Design, Modeling, and Experimental Characterization of a Rod-Driven Continuum Robot with Asymmetric Joints for Active Chest Catheters
Mohammadmehdi Lari, Matteo Russo
AI summary
Problem
Manual chest tube insertion is blind and risks damaging internal organs, while existing continuum robots lack the necessary payload capacity, slenderness, and disposability for this procedure.
Approach
The authors designed a multi-backbone robot using asymmetric rolling joints to increase leverage without widening the diameter, and developed a static model that predicts shape from motor torque by accounting for friction and gravity.
Key results
- Asymmetric joint design doubles mechanical advantage while maintaining a 6.2 mm diameter
- Static model achieves 2.25% configuration error, outperforming traditional PCC models by over five times
- 3D-printed prototype successfully manipulates a 28F chest tube at ~44 Hz
- Cost-effective, disposable architecture meets critical medical sterility requirements
Why it matters
Provides clinicians with a controllable, disposable tool to significantly reduce the high complication rates of blind chest tube insertion.
Abstract
Thoracostomy involves draining fluid from the pleu- ral 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 en- countered 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 of- ten neglected for these robots. Two prototypes were 3D-printed, al- lowing 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%.