Closed-Loop Shape-Forming Control of a Magnetic Soft Continuum Robot

Continuum manipulators are frequently employed in endoluminal interventions, however, a lack of softness and dexterity in standard manipulators can risk trauma during navigation and limit reachable workspace. Magnetically actuated Soft Continuum Robots (MSCRs) offer enhanced miniaturization potential and reduced rigidity due to their external actuation. Magnetizations pertaining only to the tip of the robot offer a limited range of deformation options where more versatile MSCRs can be embedded with distinct, lengthwise magnetization profiles. These full-body bespoke profiles allow the robots to form pre-determined shapes under actuation. Here we propose an approach to model and control MSCR behavior in closed-loop. We employ this system to achieve shape forming navigations subject to variations in initial conditions. To validate our methodology, we conduct experiments using a 50 mm long by 1.8 mm diameter MSCR navigating through a soft phantom from the tip of a duodenoscope. The proposed system is capable of rejecting variations in the angle at which the MSCR is inserted. We employed homogeneous magnetic fields for actuation and closed-loop vision-based control to manipulate the lengthwise body shape of our MSCR. The performance of this closed-loop approach is compared with an open loop counterpart, which fails in all but one navigation attempts into the pancreatic duct.