Design of a Variable Stiffness Continuum Robot for Endoscopic Submucosal Dissection

The incidence of gastrointestinal malignant tumors has been showing an upward trend, and endoscopic submucosal dissection (ESD) has become the preferred surgical procedure for early-stage gastrointestinal cancers in recent years. However, there are numerous challenges in using traditional single-channel endoscopy for ESD. Addressing the issue of limited instrument flexibility and loading capacity due to the confined working environment in ESD, and considering the operational requirements of gastrointestinal endoscopic surgery, this paper proposes an innovative five-degree-of-freedom variable-stiffness continuum robot based on the principle of single-cord force locking. The robot’s base is designed similarly to a gimbal mechanism, allowing adjacent bases to rotate freely around the contact ball. By tensioning the pulling ropes, friction between the bases is increased, achieving the effect of variable stiffness. This paper establishes a kinematic model, and elucidates the working principle of variable stiffness. Experiments verify that the tip of the continuum robot can withstand a radial load of 2.5N and achieve trajectory tracking with small error, demonstrating significant potential for providing flexible operation and robust load capacity in ESD surgery.