Towards a Physics-Based Model for Steerable Eversion Growing Robots

Soft robots that grow through eversion/apical exten- sion can effectively navigate fragile environments such as ducts and vessels inside the human body. This letter presents the physics- based model of a miniature steerable eversion growing robot. We demonstrate the robot’s growing, steering, stiffening and inter- action capabilities. The interaction between two robot-internal components is explored, i.e., a steerable catheter for robot tip orientation, and a growing sheath for robot elongation/retraction. The behavior of the growing robot under different inner pressures and external tip forces is investigated. Simulations are carried out within the SOFA framework. Extensive experimentation with a physical robot setup demonstrates agreement with the simulations. The comparison demonstrates a mean absolute error of 10–20% between simulation and experimental results for curvature values, including catheter-only experiments, sheath-only experiments and full system experiments. To our knowledge, this is the first work to explore physics-based modelling of a tendon-driven steerable eversion growing robot. While our work is motivated by early breastcancerdetectionthroughmammaryductinspectionanduses our MAMMOBOT robot prototype, our approach is general and relevant to similar growing robots.