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

[Yeon Grace Lee]

Hi,

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
/home/yglee/.ros/log/7c565b12-8dce-11df-b146-00236c960005/roslaunch-yglee-laptop-2123.log

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

SUMMARY
========

PARAMETERS
 * /robot_description

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

WARNING: IP address 127.0.1.1 for local hostname 'yglee-laptop' does not
appear to match
any local IP address (127.0.0.1,192.168.2.153). Your ROS nodes may fail to
communicate.

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]
ROS_MASTER_URI=http://yglee-laptop:11311/

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
description
[robot_state_publisher-2] process has died [pid 2161, exit code 255].
log files:
/home/yglee/.ros/log/7c565b12-8dce-11df-b146-00236c960005/robot_state_publisher-2*.log
^C[state_publisher-3] killing on exit
[rosout-1] killing on exit
[master] killing on exit
exiting...
shutting down processing monitor...
... shutting down processing monitor complete
done


Thank you in advance for your help.

Grace L.
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