Excellent, this sort of project used to be set as a final year degree project with the student expected to take an academic year over it. That was done with photo cell and light beam providing the positional feedback.
How did you isolate the electro magnet from the permanent magnet? Was it a case of only measuring the hall effect device when the magnet was turned off or is there an other trick to it?
A movie would be good as a still can look like you just caught it right.
Well done again.