Hello ROS Gurus,

I couldn't find the answer to this question in the archives or the 
documentation for the PR2 arm navigation or David Lu!!'s arm kinematics. 
  So apologies if I missed something so basic.  I am running David's 
arm_kinematics package on my home built robot that has 4-joint arms, and 
as a test of the IK calculations and my link measurements, I am 
comparing the solution when all joints positions are set to 0 with what 
I can measure with a ruler.  However, it's not clear to me if the link 
coordinates returned by get_ik are for the origins of the links 
themselves or the origins of the joints.  My ruler measurements come out 
in between which means my measurements are wrong or my understanding of 
what the IK solution is providing.  (Or most likely, both.)

Thanks!
Patrick Goebel
Behavioral Sciences
Stanford University