I'm trying to obtain the dynamic model of a 3D robot (academic problem), I have obtained the D-H table, the transformation matrix for each pair of links and the total transformation matrix. Now I'm struggling with computing the total Kinetic energy (for using it in the Lagrangian approach).
In some texts, only the linear velocity is used in computing the kinetic energy, even if there are revolute links, that is:
$K=\frac{1}{2}m~v^2$
But in some others, both the linear and the angular velocities are considered :
$K=\frac{1}{2}m~v^2 + \frac{1}{2} I~\omega^2$
I'm a little bit confused with this, when and when not to use the angular contribution to the Kinetic energy?