5-DOF Manipulation of an Untethered Magnetic Device in Fluid using a Single Permanent Magnet

This paper presents a three degree-of-freedom (3-DOF) closed-loop position and 2-DOF open-loop orientation control method for an untethered mockup magnetic capsule endoscope in fluid with a single permanent magnet positioned by a commercial robotic manipulator and a 3-DOF capsule-position localization system. Using traditional methods known to roboticists, we study the kinematics of untethered magnetic manipulation using a single permanent magnet as the end-effector of a robot manipulator. We present a control method that maintains 5-DOF control of a magnetic capsule when the robot manipulator is not near a kinematic singularity, and seamlessly enables a capsule’s position to be controlled when the manipulator nears a kinematic singularity by sacrificing control over the capsule’s orientation. We demonstrate the method’s robustness to a control rate of 25 Hz, reduced localization rates down to 30 Hz, and the presence of manipulator singularities. 5-DOF manipulation of an untethered device has been previously demonstrated by electromagnetic systems only. This work has applications for robotic capsule endoscopy of a fluid-distended stomach.