Thank you very much for the thoughts on control electronics. I am interested in seeing how the Pi3 with i2C would work for control, as you mentioned. I will look into those encoders as well for some of the closed-loop control.
This is the URDF I had found for the Thor arm. I don’t know how accurate or complete it is, but it looks like someone else has started on this road before: ;https://github.com/b-adkins/thor_arm_description
The same user put together a MoveIt package I using that URDF as well: ;https://github.com/b-adkins/thor_arm_moveit
I will let you know what I find for ROS integration and controlling Thor from a Pi!
David