Modeling magnetic torque and force for controlled manipulation of soft-magnetic bodies

Abstract

We calculate the torque and force generated by an arbitrary magnetic field on an axially symmetric soft-magnetic body. We consider the magnetization of the body as a function of the applied field, using a continuous model that unifies two disparate magnetic models. The continuous torque and force follow. The model is verified experimentally, and captures the often-neglected region between weak and saturating fields, where interesting behavior is observed. We provide the optimal field direction for a given field magnitude. We find a maximum possible torque, which can be generated with relatively weak applied fields. This paper facilitates systems-level analysis, simulation, and real-time control of soft-magnetic bodies.

Superparamagnetic swimming microrobots with adjusted magnetic anisotropy

“…Applying magnetic force and torque, remote control of untethered micro-and nanoscopic devices can be achieved [1]. These devices are desirable for various applications, including targeted drug-delivery and micro manipulation.…”

Minimum Bounds on the Number of Electromagnets Required for Remote Magnetic Manipulation

“…However, if the object is made of soft-magnetic material (e.g., Nickel-Iron), (12) becomes quadratic in current, because the dipole moment m is a function of the applied field strength. For ellipse like shapes, the function M (B) has been characterized in [26] and [27]. A magnetic-manipulation system generates a field and gradient that can be controlled to apply a desired force and torque on an object.…”

Invariant trajectory indexing for real time 3D motion recognition

“…where B is the field at the location of m, F is force (N), and T is the torque (N·m), expressed in the same frame in which the spatial derivatives are taken [18]. From (2) we see that the force in a given direction is the inner product of the derivative of the field in that direction and the magnetization of the magnet placed in the field.…”