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DelftX: ROS1x Hello (Real) World with ROS – Robot Operating System

Known issues

Welcome to the known issues page. On this page, we will try to detail as many known issues we know of that you might run across during or even after this course. Please keep in mind they might be updated at any time - so be sure to check back here if you run into any errors!

Installing new software inside the Course Command Shell (CCS)

This image is read-only! So, if you try to implement solutions after googling your problems with 'sudo apt-get install ...', inside the Course Command Shell, it will not work. All necessary installs for this course have already been considered. So, you will never have to run 'sudo apt-get install ...' yourself, except for when you install Singularity in the Course Setup (Week 0).

General ROS issues

  • The command rosmsg show followed by a Tab completion does not always work if you are in the msg folder. This is a known ROS issue and it has not yet been solved.
  • It is common that beginners in ROS tend to forget to source their workspace setup files. ROS commands will only work if you have sourced your workspace setup files.
  • Getting the prompt back to type on the terminal: This is a common confusion when we start learning ROS after we start a node with rosrun or roslaunch. There is a constant output on the terminal and we cannot type anything anymore. You can get back the terminal by pressing Ctrl+C which will terminate the ROS nodes that you started. If you want to keep the node(s) running and inspect what is happening, start another CCS and type your commands there. You might be advised (via Google search, for example) that you can also use Ctrl+Z combination to get the terminal back. Do not use it without understanding what it really does.

Xacro related issues

  • Upon loading a xacro file, you may see some messages like:

"xacro: in-order processing became default in ROS Melodic. You can drop the option"
"deprecated: xacro tags should be prepended with 'xacro' xml namespace"

In the context of this course, this warnings are harmless and may be ignored.

General course issue

  • Do not create a ROS package inside a ROS package. Execute the catkin_create_pkg command only from $HOME/hrwros_ws/src/hrwros.
  • You can edit your files only from outside the Course Command Shell (CCS). Use gedit or nano as an editor. They are simple and intuitive to use.

Ubuntu system other than English (Solved)

  • If your system language is something other than English, the downloads folder may be called something else by default, although this was an issue causing the CCS icon not to be launched, it has been solved and the shortcut should work now in any language.

If you had this issue before, please re-run the course starter installation script

bash $HOME/Downloads/install-hrwros-starter.sh

To get the updated version of the launchers, and keep the hrwros-21.sif in your system Downloads folder.

Modules not loading

  • When running some graphical programs inside the CCS (i.e. rq_graph, rviz, gazebo, etc) you may see this message:

Gtk-Message: nn:nn:nn.nnn: Failed to load module "canberra-gtk-module"

     You can safely ignore this error, as it does not affect any of the programs.

Warning during compilation of gazebo components (from week 3 onwards)

  • When running the catkin build command to compile packages that include gazebo components, you will see this warning message:
Warnings   << hrwros_gazebo:cmake /home/user/hrwros_ws/logs/hrwros_gazebo/build.cmake.000.log 
CMake Warning (dev) at /usr/share/cmake-3.10/Modules/FindBoost.cmake:911 (if):
  Policy CMP0054 is not set: Only interpret if() arguments as variables or
  keywords when unquoted.  Run "cmake --help-policy CMP0054" for policy
  details.  Use the cmake_policy command to set the policy and suppress this
  warning.

  Quoted variables like "chrono" will no longer be dereferenced when the
  policy is set to NEW.  Since the policy is not set the OLD behavior will be
  used.
Call Stack (most recent call first):
  /usr/share/cmake-3.10/Modules/FindBoost.cmake:1558 (_Boost_MISSING_DEPENDENCIES)
  /usr/share/OGRE/cmake/modules/FindOGRE.cmake:318 (find_package)
  /usr/lib/x86_64-linux-gnu/cmake/gazebo/gazebo-config.cmake:175 (find_package)
  CMakeLists.txt:24 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

You can safely ignore it, as it does not relate to any of the components of this course.

Gazebo

  • Gazebo makes use of some basic models that do not get installed but have to be downloaded upon first use. The first time you start Gazebo it may take some time for this process to complete. Do not be alarmed if Gazebo does not start completely in that case, or if it takes some more time before it shows the simulation world. After this first time, Gazebo should start without issues. If that is not the case, please post on the forum with a clear description of what you see, and if possible a screenshot of your terminal.
  • Gazebo can sometimes be a little difficult: it may not load all simulation models correctly, some models may be missing or be in the wrong location. If this happens while starting up the HRWROS factory, terminate the ROS launch (using ctrl+c), wait for everything to shut down and simply retry.
  • You may see some warning messages when launching gazebo: This is expected and these warnings are nothing be worry about. Gazebo will still function normally.

Gazebo may complain about not being able to load modules "gail", "atk-bridge" or "unity-gtk-module".
Also, you may see  messages like (gzclient:2485): dconf-CRITICAL **: 09:18:24.383: unable to create directory '/run/user/1000/dconf': Permission denied.  dconf will not work properly.

  • You may see an error message when launching gazebo [Err] [REST.cc:205] Error in REST request, That's a known issue of gazebo, it does not affect anything, but if you want to get rid of the message you can follow this instructions.

How do I open multiple course command shells?

- You can open new CCS with by right-clicking the HRWROS icon and selecting New CCS or New CCS (Nvidia).