A Controllable Stiffness Robotics for Natural Orifice Transluminal Endoscopic Surgery

Abstract

Natural orifice transluminal endoscopic surgery is a new minimally invasive surgery, with no surface scars, less postoperative pain, short recovery time, less postoperative morbidity and other advantages, is the development direction of minimally invasive surgery in the future. In order to smoothly pass through the natural orifice of the human body, its surgical instruments use flexible instruments, which leads to the lack of operation force during the operation, and the safety of the operation cannot be guaranteed. In this paper, a flexible robot with controllable stiffness is designed to solve the problem of insufficient stiffness of flexible surgical instruments. According to the method of wire tensioning and variable stiffness, a miniature natural cavity surgical robot variable stiffness joint is designed. According to the mechanical limit, its motion ability is analyzed. The principle of variable stiffness of tensioned variable stiffness joint is analyzed, and the solution equation of friction moment of variable stiffness joint is derived. Finally, the relationship between tension force and stiffness is verified by experiments. The maximum static load test was carried out and the invisible variable load range of the joints with variable stiffness was obtained under certain tension conditions.