A Novel Distal Hybrid Pneumatic/Cable‐Driven Continuum Joint with Variable Stiffness Capacity for Flexible Gastrointestinal Endoscopy

Abstract

The robot‐assisted flexible access surgery represented by the emerging robot‐assisted flexible endoscopy (FE) and natural orifice transluminal endoscopic surgery demands flexible and continuum manipulators instead of the rigid and straight instruments in the traditional minimally invasive surgery (MIS). These flexible manipulators are required to advance through the tortuous and narrow anatomic paths via natural orifices for dexterous diagnostic examination and therapeutic operations. Therefore, developing flexible endoscopic manipulators with the capacity of snake‐like movements for flexible access and variable stiffness regulation for operations to address these flexible access surgical difficulties is demanding but remains challenging. To address such challenges, herein, it is proposed that a novel distal continuum joint based on the hybrid pneumatic and cable‐driven approach achieves variable stiffness capacity, excellent bending characteristics in both flexible and rigid states, satisfactory motion consistency and shape‐locking ability during the rigid‐flexible transition, and relatively high loading capacity for flexible gastrointestinal endoscopic robots. Characterization experiments validate these performances, and phantom and ex vivo experiments have been performed to demonstrate the feasibility and effectiveness for FE. The presented method demonstrates an effective and practical approach to enabling continuum robots with both flexible access and tunable stiffness capacity and supports a convenient extension for MIS applications.

An Online Model-Free Adaptive Tracking Controller for Cable-Driven Medical Continuum Manipulators

“…The cable-driven continuum manipulators have exhibited great potential and promising applicability for these robotic systems (e.g. EndoMaster System designed by Nanyang Technological University [9], K-Flex Intuitive [11]) due to their outstanding structural compliance, environmental adaptability, and flexible access capability in narrow cavities and tortuous anatomic pathways [12], [13]. However, these continuum manipulators commonly experience large and nonlinear deformation, complex friction, and significant hysteresis behaviors [14], [15].…”

“…where 𝜂𝜂 represents a step-size constant, and the role of 𝜂𝜂 and 𝜇𝜇 in (15) are similar to that of 𝜌𝜌 and 𝜆𝜆 in (13).…”

An Operating Stiffness Controller for the Medical Continuum Robot Based on Impedance Control

“…Moreover, applying these external stimulations requires additional energy exchangers, resulting in larger joint diameters, poor biocompatibility, and high leakage risks. An alternative approach for stiffness adjustment includes mechanical designs like unit-locking mechanisms [ 31 , 32 ] and jamming-based methods [ 33 – 37 ]. To adjust manipulator stiffness, unit-locking mechanisms reorganize mechanical engagement through gears, racks, etc.…”

Development of a Novel Ball-and-Socket Flexible Manipulator for Minimally Invasive Flexible Surgery

“…Therefore, flexible manipulators are required to feature sufficient payload to provide adequate interaction forces and maintain stability under external loading [7]. However, there is a dilemma between high dexterity and high payload, which needs to be balanced effectively [8,9]. In addition, surgeons typically need to rotate the manipulator to adjust the attitude of surgical tools when performing surgical operations such as endoscopic exploration, drilling, and suturing.…”