulation, and the experiments. Thanks to its physically embodied intelligence, the mechanism has a simple scalable structure and the response time is immediate. We applied this mechanism to control the stiffness of the steerable needle. Varying the stiffness grants the additional degree of freedom to control the needles trajectory, which can expand the workspace of the steerable needle. English IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC Continuously Variable Stiffness Mechanism Using Nonuniform Patterns on Coaxial Tubes for Continuum Microsurgical Robot Article 10.1109/TRO.2019.2931480 1 IEEE TRANSACTIONS ON ROBOTICS, v.35, no.6, pp.1475 - 1487 IEEE TRANSACTIONS ON ROBOTICS 35 6 1475 1487 scie scopus 000502287300013 2-s2.0-85076437463 Robotics Robotics Article Electron tubes Robots Minimally invasive surgery Time factors Instruments Analytical models Mechanism design medical robots and system steerable catheters needles surgical robotics variable stiffness mechanism