Eddy-Current Actuation

Oscillating electromagnets pulling and pushing on an aluminum plate. Normally aluminum is non-magnetic: the electromagnets induce a current in the plate and can control the force with the plate by varying their phase.

Aluminum and other conductors are common spacecraft materials. These materials are not usually ferromagnetic, so stationary magnetic fields cannot manipulate them. Permanent magnets and current loops may also be used to generate time-varying fields. Time-varying magnetic fields induce currents in the conductors without contact. Removing contact reduces risk of collision as well as wear. Mechanisms such as eddy current brakes, dampers, and aluminum separators have used the resulting forces and torques in terrestrial applications. We seek to broaden applications for multi-degree-of-freedom mobility and actuation in microgravity environments.

How does it work?

Maxwell’s equations show that a time-varying magnetic field will induce an electric current in a conductor. This induced current, known as an “eddy current”, experiences a force caused by the same magnetic field that generated it. Unlike magnetic attraction caused by static fields, eddy currents can be formed in any conductor, including the aluminum skin of most man-made objects in space. The idea of this project is to use these forces to create 6-DOF actuation forces.