I'm trying to build the dynamic model of a 6DOF robot, and the company that has built it, kindly provides a document having the masses, centres of mass, principal axes of inertia and principal moments of inertia taken at the center of mass, taken at the center of mass and aligned with the output coordinate system, and taken at the output coordinate system (I've come to known that this was obtained from a tool in SolidWorks)
The robot has 6 actuators responsible for the motion of each one of the 6 links available. The problem that I have here is the way I should calculate the inertia matrix $M(q)$. Since the matrix has to have a 6x6 dimension, I know that I have to do some kind of "combining" between one link and the correspondent actuator. The problem is that I don't really know how can I find the respective centre of mass between the two "objects" and the respective moment of inertia of the "multiobject". I've seen people saying that it is simply the summation of the respective moments of inertia but they need to be in respect to the same orientation and translation.
Can anyone shed some light into this? Suggestions would be greatly appreciated.