# Revision history [back]

### Problem with SDF files or robot_description parameter

So I am working my way through some of the tutorials for ROS/Gazebo. I am running into some issues with ROS Control with Gazebo Tutorial however. In particular when I launch the robot_control package, I get an error saying

Could not find parameter robot_description on parameter server


After a little digging I added the following to my launch file:

<param name="robot_description" textfile="path/to/robot.sdf"/>


to set the robot_description parameter. However after I did that I get the error:

/opt/ros/hydro/lib/robot_state_publisher/robot_state_publisher
[ERROR] [1376891403.184690567]: Could not find the 'robot' element in the xml file
[ERROR] [1376891403.184756779]: Could not generate robot model
[ERROR] [1376891403.184774430]: Failed to extract kdl tree from xml robot description


So I am guessing that what is happening is that robot_state_publisher is looking for a URDF file while I am providing a SDF file. How do I get around this?

### Problem with SDF files or robot_description parameter

So I am working my way through some of the tutorials for ROS/Gazebo. I am running into some issues with the ROS Control with Gazebo Tutorial however. In particular when I launch the robot_control package, I get an error saying

Could not find parameter robot_description on parameter server


After a little digging I added the following to my launch file:

<param name="robot_description" textfile="path/to/robot.sdf"/>


to set the robot_description parameter. However after I did that I get the error:

/opt/ros/hydro/lib/robot_state_publisher/robot_state_publisher
[ERROR] [1376891403.184690567]: Could not find the 'robot' element in the xml file
[ERROR] [1376891403.184756779]: Could not generate robot model
[ERROR] [1376891403.184774430]: Failed to extract kdl tree from xml robot description


So I am guessing that what is happening is that robot_state_publisher is looking for a URDF file while I am providing a SDF file. How do I get around this?