Error: gazebo_ros_control plugin is waiting for model URDF in parameter

Question

Please help.

Very few times the gazebo opens with the loaded model, almost 99 times it fails with the below error.

After searching for one day in all forums I tried the following, so far no luck :( 1) runnning verbose:=true 2) running rosrun gzclient and then the launch file 3) making sure box size is not zero 4) transmission type properly mentioned 5) gazebo ros control plugin installed and mentioned in model file 6) gazebo ros control plugin installed (please note that i was able to run the same launch before, suddenly this error is coming up) 7) checked namesapce

Error trace:

balaji@balaji:~/Documents/balaji/unl/Media/Downloads/robot_ws_final$ source devel/setup.bash 
balaji@balaji:~/Documents/balaji/unl/Media/Downloads/robot_ws_final$ roslaunch robot_gazebo robot_world.launch 
... logging to /home/balaji/.ros/log/e78e4fbc-7f83-11e7-9f51-9801a7b07983/roslaunch-balaji-31825.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
WARNING: disk usage in log directory [/home/balaji/.ros/log] is over 1GB.
It's recommended that you use the 'rosclean' command.

xacro: Traditional processing is deprecated. Switch to --inorder processing!
To check for compatibility of your document, use option --check-order.
For more infos, see http://wiki.ros.org/xacro#Processing_Order
started roslaunch server http://balaji:45487/

SUMMARY
========

PARAMETERS
 * /first_pelican/image_processing_node/namesapce_deploy: first_pelican
 * /first_pelican/joint1_position_controller/joint: palm_riser
 * /first_pelican/joint1_position_controller/pid/d: 10.0
 * /first_pelican/joint1_position_controller/pid/i: 0.01
 * /first_pelican/joint1_position_controller/pid/p: 100.0
 * /first_pelican/joint1_position_controller/type: effort_controller...
 * /first_pelican/joint_state_controller/publish_rate: 100
 * /first_pelican/joint_state_controller/type: joint_state_contr...
 * /first_pelican/robot_description: <?xml version="1....
 * /first_pelican/smart_exploration/dist_x: 0
 * /first_pelican/smart_exploration/dist_y: 0
 * /first_pelican/smart_exploration/namesapce_deploy: first_pelican
 * /rosdistro: kinetic
 * /rosversion: 1.12.7
 * /use_sim_time: True

NODES
  /first_pelican/
    controller_spawner (controller_manager/spawner)
    image_processing_node (image_processing/image_processing_node)
    mybot_spawn (gazebo_ros/spawn_model)
    robot_state_publisher (robot_state_publisher/robot_state_publisher)
    smart_exploration (robot_exploration/smart_exploration)
  /
    gazebo (gazebo_ros/gzserver)
    gazebo_gui (gazebo_ros/gzclient)

auto-starting new master
process[master]: started with pid [31839]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to e78e4fbc-7f83-11e7-9f51-9801a7b07983
process[rosout-1]: started with pid [31852]
started core service [/rosout]
process[gazebo-2]: started with pid [31864]
process[gazebo_gui-3]: started with pid [31879]
process[first_pelican/mybot_spawn-4]: started with pid [31886]
process[first_pelican/controller_spawner-5]: started with pid [31887]
process[first_pelican/robot_state_publisher-6]: started with pid [31888]
process[first_pelican/image_processing_node-7]: started with pid [31889]
process[first_pelican/smart_exploration-8]: started with pid [31890]
[ WARN] [1502559016.978709697]: The root link chassis has an inertia specified in the URDF, but KDL does not support a root link with an inertia.  As a workaround, you can add an extra dummy link to your URDF.
[ INFO] [1502559016.986332012]: Got param: 0.000000
[ INFO] [1502559016.995995700]: Got param: 0.000000
[ INFO] [1502559016.999604731]: Got param: first_pelican
[ INFO] [1502559017.008884277]: In image_converter, got param: first_pelican
SpawnModel script started
[INFO] [1502559017.185603, 0.000000]: Loading model XML from ros parameter
[INFO] [1502559017.190666, 0.000000]: Waiting for service /gazebo/spawn_urdf_model
[ INFO] [1502559017.208092409]: Finished loading Gazebo ROS API Plugin.
[ INFO] [1502559017.209366293]: waitForService: Service [/gazebo/set_physics_properties] has not been advertised, waiting...
[INFO] [1502559017.386893, 0.000000]: Controller Spawner: Waiting for service controller_manager/load_controller
[ INFO] [1502559017.566665686, 246.206000000]: waitForService: Service [/gazebo/set_physics_properties] is now available.
[ INFO] [1502559017.611486634, 246.249000000]: Physics dynamic reconfigure ready.
[INFO] [1502559017.795112, 246.428000]: Calling service /gazebo/spawn_urdf_model
[ INFO] [1502559018.103326226, 246.494000000]: Camera Plugin: Using the 'robotNamespace' param: '/first_pelican/'
[ INFO] [1502559018.107184854, 246.494000000]: Camera Plugin (ns = /first_pelican/)  <tf_prefix_>, set to "/first_pelican"
[ INFO] [1502559018.628739638, 246.494000000]: Laser Plugin: Using the 'robotNamespace' param: '/first_pelican/'
[ INFO] [1502559018.628941833, 246.494000000]: Starting Laser Plugin (ns = /first_pelican/)
[ INFO] [1502559018.630496093, 246.494000000]: Laser Plugin (ns = /first_pelican/)  <tf_prefix_>, set to "/first_pelican"
[INFO] [1502559018.650747, 246.494000]: Spawn status: SpawnModel: Successfully spawned entity
[ INFO] [1502559018.669444812, 246.494000000]: Loading gazebo_ros_control plugin
[ INFO] [1502559018.669578793, 246.494000000]: Starting gazebo_ros_control plugin in namespace: first_pelican
[ INFO] [1502559018.670483364, 246.494000000]: gazebo_ros_control plugin is waiting for model URDF in parameter [/robot_description] on the ROS param server.

Answer 1

I know it has been some time since this question has been asked, but if someone is still looking for an answer then please find it below:

I was able to load the robot after making changes in the launch file. I had to set the robot_description parameter outside of the <group> tags. I then loaded or spawned the URDF in Gazebo inside the <group> tags, please find the changes below:

<arg name="robot_description"
     default="$(find urdf_test_pkg)/model/robot.xacro"/>
<param name="/robot_description"
   command="$(find xacro)/xacro --inorder $(arg robot_description) namesapce_deploy:=$(arg ns_1)"/>

<group ns="$(arg ns_1)">
    <node name="mybot_spawn" pkg="gazebo_ros" type="spawn_model" output="screen"
    args="-urdf -param /robot_description -model mybot_$(arg ns_1)
                -x $(arg x) -y $(arg y) -z $(arg z)
                -R $(arg roll) -P $(arg pitch) -Y $(arg yaw)" respawn="false" />

    <!-- convert joint states to TF transforms for rviz, etc -->
    <!-- Notice the leading '/' in '/robot_description' -->
    <node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" respawn="false" output="screen">
        <remap from="/joint_states" to="/$(arg ns_1)/joint_states" />
    </node>
</group>

Please note that this answer is based on the solution provided in the following website: https://answers.ros.org/question/268655/gazebo_ros_control-plugin-is-waiting-for-model-urdf-in-parameter/ . For more details about the question and answer then please visit the above link.