Let's take a 6 DOF robotic structure. It's consisting of the 3 DOF global structure for the position - and the 3 DOF local structure for the orientation of the endeffector.
If the last 3 axis (of the local structure) are coincident in one point, the inverse kinematics can be solved analytically by decomposing it into a position- and orientation-problem.
But is it possible to solve the inverse kinematics analytically if the last 3 axis are NOT coincident in one point? I've read several papers that claim that due to high non-linearity of the trigonometric functions and motion complexity in 3D-space, a 6 DOF serial chain cannot be solved analytically.
Does anybody know if this is right?