Eddy Current Actuators for Spacecraft
As the pace of space exploration increases, spacecraft will need to complete more tasks that require physical interactions with resident space objects. Close interaction between a spacecraft and any other object, be it another spacecraft, an asteroid, or a piece of debris, has always been inherently risky. If the target of the interaction was not designed with electromagnetic coupling in mind, the spacecraft must exert force through direct mechanical contact, increasing the danger to the spacecraft significantly. Current methods of accurately positioning macroscopic objects require direct physical contact, whether through linkages, wires, or simple grapplers. While these methods are effectual, the contact between an actuator and an object not specifically designed for grappling is risky: for example, a grappler may apply excessive force and damage the object, or unanticipated movement of the target may result in a catastrophic collision. Actuators utilizing eddy current interactions present a solution to this problem.
A spacecraft actuated with eddy currents inspecting the ISS.
By creating a changing magnetic flux within a conductor we can induce a current opposing the change in the magnetic flux. This induced current, when produced in a bulk of connective material rather than a wire coil, is known as an "eddy current." The force that the magnetic field imparts on the eddy current can act not only radially, but in all three rotational and translational directions, depending on the magnitude and direction of both the current and magnetic field. Unlike magnetic attraction caused by static fields, eddy currents can be formed in any conductor, including the aluminum honeycomb isogrid that comprises the structure of most spacecraft.
A demonstration of actuation through eddy-current interactions.
More videos coming soon! Please check back in the first few weeks of october '11.
Team Members
- Ben Reinhardt
Funding
- NASA Space Technology Research Fellowship