During thirth visit (13/03/2014)
We thought that the detaching and the attaching would happen in the same direction,
but then the problem occurs that the arm collapses.
We got the idea to the two moves in the opposite direction.
We decided not to work out prototype 28, because we found a solution for the collapsing arm now.
Problem: The arm collapses
problem 2: magnet is not strong enough
There is still room for improvement .
We need to thing about the fixing method to the wheelchair.