Design, modeling, and experimental characterization of a rod-driven continuum robot with asymmetric joints for active chest catheters

Thoracostomy involves draining fluid from the pleural cavity using chest tubes. This medical intervention is currently performed manually by inserting a hollow flexible tube, risking damage to vital organs, including the lungs, diaphragm, spleen, and mediastinum, due to the lack of control over the tube's path inside the patient's body. Inspired by snake-like structures, continuum robots are particularly well-suited to address the challenges encountered during thoracostomy. Taking advantage of their slender shape, they can nest inside the tubes and guide them from within without requiring further incision. However, available continuum robots are not suitable for this application due to geometrical and payload requirements. In this letter, a novel design is presented, leveraging a multi-backbone structure with asymmetrical rolling joints to enhance payload capacity and dexterity while maintaining the slender shape of the robot. A static modeling approach is proposed to estimate the configuration of the robot given the force applied to the robot, including the effects of friction and gravity often neglected for these robots. Two prototypes were 3D-printed, allowing for after-use disposal due to their cost-effectiveness, thereby preventing cross-contamination. Stiffness and position error were evaluated for the prototypes, demonstrating a modeling accuracy of 2.25%.