Im not quite sure what your trying to get at. If your standing on a rotating platform and your trying to match your rotation speed to the rotation speed of the platform based on how far away from the center point it doesnt matter, just match the speed. Whether you are standing in the center or 50 yds away your rotation speed stays the same. You are just traveling faster forwards.

However If your walking forwards on a circular platform and your trying to set your rotation match to match the arc of the circle so you dont fall off at x forward speed. You just use rotationspeed = forward speed / distance to center. It will change your rotation speed to match your forward speed so you always are following the arc. Heres an example:

The top 3 cubes all have the same rotation speed even though they are all at different radius’. You can tell they still match up.

In The bottom example the cube will adjust its rotation speed according to its forward speed and the distance to the center so it matches the arc regardless of your forward velocity.

turnstuff.blend (451 KB)

If ive completely missed what your talking about I apologize