MR compatible continuum robot based on closed elastica with bending and twisting

In this paper, we propose a novel continuum robot based on closed loop elastic structure with bending and twisting. The proposed continuum robot consists of an elastic tube and a closed loop arm completely independent from the tube. The closed loop arm is a simple thin belt-shaped elastic strip which has two translational joints and one rotary degree of freedom. Here we found that when the closed loop arm was inside the tube and the one side of the translational joint was pushed or pulled, the tube could be bent easily. Based on this basic result, we proposed three types of the closed loop arm shape using bending and twisting of the elastic strip and showed that these arms made the tube deformed into completely different shapes including 180 degrees of rotation. The proposed mechanism was applied to two prototypes. One of them is the magnet resonance compatible manipulator which consists of the β titanium pipe of outer radius of 3 mm and the wall thickness of 0.2 mm and the polyetheretherketone resin elastic strip.