Transendoscopic Telerobotic System: Heterogeneous Flexible Manipulators for Bimanual Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) is an effective technique to resect early cancers in the gastrointestinal (GI) tract. Bimanual telerobotic manipulation is an approach to performing ESD intuitively and efficiently, which requires two robotic instruments with flexibility, stiffness, dexterity, and accuracy. In detail, specific elementary ESD action requires a corresponding priority of the above properties. In this article, we propose the first heterogeneous flexible manipulators (HFMs) for bimanual ESD, which can take advantage of different mechanical structures toward specific ESD actions. The grasping instrument employs a serial articulated manipulator (SAM) to perform multidirectional (relatively higher dexterity) and stable (relatively higher stiffness) traction for better submucosal visualization. The electrosurgical instrument utilizes a parallel-continuum wrist (PCW) to execute safe (higher-accuracy) tissue dissection. Both HFMs have sufficient flexibility (i.e., lower bending stiffness values than the endoscope) to go through the flexible endoscopic working channels. Based on the HFMs, we establish a transendoscopic telerobotic system. The kinematics of the SAM and PCW are built in the endoscope frame using the Denavit–Hartenberg (DH) method and the Cosserat rod method, respectively. Through simulation, the SAM is proved to have higher dexterity than the PCW, and they share enough workspace to cover lesions with diameters over 30 mm. The HFM-based robotic system is validated to perform efficient and safe ESD through ex vivo tests with tiered difficulty. The HFMs may offer a feasible strategy to develop robots for more forms of surgery by leveraging different mechanical structures for specific ESD actions.