Issues when building and running an example

[ArkadiuszNiemiec]

I am trying to run px4_ros_com on Ubuntu 18.04 but have some problems. Can you tell me what's wrong? This is what I did:

1. Installed the PX4 Firmware by using ubuntu_sim_nuttx.sh
2. Added export FASTRTPSGEN_DIR=/home/aniemiec/eProsima_FastRTPS-1.7.1-Linux/bin to ~/.bashrc and restarted the session
3. Built ROS2 Crystal by following Building ROS 2 on Linux
4. Cloned the px4_msgs to ~/ros2_ws/src/
5. Cloned the px4_ros_com to ~/ros2_ws/src/
6. Installed genmsg by executing sudo apt install ros-melodic-genmsg
7. Sourced ros by executing source /opt/ros/melodic/setup.bash
8. Sourced ros2_ws by executing source ~/ros2_ws/install/local_setup.bash
9. Built a ros2_ws by executing colcon build --symlink-install
10. Sourced ros2_ws by executing source ~/ros2_ws/install/local_setup.bash
11. Started a PX4 instance in another terminal by executing cd ~/src/Firmware/; make px4_sitl_rtps gazebo
12. Executed micrortps_client start -t UDP inside a NuttShell
13. Started micrortps_agent -t UDP in first terminal.

To test my setup I opened a third terminal, sourced ros2_ws and listed topics. This genertated an error:

/usr/bin/python3: symbol lookup error: /home/aniemiec/ros2_ws/install/rmw_fastrtps_shared_cpp/lib/librmw_fastrtps_shared_cpp.so: undefined symbol: _ZN8eprosima8fastrtps6Domain17createParticipantERNS0_21ParticipantAttributesEPNS0_19ParticipantListenerE

Sourcing ros2_ws by source ~/ros2_ws/install/setup.bash generates this message:

aniemiec@r2d2l:~/ros2_ws$ source ~/ros2_ws/install/setup.bash 
ROS_DISTRO was set to 'crystal' before. Please make sure that the environment does not mix paths from different distributions.
not found: "/home/aniemiec/ros2_ws/install/ament_index_cpp/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_core/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_export_definitions/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_export_include_directories/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_export_libraries/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_export_interfaces/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_export_link_flags/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_include_directories/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_libraries/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_cmake_export_dependencies/local_setup.bash"
...
not found: "/home/aniemiec/ros2_ws/install/examples_rclpy_executors/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/examples_rclpy_minimal_publisher/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/examples_rclpy_minimal_subscriber/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/test_launch_ros/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/rqt/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/topic_monitor/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/ament_uncrustify/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/demo_nodes_py/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/examples_rclpy_minimal_client/local_setup.bash"
not found: "/home/aniemiec/ros2_ws/install/examples_rclpy_minimal_service/local_setup.bash"
ROS_DISTRO was set to 'melodic' before. Please make sure that the environment does not mix paths from different distributions.

This sourcing allows me to run ros2 topic list but I got this error when I echo any topic:

aniemiec@r2d2l:~/ros2_ws$ ros2 topic echo /SensorCombined_topic
Traceback (most recent call last):
  File "/home/aniemiec/ros2_ws/install/ros2cli/bin/ros2", line 11, in <module>
    load_entry_point('ros2cli', 'console_scripts', 'ros2')()
  File "/home/aniemiec/ros2_ws/build/ros2cli/ros2cli/cli.py", line 69, in main
    rc = extension.main(parser=parser, args=args)
  File "/home/aniemiec/ros2_ws/build/ros2topic/ros2topic/command/topic.py", line 43, in main
    return extension.main(args=args)
  File "/home/aniemiec/ros2_ws/build/ros2topic/ros2topic/verb/echo.py", line 70, in main
    return main(args)
  File "/home/aniemiec/ros2_ws/build/ros2topic/ros2topic/verb/echo.py", line 81, in main
    node.node, args.topic_name, args.message_type, callback)
  File "/home/aniemiec/ros2_ws/build/ros2topic/ros2topic/verb/echo.py", line 124, in subscriber
    msg_module = import_message_type(topic_name, message_type)
  File "/home/aniemiec/ros2_ws/build/ros2topic/ros2topic/api/__init__.py", line 71, in import_message_type
    module = importlib.import_module(package_name + '.' + middle_module)
  File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 941, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 953, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'px4_ros_com'

I have also tested scripts and followed instructions in PX4 docks but ended up with same results.

[TSC21]

@ArkadiuszNiemiec you have a full guide here explaining how to setup the environment. You also have build scripts here that do all the above job for you. Please do follow the guide or use the scripts and come back if you are not successful.

[ArkadiuszNiemiec]

As I said: I have also tested scripts and followed instructions in PX4 docks but ended up with same results. But I will do a clean VM with Ubuntu 18.04 and test it again.

[TSC21]

Try using the build_all.bash script and then use the respective opened terminals to launch the respective daemons and nodes. If you are not planning to use ROS 1, then just use the build_ros2_workspace.bash. Any if these scripts will setup the environments properly on your terminals.

[ArkadiuszNiemiec]

I have prepared a Dockerfile to test px4_ros_com: https://github.com/ArkadiuszNiemiec/px4_ros_com/tree/master/docker Dockerfile includes your px4-dev-ros2-crystal image, clones PX4 Firmware and do a px4_ros_com setup the same way the docs and script does:

# --- px4_ros_com ---
RUN ["/bin/bash", "-c", "\
    cd ${HOME_DIR} && \
    mkdir -p ${HOME_DIR}/px4_ros_com_ros2/src && \
    git clone https://github.com/PX4/px4_ros_com.git ${HOME_DIR}/px4_ros_com_ros2/src/px4_ros_com && \
    git clone https://github.com/PX4/px4_msgs.git ${HOME_DIR}/px4_ros_com_ros2/src/px4_msgs && \
    source /opt/ros/melodic/setup.bash && \
    source /opt/ros/crystal/setup.bash && \
    cd ${HOME_DIR}/px4_ros_com_ros2 && colcon build --symlink-install --event-handlers console_direct+ \
"]

At the end I am launching a screenrc file that has three sessions: first launches a px4_sitl_rtps, second one launches micrortps_agent -t UDP and the third one is launching sensor_combined_listener. I am manually starting the micrortps_client start -t UDP in SITL session.

1. When I change line 36 in Dockerfile (cd ${HOME_DIR}/px4_ros_com_ros2 && colcon build --symlink-install --event-handlers console_direct+ \) to ${HOME_DIR}/px4_ros_com_ros2/src/px4_ros_com/scripts/ build_ros2_workspace.bash I got this message:

   Cloning into '/root/px4_ros_com_ros2/src/px4_ros_com'...
   Cloning into '/root/px4_ros_com_ros2/src/px4_msgs'...
   ROS_DISTRO was set to 'melodic' before. Please make sure that the environment does not mix paths from different distributions.
   Cloning into 'ros1_bridge'...
   [3.793s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/demo_nodes_py' with build type 'ament_python' has no 'setup.py' file
   [3.844s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/examples_rclpy_executors' with build type 'ament_python' has no 'setup.py' file
   [3.846s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/examples_rclpy_minimal_client' with build type 'ament_python' has no 'setup.py' file
   [3.849s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/examples_rclpy_minimal_publisher' with build type 'ament_python' has no 'setup.py' file
   [3.851s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/examples_rclpy_minimal_service' with build type 'ament_python' has no 'setup.py' file
   [3.854s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/examples_rclpy_minimal_subscriber' with build type 'ament_python' has no 'setup.py' file
   [4.123s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/teleop_twist_keyboard' with build type 'ament_python' has no 'setup.py' file
   [4.179s] ERROR:colcon.colcon_core.package_identification:ROS package '/opt/ros/crystal/share/topic_monitor' with build type 'ament_python' has no 'setup.py' file

   so I changed the script to manually building the px4_ros_com_ros2 workspace. I will test if further.

2. micrortps_client status confirms that the client is working on PX4 SITL but there's no message in micrortps_agent and in sensor_combined_listener.

3. Typing ros2 topic hz /SensorCombined_topic in fourth sessions returns:

   WARNING: topic [/SensorCombined_topic] does not appear to be published yet

   OR

   Cannot echo topic '/SensorCombined_topic', as it contains more than one type: [px4_msgs/SensorCombined, px4_ros_com/SensorCombined]

[TSC21]

The problem you report in 3. is known and is going tl be solved soon (it has to do with the major reestructure that happened on the repo).

[ArkadiuszNiemiec]

And the problem no 1 is the problem with using a script in Dockerfile. The '$ROS_WS_DIR' is / and that's not a correct path. We can ignore it.

So the only problem is that sensor_combined_listener is not reporting any data and I cannot print them using ros2 topic echo.

[TSC21]

And the problem no 1 is the problem with using a script in Dockerfile. The '$ROS_WS_DIR' is / and that's not a correct path. We can ignore it.

The only problem there is that you are not using the script correctly. It should be ./build_all.bash --ros1_ws_dir <your/path/to/ros1_ws>.

[TSC21]

So the only problem is that sensor_combined_listener is not reporting any data and I cannot print them using ros2 topic echo.

Solution coming soon.

[ArkadiuszNiemiec]

Ok, thanks. I will debug the software myself so I can contribute in the future.

[TSC21]

@ArkadiuszNiemiec the related issue is https://github.com/PX4/px4_ros_com/issues/14 and it got fixed now. Closing this as solved.

[ArkadiuszNiemiec]

@TSC21 yes, this fixes my problems. Thanks.