Kinematic Model Of A Magnetic-Microrobot Swarm In A Rotating Magnetic Dipole Field

This letter describes how a rotating magnetic dipole field will manipulate the location and shape of a swarm of magnetic microrobots, specifically microrobots that convert rotation into forward propulsion, such as helical swimmers and screws. The analysis assumes a swarm that can be described by a centroid and a covariance matrix, with the swarm comprising an arbitrary and unknown number of homogenous microrobots. The result of this letter is a kinematic model that can be used as an a priori model for motion planners and feedback control systems. Because the model is fully three-dimensional and does not require any localization information beyond what could realistically be determined from medical images, the method has potential for in vivo medical applications. The model is experimentally verified using magnetic screws moving through a soft-tissue phantom, propelled by a rotating spherical permanent magnet.