I believe with that cable configuration, Yaw motion isn't really possible. I'm sure it would help with motion programming with the VR, but perhaps true Yaw wouldn't be entirely necessary. Good questions though.
For your last question, I do think that's the way they would need to add Yaw if desired. Otherwise more cables and/or a different configuration would be needed.
For your last question, I do think that's the way they would need to add Yaw if desired. Otherwise more cables and/or a different configuration would be needed.
As an example, check out the robocrane design from NIST: http://www.nist.gov/el/isd/gantry-2.cfm