I am trying to calculate the pitch, yaw and roll of the forearm using two sets of two 3d(x,y,z) coordinates during movement, a set for the wrist and a set for the elbow. I would like to know how to calculate pitch, yaw and roll angles from these two coordinate sets? The order of the rotations is not important, they can be treated as individual rotations.
I have seen that the roll cannot be calculated with two points alone. If this is the case, how can I calculate roll, presumably using three points? Also why can roll not be calculated with only two points?
The rotations are required to work out maximum and minimum joint angles.
Any help with this could be greatly appreciated.