This represents the motion of polar manipulator.
Bodies are indicated by C(1) and C(2)
The base rotates about the horizontal 3-axis
The base extends outward along the moving x axis
In this problem, the point of interest -- the green grasper is the green cone at the tip.
The red ball is the tracker
The red ball is not a computer graphics child of the red arm. Rather, it is a free object: its position is computed from Equation (g) in Problem S.P.12.1
All frame connections are shown by the combined (frame, location) notation
Finally, a blue velocity vector is place on the red ball. It's components are obtained via equation (p) of problem 12.4
Notice that as the arm extends outward, the velocity has an initial component in the local x1 direction, but soon, the tangential velocity component dominates.