Levitron research agenda

Significance:

Suppose we want to see the image of a delicate or enclosed space which is ordinarily inaccessible (see, for example, the article: New robots may aid Old Ironsides). Ideally, we would want a completely untethered floating camera. Let us examine the possible implementations of such a platform: (i) A miniature helicopter of some sort would create a downdraft, and would be extraordinarily difficult to construct. (ii) A lighter-than-air vehicle would have a low payload to volume ratio. (iii) A magnetically suspended platform has neither disadvantage (as long as the material to be inspected is not ferro-magnetic).

The Levitron is a toy which consists of a small spinning top which floats in the air, magnetically suspended about three inches above a static magnetic base. The top can be kept suspended indefinitely if small periodic magnetic pulses are present in the base (to keep it spinning).

My long term research agenda is to build on this principle, to make the top able to move around freely in x,y,z, to expand the workspace by getting the top to rise higher, and eventually to attach a miniature scanning camera and transmitter to the top, so that this technology can be used to explore delicate otherwise inaccessible locations and cavities.

Related work:

• Stability of Levitrons
• A nice intro to the physics of Levitrons
• (Simon97) Spin stabilized magnetic levitation
• the original 1983 U.S. patent by Roy Harrigan
• the much later (and technically incorrect!) 1995 U.S. patent by Bill Hones (who has apparently `borrowed' and commercialized Harrigan's invention).

Goals:

• Make a version of the Levitron in which the floater can move laterally over a magnetically active surface
• Determine the minimum resolution of a two dimensional array of coils (a magnetic image) that will simulate the magnetic base, and allow movement
• Attempt to make an antialiased magnetic image - one that can effect the same magnetic force upon the floater, but shifted by subpixel amounts.
• Determine how fast the floater can be moved without losing stability
• Create a non-rotating (but rotatable) platform by tethering 2N floaters whose rotations cancel out.

Research tasks:

• Try out a much larger coil - to get greater height
• Implement a simulator
• Build the coil array
• Build a controller
• Construct the control software API
• Construct control algorithms
• Make the floater responsive to its environment
• Design and try to implement two (or 2N) tethered floaters, rotating in opposite directions, to lift a stable non-rotating (but freely rotatable) platform. What is the optimal spacing between these tethered (and mutually repulsive) floaters?
• Steer this platform by manipulating the magnetic image beneath.