[ros-users] roll in PR2 end effector

Dear all,

I am writing a program for the SBPL arm planner. In this regard, I had a
conceptual doubt regarding the roll of the end effector (as computed by the
forward kinematics solver).

If I start with a roll of 0.5 radians, and add a roll of -0.5 radians, I am
supposed to end up at '0' right?? But when I change the roll by the
indicated amount, the forward kinematics solver does not indicate a
resultant roll of 0.

I am assuming that the wrist roll is about the end effector length axis. And
any change in wrist pitch (or change in forearm roll angle) is completely
decoupled with a change in wrist roll.

Please let me know where I could possibly be going wrong.

Thanks
Gokul.