The robot‐assisted flexible access surgery represented by the emerging robot‐assisted flexible endoscopy (FE) and natural orifice transluminal endoscopic surgery demands flexible and continuum manipulators instead of the rigid and straight instruments in the traditional minimally invasive surgery (MIS). These flexible manipulators are required to advance through the tortuous and narrow anatomic paths via natural orifices for dexterous diagnostic examination and therapeutic operations. Therefore, developing flexible endoscopic manipulators with the capacity of snake‐like movements for flexible access and variable stiffness regulation for operations to address these flexible access surgical difficulties is demanding but remains challenging. To address such challenges, herein, it is proposed that a novel distal continuum joint based on the hybrid pneumatic and cable‐driven approach achieves variable stiffness capacity, excellent bending characteristics in both flexible and rigid states, satisfactory motion consistency and shape‐locking ability during the rigid‐flexible transition, and relatively high loading capacity for flexible gastrointestinal endoscopic robots. Characterization experiments validate these performances, and phantom and ex vivo experiments have been performed to demonstrate the feasibility and effectiveness for FE. The presented method demonstrates an effective and practical approach to enabling continuum robots with both flexible access and tunable stiffness capacity and supports a convenient extension for MIS applications.

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This work proposes a novel flexible manipulator consisting of a series of 2-DOF vertebrae based on a ball-andsocket joint that is connected by a ball-shaped surface and a cupshaped socket and constrained by pins for circumferential rotation. This manipulator can demonstrate outstanding torsional stiffness since the circumferential rotation between the vertebrae is constrained by four ball pins. The point contact between ball pins and guideways effectively reduces the friction between the vertebrae, thus allowing the designed manipulator to yield a smooth bending shape with constant curvature. This manipulator features high axial and torsional stiffness, excellent bending performance, sufficient loading capacity, and convenient integration with surgical instruments. Moreover, the excellent torsional stiffness enables this manipulator to efficiently transfer torque and be applied in in-situ torsional motion, effectively addressing the typical issue of limited dexterity for torsional motion. The kinematic modeling of the proposed manipulator under in-situ torsional motion has been derived, and its workspace has been analyzed. A robotic system has been assembled, and experiments have verified the proposed design and modeling validity. The results show that the maximum position errors in bending motion are 2.39% (horizontal direction) and 1.98% (vertical direction), and its torsional stiffness is 21.13N•mm/deg, which is 46 times higher than that of a typical spherical flexible manipulator (SFM). Such merits support this manipulator excellently performing the in-situ torsional motion with a maximum average position error of 3.58%. Furthermore, a phantom test of the larynx has been performed to verify the potential of clinical feasibility.

Flexible Endoscopic Robots In article number http://doi.wiley.com/10.1002/aisy.202200403, Shuxin Wang, Chaoyang Shi, and colleagues propose a novel distal continuum joint based on the hybrid pneumatic and cable‐driven approach, which achieves excellent bending characteristics in both flexible and rigid states, variable stiffness, and high loading capacity for flexible gastrointestinal endoscopy. The presented method demonstrates an effective and practical approach for flexible endoscopic robots to achieve flexibility for access and rigidity for operation.

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