Purpose: The development of surgery is to be minimally invasive and collaborative with robot systems, which has caught increasing attention in recent years. However, the narrow access routes and confined working spaces in vivo usually make distal end-effectors of surgical systems not easy to operate. To overcome this problem, a novel cable-driven distal end-effector mechanism designed for single-port robotic surgery was proposed.
Methods: A cable-driven joint structure and the corresponding methods of threading cables were proposed which can maintain the length and even the tension force of cables constant during operation. Based on the proposed joint structure, the cable-driven distal end-effector mechanism consists of a parallelogram mechanism and a snake mechanism. The parallelogram mechanism is used to enlarge its reachable workspace through establishing the triangulation of operation. The snake mechanism is used to achieve the expected pose through providing sufficient bending degrees of freedom. All of the degrees of freedom can be decoupled at the expense of a slightly more tedious process of threading cables.
Results: The primary prototype and its miniature assembled and threaded manually performed as expected regardless of bend, translation and their combination. But the inadequate tension force of cables and assembly errors affect the load capacity and accuracy, which need to be improved by automatic assembly.
Conclusion: A cable-driven distal end-effector mechanism composed of a parallelogram mechanism, and a snake mechanism used for single-port robotic surgery was proposed. The mechanism adopts a novel cable-driven joint structure and corresponding methods of threading cables to keep the length and even the tension force of cables constant during surgery.
Keywords: Cable-driven; Mechanism design; Minimally invasive; Single-port surgery; Surgical robot.