Design and modeling of a silicone-based bendable tip for colonoscopy

In this paper, the authors describe the design of a bendable robotic tip for semi-autonomous colonoscopy called COLOBOT. It is a flexible robotic manipulator made of silicone rubber in view of the compact size and safety compatibility in the medical context. The outer diameter of the tip is 17 mm which is lesser than the average diameter of colon (20mm). Three servo-valves are used to control the pressure of each chamber of this tip to obtain the flexible movement of this tip. The promising results of this new prototype show that it can bend until 120 degrees under the pressure of 2 Bar. Based on the geometric deformation, a direct kinematic model analogous to the forward kinematics of a conventional industrial robot kinematics chain has been put forward. A polynomial approximation is used to characterize the behavior of each chamber actuator. This kinematic model is then validated experimentally and can be used to optimize the structure and the actuator. KeywordsMicro-robot, colonoscopy, modeling, medical robot Kinematics, silicone rubber, continuum robot, actuator