Hi Henry - 
 
There are two links that could be considered root links in the urdf, this is a bug in lxf2urdf. Can you send me your ldr and lxf files so I can find the bug in the script. 

Thanks

-Melonee

On Sep 9, 2010, at 7:03 AM, Henry Acevedo <henryacev@hotmail.com> wrote:

> Hi
> 
> I did create a new ROS package, and model using LDD and I have also replace the ldraw.xml previous creating the new model, my model uses all three motors, two touch sensor, ultrasonic and colour sensor. also I did test all input from sensor and motors (all OK)
> 
> once i did use rosrun nxt_lxf2urdf lxf2urdf.py Explorer.lxf Explorer.ldr >robot.urdf; i did't have any error, so then as testing proposes I did tried to execute roslaunch explorer_nxt robot.launch, but I got an error,
> 
> Initially I though was in need to chenge the name of the link on the udf file, and I did change it to reflect what I have in my robot.yaml file, but the error still persist.
> 
> could you please advice
> 
> ros@robotics:~/nxtros/nxt/nxt/explorer_nxt$ roslaunch explorer_nxt robot.launch
> ... logging to /home/ros/.ros/log/099e679a-bc09-11df-9f7c-001b77c34136/roslaunch-robotics-7369.log
> Checking log directory for disk usage. This may take awhile.
> Press Ctrl-C to interrupt
> Done checking log file disk usage. Usage is <1GB.
> 
> started roslaunch server http://robotics:47600/
> 
> SUMMARY
> ========
> 
> PARAMETERS
>  * /robot_description
>  * /robot_state_publisher/publish_frequency
>  * /nxt_ros/nxt_robot
> 
> NODES
>   /
>     robot_state_publisher (robot_state_publisher/state_publisher)
>     nxt_ros (nxt_ros/nxt_ros.py)
>     joint_state_publisher (nxt_ros/joint_states_aggregator.py)
> 
> ROS_MASTER_URI=http://robotics:11311/
> 
> core service [/rosout] found
> process[robot_state_publisher-1]: started with pid [7388]
> process[nxt_ros-2]: started with pid [7389]
> process[joint_state_publisher-3]: started with pid [7390]
> [ERROR] [1284040920.153455092]: Two root links found: 'ref_0_link' and 'ref_139_link'
> [ERROR] [1284040920.153671740]: failed to find root link
> [ERROR] [1284040920.157419633]: Could not generate robot model
> [ERROR] [1284040920.158312623]: Failed to extract kdl tree from xml robot description
> [robot_state_publisher-1] process has died [pid 7388, exit code 255].
> log files: /home/ros/.ros/log/099e679a-bc09-11df-9f7c-001b77c34136/robot_state_publisher-1*.log
> [INFO] 1284040920.745409: Creating motor with name l_motor_joint on PORT_C
> [INFO] 1284040920.751772: Creating motor with name r_motor_joint on PORT_B
> [INFO] 1284040920.752178: Creating motor with name a_motor_head on PORT_A
> [INFO] 1284040920.752524: Creating touch with name touch_sensor_r on PORT_1
> [INFO] 1284040920.758945: Creating touch with name touch_sensor_l on PORT_2
> [INFO] 1284040920.763690: Creating ultrasonic with name ultrasonic_sensor on PORT_4
> [INFO] 1284040920.871954: Creating intensity with name intensity_sensor on PORT_3
> 
> 
> from the logs
> 
> [ros.urdf] [2010-09-09 15:02:00,153] [thread 0xb688f710]: [ERROR] Two root links found: 'ref_0_link' and 'ref_139_link'
> [ros.urdf] [2010-09-09 15:02:00,153] [thread 0xb688f710]: [ERROR] failed to find root link
> [ros.kdl_parser] [2010-09-09 15:02:00,157] [thread 0xb688f710]: [ERROR] Could not generate robot model
> [ros.robot_state_publisher] [2010-09-09 15:02:00,158] [thread 0xb688f710]: [ERROR] Failed to extract kdl tree from xml robot description
> 
> 
> Thanks
> 
> 
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