This is why I suggested using electromagnets. You can get some insane force levels out of a good, hand wound electromagnet.

g.

Well, I would never say never...:)

Could you recommend some good manufacturers?



CyBerkut,

I would like to have min.3-4kg (at max deflection) on a 500mm long stick. Required deflection is +/-20deg.

I have an idea how to maintain the distance between the magnets, I will make some sketches and come back with it later.

I've never purchased a commercial electromagnet VO101MMaister, I've always wound them by hand. I think Google would serve you well here.
g.

Aren't we discussing about reinventing the wheel, though? You can get pretty good force out of an electromagnet attached to a shaft and perhaps geared down... hey, what about just using an electric motor? There's a few interesting links here: http://www.simprojects.nl/diy_force_feedback.htm
I think I'd just use a couple of servo arrangements to move the centering device, limiting the maximum force to that provided by it.

Yes, you could be right. That link is interesting, thanks. As I mentioned in OP the magnet-method is low force and I am happy with this since I always prefer low force on my sticks anyway. There are probably easier ways to achieve kilograms of force if desired.