Hi Chad!

On 12/17/2010 05:23 AM, Chad Rockey wrote:

So I have been following the really nice (R2D2) tutorials on URDF, thanks a lot for those! I've managed to get our robot model into RVIZ and follow base_link, but the transforms on the URDF besides base_link all seem to time lag, causing some jittery looking motion:

[...]

We are playing data from a recorded bag file using --clock and have set use_sim_time to true.

I experienced the same when playing back motions of a 25-DOF humanoid from a bag file, see
http://ros-users.122217.n3.nabble.com/Bag-file-recording-playback-asynchronous-in-RViz-td1400821.html

The reason (as I understood it) is that RViz displays all data by the time it arrives, and the bag file is played back in the same manner it was recorded - asynchronuously, and not necessarily according to the timestamps of the actual messages.

Fortunately, that's easy to fix with the rosbag API by changing the timestamps in the bagfile, see the thread linked above. We also have a tool for this bagfile reordering in our Freiburg repository at http://code.google.com/p/alufr-ros-pkg (see sync_bagfile.py in fr_tools, freiburg_tools stack).

Cheers,
Armin

-- 
Armin Hornung
Humanoid Robots Lab, Albert-Ludwigs-Universität Freiburg
Contact: http://www.informatik.uni-freiburg.de/~hornunga