An interesting project.

In theory you should be able to build a proof of concept with permanent
magnets for your electromagnets. It looks like you are trying to create a
magnetic valley between the two electromagnets on each corner.
Since you are trying to use repulsive forces, I would suggest making them
point outwards from within the vertices of the platform,
rather than inwards as you currently do. That way the system is self balancing.

Think about the individual force vectors you are creating with the corner
magnets, what happens as the spacing changes, and what you need them to do for you.

What kind of loads are you planning to put on this platform? What size in
real life?

Robert

Brendan Moran wrote:
>
> At 08:19 PM 21/10/2003 +0200, you wrote:
> >What 'magnetic dipoles' ? You can use F=B*I*l (Laplace magnetic force)
> >where B/H=Mu for isotropic media (i.e. air coils and no armature).
> >H=I/(2*PI*d) at a distance d from an infinitely long wire carrying a
> >current I, and H=2*I/r in the center of a single turn coil of radius r,
> >H=N*I/l inside a long and narrow solenoid (the last formula is empirical
> >afaik - the exact version is very hairy). If the coil(s) have cores with
> >Mu different from air then B will be non-linear and probably change with
> >the inverse square of the distance if the distance between the poles is
> >reasonably large (larger than the diameter of the pole pieces) so
> >alignment errors do not play a major role. So F ~= N*I*B/(l*r*d^2) for d
> > >= 2r where B is the induction from a nearby magnet or other coil. Try a
> >book near you ?
>
> The very first thing I did was look in my old physics text book.  It didn't
> seem to be any help, which is why I came here.  Perhaps I should have tried
> a little harder to develop my own equation, I don't know.
>
> This all looks very helpful, but let me make sure I've got the variables
> right.  (sure would throw a wrench in the works if I had that wrong)
>
> F: Force
> N: number of turns in the coil
> i: current in the coil
> B: you stated
> L: length of the coil
> r: radius of the coil
> d: radius of separation between the coil and the other source of magnetic
> field.
>
> Now all I have to do is try to apply the Mu of a ferrous material (like a
> steel bolt) to this equation.
>
> Well, anyway, for a better idea of what I'm trying to accomplish, have a
> look at http://members.shaw.ca/annirak/index.htm, and have a look at the
> "[EE]: Active maglev with permanent magnets & solenoids" thread
>
> Thanks for the help, that's pretty well does it.

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