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Help with launch of 2 robots

asked 2019-09-18 15:38:39 -0500

teddy_roskvist gravatar image

updated 2019-09-19 15:37:11 -0500

jayess gravatar image


I'm new, but getting there...

I'm trying to spawn 2 robots in gazebo using ros

  1. A robot controlled using joystick - package: joy
  2. A "Compass" pointer robot controlled by a I2C compass

All code is available here: Git rep - For easy overview

I use 3 launch files - 1 to start and launch the other 2

Launch command: roslaunch mybot_gazebo start2.launch

I get this error and cannot find the error:

(Complete terminal launch and error output is available in the in the git rep)

[ERROR] [1568837262.438582681]: Could not find parameter robot_description on parameter server
[compass/robot_state_publisher1-8] process has died [pid 14585, exit code 255, cmd /opt/ros/melodic/lib/robot_state_publisher/robot_state_publisher /joint_states:=/compass/joint_states __name:=robot_state_publisher1 __log:=/home/thr/.ros/log/9acdfe50-da37-11e9-a0b0-00044b8c64bc/compass-robot_state_publisher1-8.log].
log file: /home/thr/.ros/log/9acdfe50-da37-11e9-a0b0-00044b8c64bc/compass-robot_state_publisher1-8*.log


  • Nvidia Jetson TX2
  • Ubuntu 18.04
  • Ros Melodic
  • Gazebo v9.0.0

Main launch file:

  <param name="/use_sim_time" value="true" />

    <include file="$(find gazebo_ros)/launch/empty_world.launch">
                <arg name="world_name" value="$(find mybot_gazebo)/worlds/"/>
                <arg name="gui" value="true"/>

  <!-- include our robots -->
  <include file="$(find mybot_gazebo)/launch/mybot_twoPc.launch"/>

Robot/Compass launch file:


<group ns="nanobot">
    <param name="robot_description" command="$(find xacro)/ '$(find mybot_description)/urdf/mybot.xacro'" />
    <node name="mybot_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param robot_description -model mybot" />
    <include file="$(find mybot_control)/launch/mybot_control.launch" />
<group ns="compass">
    <param name="compass_description" command="$(find xacro)/ '$(find mybot_description)/urdf/compass.xacro'" />
    <node name="compass_spawn" pkg="gazebo_ros" type="spawn_model" output="screen" args="-urdf -param compass_description -model compass" />
    <include file="$(find mybot_control)/launch/compass_control.launch" />

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Could you please update your question to include the relevant files and output? It's actually easier to have everything in the question than to have to navigate through the GitHub repo and find the correct files

jayess gravatar image jayess  ( 2019-09-18 19:07:14 -0500 )edit

Thanks with the help of the reformatting of the sourcecode

teddy_roskvist gravatar image teddy_roskvist  ( 2019-09-19 15:43:38 -0500 )edit

2 Answers

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answered 2019-09-19 00:06:39 -0500

ffusco gravatar image

I think the problem is that you did not remap robot_description for the state publisher. In mybot_twoPc.launch you load the URDF inside compass_description, then include the file compass_control.launch (from pkg mybot_control). In there, you load again the URDF in compass_description (it is not necessary, but it does not cause any trouble) and finally start robot_state_publisher1. By default, such node assumes to find the robot description into robot_description. Since you use another name, you should change it to be:

<node name="robot_state_publisher1" pkg="robot_state_publisher" type="robot_state_publisher" respawn="false" output="screen">
  <remap from="robot_description" to="compass_description"/>
  <remap from="/joint_states" to="/compass/joint_states" />

Hope this solves the issue!

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answered 2019-09-19 15:48:36 -0500

teddy_roskvist gravatar image

I have solved the issue. I have done a lot of trail’n error editing, so im not quite sure what solved it, but the remapping seemed to be part of it

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Asked: 2019-09-18 15:38:39 -0500

Seen: 166 times

Last updated: Sep 19 '19