[ros-users] urdf meshes generate "No root link found" error

Yeon Grace Lee yeongrace.lee at gmail.com
Mon Jul 12 16:08:49 UTC 2010


I am currently writing an urdf file for a human model. The human model ran
fine in rviz when I used geometric shapes for links. Recently I have
uploaded STL files and changed the link geometry to that of a mesh. This has
generated a "No root link found" error even though nothing has been changed
in parent-child relationships in joints and names of links and joints have
stayed constant. I have also opened up my STL files in blender and they all
have no problem opening and displaying the models (they have been exported
from Maya). I'm not quite sure what I am missing in my urdf or my
state_publisher file. It may be something simple that I am not aware of. I
have attached the two files (model.xml and state_publisher.cpp). The error
generated is below:

yglee at yglee-laptop:~/ros/ros/HUMAN$ roslaunch HUMAN launch_file.launch
... logging to

started roslaunch server http://yglee-laptop:42319/


 * /robot_description

    robot_state_publisher (robot_state_publisher/state_publisher)
    state_publisher (HUMAN/state_publisher)

WARNING: IP address for local hostname 'yglee-laptop' does not
appear to match
any local IP address (, Your ROS nodes may fail to

Please use ROS_IP to set the correct IP address to use.
starting new master (master configured for auto start)
process[master]: started with pid [2137]

setting /run_id to 7c565b12-8dce-11df-b146-00236c960005
process[rosout-1]: started with pid [2148]
started core service [/rosout]
process[robot_state_publisher-2]: started with pid [2161]
process[state_publisher-3]: started with pid [2163]
[ERROR] 1278950383.696006000: No root link found. The robot xml is not a
valid tree.
[ERROR] 1278950383.696138000: failed to find root link
[ERROR] 1278950383.696279000: Could not generate robot model
[ERROR] 1278950383.696612000: Failed to extract kdl tree from xml robot
[robot_state_publisher-2] process has died [pid 2161, exit code 255].
log files:
^C[state_publisher-3] killing on exit
[rosout-1] killing on exit
[master] killing on exit
shutting down processing monitor...
... shutting down processing monitor complete

Thank you in advance for your help.

Grace L.
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