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Manipulation with a Single Permanent Magnet for Capsule EndoscopyOn this page... (hide) Externally applied magnetic fields will enable untethered devices to navigate the body for minimally invasive surgical and diagnostic procedures. We are particularly interested in active capsule endoscopy. Much of the prior research done on helical swimmers and screws has utilized electromagnetic coil arrangements for control, but these are difficult to scale up to the size of a human body. We believe that it is possible to control such device using a single permanent magnet moved and rotated dynamically through space.
Using Rotating Dipole Fields for Magnetic Capsule Endoscopy of the Small Bowel 5-DOF Control for Capsule Endoscopy of the Stomach Generating Fields with Permanent MagnetsThe Spherical-Actuator-Magnet Manipulator (SAMM) is a permanent-magnet robot end-effector. It comprises a spherical permanent magnet and three mutually orthogonal onmiwheels that enable rotation of the magnet about arbitrary axes of rotation, without singularities or workspace limitations. Hall-effect sensors on the SAMM enable estimation of the orientation of magnetic dipole. More details can be found in the paper The Spherical-Actuator-Magnet Manipulator: A Permanent-Magnet Robotic End-Effector.
The manipulation methods that we have developed utilize a point-dipole model of the field generated by the permanent magnet. Only spherical magnets have a field that truly looks like a point dipole, and for other magnet geometries the model is just an approximation. We found the aspect ratios for a variety of common geometries (axially magnetized cylinders, diametrically magnetized cylinders, washers, rectangular-cross-section bars) that result in a minimum error when using the point-dipole model. More details can be found in the paper Optimal Permanent-Magnet Geometries for Dipole Field Approximation.
Selected PublicationsK. M. Popek, T. Hermans, and J. J. Abbott, "First Demonstration of Simultaneous Localization and Propulsion of a Magnetic Capsule in a Lumen using a Single Rotating Magnet", IEEE Int. Conf. Robotics and Automation, pp. 1154-1160, 2017. Best Paper Award in Medical Robotics.
S. E. Wright, A. W. Mahoney, K. M. Popek, and J. J. Abbott, "The Spherical-Actuator-Magnet Manipulator: A Permanent-Magnet Robotic End-Effector", IEEE Trans. Robotics, 33(5):1013-1024, 2017.
K. M. Popek, T. Schmid, and J. J. Abbott, "Six-degree-of-freedom Localization of an Untethered Magnetic Capsule Using a Single Rotating Magnetic Dipole", IEEE Robotics and Automation Letters, 2(1):305-312, 2017.
A. W. Mahoney and J. J. Abbott, "Five-degree-of-freedom Manipulation of an Untethered Magnetic Device in Fluid using a Single Permanent Magnet with Application in Stomach Capsule Endoscopy," Int. J. Robotics Research, 35(1-3):129-147, 2016.
A. W. Mahoney and J. J. Abbott, "Generating Rotating Magnetic Fields with a Single Permanent Magnet for Propulsion of Untethered Magnetic Devices in a Lumen," IEEE Trans. Robotics, 30(2):411-420, 2014.
A. W. Mahoney, S. E. Wright, and J. J. Abbott, "Managing the Attractive Magnetic Force between an Untethered Magnetically Actuated Tool and a Rotating Permanent Magnet," IEEE Int. Conf. Robotics and Automation, pp. 5346-5351, 2013.
A. W. Mahoney and J. J. Abbott, "5-DOF Manipulation of a Magnetic Capsule in Fluid using a Single Permanent Magnet: Proof-of-concept for Stomach Endoscopy," Hamlyn Symp. Medical Robotics, pp. 114-115, 2013. Best Poster Award. The definitive version of this work is in the journal paper "Five-degree-of-freedom Manipulation of an Untethered Magnetic Device in Fluid using a Single Permanent Magnet with Application in Stomach Capsule Endoscopy." A. J. Petruska and J. J. Abbott, "Optimal Permanent-Magnet Geometries for Dipole Field Approximation," IEEE Trans. Magnetics, 49(2):811-819, 2013.
K. M. Miller, A. W. Mahoney, T. Schmid, and J. J. Abbott, "Proprioceptive Magnetic-Field Sensing for Closed-loop Control of Magnetic Capsule Endoscopes," IEEE/RSJ Int. Conf. Intelligent Robots and Systems, pp. 1994-1999, 2012.
A. W. Mahoney and J. J. Abbott, "Control of Untethered Magnetically Actuated Tools with Localization Uncertainty using a Rotating Permanent Magnet," IEEE Int. Conf. Biomedical Robotics and Biomechatronics, pp. 1632-1637, 2012.
A. W. Mahoney, D. L. Cowan, K. M. Miller, and J. J. Abbott, "Control of Untethered Magnetically Actuated Tools using a Rotating Permanent Magnet in any Position," IEEE Int. Conf. Robotics and Automation, pp. 3375-3380, 2012.
A. W. Mahoney and J. J. Abbott, "Managing Magnetic Force Applied to a Magnetic Device by a Rotating Dipole Field," Applied Physics Letters, 99(134103):1-3, 2011.
SponsorsThis material is based in part upon work supported by the National Science Foundation under Grant No. 0952718. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. |