[ros-users] robot_state_publisher

Ugo Cupcic ugo at shadowrobot.com
Wed Apr 7 10:08:33 UTC 2010


The urdf model which doesn't work contained two links and a joint. I 
tried it once more and I don't get a warning in the rxconsole. Still the 
robot_state_publisher didn't subscribe to the /joint_states topic.

The dummy.xml file I attached is my simplified urdf model that doesn't 
work. I have a more complete urdf model which works fine.



Wim Meeussen wrote:
> Ugo,
>> I figured it out. My urdf model didn't have the same number of joints as
>> my published joint_states messages.
> I don't think this was your problem. The robot state publisher does
> not care about additional/missing joints in the joint_states message.
>> rostopic info /joint_states
>> Type: sensor_msgs/JointState
>> Publishers:
>>  * /shadowhand_publisher (http://ulster:35258/)
>> Subscribers: None
> The output above shows the problem: no node is subscribed to the
> joint_states topic. So the robot state publisher is not receiving any
> messages. This should only happen when you give the robot state
> publisher a urdf with no or only one link. In that case, the robot
> state publisher couldn't possible publish anything, and it therefore
> does not subscribe to the joint_states topic.
> But, you should have seen a warning in 'rxconsole'. It should have
> shown either "Robot state publisher got an empty tree and cannot
> publish any state to tf" or "Robot state publisher got a tree with
> only one segment and cannot publish any state to tf". After it shows
> this warning, the robot state publisher just sits there, unable to do
> anything. I guess that is quite a confusing state. We had a discussion
> about this here <https://code.ros.org/trac/ros-pkg/ticket/3224>.  Feel
> free to add comments based on your experience with the robot state
> publisher.
> Wim
> --
> Wim Meeussen
> Willow Garage Inc.
> <http://www.willowgarage.com)
> _______________________________________________
> ros-users mailing list
> ros-users at code.ros.org
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Ugo Cupcic         |  Shadow Robot Company | ugo at shadowrobot.com
Software Engineer      251 Liverpool Road
need a Hand?           London  N1 1LX       | +44 20 7700 2487
http://www.shadowrobot.com/hand/              @shadowrobot

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