Performance Evaluation of Extensible Cable-Driven Flexible Actuator for Colonoscopy

Double Balloon Colonoscopy (DBC) is an endoscopic technique used to examine the small bowel, enabling mucosal biopsy and diagnosis. However, existing designs face challenges, including complex actuation, limited bending, and low payload capacity, which lead to longer procedures and patient discomfort. To tackle these challenges, this article presents a design evaluation of an extensible two-section soft robot based on cable-driven actuation for colonoscopy. Each section can bend in two perpendicular planes by tensioning and retracting four cables distributed by 90°. Its distal section can also extend and compress, resembling a soft spring. A nonlinear static analysis based on the Yeoh model is carried out to verify the movement capacity of the prototype concerning stress and deflection. The robot’s performance is evaluated by conducting a series of experiments, including bending capability, repeatability, and payload capacity. The results show that the distal section is compressed up to 68% of its normal length, and the robot achieves a bending angle of 270°. Furthermore, it succeeds in bending while carrying a load of 100 g. • Proposing a design of an extensible soft robot for colonoscopy. • Conducting nonlinear static analysis to analyze its bending behavior. • Design enhancement to avoid large deflections during the procedure. • Derivation of the kinematic model approach, including extension phase. • Experimental validation of the prototype’s performance.